Prop tuning gurus

[Tail_Gunner]

Re: Prop tuning gurus

Well, if that is true then why did you blame it on aluminum PROP FLEX.

H

Ok we are coming together here...I said deformation..you said blade geometry...That would be deformation of the blade geometry....... Now someone did mention flex...should we smite the sacran...

Now i did say that the alum props were deforming under the pressure and load of a boat that large and a motor with that much thrust....And as below ...that be'd a opinion and your milage may vary..

 

[hwsiii]

Re: Prop tuning gurus

Sounds right to me Gunner. LOL

H

 

[getusummm]

Re: Prop tuning gurus

Jersey, I have the same boat as you and also have the same engines. I think you are not going to get much more, if anything, than you did with the 15x17. The most i would do in your case is try a 15x15 or 15x16 yamaha sws prop, even if it means having your 15x17 pitched down to 16" pitch. It is a heavy boat and needs more hp. Have you considered a 300 or even 350 4stroke? 3800-4200 was always my cruise rpm also. Granted I have not run my yamaha engines on this hull, but I have run the engines on other hulls quite a bit. I have seen numerous posting on the "good go 28" with 225-250hp and your speeds are inline with all the others I have seen, actually a little higher with the 15x17. One thing you havent mentioned is fuel consumption. That should be a very important part of your tuning process. I think dropping the pitch a little is going to lower your speeds versus rpms, but load the engine less, thus burning less fuel. Remember, these engines will burn 30gph at wot. I choose to go a different route with my boat primarily because i tend to go 50-100miles offshore. I have better piece of mind with twins that far out. Not to mention the extra power on tap if it gets rough. I can just trim the motors , set the trim tabs down and start plowing through for a better ride than skipping wave to wave and pounding my teeth out. I am in the process of closing in my transom completely, installing a twin outboard bracket and will give my pair of yamaha 250s a shot. I have a thread in the restoration forum if you care to check it out.