Help with prop size questions.

[JT36]

Hi all, I'm new at this but here it goes. I have a 95 Starcraft Starcaster 1700 alum. bass boat with a 1995 40hp mercury. I hit a metal beam under the water and shaved off a little of one of the 3 blades. It has stamped on it 48-73138 A40L 14p. I figure that the 14P is the pitch but nowhere on it is stamped the diameter. Best I can figure it's 10 1/4. My main question is do I have to stay with a 10 1/4 if that's what this one is or can I go up to a 10 3/8. 2nd, what would the L in A40L stand for as when I try to match this prop with am OEM most end with just A40. The WOT on this motor is recommended 5,000 - 5,500 rpm. Actual is approx. 4,800. Again, I'm new to boats and boat motors so I hope you can excuse my inexperiance.

 

[Georgesalmon]

Re: Help with prop size questions.

You can go to 10 3/8 if you have room it might lower rpm a very very tiny bit. But, if your WOT is 4800 and motor rated for 5000-5500 you might want to consider lowering the pitch. I am no expert but from reading and expierence with my own boats I would try a 12P. Might get you to about 5200 which would be good for your motor.

 

[jimmbo]

Re: Help with prop size questions.

An 11in might be a better choice, it should get closer to 5500

 

[steelespike]

Re: Help with prop size questions.

if you look up props for your 95 40hp Merc the diameter will be correct.
Diameter is a secondary consideration. You may notice that as pitch goes up diameter goes down.
Also usually a 4 blade will have a smaller diameter.
If you get us the info needed in "read this first" at the top of the prop forum we can help tell if your setup is working.
Sometimes the rpm is not accurate so may read to high or low.

 

[JT36]

Re: Help with prop size questions.

Hi guys, Thanks for your replies. Sorry it's taken a while to get back. Wife had surgery yesterday. Anyway, I did go out and look at the prop area and it looks like I would have at least 2-3 more inches to work with on diameter before blades would hit anything. What would be a general guess at what I could expect for mph for this boat and motor. It's a 17' alum. hull bass boat. Tag on inside says max. weight 1050lbs persons, motor and equip. Max motor is 90 hp.

 

[JT36]

Re: Help with prop size questions.

I also just went out and looked at the mounting of the motor not knowing if this will help but it is mounted in the 1st of 5 holes putting it as deep as it can go. Should I bring it up out of the water a little or is this average height for this boat?

 

[jimmbo]

Re: Help with prop size questions.

Depends on where the antiventilation plate is in relation to the bottom of the hull. For your rig the AV plate should be between 1/2 inch below the bottom of the boat to even with it.