would 4-blades help?
 

I would like to be able to stay on plane at lower speeds without putting the k-planes all the way down, and be able to run a little more positive trim at cruise to high speeds without getting into a porpose. Currently running 21P Yamaha offshore 3-blade props (32 Scorpion cc with twin V6-250HP Yamahas). Boat speed is pretty close to what the BAM calculator predicts (low 50's, best guess is it weighs about 8000 lbs) and the prop slip computes at 15% which is pretty good.

Can I find some 20P 4-blades (I doubt the engines would pulll 22P since they don't have much torque compared to v8's)? I think 4-blades would help with the low speed planing, will they also pull a little more positive trim?

Thans - Greg

Re: would 4-blades help?
 

Yes, 4B props will hepl you to achieve your goals. If you post some of your performance data we can take a look and possibly make a recommendation for you.

Julie

Re: would 4-blades help?
 

I had the boat out yesterday. It was hot (92) so might get a touch better on a cooler day.

Top speed with it still trimmed pretty flat was 54 mph (gps) at 5400

Cruise at 4000 RPM is about 35 mph, 5000 RPM about 48

Min planning is about 2800 rpm and 13-15 mph depending on how far down I had the k-planes (they are the long 380's, motors are on a bracket so well aft of the transom as well).

I can't really run the boat between 3000 and 4000 RPM as one prop of the other will break loose and rev up and I have to either throttle back down to get it to catch or just throttle up and let them hook back up at 4000 RPM once the boat accelerates.

-Greg

Re: would 4-blades help?
 

Greg, sent you a PM, have props I am in Ocean City MD

Re: would 4-blades help?
 

Julie, Any suggestions yet?

-Greg

Re: would 4-blades help?
 

Is your gear ratio 1.81 or 1.75?

Julie

Re: would 4-blades help?
 

Ratio is 1.81 according to the owners manual. - Greg

Re: would 4-blades help?
 

Dependant upon which model 250's you have, you are running in the power band of the motor so you are OK there. I wuld like to see you in a set of 22P Bravo I props that will most likely need to be modified but I think they are the correct prop for your application.

Julie

Re: would 4-blades help?
 

They are 1993 TXRR250 motors (carb versions). Manufacturers recommended RPM is 4500-5500, they are definitly happier above 4500 (albet pretty thursty at 4800-5000 where I usually cruise them). What do you think of the Revolution 4 compared to the Bravo 1. Several people running 30's CC's have had good luck with them. I had 22 Bravo 1's on my Formula 402 (Scottc has it now), I might be able to talk him into letting me try them if I can get the right thrust washer for the Yamaha (I heard they are different).

Send me an e-mail if you'd prefer to discuss options offline.

Thanks - Greg

Re: would 4-blades help?
 

Yes, Rev 4's!! Not the Bravo 1's.

Call and we'll get you some test props.