recomend pitch on my prop

glasstream.

Recruit
Joined
Sep 18, 2003
Messages
2
I've got a OMC 4.3 ltr. Cobra. My boat is a bow rider (20 ft.) My local repair shop lost my orriginal stainless prop, and after discounting my service price, gave me a dinged up alluminum. It's pitch is 19. I'm having trouble coming out of the hole, and planing out quickly like before. The local "prop shop" is telling me to just down-size the prop pitch. Does anyone know what the proper pitch should be on this type of application to give me the same power and top speed I used to have? I know it's a trade off, but I'm considering looking more into my engine performance... etc.<br />Please advise.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,285
Re: recomend pitch on my prop

Without knowing your rpms at WOT.....<br />I'd think the next logical step would be try the 17" prop,+ See how it runs.... Every boat is Different....
 

djvan

Chief Petty Officer
Joined
May 3, 2003
Messages
411
Re: recomend pitch on my prop

I just ran my boat on the link above. I am currently running a stainless prop with a 19" pitch. Tops out about 39 mph, pulls tubes and boards pretty good. The site above recommends a 25" pitch, this seems wrong to me.<br /><br /> Just wanted to report before you order an expensive prop on this advice.<br /><br />HTH's<br /><br />DougV>
 

loadnet

Petty Officer 1st Class
Joined
Aug 27, 2003
Messages
225
Re: recomend pitch on my prop

If your WOT is up to factory specs for engine/boat length/weight/etc., combintation and you're looking for a better hole shot you may be able to go to a larger diameter prop, or even a 4 blade, utilizing the same pitch you have now.<br /><br />When increasing the diameter of your prop keep in mind that aluminum props will bend-flex to the rear, where as stainless props do not, so you want to make sure you have room between your aluminum prop and the (trim tab)(upside down adjustable skeg) mounted just above your prop so they don't collide at higher rpms. <br /><br />Some outdrives don't have a trim tab above the prop and if yours does not then the aluminum prop flex info is not an issue.<br /><br />If your RPMs at WOT are not making it to 3000 or 3500 then I would for sure, downsize your pitch to 17 like Bondo says. <br /><br />Dropping from 19 to 17 Pitch will increase your RPM at WOT but I'm not really convinced it will get you outa the hole quicker than you're getting out now.<br /><br />Maybe you could get back to the board here with more info on WOT RPM etc.<br /><br />Also make sure whoever you purchase your prop from will let you exchange it at no cost till you get the correct one you need. <br /><br />Please note that I am not a prop pitch expert.<br />I am only trying to assist with facts I've experienced personaly with my own boats over the years.
 
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