porpuses at midrangecruise
 

ive got a checkmate 242convincor, with a 7.4 carb motor, everyhting runs good...........but at midrange speed, cruising at 28-32mph the boat porpuses terribly. i have to keep trim ALL the way down AND set my tabs down to 14, which is about 65% down. just to steady it. top end it runs real smooth.
ive run a 23 mirage plus, and had it redone by Darin at Houston with the accel. design. still porpuses.

any suggestions, is it prop,hull,or what

thanks everyone for the help, this is a great forum!!

kevin

Re: porpuses at midrangecruise
 

Kevin, Glad to see you hear. you might want to try a four blade prop and see how you like it,I might have one for you to try ,if so I will call you .also check the hull as we talked about,but I would think it's fine .

Darin

Re: porpuses at midrangecruise
 

WW, well, it does answers my question, good to know that its not just me!! it really does disappoint me that this is so common, is it common with other hulls too? or just checkmate?

Darin, Ive tried a 4 blade merc "offshore" prop, a demo, but only 19 pitch, so it was kind of hard to hit all the same rpms etc to compare. let me know what you have on hand, id love to try anyways

thanks
kevin

Re: porpuses at midrangecruise
 

I used a 4 blade hydromotive on my 253 Checkmate. They need good stern lift for a better ride. I would have to keep 1 tab down about 6% (to compensate for prop torque), and the trim set at 1/4 on the gauge.

Re: porpuses at midrangecruise
 

I had a 23'er with a 454 and the combo of a heavy back end and light bow did the same for me. I tried different props but ultimately putting on K-planes did the trick. I had bennetts on before and there was not enough surface area in the water to push the bow down. Also, a couple hundred pounds of sand under the front bunks works too. Your front end is too light. Years ago Fountain had a small boat with a water ballast tank towards the bow you could fill and pump out for front end weight. 200-300 lbs in the front of the cabin would work wonders I assure you! K-planes are worth the money if you plan on keeping the boat a long time.

Re: porpuses at midrangecruise
 

Ck. to see if the bottom is true.

Could have a rocker in the bottom.

Re: porpuses at midrangecruise
 

I'd still mess around with some four blades.My buddy has a 28' Convincor with 23 mirages on it and it rode awful!!! He picked up a pair of Hydromotive Quad 4's and it is a completly different boat.He lost a little on the top side but we talked to Hydromotive and they said they can take care of that needless to say he is very happy now.

Re: porpuses at midrangecruise
 

I have an 89 251. Using a Hydromotive quad 4 prop and a sea land stern jack. 30MPH on smooth water, no chop trim down no tabs st8 as an arrow. This set up works for me.

Re: porpuses at midrangecruise
 

Kevin I have a Hydromotive 22 pitch Quad four I can send you and try if you want. I think the others here are right .You are more than welcome to try it. just call and ask for Kim and she wil get it shipped. :)

Re: porpuses at midrangecruise
 

Darin,
thanks for the offer, i think ill take you up on it. Ill call today to get it shipped. Thanks for the great help!!

thanks everyone, ill try some extra weight upfront, the pump out idea sounds good, the best of both worlds.

ill keep you posted on any new results!!

kevin

Re: porpuses at midrangecruise
 

I have a 94 253. I use a 23 pitch mirage prop and it porpoises at slower speeds too. But I just crank it up to 45 mph and it loves it. My motor is getting into it's happy spot by then and I hate lugging it at lower rpm's. I know this is a different take on this subject. I just drive faster. I showed my wife the difference and now she loves going faster cause it's a smoother ride. I think my hull just performs better from 45mph and up. I would think mid range cruise on your boat would be about 40mph, not 28-32.

Re: porpuses at midrangecruise
 

i can understand the "speed it up" theory, but ive got the sport model with no windsheild and the slower speeds keep my family happy at this point.

i guess im looking for the best of both worlds......
thanks for the input
kevin

Re: porpuses at midrangecruise
 

Kevin, Prop is going out tonight.

Hydromotive Quad Four 22 pitch Satin Finished.

if you do not want the prop return with 25.00 for shipping.

if it's damaged (Bad) send 135.00 and the prop,plus 25.00 for shipping..

IF YOU WANT TO BUY IT, 375.00 PLUS SHIPPING

IF YOU WANT IT LABBED AND modifacations to it, add 100.00

mirrior polishing add 50.00

Hope you like the prop. Darin

Re: porpuses at midrangecruise
 

agreed.....cant wait to try, thanks Darin.

Re: porpuses at midrangecruise
 

BTW, can I test it until June 2005, then send it back with $25??

just kidding!!!

Re: porpuses at midrangecruise
 

Sorry Darin, guy at work was signed in and I forgot to change it!!!

Boatn70

Re: porpuses at midrangecruise
 

well, i havent checked the bottom yet but i ran a Mirage 23, not a plus, it ran better, less porpoising but i needed much more trim, i actually ran a little faster. runnning the boat at just a little more speed to cruise was also a key idea. boat does run real well at 40mph.

thanks everyone, ill post when i try the prop from Darin next week!!