1998 Bayliner 1954 Capri Prop/RPM

[Jbwardfamily]

I just bought a 1998 Bayliner 1954 Capri with a 3.0 Mercruiser. It has a 19 pitch aluminum prop and is running close to 5000 RPMs at WOT. Im maxing out at 42mph and know that I won't ever get much more than that. That's fine with me. My question is whether it's a good idea to move up to a 21 pitch to get my RPMs down. 5000 just seems high to me and I don't want to push a 16 year old engine harder than I have to. We like to ski and wakeboard and I worry that the hole shot will suffer too much.

Any advice?

 

[Bondo]

I just bought a 1998 Bayliner 1954 Capri with a 3.0 Mercruiser. It has a 19 pitch aluminum prop and is running close to 5000 RPMs at WOT. Im maxing out at 42mph and know that I won't ever get much more than that. That's fine with me. My question is whether it's a good idea to move up to a 21 pitch to get my RPMs down. 5000 just seems high to me and I don't want to push a 16 year old engine harder than I have to. We like to ski and wakeboard and I worry that the hole shot will suffer too much.

Any advice?

Ayuh,.... It Should be turnin' 'bout 4800 rpms at Wot,.....

 

[steelespike]

Is your speed by gps? Only surely accurate speed.
How close to 5000. 4400 to 4800 is the rating.
42 @ 5000 indicates 6% slip.Unusually low. Low double digits is more typical.
I suspect if you check gps speed it will be closer to 40.
If almost 5000 is really 4900 I think you can see it doesn't warrant a prop change.
just a throttle reduction.The 19 will give stronger hole shot and respond better to added load
or water sports. A 21 will lower rpm,slow hole shot and struggle more with water sports.
Actually may make the motor work harder.

 

[Jbwardfamily]

Thanks. I'll stick to a 19. The prop itself is a little banged up so I may just change it out for another 19. Would a 4 blade offer any improvements over the 3 blade? What diameter works best?

 

[steelespike]

Diameter is a secondary consideration and typically just follows the pitch.As pitch goes up usually diameter goes down and viceaversa.
A 4 blade usually improve grip,may improve hole shot,may seem smoother and may stay on plane easier at reduced throttle.
Also may respond better around the dock.
However it may lose a little top speed.
It is usually suggested to drop an inch pitch when going to a 4 blade to maintain rpm.
If the boat is new to you I think I would run it some as is till you get an idea how it acts in different situations.