How fast can I go
 

Hello :)

I have a 21 foot prowler boat by Cooper Yachts that I'm going to repower and I'm curious as to what you guys think about the hull design...

Right now it powered by a 4.3 mercruiser alpha one and I'm building a 383 for it.

Right now it does 45 and my goal is 55+

I don't know how much it weighs and I don't know what the beam is... So I'm hoping you could take a look at the pictures and hazard a guess :)

I'm thinking it should do 60 without running into chine walk but I'm no expert... To get me close I figure I need another 150 hp but maybe not?

Opinions?

Thanxs

Ps I'm aware of the alpha one hp limitations... Going for a re=gear or maybe a sei drive... And if I can't keep the drive from blowing up I guess a bravo.. Just hear a lot of people saying I might be able to make the alpha survive if I'm nice to it lol




[IMG]http://i456.photobucket.com/albums/q...902_183939.jpg[/IMG]


http://i456.photobucket.com/albums/q...902_183951.jpg

http://i456.photobucket.com/albums/q...902_184000.jpg

http://i456.photobucket.com/albums/q...902_183925.jpg

I assume you're down at 225 horse or 190 horse with the 4.3. If it's 225, I'm guessing you'll need 130 or so HP to add 10 mph. A 383 could easily be built to about 400 HP. So, I think you'll make it to 55 and then some. At 400 horse, still with the Alpha if you're kind to it, I could see 60+.

I DON'T know the boat and whether doing that makes sense or will be within the strength margins for the layup, nor whether it the speed will work with the hull shape, etc. Guessing it's fine if things are strong enough.

Screw that SBC. Call pslonaker and get one of his super awesome custom "Shootah Bullet 540s" built in has magic room and really make that bayliner lookalike fly:picard1:

Thanks for the response...

The boat is mint... And I got it for the right price. Trading it in and buying a boat that does what I want is going to cost more than the motor and I'll still be with a boat with an old motor... Most of the boats around here in the 20 thousand dollars range (Vancouver Canada) are stock (meaning 50mph) or rotten... I don't think I can sell the wife on a 30 thousand dollar boat right now lol.

Like I said it's mint... Never seen a winter outside and always in a heated shop for the winter. It's well built... definitely not a bayliner. Cooper Yachts only built these small boats for a handful of years so there's not much information about them... Other than there bigger boats are well regarded.

I really didn't want to buy the boat when I saw it but couldn't pass on a boat in the kind of shape it is in for the price point... It was perfect except it's to slow. Now that I have 4 seasons on it I can justify spending some money...it hasn't cost me a dime lol.

My worry is if the hull can do 55+. Building hp isn't cheep and like it's been said a 383 can be built for way more than the boat could reasonably handle.

It looks to have a small pad and lifting streaks to the transom. They should help to keep the back of the boat from getting to loose on you. I don't see any trim tabs, might want to put some on it to add some stability. I think 55 is obtainable, maybe 60.

Thanks... That's the opinion I was looking for...

I know it's not an offshore boat but thought you guys might have an opinion on the hull...

I'll definitely look into trim tabs...

What length of tabs and where would you place them in relation to the keel?

Read somewhere about smart trim tabs... Any good?

I wouldn't go crazy with expensive trim tabs, you would probably be fine with a Bennett trim tab kit. Your going to want to put them on the outer edges of the transom. You can mount them to match the V angle or have them mounted straight. It's kinda preference, some say if you angle the to match the V that they will cause the back of the boat to walk in one direction or another. There was a post a while back on this subject you can do a search and find it. I don't know anything about automatic trim tabs. Me personally I like to control them my self to be able to compensate for different variables. So no I wouldn't go with the automatic trim tabs.

Does it porpoise now ?

if you have the space, fog, winterize, and store that 4.3 so when it's time to move on, the stroker can stay with you.