What prop for this boat. (Have ALL info inside)

[Fordiesel69]

Boat is a 1989 Wellcraft eclipse 233. It is a 23' with a 102" beam. Weight on title is 4200LBS.

Engine is a 305 mercruiser with a 2 bbl carb. Drive is a 1.62 ratio. Right now we have a 14x19p prop on it. It seems too doggy out of the hole and 3700-3800 is all it will run WOT and speed shows 43MPH which can;t be right.

I found someone who has the same boat but with a 350 engine and they are running a 17p. Which is right, a 17p or 15p?

 

[usskydvr]

Re: What prop for this boat. (Have ALL info inside)

You need to get those RPM's up. Go with the 15. That should add another 700 or so RPM.

 

[Fordiesel69]

Re: What prop for this boat. (Have ALL info inside)

This same boat with a 350 engine the guy claimed came from factory with a 17p prop. Would going that far down to a 15p be wise? I will gladly try that but I hate to blow the money and have it need a 17p.

Is it true 1 pitch = 200 rpm? so going from a 19p to a 17p will give 400 rpm increase?

 

[usskydvr]

Re: What prop for this boat. (Have ALL info inside)

Every 2" of pitch change is about 300-400 RPM (everything else being equal.. same brand/model of prop) Look for a used prop on Ebay, unless you can find a dealer that will let you demo a prop.

 

[Fordiesel69]

Re: What prop for this boat. (Have ALL info inside)

15P just sounds so small for only a 23' boat. I can see running a 15P on a 25' boat, but maybe before I go prop shopping, maybe looking in to carburation / timing may be better.

A 350 vs a 305 engine normally would not be proped differently. So if the 350came with a 17p, would I still want to chance a 15p?

 

[usskydvr]

Re: What prop for this boat. (Have ALL info inside)

Why do you say 'normally' a 350 and a 305 would be propped the same. You are talking almost 40hp difference. They certainly would/should not be propped the same. ( they COULD be, but it would not be optimum for one of the engines.) Regarding the tune-up. Always a good idea to verify all is good. For a quick max RPM (I know, it won't be under load) check, can you get there on the muffs, or at the lake with no prop.? And finally just for comparison my neighbor has a 2009 20' Monterey with a Volvo 5.0 270hp.
3500lbs dry.
The boat came with a 19. He wanted better power for pulling a skier and typically has 3-4 adults onboard. He went to a 17 and really liked it.

 

[Fordiesel69]

Re: What prop for this boat. (Have ALL info inside)

I got a 15x15p solas amita 3 off here. It runs right up to 4400 rpm trimmed correctly up. With drive in full down, only 4200 rpm. Seems like the take off thrust is double over the 19p, I mean like we supercharged it!!! Except now the down side is at 3400RPM it used to be 34 MPH, now it is only 27MPH. Seems like we lost 7MPH all over the range. WOT is about 40/41 MPH tops.

Would this increase fuel consumption over the 19p, or decrease it if we drive it right?

 

[usskydvr]

Re: What prop for this boat. (Have ALL info inside)

WOT fuel consumption will increase. At cruise your mileage should be close. depends on how loaded you are. The bigger the load the better off you are. Pulling a skier you will get better milage. If you typically have only 1-2 folks and a light load and are going to just cruise all day then a 17 pitch would work. All props are a compromise.

 

[steelespike]

Re: What prop for this boat. (Have ALL info inside)

To me a 15 seems really small. If your propped for a light load there isn't much room
if you need more load help. I think I would check the motor health.
Compression,throttle plates opening all the way.Bottom clean and smooth.
Timing right and advancing as it should.When doing compression note the position and condition of the plugs.
As far as the reduced speed at 3400 its possible 3400 now requires less throttle
Whether it can make up the 7mph difference I don't know.
To me it doesn't seem that they would design a boat that had too be propped
to those specs.

 

[NelsonQ]

Re: What prop for this boat. (Have ALL info inside)

I'd go with the 17P and if you want better hole shot, you could consider a 4 blade prop as well.

 

[Fordiesel69]

Re: What prop for this boat. (Have ALL info inside)

To be clear, this identical boat when equipped with a (5.7L) 350cu in engine runs a 17p from factory. I found 2 owners to confirm this. With a 305 cu in I do not beleive it should still be proped to a 17p being the 305 is less HP.