Prop help

[jp]

I have a Nitro 929 CDX with a Mercury 225 OptiMax motor containing a Mercury Tempest Plus 25 pitch prop. I bought the boat 2 years ago and was told the prop wasn't right for the boat because it doesn't come out of the hole very well. Once on plane, the boat scoots. Yet with a 1/2 tank of gas and another fisherman, it struggles to get on plane. When I'm by myself, it does just fine. I purchased a hydrofoil and it helped a little. I know very little about props and thought I'd ask the experts. Questions:

- Would a different pitch prop help in this situation?
- If so, any suggestions?

Appreciate any help!

[Embrey]

I have a Nitro 929 CDX with a Mercury 225 OptiMax motor containing a Mercury Tempest Plus 25 pitch prop. I bought the boat 2 years ago and was told the prop wasn't right for the boat because it doesn't come out of the hole very well. Once on plane, the boat scoots. Yet with a 1/2 tank of gas and another fisherman, it struggles to get on plane. When I'm by myself, it does just fine. I purchased a hydrofoil and it helped a little. I know very little about props and thought I'd ask the experts. Questions:

- Would a different pitch prop help in this situation?
- If so, any suggestions?

Appreciate any help!

you might try taking one or all of the vent holes out of the side of the prop if not done already. if thats not it, try a 24 pitch for more hole shot. if its not close with your current prop, your top speed rpm should be a little low

[HURRICANEBOB]

Without info like WOT RPM, load, and exact info on the prop, boat weight, boat engine trim settings, it would be a shot in the dark. Is the prop you have absolutely in perfect shape, or sodes it have a couple dings or bends?

Gut says, the prop is slipping underload at the bottom end.

Here's a link to some resources you may want to read and consider. This may help you to first identify the exact operating parameters of your current prop, and from there make logical adjustments.

http://www.rbbi.com/folders/prop/propcalc.htm

Lots of lnks there. But unless you have a freind with a bunch of props to trial and error with, you risk buying based on others "guess", and spending money that doen't really solve the problem.

[stuck1]

I second the vent plugs. They will be little black plastic pieces on your prop maybe the size of a quarter. You can pick up many different sizes from a local boat store for cheap. They come in 4 different sizes, no hole, small hole, med hole, large hole. If your boat is bogging down out of the hole, then you want to go with a larger opening. This takes some experimenting. If you notice the motor rev up too high (blow out) then you opened it up too much, and need to put a smaller opening plug in.. A 225 opti should have no problem turning a 25 pitch tempest. There could be damage to the prop as well, but I'd start with the cheap solution first. If this doesn't help, I would look into shipping the prop of to Mark Croxten, and maybe have him take a look at it. If i were you, I'd also try looking around on the bass boat central forums and see what others with your same setup are running. There are a lot of variables that come into play as well. If you could post back some more info, people will have an easier time trouble shooting. Ideally, WOT rpm, water pressure, time to plane, top end speed, prop to pad measurement, and more in depth description as to what the motor is doing while trying to plane (revs high, bogging, sputtering, etc.).

[sweetwater]

Hurricanebob is right about the complexity of setting up boats. My Dad was a outboard mechanic/boat dealer and he was very good at setting up bass boats to perform. He used to say setting up boats was like putting together a puzzle without being able to see the pieces.

There are things like vent holes, prop pitch, prop diameter, number of prop fins, boat length, boat weight, hull design, weight placement in the boat (especially drivers, livewells and batteries), engine torque, chine walking as well as comfort and economy to consider when setting up a boat. Every boat reacts differently to changes.

Just a shot in the dark but have you tried lowering or raising the engine a little?