help big issue probably the prop?

[betayv]

hello there I have a wellcraft eclipse 232 1995 with a mercruiser i/o 228/305 1.5 ratio the prop that Im using now is a 4 blade 14 inch 21 pitch I cant reach my wot rpm I already did a complete tune up on the boat and Im still having the same issue my speed at 3100 RPM is 29.5 mph, I used the formula and is showing a slip of 29, that is too high what prop should I go? thanks....

 

[bekosh]

Re: help big issue probably the prop?

That's a strange setup you have there. I presume that it is not original. Wellcraft doesn't even list a 5.0l/305 as being available for that boat. That is a lot of boat for that motor.

That being said, you are WAY over propped. I turn a 21p on my boat with the 7.4l/454 big block. You'll need to drop to at least a 17p, more likely even less (15p?) to get your RPMs up.

Here is the Wellcraft Datasheet for the 1995 232 Eclipse.

 

[ufm82]

Re: help big issue probably the prop?

I'd look at something else besides just the prop- even though the datasheet shows nothing smaller than the 5.7 the 305 should still be able to turn the 21p faster than 3100 rpm. It seems that even going to a 17 would only boost his RPM by 600-800 rpm. That's still below recommended WOT. And the prop is a 14 and the datasheet says a 15 Mirage which is a lot more blade surface than the 14. Is the engine running properly? Linkage OK? It would seem to me that there is something else in play here besides being overpropped.

UFM82

 

[betayv]

Re: help big issue probably the prop?

hey bekosh yes I bought the boat without the engine and I put the 228/305 that was in my 22 cruiser, I will assume even if the engine is too small for the boat should be able to reach the MAX WOT RPM, the engine running fine like I posted before new cap, rotor, wires, fuel pump, carburetor was rebuild by the shop I have two carburetors and both of them are giving me the same RPM,.

 

[steelespike]

Re: help big issue probably the prop?

First thing I would wonder is if there is a gear ratio chenge between the 300hp and 228?If so its difficult to make up for with a prop.A 21 does seem like a lot of prop
Close to 4,000 dry.

 

[180shabah]

Re: help big issue probably the prop?

You ran out of power.

1.5 and a 21" prop is way too much for a 305 in a boat that size. Need to look at 1.6 ratio and probably still dropping to a 17" or so.

Although, you might get away with prop only - 15" might be enough to get what you need. you will pick up MORE than the standard 200 rpm/inch, cause right now you making no where near full power. You'll be lucky to hit 40mph with this setup.

 

[betayv]

Re: help big issue probably the prop?

hey guys I bought a new prop is a 14 1/2 diameter 17 pitch, the boat seems to respond better my RPM when up to 4200 my speed is 29 mph , but I like how the boat respond with the new prop, another thing I forgot to mention is my bottom paint, the previus owner painted black and is not a smooth paint, will I get more speed if I remove that paint and trow a nice new anti fouling paint on it, thanks guys.

 

[bekosh]

Re: help big issue probably the prop?

I don't think new paint would make a difference. At most it would only get you 1-2mph wot.

180shabah is right. You are running out of power. Going further down in prop size, 15p, or changing the gear ratio to 1.6 might help.

But the bottom line is you are 40-75hp less than that boat was designed for and way short of torque. It's going to struggle out of the hole and be slow at wide open. I doubt there is anything you can do that can get that setup much over 30mph.

If you can do it, I would recommend pulling and selling the 305 and find a used 350 to put in. In the long run I think that you would be much happier.

 

[fossill]

Re: help big issue probably the prop?

Yup, that 305 isn't enough engine for that boat. Doesn't have the torque along with the HP.

 

[betayv]

Re: help big issue probably the prop?

thank you guys yes after the summer that will be done I will start to hunt for a 350 thanks....