1977 OMC 235 - Top Speed??

[Mkongsiri]

Hi,

I was hoping someone can tell me what I can expect for a top speed for my 1977 Carver 2547 with OMC 235 sterndrive. I assume there's alot of factors involved in calculating top speed. My boat is a 26 foot cabin cruiser weighing about 4600lbs. After a fresh engine rebuild, I'm only seeing about 16 knots at 3600 RPM with a half tank of gas and 4 people onboard. I haven't pushed it more than that while the engine is still breaking in. I dont see getting alot more speed as Ive been told to keep RPM's below 4000 while cruising. I'm new to boating and I have no idea what speed I should be expecting. It just seems slow to me as other similar sized single engined boats are flying past me. Hope someone can provide any insight on this. Would changing the prop to a different pitch make any difference? It looks like I have the original stock prop. Thanks for any input!

 

[southkogs]

What are you propped at? I would think cruising on plane between 20 & 25 MPH. Not sure what top end would be.

 

[Mkongsiri]

Thanks Southkogs, I honestly have no idea what pitch or type prop I have, it just looks like the origional. I look into it, does it make a difference?

 

[southkogs]

Prop diameter and pitch will make a difference, but so will engine output. Is yours a electric shift Stringer?

 

[Mkongsiri]

Yes, it's the electric shift on a 351W engine. This is an image I found on the net of the prop, I assume its the original. What would be the size\pitch prop that would work best for this unit besides the this one?

 

[jerryjerry05]

The prop??? It could be the original??? If it is it could be wore down.
You need to figure out the size? It might be on there, pressed into the metal.
Find out? Then measure the diameter and see if it's worn down.
My father had a 66 Johnson 65hp.He NEVER hit sand or rocks.
The prop actually wore down about 1/4in and the performance was hurting.

To figure out your speed? You need to get all the particulars, weight, load , size etc.
Then send this info to Michigan Propeller and see what they recommend.
They'll tell you the size prop you should have.
The Carver Corp. I think is still in business.
They might have the original specs on your boat???
Send them the hull#.
You should be about 30mph at WOT.
With a 4 bbl. carb it's gonna hurt($$$ running at that speed.

 

[southkogs]

I'm not sure what they were standard with originally: a lot of considerations go into that. I'd look at the stampings as Jerry says and see what it is. I'm going to guess at a 14 x 16, but that's just a guess. You can have a prop shop look at 'em and even rejuvenate them - in my area it's about 1/2 the price of a new prop. They can change the pitch, but that it's no advantage to just buying a new one.

As far as cruising goes, I would think you can run your RPMs up a little higher (more like 4,600) if you want the added speed. For myself, I generally get my boat up on plane, and then work the throttle back until we're starting to "slush up" a bit. Nudge 'em back forward so the plane is still established and then leave it. Wind up in the low 20's most of the time, and reasonably efficient ... for a boat.