two blade vs three blade prop

[boatsalotjay]

I have a '58 mercury 40hp on a 15' hydrocraft. The boat is supposed to weigh 500lbs empty but loaded it probably weighs closer to 800lbs. It has a two blade bronze prop with a pitch of ten. I was wondering if a three blade prop would really increase performance, or if I need more pitch. I know very little about any of this stuff, so some help would be appreciated. thanks

 

[JB]

Re: two blade vs three blade prop

More blades = more grip and more drag, Jay.<br /><br />A three blade of the same pitch will improve hole shot and reduce top speed.<br /><br />Four blades? Even more of the above.<br /><br />Good luck.

 

[BillP]

Re: two blade vs three blade prop

JB, <br />Prop technology seems to be going the other way these days. Virtually all of the F1 guys are getting best speed with 5 blade cleavers. I suspect we will start seeing those cuts for pleasure boats any day now.

 

[boatsalotjay]

Re: two blade vs three blade prop

Thanks guys, I guess I should have said that I can't even get the boat on plane and need to know if a three blade would do that. Maybe that is what you said but I am not to up to date on boating terms yet.

 

[Solittle]

Re: two blade vs three blade prop

I suspect that you have more than prop problems. A well running 40 hp (of any year) should make a 15'er fly.

 

[boatsalotjay]

Re: two blade vs three blade prop

What kind of problems would you say they are? This motor runs great, and I just had a resealed lower unit put on. Could it be over revving cause of too little pitch? I have a buddy with a <br />15' v-hull, and a 40hp johnson that runs a 15" pitch, I'm thinking I don't have enough. Also, the serial # says it is a 40hp, but my mechanic thinks its a 30hp. Would a 30hp still do the job?

 

[Bass Runner]

Re: two blade vs three blade prop

I bet if you check your boat weighs more than that, and a 40hp isn't a powerhouse to begin with I think you may be underpowered to begin with, maybe your flotation is soaked up if that's the case your boat can wiegh over a 1000lbs. Just my thoughts