Resource for Prop

[frustratedboater]

I have rebuilt a 2000 Mercury, 40hp 4-Stroke Bigfoot and have need for a 15-pitch prop for it. It is mounted on an Alumacraft duck boat and have used an 11p (screamed and went nowhere) and had an old 21p that fit and can't get the rpm's up. I went into my local Eastern Marine store and Their Michigan book (I think it was) did not list my prop. Can someone direct me to a couple options out there?

 

[jimmbo]

I hear these guys sell props on line
http://boatpropellers.iboats.com/Me...ers/?chart=52&engine_id=267&cart_id=881092755

 

[Faztbullet]

Would a 14P work??? Try craigslist for used(like below) or here on site.
http://boatpropellers.iboats.com/Me...-135-15_Propeller/294/7293/?cart_id=463931073

 

[achris]

Here's the Merc range of 15" pitch props for that engine.

 

[frustratedboater]

Wow, woke up to some great tips and advice, THANKS! I am not super knowledgable about props and sizing-bought a stainless prop and was the wrong size. The hub was a bit too big and didn't match up right, so I wanted to be sure this time. I so appreciate the assistance..

 

[achris]

It used to be that if you went from aluminium to SS, you dropped a couple of inches. But prop manufacturers have gotten a lot better at controlling dimensions during manufacture, and now, it's size for size. If you want to replace an aluminium prop with a similar style SS, then you do a direct change, same pitch.

If you're changing from 3 blade to 4 blade (or vicky verka), then you do need to do the trials again.

Chris......

 

[frustratedboater]

Thanks for the tip achris. My setup came with an 11p and it screamed and went nowhere. I don't have any history on the motor, but with a pitch like that, it seemed it was outfitted for a pontoon setup, something that would be pushing a lot of weight. Funny thing, when my first sea trial, the whole shot was incredible!! It just about knocked my son off the front seat!

My plan is probably to just do a replacement. I run it on a duck boat and often hit muddy bottom and would LOVE a SS prop, but can't afford to try this and try that (and the cost right now). Your info was helpful. Thanks.

 

[frustratedboater]

Faztbullet: Yeah, That's how I purchased my other larger prop and I'd rather get one I know is going to fit for an extra $25, or so, chasing people around.. I bought 2 props from a guy up in CT who bought 2 Michigan Wheel's, I think 13p and a 21p. for my Merc 25hp, paid like $62 w/shipping for both, brand new! With hubs still in the box! That's exactly what the guy did, test the pitches...

 

[achris]

You have access to an accurate tacho? You need that to get the prop right. You need to be hitting between 5500 and 6000 rpm at wide open, normal trim and with a normal load. My personal preference is to prop for the upper end. The only exception to that is the 2+2 engines (100, 115, 125hp).

Chris.....

 

[ahicks]

If your 40hp Merc is similar to the 40 and 50 hp Honda's I spend a lot of time with, a 15" is too much prop even on a light alum. boat. I've found 13" and 14" props about right most often.

11" works good on a pontoon boat. You'll have no trouble selling that one.

 

[achris]

If your 40hp Merc is similar to the 40 and 50 hp Honda's....

Nope. This one has a bigger gearbox (called surprisingly enough, 'Bigfoot'), and a lower reduction, so a 15" might just be the ticket.

Chris.....

 

[frustratedboater]

Thanks for directing me to the prop sources. Looks like I have a nice option to choose from. I agree, the Bigfoot's prop face is really large for that large gearbox. It's a nice motor and very glad I went through the whole thing and did it right.