Just got a Chaparral 198 CXL with a 4.3, now need the right propeller.

[FGraham]

Hi, everyone! I've been browsing the site as a guest for a while now, and I finally signed up because I need some advice. I recently purchased a 1986 Chaparral 198 CXL (cuddy) with a "3 year old" Non Vortec GM crate motor and a 2 barrel Rochester carb. Engine runs great, but boat seemed sluggish. It has a Merc Alpha One outdrive with the 1.81 gears. Today I took off the prop (because I sharpened it on a rock over the weekend haha) and discovered it has a 15 inch, 23 pitch cupped Michigan propeller on it. I know that's not the right one, but I'm curious as to what is. WOT on the boat only gets to about 4300 RPM, and the boat hurts to reach 40 MPH. It will not plane off with 2 passengers, unless one goes up in the cuddy. From what I can tell, the boat weighs 2900 LBS. Math I've done says thats a slip percentage of over %25....

I mostly plan to cruise in the 25-35 range, and would like to get the RPMS down around that area (30 MPH is about 3600 RPM). I don't have much need to go faster than low 40's.

I think I'm going to go with a 4 blade prop since I'm not overly interested in top speed, I just dont know what to go with. There are not many marinas in my area, as I live in Mass and fun is illegal here, so trying one out before I buy Isn't really an option.

I'm also considering putting the edelbrock 4 barrel intake and 500 CFM carb on it, and was curious if anyone had any insight into that. I know its the wrong forum for that, and I apologize in advance. Thanks for any input!

 

[SkiDad]

you want a lower pitch - 21 3 blade or maybe 20 4 blade - a new prop will run so much better with no blade damage.

 

[Watermann]

The 19' Chris Craft cuddy I had as a donor boat came equipped with a 13.75" x 21 which I understand is a standard size so going to a 14 x 20 4 blade should do the trick. The only difference is mine's the 205 HP LX with the 4 BBL your looking to convert yours to. I don't know of any reasons you couldn't do the manifold and carb upgrade. Also if you have one of those whale tail things on there you should remove it when you get the new prop.

 

[Ol' Man]

I had the same boat years back and I ran a 21 3 blade prop performed all round. But after thinking back, mine had an OMC Stringer 800 outdrive, shouldn't matter. Same boat, same power.

 

[steelespike]

Some of that slip is the prop being so far out of ideal pitch. If a 21" gets you 4800 at 13% would net about 45 mph.
Don't know but maybe thats it for 2 barrel 19ft cuddy.

 

[jestor68]

It sounds like everyone has you going in the right direction concerning pitch.

A Doel Fin hydrofoil will get the tail heavy cuddy up on plane much easier than without.

 

[FGraham]

Alright thanks guys. I think I'm going to go with a cheap aluminum 20 pitch 4 blade for now. If It's not the correct one, I'm sure I can find the same rock I removed my last prop with, and then have an excuse to buy another one!

 

[steelespike]

It's probably better to sell the old prop if its not quite right or its sometimes good to have a spare.

 

[Chris1956]

I had the 4.3LX powerplant in an 19 (18 foot plus swimplatform) SeaRay. I ran a 21P Rapture.

You will likely need a 19 or 21P prop. I would recommend a Turing Point Hustler in 3 or 4 blade. There is no way to know exactly what pitch you need, but I would lean toward the 19P.

I doubt you will see 45MPH, but 40MPH is probable.

 

[500dollar744ti]

Are you trimming out at WOT? On my boat, I can get 5 more mph trimming out.

 

[FGraham]

Yeah, Installed the new 19 Pitch 14.3 Diameter 4 blade prop I bought off Cabelas, I forget the brand. Boat is MUCH happier now. Trimmed out, top speed is 41 now at 4600 RPM, but it planes off at 15 MPH with 4 people and a full tank of fuel. The slip calculator I use says my slip is only %11 at WOT. Seems to be using much less fuel as well. Maybe over the winter I will do the 4 barrel conversion and put a 21 prop on, but for now I'm happy. Thanks for the input everyone!