5.2 kevlacat prop advice

[wahoofishingcrew]

G'day guys,

I have recently bought a 5.2 kc tournament running 60hp mercury bigfoot/high thrust 4strokes. I have read all the prop posts that seem to be a few years old now. Most people seem to be running the yammy 4stroke 60s with the best prop being 13.5 x 15p. Looking at the specs between the yammy and the merc they both seem to have the same gear ratio so just wondering if I should look at getting bigger props for my mercs. I am currently running 14 x 13p alloys, which are likely the stock ones that came with the motor. At WOT its pulling 6200rpm and about 45kph. It seems to need to cruise at about 5000/5200rpm and about 38/40kph. It seems to fall off the plane quite easily too so it feels like you need to keep the revs up. The wot rpm for the motors is 6000rpm. Just wanting some opinions on whether to go to a 14 or 15p? Normally I would go off what Solas recommend however they are suggesting 4 blades which from what I've read isnt a good move on these boats, so I thought I'd get some advice on here first.

The boat is running the original pods and the motors are set 2 3/4in above the hull. At wot with the motors trimmed right out I can see the cav plates however they are probably about an inch under the water. I have 2 holes to come up if needed however most people seem to have found 2 3/4in to be the perfect spot.

Also can anyone confirm the fuel tank size, Ive read a few different things between 100 and 130 litres? Keen to hear any suggestions on the best way to go with the props and how get the most out of the boat.

Cheers
John
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[myusernam]

Aren't they the same motor? Sounds like u should just try those bigger props

[fromeo]

I have 25" XL High thrust Yamaha 60hp 4 strokes , your POD's are made for 20 " motors so I am assuming yours have 20 " legs , in any case I run 13 pitch Solas alloy Amita 3 blade props which give me good performance offshore , good grip and hole shot , and similar RPM's as yours , but I do carry heavy loads . I have run Yamaha 15K props but I find that they labour the motors when I ran with heavy loads , in lite trim they run well and the boat will cruise at 4800 RPM instead on 5000 - 5100 RPM for 22 knots . They typically not fast boats , unless you put a Pair of 90 HP on them to get the most out of the hull design, then they get well into the mid to high 30 knot range , but you will need to change the PODs to take the extra weight of the 4 stroke 90 hp suzuki's .. unless you go 2 stroke yammies.. Hope this helps .

[wahoofishingcrew]

Thanks fromeo, thats a big help. I generally run the tanks full with 2 or 3 people on board, fishing gear and ice. How does this compare to the load you run? Do you typically cruise around the 5000rpm while traveling also?

[fromeo]

Depending on sea conditions 20 to 22 knots would be my cruise speed at 5000-5100 rpm my load would be 4 people and gear full 2 x 215 ltr tanks , 200 ltr ice chest full of ice , you just get use to running them at that RPM the motors I have 500 hours on mine and the mechanic says they are as good as they day I brought them. on the fuel typically you will get 208 ltrs of usable fuel out of the tanks ... mate at the end of the day they are not a race boat with sixties , don't know about the 70's , I had a conversation with a 5.2 owner who re-poded his 5.2 with the newer kevlacat pods and put a pair of suzuki 90's on it and he said it was a weapon , better ride at speed but became a little unstable at over mid 30 knots which he fixed by putting on Permtrims , they are a good sea boat for there size and i go out with confidence, safety being my priority , have been caught in some nasty stuff and always felt safe , won't get you home fast but it will get you home. my motors are set 2 3/4 inch above from the bottom of the hull to the cav plate and my cav plate is above the water when traveling . if yours is below the water line i would try lifting them if you have more adjustment.

[wahoofishingcrew]

Thanks mate, definately not a fast boat with the 60's but like you say they are comfortable and safe, which is the main reason I bought it. I owned one going back with 70yammy 2strokes and the performance of the 60's is quite similar. I used to cruise around the same speed, they were reving less, but around the 20-25 knots seems to be the most comfortable.

I seem to be able to pull 6100-6200 wot still when I'm fully loaded so maybe I should try going to a 14p prop, which might drop the revs back to around 6000 WOT for the weight I carry. It certainly is responsive with the 13's though. Do you think theres much fuel economy to be gained by bringing back the cruise to 4800rpm? Not sure what real world difference that 200/300rpm makes? If it's not much I might be better staying with the 13's for the better hole shot & response in swell.

Thanks for the advice on the motor height, I might try it up one hole to get the cav plates above the water. I'm heading out on Saturday so I'll try and grab a photo of where it's running now.

Did you pull up your floor and fit the 215 litre tanks?

Thanks for your help

[fromeo]

opps sorry typo... 2 x 115 ltrs tanks is what its got with a usable 108 ltrs per side before it runs out totally .., yes i think that going the 14p would be a good idea and lifting the motors will help you may even be able to move to a 15p , just seems strange that at at 2 3/4 the cav plate is still in the water whilst traveling in your case . from memory my fuel consumption went up by 0.2 lts per NM both engines, when I went from the 15K props, to the 13p solas Amita's where I am getting 1.6 ltrs per NM. I m Happy though love the extra low down grunt even with the extra weight I carry. PS in lite Trim I can redline my motors at 6000 RPM .

[wahoofishingcrew]

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Sounds like yours is set up perfectly Fromeo! I was measuring my motor height again this arvo and I am a bit confused. Should it be 2 3/4 inch (70 mm) above the hull when the motor is trimmed right in or when it is trimmed level with the hull? I was measuring it trimmed in. When I trim the motor level I am only 40mm above the hull, which might explain why my cav plates are still under. I have attached a couple of pics with the motors trimmed level. What do you think?

[dan12345]

hey wahoo Bit off off topic but do you the exact width of your boat gunnel rubber to gunnel rubber. I have a kc at home but am not at home to measure it for another 4 weeks and have a friend who wants the measurement for a garage he's building


My last kc was set up 2/34 inch up when motors were trimmed level and i had very similar figures to fromeo

[wahoofishingcrew]

Hey Dan, 2300 from rubber to rubber but the trailer guards are slightly wider and measure 2420mm

Thanks for the height, looks like I might need to go 2 holes

[dan12345]

Hey Dan, 2300 from rubber to rubber but the trailer guards are slightly wider and measure 2420mm


Legend thanks heaps for that. Going from your current measurement i would go up a hole mate and see how she runs then. I moved mine through every hole from lowest to the top till i found the happy medium( which happened to be around 2 3/4)

[wahoofishingcrew]

Thanks Dan, what should I be looking for as I go higher? Is it basically the heighest I can run them without any cavitation? Raising them should free up a few revs but as I'm already getting over 6000 I might need to go up a prop pitch to see any cruise/speed difference?
Thanks for the help guys!

[dan12345]

HI mate I'm no expert, but the way i worked my height was kept raising them to the point where there was to much cavitation and aeration then went one hole lower. This gave me a sensible trim range for the motors and also the best cruise speed for my general loads without over reving or labouring the donks.. When i did my testing i put eskys in my boat and filled them with water and put them in the locations where my weight is normally carried. no point setting it up without all the weight and then thinking it will be better when put normal load in it well thats my opinion anyway. There is plenty of guys on here who have a lot more motor setup experience on here then me especially with this hull. i think fly1 and dean both had one with 60 yammies maybe give them a pm and see what their thoughts are

[wahoofishingcrew]

Thanks mate, good point on testing it with a full load. I'll see if I can get onto fly & dean cheers

[U4REEL]

Hey wahoo, 2 and 3/4 was perfect for mine with f60s also. I tried higher and picked up a couple of knots top end but the little cat hated it, in anything that wasn't flat water.

[Dean1]

Wahoo you will notice a huge difference lifting them the 30 odd mill. Youl pick up about another 500 rpm so youl have to go the a 15p prop or a custom solas. Ian (finding time) got 1/2 inch shaved off 15p props and rated that move. My next move was solas props but never got around to it. From memory Fly tried solas and went back to a 15p factory prop. Lift them 2 holes I say whats the spacing between 2 holes measure?

[Dean1]

Just saw pic with tape measure I missed that one. Maybe try 2 holes and she cavitates too much go back down a hole. Youl be amazed at the difference 😆

[GBC]

I thought Finding Time gave up on trying to make a 18 kc go quick and just kept a big bag of pot on board. Slowest boat in the world.

[wahoofishingcrew]

Thanks guys, I lifted it 2 holes last night so its now 70mm above the hull. Took it out this morning and its made a huge difference. Gets out of the hole even easier than before and it doesnt fall off the plane as I slow down anymore. It was rough as today but it didn't cavitate at all so Ill give the 15p props a go now. With the engines lifted Im getting 35kph at 4900/5000rpm and a WOT of 50km at 6200rpm. Im very keen to give the 15p a go and get the revs down a bit. The boat seemed to ride best about 35/40kmh in the rough water, it got a little smoother when I tried pushing it a bit harder but it was starting to get some serious air off the swells!

Thanks for the advice, I'll let you know how I get on with the new props.

[wahoofishingcrew]

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Here are a couple of pics of how they are sitting now. The splash plate on thr leg is about level with the bottom of the pod. I definitely need to make up some bigger splash guards like I saw in one of your other posts Dean1. Now that they are sitting higher they are throwing wash all over the place at slow speed.

Its amazing the amount of difference that extra 30mm made! Thanks guys

[FisHard]

Its amazing the amount of difference that extra 30mm made! Thanks guys[/QUOTE]
That's what my missus says...

[Dean1]

Thats good it would be alot lighter in the steering now and it will feel alot more flighty. Youl get better fuel economy as well.
I got 23 kts or 43klms at 4800rpm. 28kts at 5500rpm with the 15k props. Nice looking kc mate. I love the black mercs 👍

[wahoofishingcrew]

Thanks for the figures Dean, gives me something to aim for. With the props that Ian has shaved, do you mean the diameter as in he went from 13.5 x 15p to a 13 x 15?

[Dean1]

Thanks for the figures Dean, gives me something to aim for. With the props that Ian has shaved, do you mean the diameter as in he went from 13.5 x 15p to a 13 x 15?Yes mate pretty much. Im not sure on the diameter of a 15k yammy prop but im pretty sure he took a 1/2 inch off each blade. He lost some top end speed but the motors worked alot easier and got out of the hole quicker. Flick him a message. A guy at maroochydore used to do it but hes no longer there. Keep us updated. Cheers

[GBC]

Might take a while to get an answer, he's off Tahr hunting in the NZ southern alps at present.

[wahoofishingcrew]

G'day guys, finally had a chance to give the new props a decent test. Weather has been shocking up here so haven't been able to get out much lately.

I got a set of 13.5 x 15p solas alloy props. The first run I did with them was loaded more than I normally run, 4 blokes and gear on board plus the centre esky full of bait, ice, fish and full of fuel. The poor little KC struggled, it was only pulling 4400rpm WOT and 38kmh. The following day I put the old 13.75 x 13p props back on and the same load again and it ran almost exactly as it would with a normal load, cruise 40km at 5000rpm and WOT pulled 6000rpm. Have to agree with what fromeo said earlier about the 13p props being the go if running alot of weight all the time. They pulled it out of the hole no problem where as the 15ps were really struggling.

Yesterday I put the 15p's on again and ran a normal load, full of fuel, 2 people and gear. The props performed really well cruising at 42kmh at 4400rpm, 50km at 4800. WOT pulled 5700/5800rpm however the speed only increased to 52kmh. How is it that an extra 900ish rpm doesn't achieve any more speed?

Cruising on 50kmh, it feels like the boat is being thrown from the water instead of just the nose coming out at 40kmh. I passed a KC2100 yesteday and the swell was about 1m in quite a sharp chop and noticed the entire boat was coming out of the water with just the legs of the outboards staying in. Is this a typical KC thing, or is it better to back off slightly and keep some boat in the water? :o

As far as the props go, I think I'll keep the 13's in the shed and put them on when I plan to take a bigger load than normal and the rest of the time I'll run the 15's. Anyone have any ideas why I'm not picking up anymore speed with the extra rpm?

Thanks for the help everyone. Dean cheers for the PM too, I will give you a call about the spinouts one weekend soon.

Cheers
John

[wahoofishingcrew]

Also a quick question about fitting the newer 1900 pods to the older hull. Has anyone actually done this? I have read alot of posts where it said it is possible however didn't see any where anyone had actually done it. Do these new pods suit a standard shaft motor or are they for the extra long shaft too?

[Darren Mc]

I have no experience with Cats at all, but if at 50k's per hr it's starting to feel the way you said it is then you wouldn't want too much more speed would you?

[Flex]

I owned a 5.2 kc with f60's for a while. They are by nature a flighty boat, being 17f long and light. I found pushing the boat at 48-50km was its best ride on your average 10-15k day with a bit of chop. Anything less and the nose starts to fall down ever so slightly into the face of next wave. If you push it harder the nose is always going upwards and softens the ride.

The issue was running at above 50km/h with twin 60's puts motors in self destruct range for rpm's.

Dontget get me wrong the ride is still fantastic, but the hull isn't performing at its best.

all depends how far offshore you go to how fast you need to run too.

[Darren Mc]

Sounds like the 60's just run out of puff. Probably need to go up in hp to get more speed out of her hey. Would this be correct?

[wahoofishingcrew]

Anything less and the nose starts to fall down ever so slightly into the face of next wave. If you push it harder the nose is always going upwards and softens the ride.

The issue was running at above 50km/h with twin 60's puts motors in self destruct range for rpm's.

Thanks flex, I know what you mean about the nose dropping that bit around the 40kmh mark, it seems to come down alot harder than at 50. At 50 it seems like there was very little boat in the water, so didn't want to come unstuck having too much lift. Are these hulls designed to come almost completly out the water between waves?

I also agree about having to run them hard, 4800-5000rpm seems about the spot. I am half tempted to go to the bigger pods for a bit better floatation in the rear and that bit more waterline length, however don't know if it is really necessary with the 60's. My current motors have low hours and 40-50kmh cruise is fine for me, so I will get some use from them before looking into the 90s down the track.

[Flex]

if there is any boat designed to jump from wave to wave its a cat:)

All depends how hard you want to push it, each person has their own level of crazy..lol.

Often wave jumping does wash a bit of speed off if you go to high so its nice to keep it gliding across consistently. Especially with low torque motors they can bog down easy and slow you down so your constantly going from 35-42km/h the whole trip. The 5.2 performs very well with 60s and amazing with 90's. So I wouldn't be disappointed with the 60's.

The 5.2 with 60's is a damn nice boat. But I sold mine as I travel up to 150km out at times and it just to slow for me I was always pushing the motors at 5200rpm+. But as I mentioned all depends on where and how you fish.

[fromeo]

Wahoo,

I have talked to a guy who has installed suzuki 90 4strokes with the newer pods , they fit but need to plug existing holes and re-drill for the new , they do fit and are made to accept the 25 " leg , he said that it absolutely transformed the boat into a weapon the shear power provided effortless performance.

[Lovey80]

Wahoo, I have Dean's old KC now and considering that I'll need to have these F60's last until one of the manufacturers releases a 90hp four stroke under 120kg, I felt uneasy with WOT topping out at 5400-5500 RPM.

I took the props in to Craig at Solas and had him shave them. Fantastic bloke that knows his shit. I took the boat out Sunday with full tanks, ice and 3POB. Top speed at WOT on almost glass conditions was 57km/h at 5800 rpm into a light breeze. I'm happy with those figures now.

[wahoofishingcrew]

Lovey80 thats great info thanks mate. How much did you have shaved off? Was it the diameter of the prop you reduced or the cupping?

[Lovey80]

Lovey80 thats great info thanks mate. How much did you have shaved off? Was it the diameter of the prop you reduced or the cupping?

A bit of both actually. The tips of the blades were rounded off a bit and about 5mm of the forward edge of the blades came off.

[wahoofishingcrew]

Thanks mate,that performance with 3pob sounds about as good as it gets with the 60s. Are your props the alloy solas amita 13.5x15p or the stock yammys? I posted mine down to craig today, be interesting to see how it goes on my mercs.

[Lovey80]

Mine are the standard Yammy's.

[Dean1]

Interesting to see you had the props done. I was about to get them done the next week when I owned the boat if you didnt buy it. Sounds like it was worth the excercise! How is the old girl going mate? Have you been getting out in her much?
No worries wahoo give me a buzz mate ill get you sorted with that its worth the effort trust me.
Cheers

[Lovey80]

The KC is going nice. I've replaced the VHF and added an AM/FM last week. Replaced the ally spin outs in the back corners with Stainless ones (bound up and wouldn't come out). Replaced the helm seats with new ones and just had the box seats recovered. Installing a new chart plotter tomorrow and hopefully outriggers the next day. Just did the 400 hour service and they are still going like new. Have an issue with the trim and tilt to sort out also.

[Smithy]

Sounds like you need to shave the 15" ones or get a heap of cup on the 13" ones. A SS 15" will be better than an alloy one. SS is more efficient as it bites more and doesn't flex.

[wahoofishingcrew]

Just a quick update, Shane from Solas called after receiving my props that I sent to be trimmed. He said as they are Solas design and not yammy that was really against trimming them. He thinks trying a 14p is a better option and says it should lift the revs a bit without affecting the speed very much. I have my doubts on this but he is the prop expert. The props are still new so he is sending 14ps to try at no charge so its worth the exercise. If its no good Ill insist on getting the 15s trimmed s bit. I was surprised hiw against it he was, he said its a bit of a last resort and they usually only take 1/8inch off at a time as its very much a trial and see type thing and is easy to mess up then you're stuck with props that are only good for paperweights. Sounds like Craig did a great job first up on your props tho lovey80 so will be interesting to see what happens

[Lovey80]

If yours are the solar props they will be a different shape to the Yammy ones so maybe that's where Craig is suggesting the shaving won't be worth it. He knows what he's talking about so you should be right following his advice.

[Smithy]

If they have 14" that sounds to be the go. Craig has been around the traps for ever. I remember him at Caloundra Marine when Flynny had it and all the BASS guys went there.

[wahoofishingcrew]

Cheers Smithy I'll give them a go, just hope I don't loose too much speed again. I was talking with Shane from Solas, he has been a great help with previous boats I have propped. If the 14s are no good I will try and get hold of Criag and see what he thinks too. Hopefully will get to give them a run this weekend and will let you know how they go

[fromeo]

Hi Wahoo any update on the 14p props ..

[wahoofishingcrew]

Hey fromeo, sorry I meant to get back on here sooner. I got the 14's and 15's out again on the weekend and compared them all with the same load of full fuel, 2 POB, full gear, centre esky with ice/bait etc. The figures are;

13.75 x 13p alloy merc props - WOT 6200/45kph Cruise 5000rpm/35kph
13.5 x 14P alloy solas amita 3- WOT 5800/52kph Cruise 4800rpm/44kph (5000rpm/45kph)
13.5x15p alloy solas amita 3- WOT 5600/53kph Cruise 4800rpm/50kph (4400rpm/45kph)

The big difference between the 14's and 15's seems to be that when I put an extra 2 POB and slightly more get, the 15's really stuggle, my WOT drops to less than 5000rpm/44kph but with the 14's it stays almost the same. I Pm'd lovey80 to see how his trimmed props are going and he said "last night 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"

The extra 5-6kph that the 15's give at cruise makes a huge difference to how the hull performs in the rough weather, they are just really weight sensitive. I'm really not sure if I should play with trimming the Solas props to try and pick the revs up a touch on the 15's hopefully without loosing much speed. What do you guys think?

I wonder how stainless props would change things? Do you think as they should give less slip which in a 15p might help to push the weight a bit better?

Thanks for the help guys, despite all the prop posts I am stoked with the boat and am quite enjoying trying to get the most performance out of it.

[GBC]

22 knots sticks on the dash - sounds about right. Save your money and buy a big joint for when it glasses out.

[Lovey80]

Those 14's sound like the way to go. Remember also my last trip that you quoted was a glass out with me sitting on WOT on full trim driving with my feet. The -60 fuel is what I had used from full tanks so roughly 160l of fuel on board.

[Dean1]

The KC is going nice. I've replaced the VHF and added an AM/FM last week. Replaced the ally spin outs in the back corners with Stainless ones (bound up and wouldn't come out). Replaced the helm seats with new ones and just had the box seats recovered. Installing a new chart plotter tomorrow and hopefully outriggers the next day. Just did the 400 hour service and they are still going like new. Have an issue with the trim and tilt to sort out also. Sounds good. Those back spinouts I replaced with those alloy ones as I couldnt find stainless big enough to cover the hole. I had to regularly grease them and always pulled them out after every trip to let it all breathe and stop them from seizing in place. It had plastic ones there from factory can you believe it! Sounds like your using her anyway thats good. Always something to replace on boats.
Youl get many years out of those donks ;).
Cheers

[wahoofishingcrew]

G'day guys, Spoke to Solas again and they agree the 14s are about as good as it's going to get. They said there would be no real improvement in speed/pushing weight with a SS prop, only that the fuel economy might improve a little.

Cheers for the help!

[fromeo]

Hay Wahoo thanks for the post , now that you have sorted the props enjoy your 5.2 , I have had mine for 15 Years and have never seen the need to change , its a good allrounder and you can mix it up with the big boys in the rough when you need to ... ENJOY ps recommend replacing those back hatches with alloy ones , the plastic ones will eventually fail . and if you can replace the ones on the pods with a set of armstrong hatches , same ones as on the newer pods , google them they are excellent. easy to open and check , seal great no issues

[Lovey80]

After my experience with the Alloy ones binding up so bad that I had to make up a cheater bar to try and get them to spin only to put so much pressure on the deck plate as to have all the sika let go I would recommend stainless steel anywhere that someone has to stand on them.

[fromeo]

Tip for the guys using alloys spin outs , I stop them from binding by using lanolin grease works a treat just spin off every 3 months for a quick hull check, quick thread clean and coat of lano and they wont bind , would probably work on most spin outs I would say..