Prop for small aluminum boat

[Grant Brown]

I have a Lund Laker 14 foot with a side console and remote controls. I have a CMC PT-35 Tilt and trim unit installed.

1) Performance issue you are trying to correct.
The boat is still very sluggish out of the hole, and seems to rev a little high for my liking.

2) Current prop manufacturer, model, aluminum or stainless as a minimum.
Honda aluminum

3) Current prop diameter and pitch (required).
9" 12P, 3 blade

4) Wide open throttle RPM and speed with an average load (very helpful)
6100 RPM, about 27 mph on speedometer

5) Engine/drive make, model, year, and HP
Honda BF30 20" 1996

6) Boat make model, year, length and weight
Lund Laker, 1996, 14 foot ~320 pounds, 2 guys and day gear is an average load.

Can anyone please advise what I can do to lower WOT RPM and increase holeshot?
These pics were before the CMC installation

 

[Texasmark]

Re: Prop for small aluminum boat

Increase pitch about 150-200 rpm per inch to get your WOT rpms to the upper limit of mfgrs operating range.

If you are over revving out of the hole you have something allowing your prop to ventilate. How about some photos of how your engine is positioned for the hole shot.

Can't up the WOT rpms and improve the hole shot unless you use a vented/ported prop.

That rig ought to perform beautifully.

Need a couple more pictures: Side view of the bottom of the boat and engine in the vertical position.

Rear view of the prop, AV plate, and bottom.

Mark

 

[Grant Brown]

Re: Prop for small aluminum boat

I didn't do a good job describing the problems.
1) Slow out of hole, a bit of a dog I figured it would pop up a bit better with the CMC tucked in nice and close. It is not over-revving during hole shot (not ventilating or spinning hub).
2) WOT is around 6100-6200 rpm at about 27 mph on the speedo. 5700 Seems like the sweet spot for this motor but is only moving at 21 mph. 6100 seems to be really buzzing the valves and it makes a lot of noise. I do not like to run it like that, but I know my kid will when he is old enough...

 

[jestor68]

Re: Prop for small aluminum boat

Slow to plane?

 

[steelespike]

Re: Prop for small aluminum boat

It appears,guessing fuel, passenger weight,gear and motor at 160, battery your total is about 1000lbs.
Your performance indicates 18% slip, a little high.
I think a 12" solas 4 blade prop "should"improve slip, reduce rpm,improve hole shot,stay on plane better at reduced throttle,seem smoother,and respond better around the dock.
Is the antivent plate just above the prop about even with the bottom of the transom?

 

[jestor68]

Re: Prop for small aluminum boat

Currently, the "standard" prop listed for the BF-30 is a 9-7/8 X 12. Solas lists a 9-9/10 X 12.

Either of those would serve to reduce your rpm a bit, while probably performing better than the older prop that is on there.

The Doel Fin is what will get you up on plane in half the time.

 

[Grant Brown]

Re: Prop for small aluminum boat

I think the CMC Tilt Trim is setting the motor too far back and possibly up to high. I have read that there are issues with it on smaller boats. I plan to lower the unit and see how it runs. I have a hydrofoil to use when I get it closer to dialed.

 

[Sea Rider]

Re: Prop for small aluminum boat

What's the max rated HP engine for that boat ?
What's the max wot rpm achieved with just you alone ?
What's the max wot rpm factory stated for thaT 30 HP engine ?
-Probably that engine has not enough power to power nicely that fully rigged boat + you are over revving ?

Happy Boating