kevlacat 5.2 and f60 yammies where did i go wrong

[fromeo]

Finally got my new f60's on but I don't seem to be getting the figures I am looking for ...At WOT 5400rpm for 22knts on yami digital speedo with 14k props with 10 hours on the motors .The motors are fitted so the first mounting hole in the modified pod is 325mm from the very bottom of the POD to the center of the first mounting hole. I do have another hole up adjustment if required . trimed right in the motor cav plate leading edge bottom sits 2 3/4inches above the bottom of the hull . Trimed so the cav plate sits plum vertical to the hull it sits 3 3/4 inches above the bottom of the hull to the lower bottom of the Cav plate. I have attached a few pics
Heaps of spray around the motors ( may need splash plates to solve that problem I think) any suggestions or comments would be appreciated see attached pic.

[peterbo3]

The yam site gives a rev range of 5-6000 RPM. The motors need to be able to rev out to 6K. You could be overpropped or too low. Use search.......there have been a few recent threads dealing with this exact issue. What does the dealer think? Have you been on to KC?

[Brumby]

I'd hazard a guess that with the motors set well back from the hull transom you could afford to go up some more. As said before though the other guys with KC5.2's should be able to give you more definite info. Good luck, disappointing to spend all that money and not get the result you hoped for.

[fromeo]

Thanks for the reply peter been through a few of the threads the height of the motors seems to be ok , may be some the the KC boys can confirm that , And from what i have read so far there choice of prop is a 15k seems strange to say the least havn't been in touch with KC factory as yet the dealer seems to think its ok ?

[finding_time]

Ok Your wot should be 5800 and 28 to 30 knots ! this IS what i get! The best ive gotten speed wise was 32 knots and that was down wind ( quite strong) one day I used to only get 5600 rpm with my 15k props but i damaged both props one day and when i had them repaired i had the cups ajusted to give me about 250 more rpm and this really made a differance with hullshot but i dropped maybe 1.5 knots which is fine by me! I think maybe your still to low but as soon as i can fine my motor pics i'll post!

[Captain Seaweed]

I am only guessing could you be over proped with motors sitting too deep and possibly under powered? I am only guessing here. I changed from 20 pitch to 17 as I had the same problem with rev range. I am thinking under powered as your getting spray off the motors meaning they are sitting too deep and not giving the desired output. I am only having a guess here mate and hope you can sort your problem out. I had a mate with a tinnie that the leg was too long and it had same symptoms.
Like Peter said I would also call KC.
Good Luck
Marty

[finding_time]

Spray is not an issue as it's very easily fixed with some deflectors , mine are made from that white cutting board material but Kevla cat get them made in alloy!

[fromeo]

Hi finding time,

some measurement confirmation would be great , at least I have one more hole up that i can adjust hopefully that will be enough.

[Dean1]

I tried the 14K's and they are NOT the prop for the appliciation. Are they the high thrusts?? I got the same figures as yourself, 4800 pulled only 18kts. With the 15K's I now pull 23 kts at 4800rpm. I havent reached any higher than 28kts but ive just discovered that Ive had 250 ltrs of water in my hulls. Yes Ian ive found my problem This has happened when the plastic spinouts in the rear bulkheads were shattered and water filled the rear bulkheads, obviosly filling the next bulkheads as well. They are not perfecly watertight ive found. 2 3/4 inches from bottom of hull to cav plate is the spot on height, DO NOT CHANGE IT! Go to 15K's and you will be much happier. And check your hulls for water, ive installed extra spinouts in my floor to reassure in the future, a bit of drilling etc. is required here and there tho but worth the excersize. 14's are only required if carrying ALOT of weight. Cheers.

[FNQCairns]

Are both engines singing the same? You can test this roughly by raising one engine, observing wot and rpm, then swapping to observe the other engines numbers, are they adjusted toe in or out correctly (I have no idea what it should be on your boat), is the height correct?, looks good in the pic though but higher never hurts as a test.

Is it deano here that gets really good figures out of his cat? I have said it before i do have trouble getting my brain around some of the numbers obtained here on the cats with the 50/60 yamaha's but at the same time I do not disbelieve either, just do not have the experience in cats to say for sure.

cheers fnq

PS You simply cannot go down to 13p it will be a dog, 14 or 15 is where it's at with correct WOT (your dealers comments shows him as inexperienced or lacking in character)

[fromeo]

Hi Dean,

How did water get from the rear chamber where the original spinouts are located to the next sealed chamber how do you check are sealed chamber without drilling holes ? My rear chambers always gets full of water especially now with the extra weight on the 4 st letting a heao more water through the scuppers I just cannot seam to find spin off that actually work and keep water out anyone got any sugestions

[Dean1]

Hi Dean,

How did water get from the rear chamber where the original spinouts are located to the next sealed chamber how do you check are sealed chamber without drilling holes ? My rear chambers always gets full of water especially now with the extra weight on the 4 st letting a heao more water through the scuppers I just cannot seam to find spin off that actually work and keep water out anyone got any sugestions

Well ive been reassured that the bulkheads are not watertight. Well when full of water( the rear bulkheads that is) and whilst motoring, things twist and flex a bit, thats boats. I was out the banks on a glassed out day, 2 of my overweight mates ( no names been said ) stood on the plastic pieces of rubbish spinouts and this broke them through, causing the whole bulkhead to fill. I kept the boat in the water for another 8 hours, it was sagging in the rear bigtime but it was glassed out so I hung around. Take out your rear spinouts, get a battery drill with a 1/8 bit in it and drill forward as low as you can to the bottom of the hull forward to the next bulkhead and see what comes out. I replaced mine with alluminium spinouts but bought stainless ones up the coast here for cheaper. Sikaflex them to the floor. I can talk over the phone probably easier coz theres a few other little tricks ill have to tell you.

[finding_time]

Yes Ian ive found my problem This has happened when the plastic spinouts in the rear bulkheads were shattered and water filled the rear bulkheads, obviosly filling the next bulkheads as well. They are not perfecly watertight ive found. .

I knew something was wrong!!! You have got me thinking about that water i get in my front storage areas now!

How did you find the water and how did you get the water out?

[fromeo]

Hi FNQ ,

the engines seem to run perfectly the cat is very responsive to trim , If I trim out to far its like a blizard around the back the starbord engine tries to drown the Port motor and vice versa man got to get those spray plates made up quick

[Dean1]

Spray plates on my old 70's, they now live on my F 60's. They will fix all spray issues they are amazing!