5.2m Kevlacat Re-Powering

[couldbe]

Gents,

I am looking at a 1999, 5.2m Kevlacat with Yamaha 70's. I think that they have a little life left on them but was wondering the options of repowering to a HPDI 2 Stroke or a 4 Strokes. I know that the 5.2m KC is rated to 90Hp so I did some research on engine HP and engine weights. The following is what I found.

119 Kg60 HPYamaha High thrust4 Stroke25' Leg120 Kg60 HPmercury big foot4 Stroke25' Leg122 Kg90 HPyamaha 2 stroke2 Stroke125 Kg90 HPyamaha 90's 2 strokes2 Stroke138 Kg90 HPmerc 2 stroke2 Stroke148 Kg90 HPevrinrude E-techsHPDI25' Leg162 Kg60 HPsuzuki4 Stroke165 Kg90 HPhonda 4's 75 and 904 Stroke170 Kg90 HPMercury OptimaxHPDI172 Kg80 HPyamaha 4 Stroke181 Kg90 HPmercury 4 Stroke193 Kg90 HPsuzuki4 Stroke

From what I can see the heaviest 90HP 2 stoke (theoretically the max weight allowed) was the 90HP Merc at 138KG. Based on this logic does this mean that an Evrinrude E-Tec 90 Hp at 148KG would be OK?

Can anyone give me some information as to the best way to repower a 5.2m KC and are the engine pods the limiting factor for weight? Are all the old 5.2m in the same situation or are some suited for more weight than others?

Thanks heaps in advance.

Daniel

[finding_time]

Daniel

Mines been repowered with yamaha high thust 60 4strokes ! Top speed seems to be 30 knots with my cruise at 23-24 knots at 4600rpm i'm using 20-22l per hour at this speed and the boat goes very well. I'm not sure of the fuel capasity of the later models but if i was repowering i would go with a similar motor as any bigger i start loosing range and to me range is very important!! Sometimes i think people get sucked into larger motors ( it the nature of the male race to want bigger and faster) but i dont know if there needed in this case the high thrust 60 4 strokes seem to be a very good match.

Ian

[rat_catcher]

I'm not sure of the fuel capasity of the later models but if i was repowering i would go with a similar motor as any bigger i start loosing range and to me range is very important!!

Ian - What is the fuel capacity of your rig? And is this in two tanks and are they plumbed separately?

[Grunter71]

Ian

Another question for you. Is that 20 - 22 litres/hour at cruise speed for both motors?

[finding_time]

Each side has 110 litres so 220 litres for the boat and there separate systems one tank feeds one motor.

Each side is using between 10 and 11 litres per hour at cruise of between 22-24 knots so 22 per hour for the boat.

Giving me a range of about 200nm or360 km's before the need to carry extra.

These figures are bassed over the last 60 hours of use


Ian


Couldbe


Pm Kittycat( wayne) he knows alot more about the KC than me. He runs 75 honda 4 strokes on his and is getting about 1 km to the litre as oposed to my 1.4-1.6 to the liter i'm getting. This could be due to the larger motors and also the fact that he drives a little harder than me;D I'm a bit soft:-[

Ian

[Kerry]

ian,

Where did the 90hp max figure come from? Is this for the original 5.2 or the new 5.2?

The original 5.2 is basically limited in engine weight by the pods.

Do not see any reason to want to go to 90's, does really serve no purpose on a 5.2?

Regards, Kerry.

[finding_time]

ian,

Where did the 90hp max figure come from? Is this for the original 5.2 or the new 5.2?

The original 5.2 is basically limited in engine weight by the pods.

Do not see any reason to want to go to 90's, does really serve no purpose on a 5.2?

Regards, Kerry.


Kerry


I agree with you regards the 90's to big! It was Daniel that mentioned them he's looking at a 1999model and maybe these have a 90 limit? I think the earlier ones like mine have a 70 or 75 limit, i'm very happy with the 60 4 strokes.

Ian

[Kerry]

The "old" 5.2 (2000) as far as I am aware existed in original form from the late 80 until discontinued sometime in early 2000 and something?

The "new" 5.2 has been reborn as a 1900 only in the past few years.

Towards the end of life of the 5.2 the 5.8 (2100) was made and this one was specifically designed from the ground up for heavier engines (a la 4S's)

So this is why I ask where the 90HP max came from with regard a 1999 5.2 as this would have to be the original 5.2 (2000) hull?

The original spec for the 5.2 was 70HP max but I have seen a 5.2 with 90 mercs but really they didn't do anything more than the 75's they replaced.

Maybe I've lost track of time?

Regards, Kerry.

[Kerry]

Each side has 110 litres so ... Ian

Ian, Have you ever filled these tanks from scratch, from bone dry?

Just curious if they are actually 110 litres (25 gall) or not?

The so called 40 gall tanks which should be 180 litres are only 160 litres, which has made me think the volume is quoted on external tank dimensions and not internal volume?

Regards, Kerry.

[finding_time]

Kerry

was unsure of this my self so tried to run them dry , there was still a fraction in ( using dip stick) but we managed to put in 105l so there probably 110 maybe just a fraction more if you include the filler hose volume

Ian

[mirage]

Daniel, everyone I have heard of has re-engined with the 60hp high thrust 4stk Yamaha and have been very happy with them. See this post from Fly_1 for some more actual figures http://www.ausfish.com.au/vforum/showthread.php?t=67347

[finding_time]

Mirage

Thanks for reposting that link as i have looked for it before!!!

[Lovey80]

Coulbe, I really wish i was in your position.

Cheers Chris

[couldbe]

Thanks for all the info so far. I think that Kerry might be right I may have assumed that the max horsepower for the 5.2m was 90HP when it might be something less. Does anyone know what the max HP and weight is for a 1999, 5.2KC.

I am happy to go with the 60HP Yamaha High Thrusts and got a quote for $8100 for each + installation but just want to explore my options first. The reason I was asking about the extra HP in 90's was that i do a lot of extended crusising around the Barrier Reef and the extra speed would be useful. Can anyone recommend a place to get the motors from in Brissy?

Cheers
Daniel

[couldbe]

Thanks for all the info so far. I think that Kerry might be right I may have assumed that the max horsepower for the 5.2m was 90HP when it might be something less. Does anyone know what the max HP and weight is for a 1999, 5.2KC.

I am happy to go with the 60HP Yamaha High Thrusts and got a quote for $8100 for each + installation but just want to explore my options first. The reason I was asking about the extra HP in 90's was that i do a lot of extended crusising around the Barrier Reef and the extra speed would be useful. Can anyone recommend a place to get the motors from in Brissy?

Cheers
Daniel

[rat_catcher]

Each side has 110 litres so 220 litres for the boat and there separate systems one tank feeds one motor.

Each side is using between 10 and 11 litres per hour at cruise of between 22-24 knots so 22 per hour for the boat.

Giving me a range of about 200nm or360 km's before the need to carry extra.

These figures are bassed over the last 60 hours of use

Thanks Ian. Very interesting figures as they have more range than I thought they would. Also 22-24knots is about perfect for ocean cruising.

[Dean1]

Daniel im thinking the 5.2 ur looking at is the one at harvey bay? Nice boat, I did the figures and it weighs up to be quiet a costly outfit. $8100 each for the f 60"s is a good price, about the best I could get them for. 90's are way over the top for a 5.2, jodie told me that they were max power for them but its not the case., 60 2 strokes or fours are fine. :)

[Smithy]

I know a guy that went from twin 50 4 stroke Mercs to 90 two stroke Yammies on a 5.2 KC on the say so of Fred and Michelle Temminck just before they sold KC. The 50s were way underperforming but very cheap to troll with as you could imagine. The boat was called Sealord and was on the southern end of the Gold Coast. It only lasted a week or so on the secondhand market and was bought local. It should be still around. Darren loved it with the 90s. He was doing Tweed Bar and stuff with it a fair bit back then so the 50s were too scary for him in the performance stakes.

[finding_time]

I wonder how he goes with his insurance as the compliance plate on mine states ..max hp 70

Ian

[lenm5]

Yam F60 High thrusts would be nice but are they worth spending the extra$$ over the standard ones??
I don't have a KC so wouldn't know - but I have a smaller fibreglass cat (4.6m) which runs twin Yamaha 50 4strokes.
With 2 full tanks of fuel (80L each side) it planes on a single motor.

[finding_time]

Lenm

Apparently you do need the extra umph!!! have talked to 2 people who tried 50's and they didn't work real well . My KC wont plan on just 1 motor it comes close but just doesn't quite get there. The KC 5.2 is a fair lump of boat for a 5.2 meter boat just under 1.5tonne full of fuel, what sort of cat have you got?

Ian

[Smithy]

Len,

the hight thrust is to get the 25" leg over a standard 20" one. I think the Merc EFI 60s had the option but the high thrust Yammies were working out cheaper.

Ian,

I dunno but Fred and Michelle said to go for it. I know people like Stessl and that used to give you new builders plates for upgraded motors and stuff pretty easily if you talked them into it. Len's cat is one of those Raider Cats Nobbsy used to make.

[Noelm]

you will be very lucky to get ANY cat to plane on one motor regardless of HP, it just does not work with the motor on the side, so just be prepared for a slow trip home with a single should one fail for whatever reason.

[Smithy]

Here it is with the 90s.

[Deiter]

Here it is with the 90s.


Hmmmmmm......very nice. Got any more pics of that fish Smithy.8-)

[couldbe]

Hey all,
Thanks for your help. I have finally bought my first 5.2m Kevlacat. I will pick it up on the weekend and head straight out into the deep blue see and hope that it will bring me home safely. I checked the mod. plate and the 5.2m is rated to 90HP max but I dont know what weight it is. I not going to repower her straight away but will put a few more hrs on the motors instead.

Thanks again and i will see you ont he water!!!!!

Daniel

[Smithy]

Chuck us a picture of your rig. Where did you find it?

[freddofrog]

Joining a bit late in the thread but the 1994 5.2m KC (Pro Sports) I bought came with 90hp 2st yammies @ 126kg ea. I checked with KC themselves and they said the 90st were fine.

Not sure if they are over kill or not but the max I can do so far is only around 33knots at 5,000rpm, so not too crash hot. She does however cruise very easily on around 20-22knots @ only 3600rpm, like they're barely working :)

cya
ff

[Noelm]

fredofrog, are you saying then that you only get an extra 10Knots for 1400 RPM increase?

[freddofrog]

When you put it like that it sounds quite sad doesn't it. :( I'm sure there are things I can do to get more speed but I just need time to play with it. At the moment though I'm more focused on setting the boat up to my tastes, I'll worry about speed later

[FNQCairns]

Freddo if that is your RPM at WOT (5000) you are killing those engines, they will not last .3 of the hours they should. Your numbers will improve vastly if you reprop and no longer lug the poor things, also your fuel economy will jump also.

cheers fnq

PS dont want to sound dramatic but if it were mine I wouldn't even risk running it until it is fixed.

[Noelm]

yes right on FNq u re- read and then thought he may only get 5,000 WOT surely does need some 'tuning" of props/trim something, I know a guy with a 5.2 with 90 yammies and it goes way faster than his speeds ,by the way, he just repowered also with a couple of 4 strokes and is SORT OF happy he did, to keep the weight down he went smaller in HP but is now kinda regretting the power difference, but I guess it will be OK after he gets used to it, the fuel side of things is great, but then he went from tired old carby 90HP to new 60HP efi so there should be a difference.

[Kerry]

This speed "thing" (as usual) is always overrated. BUT whatever the speed at 5000rpm, now that is a real worry and should be the FIRST thing to get right!

For what is only a relatively short boat (less than 17 feet actually) one should be very happy being able to sit around that 22-26 knot mark at 4200-4600 type rev range and being able to stay there in conditions that would see a lot of even larger vessels pulling back below 20.

Sure they might have the legs on good days but big deal, not important.

If one weighs up the size/range/fuel capacity/deck space/capability etc if you can do an honest 22-24 knots with good econ and maintain that speed in abaove average conditions then what more would you want?

Regards, Kerry.

[freddofrog]

Hi all

Don't want to hijack the thread but you may have to slow down and spell it out for me as I’m still v new to all this boating.

Why is 33knots, 5000rpm, WOT so bad and what would be the cause?

I don’t think anything is wrong with the motors as they have just been serviced and have only done 16hrs anyway so they should be in perfect condition. One of the props however is quite badly pitted but I haven’t thought much of it as it’s only the surface that’s pitted/flaking off, most likely due to sitting in the marina for the last 18months.

Also, the underside of the right pod was covered in barnacles where they obviously missed while water blasting it. That’s since been fixed. The boat also has been anti-fouled which will slow it down a touch but not that much.

What can I do to “fix” it if indeed there is a problem and what rpm at WOT should I be aiming at? With tax time coming up spending $1000(?) on new props is out of the question, at least until next financial year. Given this, would it still be ok to run it at 20 odd knots if the solution is indeed re-proping?



Cheers
ff

[Kerry]

ff, 33 knots at 5000rpm, WOT is not good as the motors must be able to reach the top end of the WOT rev range and that would be a lot more than 5000rpm.

It's not the motors but the props, too big!

For a WOT rev range of 4500-5500 on a boat like this I would want 5600rpm WOT!

[freddofrog]

I wouldn't suprised that they are way too big. The guy I bought it off didn't do things by half but by his own admission, didn't know much about boats (much like me I guess but I don't the same amount of cash!). So what size props should I be using?

[Kerry]

What size/type props are you running?

[FNQCairns]

FF it's not the speed that's in consideration it is the max RPM's you engines can make.
The more rpm's the engines max out at the easier it is doing 'work' at any and all rpms below that, pistons are made of aluminum which expand and contract differentially to the cylinder wall which is steel.

Working (lugging) the engine forces the engine run consistently high combustion temperatures at the piston crown which over expands relative to the cylinder this is a form of seizure, the rings (piston coolers) are trapped usually by carbon (insulator) due to the abuse it has already seen and they snag an exhaust port and snap or bind between piston and cyl wall and scrape the side.

This will happen to your engine/s -no doubt about it this is not a fable, instead of engines that should run until corrosion kills the entire engine it may see 3 rebuilds before corrosion sends it to the wreckers.

I have the exactly same engine as you on a mono hull and my target for heavy -all gear 3 blokes and full fuel is 5750rpm WOT, I can then be assured that at all times the engine is doing 'work' easily.
When the boat is light it will wot higher but it is the fool behind the throttle's choice what is the light weight rpm ceiling.

To get some idea of combustion temperatures and how variable they are/can be, have you ever driven a diesel vehicle and towing with an exhaust gas temperature guage fitted?

cheers fnq

[couldbe]

Well gents the time has come,
I am leaving Macaky now to head down and pick up the 5.2m KC. I should be back home tomorrow night but the weather is looking really really bad for the rest of the week so i dont think i will be getting out anytime soon. Ironic hey, once you get a boat the weather is too bad to use it. :-[

Are there any Ausfish members living in Mackay area that are keen for a fish as I am always looking for people to join me. I will put up some pics when i get her home tomorrow.

Cheers
Daniel;D

[fly_1]

I repowered mine about 12 months ago with the 60 high thrust yamahas and am very happy with it. I have done just over 210 hrs in the last 11 or 12 months and its proved to be very fuel efficient, and they have not missed a beat!! My boat also has the small tanks ( 112l of which 107l is usable), and I get plenty of range out of it. I fish from Mlba alot, and run out for an hour or so, troll at 8 kts for 9 -11 hrs, then run home at 23 kts, and average around 120l for the day!!! A good mate of mine was the original builder/designer of the kevlacats, and he thinks its the perfect match. The big problem is the weight. I have been in one with hondas on it, and it goes ok, but the extra weight is a problem. The pods haven't got the required flotation, and as cat owners will tell you, cats dont handle weight down the back very well. I think you will be very happy with the yamahas if you decide to repower with them.
Regards
Trent

[Heath01]

Gday mate,

I own a 1989 5.2KC, (personally i think the best trailer boat in the land) hehe, i started off with 60hp johnson 2 strokes, they were the originals, i recently re-did the whole boat, motors, trailer, canopy, and i have put 90hp e-tecs on it, i have just done 100hrs on them and i couldnt be happier. the boat handles 100% better, planes so easy and quite good fuel economy, around 2.7km per ltr each motor, motors are extremely quite and so reliable, starts first time EVERY time, i say its like going out fishing in a new car. i get around 70kmh top speed, however i have the long shaft, i suspect if you got extra long shaft you would get even higher speed, but does fine for me! if you have anymore questions to ask feel free,

cheers,
Heath

[boatboy50]

Heath,

Where abouts are you based?

I've seen one with 75hp ETECS, and he is quite happy.

I'm looking at the possability of repowering mine (Honda 50's) some time soon maybe.

I would be interested in your speeds vs revs data.

Regards

Darren

[evo001]

[planes so easy and quite good fuel economy, around 2.7km per ltr each motor,
cheers,
Heath[/quote]

Heath,

Does that mean that both motors combined you go 1.35km per litre?

I ask because I'm looking at changing from 90 Yamahas which give me a 1km/litre economy (both motors combined).

I'm interested in the "real life" figures you are getting and not the dealers figures I've been quoted, which have been that I should achieve 2km/litre(both motors)

Cheers from WA

[Heath01]

Hi Darren, I am based in Adelaide, my rev range on a flat day ofcoarse is 4500rpm to 58-60km/h depending on trim, that is with a full rap around bimini top canopy with front clears, so that drags a fair bit of wind, i actually havent tested with out the clears on, i enjoy the warmth to much, haha. i was looking at putting 4 strokes but i wanted a power increase (from 60's) and i if i put 4's on it i would have to put larger pods on and then it just gets pricy, my e'tecs wiegh 140kg and i certainly wouldnt go any heavier, i have had to put spring loaded scuppers on because with a couple of large guys standing at the back the water does come in a bit otherwise.

[Heath01]

Thats correct WA, i cross the st.vincent gulf here in adelaide a bit, i go from port adelaide to a place called Ardrossan which is 65km one way (130km return) and on a return trip i do around 50 to 55 ltrs per motor and if my maths serves correct i think thats around 2.7km per ltr or 1.35 km/ltr combined. that is with me and another guy my size (100kg) fairly large, hehe and crap you generally take, bait beers food not that its that heavy. i hope that helps

[Heath01]

by the way WA, that is doing around 3500rpm at 40-45km/h, thats the economy range.

[boatboy50]

Heath,

If you have any pics of your boat sitting in the water I would really appreciate if you could post them so I can see how they float.

I need XLong legs, which in the ETEC weigh 148kg from memory.

I don't like the idea of putting that much weight aft.

Regards

Darren

[Orrsum]

my father in law just put new 70hp Tohatsu's xlong on his 5.2 it has a top speed of around 33-35 knots and at 25-30 knots it uses 1.9ltr per nautical mile both motors its got 240ltr in two fuel tanks 120 each.

[boatboy50]

Hey Orrsum,

Nice rig. Is that on the Gold Coast?

Always wonder whether simple cheap two strokes are the go, but wonder about resale value.

Regards

Darren

[Heath01]

Hey Darren, i have tried but cant quite work out how to add the photo, if you send me your email address i will email it to you.

[Chimo]

Hi Heath01

Hope this is some help, as I want to see the pic too!

Go advanced when your adding photos and check out this link to learn about resizing
http://www.ausfish.com.au/vforum/showthread.php?t=54112

Cheers
Chimo

[Orrsum]

Boatboy its in Bundy

[boatboy50]

Hey Guys,

Here is the pic posted for Heath. Thank you Heath.

Also a link to another post which has pics of other Kevlacat power options.

http://www.ausfish.com.au/vforum/showthread.php?t=124821&page=8&highlight=kevlacat+repower

Regards

Darren