Trialing new F70 Yamahas on my 5.2m Kevlacat

[Dean1]

A good mate of mine works for Yamaha and is currently testing/trialing the new lightweight F70A Yamaha.

Ive been offered a pair of these gems to be trialed on my boat to compare fuel usage, speed comparisons etc to the current F60's on my boat.

This will take place in about a month or so.

Anybody thinking along the lines of repowering their 5.2 feel free for all figures/results from me.

I will be doing an approx 300 klm trip at 1770 with these motors to get a good feel of them.

Hope their not too good or ill be knocking on the bank managers door ;D

Regards Dean.

[Spaniard_King]

::) ::) ::) ::) ::) ::) ::)

Dean, once there on they will be stuck there.. :-*

Oy tell you know who that after you have tested them.. 3 month deal (should be) there 2nd hand and you want pricing acordingly;D ;D ;D 8-)

[bdaearth]

Well the only way you can test them out properly is to have the usual decky in the seat for that trip to 1770!!!!

[rcfisher]

Why do i have the feeling you are going to be knocking on the bank managers door in about a month + 24hours?????

[deckie]

Very interested to see how they go. I'm just one of many about to repower and make a choice come springtime.
How they go on your rig may determine many sales for them, so i assume they'll realise that and look after you if u want to keep them ;D

[FNQCairns]

Don't those engines take a little while to loosen up, 60hours or so?? you might find not much difference initially unless yours are already fairly shagged or something else is wrong like poor proping

[Jarrah Jack]

Don't forget Dean possession is nine tenths of the law.;D

[Flex]

Rekon they'll make much of difference?
Does anyone know the actual KW produced by either engine? I cant find the exact details anywhere.

Outboards can be rated with a 10%+/- margin. So technically the 60hp could have more HP than the 70..lol (eg 66hp v 64HP)

Im sure its not the case, but food for thought, be very interesting to know the real world difference. As both motors are same CCs

[finding_time]

Rekon they'll make much of difference?
Does anyone know the actual KW produced by either engine? I cant find the exact details anywhere.

Outboards can be rated with a 10%+/- margin. So technically the 60hp could have more HP than the 70..lol (eg 66hp v 64HP)

Im sure its not the case, but food for thought, be very interesting to know the real world difference. As both motors are same CCs

I also am interested for obvious reasons, and hope to go for a run soon( Dean) i have given it a bit of thought an it may just be they have enough to get the boat into a real sweet spot with gives you a fair bit more top end, but cats dont really seem to have sweet spots like mono's do and tend to react directally to HP. So it will be interesting!

ian

[Dean1]

Ha ha some funny comments there ;D

The motors going on are preproduction so there not for sale.

But im sure i would get looked after if I was to order up.

Im happy with my 60's so im looking at it as a free excercise to see what these 70's are made of and know what im in for if i choose them down the track.

My 60's have done 140hrs so they are freeing up now no their not shagged FNQ Cairns.

6300rpm cant wait ;D

[Dan5]

I went into the local yammy dealer yesterday to check one out......I'm looking at trading in my 07'60hp 4strk yammy on the new 70hp in tiller steer......I got quoted $10,600 for the engine......$1,100 for the tiller and a few hundred for the prop......:o :o ......so around $12,000 for a new one........Well a new 60hp with tiller and prop is still avaliable for $8,600 after the $500 cash back offer.........i don't think the extra 10hp is worth an extra $3,400......

Dan

[finding_time]

I don't think the extra 10hp is worth an extra $3,400......

Dan

That's 3,400 x 2 Dan:o


but i'm sure dan will be getting them cheap

[cormorant]

Get em to tank run them for 10 hours to loosen them up - trial motors and preproduction are often pre run anyway as they don't like to see failures.

That way you can run them hard early and not worry about the first short service.

[GTturbo]

I'am getting one here in Bundaberg for 11,600 , fitted , stainless steel prop , gauges and control box for my side console stacer 4.69.

[insideout]

Good stuff Dean!! This will be interesting thread to keep a eye on, for it will be the new benchmark for alot of KC/zuki repower/ refits in your class.
I know it has been anticipated for a while, and you make a good guineapig.....er....candidate ;D !! Only downside is you will have to work 1000 hrs a week , instead of 800 to pay for them.... Upside is...while your working, there will be more fish for me at 1770:dankk2:

[Dean1]

Good stuff Dean!! This will be interesting thread to keep a eye on, for it will be the new benchmark for alot of KC/zuki repower/ refits in your class.
I know it has been anticipated for a while, and you make a good guineapig.....er....candidate ;D !! Only downside is you will have to work 1000 hrs a week , instead of 800 to pay for them.... Upside is...while your working, there will be more fish for me at 1770:dankk2:Ha ha yeah whatever ;D

The motors are currently on a Vindicator platey so theyve been run in so to speak.

I have the LAN gauges so ill get a very acccurate reading of fuel usage etc.

Cheers..

[Noelm]

I guess in a sort of way, it would be nice if we could somehow measure the difference, lets face it, the motors are new, so we would expect them to start and run like new, right? but if you could estimate the difference in weight and what it does to the boat (like does it float mearurably lower/higher), is the boat so much beter to get onto the plane, or worse (or the same), fuel use and so on should be fairly easy to gauge, and so will speed, so it is the "funny" things that may be of interest (if you get what I mean)

[lippa]

the bloke fitting them up has every concivable gadget and gizmo for measuring all the above noel, elctirc gauges that sit on the floor wired to a laptop to test acceleration, independent fuel flow meters. its basically his job to test boat motor combo's. every base will be covered!
thats if he can work uniterupted, ie deano telling him how good 5.2kc's are evry 3 mins!!!!!! :-)

[cormorant]

the bloke fitting them up has every concivable gadget and gizmo for measuring all the above noel, elctirc gauges that sit on the floor wired to a laptop to test acceleration, independent fuel flow meters. its basically his job to test boat motor combo's. every base will be covered!
thats if he can work uniterupted, ie deano telling him how good 5.2kc's are evry 3 mins!!!!!! :-)



Does he have a dyno ??? That would be interesting!!! No bull, no prop, prop slip or hull excuses then just pure numbers and another set of motors to compare it with. Can work out true drag of boat, legs for all future combinations.

Be interesting to see any results they allow to be published but most important is real life repeatable mid range fuel consumption on nomal fuel, load carrying ability and pick up in that range with also a low speed plane ability for days you get caught out.. Top end speed is nice for magazines headlines or for those with deep petrol pockets but a lot of us don't spend a lot of the motors life there.

I think they are going to suit that hull.

Are they avaliable as a counter rotation pair?

[Spaniard_King]

He wont publish all details that we would like and there not available as counterotating pairs RH rotaion only..

Dont think any manufacturers supply counter rotaters under 100hp any more

[FNQCairns]

I have been thinking about this and i decided.... why bother! Anyway I don't think I would.

[insideout]

He wont publish all details that we would like and there not available as counterotating pairs RH rotaion only..

Dont think any manufacturers supply counter rotaters under 100hp any more

Deano, we will have to put the big bastard ( me)and all the fish on the left side to counter all that torque..

[Dean1]

I have been thinking about this and i decided.... why bother! Anyway I don't think I would. I am passionate about cats and especially these 5.2 kc's and motors are the heartbeat of your boat really so im keen to see what these motors can do for the boat.

Cats are so different to monos as in what power is needed to do what in certain situations.

5.2 kc's are one of the best trailer boats ever made and these lightweight 70 4 strokes im sure will make them even better ;D ;)

[Greg P]

Its a wet dream for you Deano ;D;D;D;D

[Dean1]

Its a wet dream for you Deano ;D;D;D;D Ha yeah something like that :P

U sold ur boat yet mate?
Deano..

[bugman]

Deano and you other boys looking to re-power.

I'm in the market for a mid range four stroke for a boat in Tasmania. If you need to get rid of a 60hp let me know.

Brett

[saltchaser]

I think the guys on hook line and sinker tv show put some new yamaha 70s on a 5.0 metre cat

[Smithy]

Just saw a 5.2 Pro Sport with new 70 Yam 4 bangers at Gav from Victory Parts.

[insideout]

any updates dean ??

[Grouse]

Hook Line & sinker website has some video's of the boats they are going to fit the Yamaha F70A too. Looks like an interesting segment, just wish they would hurry up and show the results.

[Dean1]

Just saw a 5.2 Pro Sport with new 70 Yam 4 bangers at Gav from Victory Parts. Ah i must give Gav a ring then! Funny character he is ;D Cheers for that Smithy.

No nothing happning yet Dan weve both been too busy..

[Grouse]

Pretty impressive demo on the TV show today. Two 70's on a 620 barcrusher getting above 60kph. Then on one leg, out of the water and just over 40kph. :o

[Salad Fingers]

Pretty impressive demo on the TV show today. Two 70's on a 620 barcrusher getting above 60kph. Then on one leg, out of the water and just over 40kph. :o

I don't get it? whats so spesh about that?
a 6.2m alloy boat with 140hp doing 60kmhr is pretty normal.
I'll bet they couldn't get it to hop up onto the plane and achieve 40kmhr only using one engine from a standstill though?

Two Yammy 70's is what? 240kg?
One Suzuki 140 is 185kg or thereabouts.

.....

[Grouse]

I'll bet they couldn't get it to hop up onto the plane and achieve 40kmhr only using one engine from a standstill though?

Two Yammy 70's is what? 240kg?
One Suzuki 140 is 185kg or thereabouts.

.....

Pretty sure that's what they did, that's what is "spesh".

If had an offshore boat, I would like two donks, not one.

[FNQCairns]

They had 3 blokes and a full tank of fuel too, it planed in dead calm water from a standstill on one engine...was a job well done i thought, of coarse it took ages to get there.

The engines where meeting the high end of the rpm range, think they said the boat could see 6300RPM, probably wouldn't have made it onto the plane on one engine if it where only seeing 5900.

[Salad Fingers]

Ok well thats special then, i'll pay that :)

[saltchaser]

Those new 70s got that barcrusher up and runnin.

[kitty_cat]

hey dean might be a good oportunity to get the 2 boats out together it would be interesting to see how they sit in the water side by side and performance ect
will you get to use them without the yamaha guys around not sure how they would react to a suzuki yamaha meeting.
pretty keen to tee this up plenty of guys looking at repower and could be a good pro cons list to be made.
wayne

[Smithy]

So this is the scoop on Gav's one from my mobile outboard mechanic who is pretty tight with Gav. Not a whole lot of difference to the 60s of course cause it is essentially the same motor with different porting/exhausting and all that to ring the extra 10hp out of it. The big thing my guy reckons is the new sumps are only about 1.5litres of oil to keep the weight down and leave more room for the exhaust and with about 1.0l of oil circulating through your moving parts at any given time it doesn't leave a lot spare. Dunno what engine life is going to be like. Little increase in top end speed and it can punch through waves a little bit better without having to play with throttles but certainly not worth the extra $$$s over the high thrust 60s which are significently cheaper.

[Grouse]

Also just noticed a new power report for a twin Yamaha F70A

http://www.yamaha-motor.com.au/sites/default/files/Vindicator%205.50M%20Cuddy%202%20x%20F70AETL.pdf

[FNQCairns]

Just looking at grouse's link above and I came to the conclusion that the twin 70s on that boat don't actually work very well, IMO would probably be a poor choice relative to what other choices are available.

[Grouse]

Just looking at grouse's link above and I came to the conclusion that the twin 70s on that boat don't actually work very well, IMO would probably be a poor choice relative to what other choices are available.

Yea I'm a little confused at those results as well. I'm sure when I watched the Hook Line & Sinker barcrusher demo, they said they had a 15" prop, not a 13 1/2" dia. Maybe he was talking about the pitch? I need guidance when it comes to props. Is there such thing as a 15" dia prop for that size motor?:-?

[FNQCairns]

Here we go this makes fishing boat mash meat out of the twin 70s for the HP available.

http://www.yamaha-motor.com.au/sites/default/files/Vindicator_5.50_Cuddy_F115.pdf

Grouse true, when I heard that I also wondered and decided they must have been talking 15 inch pitch like you say, 15 diameter just doesn't work unless the pitch was 13 or so...also they said it was a stainless....not that that actually makes any real difference on fishing boats.

[black runner]

Just read the Vindicator test in F&B and while the speed figures weren't anything exceptional, the twin setup held plane down to 10-11 knots, with plenty of grunt/prop grip to hold it there in rough conditions without dropping into the hole.

I suppose this would apply with the 60 as well.

Cheers

[Noelm]

Pretty sure that's what they did, that's what is "spesh".

If had an offshore boat, I would like two donks, not one.
so you don't suppose they did a quick off camera prop swap then? even if the twins could achieve 6,300RPM I would guess that the prop would be too big on a single to plane ,but not impossible (maybe) given enough time and if you dont care about the engine at all.

[Dean1]

Ive spoken to Gav who currently has these 70's on his 5.2kc. He has achieved around 31kts WOT with a 15k prop (15 pitch) as compared to 28kts with the 60's.

He states that the cruise speed/revs 4800rpm =23kts are the same as the f 60's but holds revs better through the swells than the 60's so they do obviously have more torque than the 60's.

So basically to get the extra speed revving the 70's to 6300rpm alows the extra 3 kts of speed compared to the 60's.

He has a set of 16 pitch props ordered from the states so will be interesting to see how they perform. These 16's will bring the revs down say for example 4500rpm = 23kts = more top speed.

The interesting part will be to see if the 70's have the grunt to still rev to 6300 with the 16's as i know the 60's wouldnt have a chance of working they would be terrible with 16's.

The 70's are louder than the f 60's alot more induction noise apparantly.

I havent gone any further into testing them on mine as yet i will let Gav do the hard yards 1st i think.

The motors going onto mine are believed to be Long shaft not XL i have to find out for sure otherwise it would be a waste of time..

Cheers, Deano..

[Greg P]

Not much difference anyway Dean on those numbers?? Unless there was a special price it would be hardly worth considering replacing the F60s. Replacing the 2 banger would be a different story but the price for the 70s would want to be sharp compared to 60s as well.

You reckon Yammie will ditch the F60s for the F70s??

[black runner]

You reckon Yammie will ditch the F60s for the F70s??

Wouldn't think so as the 50/60 is essentially the same motor and apart from the top end, the 70 shares many of the 50/60 components. There are many boats out there with a 60hp max power limit and need this class of motor. Maybe direct injection could squeeze a bit more from the 50/60/70 and I think it won't be too long before the first DI 4 stroke is released by Honda, Suzuki or Yamaha

Cheers

[Chris20984]

He has a set of 16 pitch props ordered from the states so will be interesting to see how they perform. These 16's will bring the revs down say for example 4500rpm = 23kts = more top speed.

The interesting part will be to see if the 70's have the grunt to still rev to 6300 with the 16's as i know the 60's wouldnt have a chance of working they would be terrible with 16's.


The motors going onto mine are believed to be Long shaft not XL i have to find out for sure otherwise it would be a waste of time..

Cheers, Deano..

Any word on how the 16's went. Does anyone have any fuel consumption figures to compare the 60 vs the 70. ??

Cheers Chris.

[Dean1]

No mate ive been meaning to give Gav another call about the props. I think fuel consumption would be very similar 60's 70's. I get 1.3klm per litre and the 90's are about the same.

Cheers..

[Danf]

A good mate of mine works for Yamaha and is currently testing/trialing the new lightweight F70A Yamaha.

Ive been offered a pair of these gems to be trialed on my boat to compare fuel usage, speed comparisons etc to the current F60's on my boat.

This will take place in about a month or so.

Anybody thinking along the lines of repowering their 5.2 feel free for all figures/results from me.

I will be doing an approx 300 klm trip at 1770 with these motors to get a good feel of them.

Hope their not too good or ill be knocking on the bank managers door ;D

Regards Dean.

Dean,
I am interested in finding out more and getting some figures on your Kevlacat upgrade to the F70A Yamahas.

[Danf]

Anyone have any reports on how twin 60 HP Mercury big foot motors perform on this vessel.

[Danf]

Has anyone got any feedback on these F70 Yamis fitted to a Kevlacat 5.2.

[Danf]

Just bumping this thread. Has anyone got any feedback on these F70 Yamis fitted to a Kevlacat 5.2.

[No Excuses]

Hi, I've just put a set of 2010 merc 60 big foots on my 5.2. Running the merc vengeance 14P props. As many blokes will attest to they are the smallest HP that you should run on these hulls but the following is what was achieved. 2 POB, fuel tanks full, some gear and mild conditions. 4800rpm saw 22/23 knots, 5000rpm saw 25/26 knots which was its sweet spot. Fuel burn was 0.7 litres a km combined. Its no rocket but its quiet, comfy and cheap to run.


Cheers Aaron

[Danf]

Thanks mate,
I am thinking about a pair of new motors to replace the 70 yamis 2 strokes.

[Smithy]

I'd be looking at either the F70 V the mid range Suzukis or Hondas. 166kg for the Honda in an XL 90hp and 158kg for a Suzuki 90.

[No Excuses]

If price isn't an issue then the 70/80/90hp Suzuki at 155kg would be the pick. With a 1.5 litre displacement they will be a lot torqier donk than the yammy 70 at 1 litre. Only down side is the added weight. Either build larger pods or put up with it.

[Lovey80]

I think the odd would need to be a significantly bigger pod as 155kg on the bum would be far too much for the 5.2kc to float.

[Noelm]

90Hp makes the old 5.2 a much better boat, but....the weight is the killer, I think there was a thread on here that someone had some bigger pods made? My mate had one ages ago with 90 2 stroke Yamahas on it, and it was so much better than another one I have been in lots of times with 70's.

[Lovey80]

I think that was KittyCat?

[Noelm]

I can't remember, but I think they has new ones made like the latest model? Can't say that I remember the end result actually being posted!

[No Excuses]

Yep wayne, AKA Kitty Cat put 90 zukes on his 5.2. He posted some impressive figures on here about them a long time ago. If I had a lazy $26k they would of been my pick and fabricated pods to suit. IMO the 70 yammy is a pimped up 60 and you'd be wringing its neck like a set of 60's. Its a lot of money to outlay only to be disappointed with performance.

[Noelm]

I think the 70 Yamaha is a motor on its own, not just a modified 60, but, I could be wrong.

[Flex]

I had 5.2 with f60s for a while. sold it cause it was to slow and engine longevity is an issue for distance I travel.
While they go ok its a shame to stick 60/70 4s motors on such a good hull.
They really need a set of 90's if your travelling any further than 50-60km offshore.

I found the nose would ever so slightly "drop" into the face of the next wave in certain conditions at its cruise speed of 4900rpm.
I kept finding the boat handled most conditions better doing 5200-5500rpm. which is just to much to be holding motors at that rpm for 2-3 hours.
Problem is sticking 90hp 4 strokes on them adds other issues like larger pods and floatation.

[frosti]

twin 90 suzies on the 1900 is a sweet rig

[Lovey80]

Flex, I have Dean's old boat and since I had the props shaved down I find that no real performance has been lost, in fact it seems to go better. I haven't noticed the nose dipping in certain conditions, though sometimes when the sea wont decide what it's doing it can be tough getting a settled ride. The 47-4900 range is certainly the sweet spot but rarely have I had it out and thought I needed more power to make it ride better. Maybe I need to see if I can get a ride on KittyKat to get some perspective. I really love the boat, it ticks so many boxes for a trailer boat that it will be a sad day to see it go soon.

[Danf]

Thanks for the response guys. I have owned this boat since 1995 previously owning a 565 Haines since 1981. The KC has been sitting idle in the shed for a long time. It is now come to a point that it needs new motors, if I intend to use it again. Re powering with the RIGHT motors is under consideration. The issue is, do I stick with 70 Yamaha 4 strokes at 120 kg, or go with a set of 90,s which all motor brands are heavier due to their larger engine displacement. The weight difference being up to about 40 kg each. These larger motors will need extra buoyancy in the pods, a new set will have to be made. I have spoken to a long acquaintance of mine who has been making alloy cats for a long time and he has reckons to make a set of pods which are an extension of the hull, as opposed to the existing ones which are raised. I suppose we have to work out the extra buoyancy that will be gained with these new pods and how much further back the motors will sit. The boat will still probably not get on the plane with a single 90 hp engine, it doesn't with a 70.

Speed was never a real problem with the 70 2 strokes although at times during those calm periods the boat seemed to take forever to get there. One thing that I can say is that most trips to the reef, the speed going out was the same as coming home. I would pass a lot of similar sized mono hulls back to port on those not so calm days.

[Flex]

Flex, I have Dean's old boat and since I had the props shaved down I find that no real performance has been lost, in fact it seems to go better. I haven't noticed the nose dipping in certain conditions, though sometimes when the sea wont decide what it's doing it can be tough getting a settled ride. The 47-4900 range is certainly the sweet spot but rarely have I had it out and thought I needed more power to make it ride better. Maybe I need to see if I can get a ride on KittyKat to get some perspective. I really love the boat, it ticks so many boxes for a trailer boat that it will be a sad day to see it go soon.


Don't get me wrong, I loved my little KC. Almost perfect alround boat if you consider towing,running cost, ride and ease of use for its size. its a super fun boat to drive and for its size its a little weapon!
The ride with 60's is far from bad, I just found it wasn't optimal.
I kept finding on a 10-15kn day I'd always want to push it over 5000rpm. especially on a 10knot day it rode a bit better going a smidge over 50km/h compared to low 40's.

Out of curiosity what speeds do you get with the shaved props?

Also Dan is your KC rated to 90hp? a lot of the earlier ones are only 70

[Lovey80]

Flex, I was a little groggy with my figures as I havent had it out in a few months as I am over seas at the moment. I went back to an old post.

I came home from the hards 4x80+kg blokes on board, -60l fuel full ice and heaps of gear. Maintained a fluctuating rev range between 55-5700 for an average speed of 53km/h was peaking up to 55 and down to 48 going up a swell.. Cruise it seemed to like the 4800-5000rpm sitting on 45-48km/h.

Most I have seen is 58k on the guage with 2 POB on a fairly glassy day.

[Danf]

Don't get me wrong, I loved my little KC. Almost perfect alround boat if you consider towing,running cost, ride and ease of use for its size. its a super fun boat to drive and for its size its a little weapon!
The ride with 60's is far from bad, I just found it wasn't optimal.
I kept finding on a 10-15kn day I'd always want to push it over 5000rpm. especially on a 10knot day it rode a bit better going a smidge over 50km/h compared to low 40's.

Out of curiosity what speeds do you get with the shaved props?

Also Dan is your KC rated to 90hp? a lot of the earlier ones are only 70

I am pretty sure it is rated at 70. Maybe I should just go with 70 yami 4 strokes. At most there will only be 2 on board. I just don't want it performing speed wise and less than the 70 2 strokes.

[Lovey80]

Danf, your boat should be rated to 90hp but getting 90's on the transom in 4 stroke is a lot of work and isn't exactly a cheap exercise. There is a member on here that used to build the pods for KC. I would just find one that has the later style pods and then measure it up and have it made. I am sure the current KC owners would replate it for you??

If not then I would just go the 70 Yams or even the 60's if the price difference doesn't make it worth while. Its only on the rarest of days that I really wish I had more HP than the 60's on mine. Sure it doesn't get out of the hole too fast but unless you have some serious bar crossings to do the 60's go just fine.

[Danf]

Danf, your boat should be rated to 90hp but getting 90's on the transom in 4 stroke is a lot of work and isn't exactly a cheap exercise. There is a member on here that used to build the pods for KC. I would just find one that has the later style pods and then measure it up and have it made. I am sure the current KC owners would replate it for you??

If not then I would just go the 70 Yams or even the 60's if the price difference doesn't make it worth while. Its only on the rarest of days that I really wish I had more HP than the 60's on mine. Sure it doesn't get out of the hole too fast but unless you have some serious bar crossings to do the 60's go just fine.

Are your motors Xlong 25 inch? Also, I should ask about trailer axles. Mine are the factory Alko rubber torsion style, which I would like to replace. I have to decide whether to go with the same or convert to leaf spring.

[Flex]

Dan how far offshore do you travel on most trips?
getting 60/70's might suit just fine for your needs. also cheaper than 90's.

as to torsion, I had a very bad experience of both front wheels falling off(literally) my dual axle trailer between brissy and mackay. looked fine from outside but inner stub part had completely corroded away.
As each axle is made to order getting it fixed was a nighmare.

If your going to do a conversion to leaf, just remember it can be trickier than anticipated. With my trailer the frame was very skinny (designed for torsion) and sticking leaf under made the hubs along way from the spring. This can cause axles to easily bend.
I think load sharing leaf springs are the cheapest and best option unless your willing to spend 4k on new alko axles every 7 years

[Chris Tucker]

I have to decide whether to go with the same or convert to leaf spring.

Go with leaf springs. emergency replacement parts in every wreckers yard if the shit hits the fan 1000km from home.

[Lovey80]

Are your motors Xlong 25 inch? Also, I should ask about trailer axles. Mine are the factory Alko rubber torsion style, which I would like to replace. I have to decide whether to go with the same or convert to leaf spring.

I rang alco in brisbane last year to ask about doing the same. It worked out at $1350 from hub to hub per axle. Worth it just to be able to bolt off bolt on in my books

Edit: I believe mine are the originals since 1998 and I have no fear of them rusting through at this point but after 18 years I am worried that the rubbers may flog out soon so will replace them.

[Danf]

I rang alco in brisbane last year to ask about doing the same. It worked out at $1350 from hub to hub per axle. Worth it just to be able to bolt off bolt on in my books

Edit: I believe mine are the originals since 1998 and I have no fear of them rusting through at this point but after 18 years I am worried that the rubbers may flog out soon so will replace them.

They get completely submerged during a launch, they fill with salt water and you can not judge how much corrosion is going on inside.
At least with springs, you get a better idea and you can wash them easier.
But, at the end of the day, it is an easier retrofit.

[Lovey80]

They get completely submerged during a launch, they fill with salt water and you can not judge how much corrosion is going on inside.
At least with springs, you get a better idea and you can wash them easier.
But, at the end of the day, it is an easier retrofit.

I had that fear also a couple of years back. When I rang Alko they said that they have never had an axle back in rusted out before the rubber eventually went. Considering these are going on 18 years now and haven't rusted out (though by the look of them you would think they are ready) I wouldn't worry about the corrosion. I am thinking though that when I replace them I may put a hose fitting in the top to be able to quickly flush them out from the inside easier.

[Mupster]

Interesting thread. How much does a typical 5.2KC hull weigh? I ask because I have a 5.2 Devilcat that weighs about 1100 kgs that I have to repower and was thinking that 70hp 4s would be too small for it but reading the tread maybe it's an option.
Originally most 5.2 Devils were powered by Yammie 90hp 2s and I was thinking 90hp 4s Sea Pro Mercs or 115hp 4s Counter rotating Sea Pro's but was concerned with the weight. Any thoughts? 70hp's are cheaper than 90/115hp.

[Flex]

Heres a few pics of mine,
happened 800km from home.. wasn't pretty
Had to use a ratchet strap around both front arms to stop the wheels faling out all together.
When it was removed the front right fell off onto the road at Rocky..lol
113381
113382
113383

[Noelm]

Good looking boat (not so good looking axle) just thinking about selling my centre console cat and looking for a late model Sharkcat like that, either with pods or without

[Danf]

Heres a few pics of mine,
happened 800km from home.. wasn't pretty
Had to use a ratchet strap around both front arms to stop the wheels faling out all together.
When it was removed the front right fell off onto the road at Rocky..lol
113381
113382
113383

That's what worries me about not being able to see inside the axle tube where the rubbers are.

[Danf]

Interesting thread. How much does a typical 5.2KC hull weigh? I ask because I have a 5.2 Devilcat that weighs about 1100 kgs that I have to repower and was thinking that 70hp 4s would be too small for it but reading the tread maybe it's an option.
Originally most 5.2 Devils were powered by Yammie 90hp 2s and I was thinking 90hp 4s Sea Pro Mercs or 115hp 4s Counter rotating Sea Pro's but was concerned with the weight. Any thoughts? 70hp's are cheaper than 90/115hp.

I can not remember the weight of the Kevlacat, but I am pretty sure it is under 1000 kg.

[Flex]

Good looking boat (not so good looking axle) just thinking about selling my centre console cat and looking for a late model Sharkcat like that, either with pods or without

Thanks Noelm,
Had the boat out a few times now. Goes fantastic I must say. I'm lead to believe the non-podded version rides a smidge better? Ive never been in one so cant comment.
But the extra deck space is fantastic and well worth it, if a little wet atm with 115's

[Lovey80]

Flex was that a result of the rubbers flogging out or did it rust through?

[Flex]

Flex was that a result of the rubbers flogging out or did it rust through?

Rubbers were fine.
If you look at the top pic closely you will see the arm that gets pressed into the axle/rubber has a sort of stub axle attached to it. maybe 300mm long or so.
This is what was rusted away totally and caused the wheels to fall off..lol.
Also the inside of the actualy axle itself was fairly rusted.

before I drove away it didn't look to bad from the outside.

[Lovey80]

How old was the trailer when that happened?

[No Excuses]

No doubt the 70 yammy is different to the 60 however I believe there is no replacement for displacement. At 1 litre (60 yammy is the same) the 70 yammy is half a litre behind the zuke. I see the rev limiter is 6300 rpm on the 70 yammy vs 6000 rpm on the 60 yammy. My concern is the extra 10hp is being achieved in the last 300 rpm which no one will ever use but technically it's legit on paper as far as Yamaha is concerned. Anyway that's my 2 cents of uneducated opinion haha.

[The Mad Cat]

From memory the salesman who just sold us an F70 said the F60 produces 60 hp at 5600 and the F70 hp is at 5800. I think I read that somewhere also.

TMC

[Danf]

The other issue that I have to consider is the fact that I can re power with Mercury 60 Hp 4 strokes which are available from the only local outboard place in town. Interesting to get figures on this boat / motor setup.

[Flex]

How old was the trailer when that happened?

I cant be 100% sure as I had just bought it when it happened, maybe 10-12y? so fair age I'll admit.
What I didn't like is being unable to see inside and whats really going on.

[Mupster]

The other issue that I have to consider is the fact that I can re power with Mercury 60 Hp 4 strokes which are available from the only local outboard place in town. Interesting to get figures on this boat / motor setup.
The Mercury Command Thrust 60hp look impressive!

[wahoofishingcrew]

I am running the merc bigfoot high thrusts on mine. There is another thread on here with the figures I got playing with solas alloy props. Over the last couple of weeks I have been trying the merc vengance stainless props. On sat I ran the 15p which with 3 POB full fuel, gear and ice in 15kt chop gave me 4800rpm 45kph / 5000rpm 47kph / wot 6000 57kph. These are by far the best props I have found so far. 45kph give me 1.5ish km/litre combined however when it sits higher on 5k rpm the economy is actually better at 1.8km/l.

They are a good boat with the 60s however if I were repowering (these were on when i bought it) I would be going the 90s. The bigger pods are just under 3k from kevlacat to retrofit onto the 5.2 hull. If you arent really happy with the figures above I think you are better to sell the 5.2 hull and put the money toward a 2400. 90s,pods,bigger fuel tanks you are getting pretty close to 2400 money anyway so my thinking is you may aswell have the bigger boat.

Cheers

[Danf]

I am running the merc bigfoot high thrusts on mine. There is another thread on here with the figures I got playing with solas alloy props. Over the last couple of weeks I have been trying the merc vengance stainless props. On sat I ran the 15p which with 3 POB full fuel, gear and ice in 15kt chop gave me 4800rpm 45kph / 5000rpm 47kph / wot 6000 57kph. These are by far the best props I have found so far. 45kph give me 1.5ish km/litre combined however when it sits higher on 5k rpm the economy is actually better at 1.8km/l.

They are a good boat with the 60s however if I were repowering (these were on when i bought it) I would be going the 90s. The bigger pods are just under 3k from kevlacat to retrofit onto the 5.2 hull. If you arent really happy with the figures above I think you are better to sell the 5.2 hull and put the money toward a 2400. 90s,pods,bigger fuel tanks you are getting pretty close to 2400 money anyway so my thinking is you may aswell have the bigger boat.

Cheers

Thanks for the heads up on these motors.
Just a question on the new gauges fitted to the dash. Have you got a pic of the setup?

[wahoofishingcrew]

113394 this is an old pic I had on my phone...can grab a better one if needed. My gauges are the needle/analog type so were same size as previous yammy ones

[Danf]

Thanks for that. Have you got a pic of the dual motor controls fitted on the side? Interested to see if there is much difference from the Yami ones.

[Lovey80]

I am running the merc bigfoot high thrusts on mine. There is another thread on here with the figures I got playing with solas alloy props. Over the last couple of weeks I have been trying the merc vengance stainless props. On sat I ran the 15p which with 3 POB full fuel, gear and ice in 15kt chop gave me 4800rpm 45kph / 5000rpm 47kph / wot 6000 57kph. These are by far the best props I have found so far. 45kph give me 1.5ish km/litre combined however when it sits higher on 5k rpm the economy is actually better at 1.8km/l.

They are a good boat with the 60s however if I were repowering (these were on when i bought it) I would be going the 90s. The bigger pods are just under 3k from kevlacat to retrofit onto the 5.2 hull. If you arent really happy with the figures above I think you are better to sell the 5.2 hull and put the money toward a 2400. 90s,pods,bigger fuel tanks you are getting pretty close to 2400 money anyway so my thinking is you may aswell have the bigger boat.

Cheers

They are by far the best figures I have heard of on a 5.2KC.

[Lovey80]

I cant be 100% sure as I had just bought it when it happened, maybe 10-12y? so fair age I'll admit.
What I didn't like is being unable to see inside and whats really going on.

Thanks for that. That alone is enough for me to go get a new set this week.

[Flex]

Thanks for that. That alone is enough for me to go get a new set this week.

yeah they were fairly old and 10y is a good run. they looked 5y old from outside.

I will say the back set of axles were fine and towed our boat another few hundred km next town with no dramas. it was taking double the weight and did it fine. maybe front set where dodgy from start?

do you think theres more or less trailer sway with independent or roller rocker?

[wahoofishingcrew]

They are by far the best figures I have heard of on a 5.2KC.

These props are certainly impressive mate. They are a completely different shape to the solas... these are a smaller almost pointed blade. Ill grab a pic and put it up. Im waiting on a 16p in the merc vengance to turn up. In theory it should drop to around 5800 wot but I have a feeling hole shot will suffer. The 15 SS rip in out the hole no worries. Its not costing me anything to trial them so I may aswell keep playing with them.

Dan Ill grab you a pic of the controls, mine are the same duel binnacle mounted through the side as the yammy ones.

[wahoofishingcrew]

113408
Dan this is the same type of control box the yammys had. I think merc may have gone to a different shape on the newest model engines

113409
15vengance next to 14p solas amita 3

113410

[Lovey80]

yeah they were fairly old and 10y is a good run. they looked 5y old from outside.

I will say the back set of axles were fine and towed our boat another few hundred km next town with no dramas. it was taking double the weight and did it fine. maybe front set where dodgy from start?

do you think theres more or less trailer sway with independent or roller rocker?

Hard to say as I've never had each on the same set up but I don't have any sway with the Al-Ko's.

[Danf]

113408
Dan this is the same type of control box the yammys had. I think merc may have gone to a different shape on the newest model engines

113409
15vengance next to 14p solas amita 3



113410

Thanks. At some stage I wouldn't mind getting a pic of you trailer axle setup.
Thanks again mate.

[wahoofishingcrew]

Thanks. At some stage I wouldn't mind getting a pic of you trailer axle setup.
Thanks again mate.

113411
My trailer is alloy. I had the front left tyre/hub snap off on me too on the old alko rubber tube ones. Using the same wheels just with single leaf springs now. Tows better on the highway feels like these springs are slightly stiffer than the old axles. Luckily mine snapped when I was at the ramp going about 5kph...it still smashed the fibreflass mudguard but glad it didnt happen on the highway

[Danf]

Thanks. This might be the way to go for me.

[dan12345]

These props are certainly impressive mate. They are a completely different shape to the solas... these are a smaller almost pointed blade. Ill grab a pic and put it up. Im waiting on a 16p in the merc vengance to turn up. In theory it should drop to around 5800 wot but I have a feeling hole shot will suffer. The 15 SS rip in out the hole no worries. Its not costing me anything to trial them so I may aswell keep playing with them.

Dan Ill grab you a pic of the controls, mine are the same duel binnacle mounted through the side as the yammy ones.



Hey mate what size are the vengeance props exactly ? x 15p those figures sound pretty good i have high thrust yams on mine and wouldn't mind trying a set as well. you don't live on the gold coast by any chance?

[wahoofishingcrew]

Hey mate what size are the vengeance props exactly ? x 15p those figures sound pretty good i have high thrust yams on mine and wouldn't mind trying a set as well. you don't live on the gold coast by any chance?

113414
They're 13 1/4 x 15p mate. The merc props have a removable hub centre so I'm pretty sure you can get a hub to run them on the yammy motors. I think alot of the difference comes from the blade shape. The 16p's should be here next week so Ill post the results once I get a chance to give them a run. The merc dealer is confident the 16ps will be the go but I have my doubts. Either way I won't be going back to the solas alloys

Not on gold sorry im up in CQ

[dan12345]

excellent thanks for that mate. maybe i will hold out for a bit till i see your results for the 16s . i think it may struggle with the 16 tho be alright once up and running but may wash off to much speed when you run up the back of a swell if you know what i mean.

113414
They're 13 1/4 x 15p mate. The merc props have a removable hub centre so I'm pretty sure you can get a hub to run them on the yammy motors. I think alot of the difference comes from the blade shape. The 16p's should be here next week so Ill post the results once I get a chance to give them a run. The merc dealer is confident the 16ps will be the go but I have my doubts. Either way I won't be going back to the solas alloys

Not on gold sorry im up in CQ

[wahoofishingcrew]

Danf I tried to reply to your PM mate but it says your inbox is full

[lembo]

In regards to the previous comments about the Alko brand suspension. I can 100 percent say I will never own it again. I have owned a 5.2 kc with it and also own half the sharkcat with Flex which had Alko IRS . The positives with the Alko IRS is lower centre of gravity which suits cats well because of having no V in the hull that's why a lot of cats have the IRS axle setup. and can be bolted straight to chassis. But that's where the positives end. The negatives are they don't tow near as well as load sharing springs, cant be inspected properly, rubbers get flogged ( especially when going over corrugations) If rubers get flogged out whole hub can slide out of housing as its only pressed in. They cost a bomb and need to be custom made by alko which is about a 6-8 week process.
tandem load sharing leaf springs in my experience tow a lot better, share load over both axles better, sway less, easy to visually inspect and clean, cost far less, can easily replace individual parts, and parts are easily available.
if I towed around Brisbane 10km each time I woldnt worry having Alko but doing regular trips Mackay to Cooktown which I do, Roller rocker tandem springs and axles all the way.
Alko regularly have problems with the IRS stuff , My local dealer warned me away from it as they see to many failures.
You guys may have different opinions but that's mine.

[dan12345]

any updates for the 16 p props mate?

113414
They're 13 1/4 x 15p mate. The merc props have a removable hub centre so I'm pretty sure you can get a hub to run them on the yammy motors. I think alot of the difference comes from the blade shape. The 16p's should be here next week so Ill post the results once I get a chance to give them a run. The merc dealer is confident the 16ps will be the go but I have my doubts. Either way I won't be going back to the solas alloys

Not on gold sorry im up in CQ

[wahoofishingcrew]

Hey Dan, only just tested the 16s on Sat... unfortunately they were too big and I was only able to pull 5500-5600 wot.

I did another trip the week before last with the 15s on though. 3 days worth of gear inc swags tents, 3 blokes, extra 60litres fuel in jerry cans so had quite a bit more weight than I'd usually run with. The 15s were great, in 20kt chop on the trip up I was getting 45kph from 4700rpm, 48kph from 5000/5100. We did 350km all up so the trip home was lighter weight which heading into 10-15kt chop gave 45kph for 4600rpm, 50kph for 5000. These vengance 15ps are awesome and are giving the best results Ive heard of with the 60 bigfoot mercs.

Still getting 6000rpm wot. The cruise speeds are alot better for the revs, really happy with them!

[Lovey80]

I want to get hold of a pair to see if they do as well on yammies

[dan12345]

Im thinking the exact same thing mate have been searching for secondhand ones all week no luck yet may have to bite the bullet and buy new ones

I want to get hold of a pair to see if they do as well on yammies

[wahoofishingcrew]

Make sure you go for that part number in the pic too as they also make a bigger diameter 15p in the same style prop. As far as I know the yammies are the same gear ratio and pretty similar so you'd think results would be much the same

[Lovey80]

Where can we see the torque curves of both engines side by side?

[Danf]

Hey Dan, only just tested the 16s on Sat... unfortunately they were too big and I was only able to pull 5500-5600 wot.

I did another trip the week before last with the 15s on though. 3 days worth of gear inc swags tents, 3 blokes, extra 60litres fuel in jerry cans so had quite a bit more weight than I'd usually run with. The 15s were great, in 20kt chop on the trip up I was getting 45kph from 4700rpm, 48kph from 5000/5100. We did 350km all up so the trip home was lighter weight which heading into 10-15kt chop gave 45kph for 4600rpm, 50kph for 5000. These vengance 15ps are awesome and are giving the best results Ive heard of with the 60 bigfoot mercs.

Still getting 6000rpm wot. The cruise speeds are alot better for the revs, really happy with them!

Impressive, thanks for that. Definitely need to go for a run.

[smclaren]

I need new props as well ... keen to know the price of these Merc's spinners with a Yamaha centre.

cheers

[dan12345]

was quoted about 530 each but didn't ask about the hub kit

I need new props as well ... keen to know the price of these Merc's spinners with a Yamaha centre.

cheers

[wahoofishingcrew]

If that is new & the same part number prop buy them... that's crazy cheap!

[smclaren]

Pretty sure this is the Merc prop in question (please correct me if I am wrong) ... http://www.boatpropellerwarehouse.com/product/28819/vengeance-13-1-4-x-15-mercury-rh-propeller-48-854354a46

Looks like this is the hub you need for Yamaha 60's ...

Yamaha 50-100 HP - use hub kit 835272Q1


Definitly validate all of the above with your friendly Merc dealer.

[dan12345]

update rung another dealer just to shop around as you do and they wanted $775 for the vengeance prop

[fromeo]

You Guys have got me thinking now , very impressive numbers for Mercury 60 , would like to see how they go with the yami high thrust 60's , could be the solution to some of the 5,2 owners including myself , would love to hear how they go with the yami,

[dan12345]

I'm very keen to try them but finding a set to trial is nearly impossible. and bit of a risk just buying them. although both motors have same gearbox ratio and also same displacement cc wise and the bore and stroke are the same from what i can gather so hoping these props will work the same on the yammie

You Guys have got me thinking now , very impressive numbers for Mercury 60 , would like to see how they go with the yami high thrust 60's , could be the solution to some of the 5,2 owners including myself , would love to hear how they go with the yami,

[Lovey80]

I am heading out on the weekend and have fixed a couple of trim issues so will get another good chance at seeing the performance of the shaved Yam props. I am feeling that a slight but more could come off them.

Sunday I was sitting on 5600rpm coming home topping out at 54kph but I wasn't able to get full trim out of the motors. I think I have fixed that issue now so will report back on Sunday.

[Danf]

If and when I re power my Kevlacat, should the fuel tanks be checked. As you know, it means cutting out the floor etc. The boat is a 94 model. Any history to suggest I should inspect these fuel tanks?

[Lovey80]

Can't comment on the fuel tanks Dan,

Just to report back on the latest trip to the northern banks and the hards on Sunday. Still having some minor trim issues where the guages think that I am at max trim and wont allow me to trim the engines all the way until they ventilate whilst underway. If I stop and bring the engines back to neutral revs I can trim them to where I want but taking off like that is a pain. In glassed out conditions with 100l less fuel but about 80kg of fish plus a fair bit of salt water (50L?) in the slurry and 3 POB I was topping out at 55kph @ 5700 RPM WOT.

Debating wether I should have a tiny bit more shaved off the props to achieve 5800-5900RPM WOT or wether the props as they are won't lose too much longevity only achieving 5700RPM?

[fromeo]

Lovey80 .. my personal opinion after having run the 15K props , on my 5.2 I was getting at WOT about 5600 in heavy loading and 5800 in light trim , I recon you need a bit more off to give you another 200 RPM .. I now run 13Pitch alloy Solas which have much better grip and good for the heavy loads I carry ( 4 guys ,full tanks , lots ice etc) . but the downside is that you will cruise at 5000rpm but effortlessly and the motors do not struggle, That;s my experience with the Yami 15 K's on 60HP high Thrust... good results of the Mercury Vengeance props though they would seem to be the go if you could get a hold of a set to trial ...

[Lovey80]

What were the WOT figures on the Solas props?

[fromeo]

WOT fully loaded with 13P alloy amita props 5900 RPM ... would easily hit the rev limiter in light trim ...forget the 15P in solas to much prop , the 14P may be what would suit you...

[Lovey80]

WOT fully loaded with 13P alloy amita props 5900 RPM ... would easily hit the rev limiter in light trim ...forget the 15P in solas to much prop , the 14P may be what would suit you...

what was the top speed at 5900?

[fromeo]

Top speed 28 knots absolute top ,flat water I don't believe you will get much more with the 13p ... but hole shot is great , don;t know if it would do any better with the stainless.

[smclaren]

I couldn't wait any longer to discuss prop choice (had spun a prop .. and they were pretty beat up anyway) so I pulled the trigger on a set of standard props.

I will however get them cupped as Gav McMullin on the Sunny Coast reckons thats a good choice for standard props.

Question is ... who does that in Brisbane and what do I ask for ? I believe there is one one guy in the area that does this type of work ?

Cheers

Steve

[wahoofishingcrew]

If anyone is chasing a set of the 15p merc vengance props shoot me a pm ... $500 each

[Danf]

Thanks for the response guys. I have owned this boat since 1995 previously owning a 565 Haines since 1981. The KC has been sitting idle in the shed for a long time. It is now come to a point that it needs new motors, if I intend to use it again. Re powering with the RIGHT motors is under consideration. The issue is, do I stick with 70 Yamaha 4 strokes at 120 kg, or go with a set of 90,s which all motor brands are heavier due to their larger engine displacement. The weight difference being up to about 40 kg each. These larger motors will need extra buoyancy in the pods, a new set will have to be made. I have spoken to a long acquaintance of mine who has been making alloy cats for a long time and he has reckons to make a set of pods which are an extension of the hull, as opposed to the existing ones which are raised. I suppose we have to work out the extra buoyancy that will be gained with these new pods and how much further back the motors will sit. The boat will still probably not get on the plane with a single 90 hp engine, it doesn't with a 70.

Speed was never a real problem with the 70 2 strokes although at times during those calm periods the boat seemed to take forever to get there. One thing that I can say is that most trips to the reef, the speed going out was the same as coming home. I would pass a lot of similar sized mono hulls back to port on those not so calm days.

Just a follow up on this post, I did not realise it was that long ago. I finally got new pair of F70 Yamahas fitted at the end of last year. I have done 21 hours on them and at this stage I can not complain. They are fitted with 15 inch yamaha aluminium props and the height is set the same as the previous 2 strokes.
The old 2 stokes were fitted with aluminium 17 inch props.
I have no intention of changing props as I am happy with the performance.
With 2 people on board and half fuel it revs to 6300 rpm at 63 km/hr.

116679116678

I am happy with the fuel economy with each motor doing around 3.1 - 3.2 km/lt @ cruise.

[Cus Cus]

Just a follow up on this post, I did not realise it was that long ago. I finally got new pair of F70 Yamahas fitted at the end of last year. I have done 21 hours on them and at this stage I can not complain. They are fitted with 15 inch yamaha aluminium props and the height is set the same as the previous 2 strokes.
The old 2 stokes were fitted with aluminium 17 inch props.
I have no intention of changing props as I am happy with the performance.
With 2 people on board and half fuel it revs to 6300 rpm at 63 km/hr.

116679116678

I am happy with the fuel economy with each motor doing around 3.1 - 3.2 km/lt @ cruise.

Those are very good numbers! Do you have a T-top or bimini top?

What speed do you get at around 4,800RPM?

I trialed mine with a 15 pitch prop and had some problems. Mainly related to the fact that mine were 20" leg engines. The 25" leg is not available in my country. I was going to space them but decided to sell and purchase new engines with 25" legs and make new pods.

Tito