Help me pick a prop 130hp Yamaha

[mpsyamaha]

Ive been working on a project boat for the last 5 months.... it finally hit the water today The boat is a 17' Anacapri with a 2000 130hp yamaha. The first prop i had to try was a 21p standard yamaha ss prop (the black painted one with the straight trailing edge blades). As I suspected, it was over-propped, but worse than i thought. It turned 4800 rpms at 43mph one direction, and 4900 at 44mph GPS in the other direction, and this was trimmed way out. The motor is 2:1 gear ratio. This was with a full fuel tank, about 50lbs worth of coolers/gear, and just myself in the boat.

In addition to being overpropped, i noticed the boats attitude doesnt respond to trim very much, not as much as id like. The prop was fairly easy to blow out while turning sharply as well. The vent plate is right at about even with the keel.

Any suggestions for props? Definitely going with an SS prop. Im thinking a 17 or maaaybe 19 of some sort with some cup to it?

 

[jestor68]

Re: Help me pick a prop 130hp Yamaha

Your rpm range is 5000-6000 rpm. You'll need to prop it to run near the high end of the range lightly loaded.

Using the tried and true rule of thumb that an inch of pitch equals 150-200 rpm change, and you need to gain 700-800 rpm, it looks like dropping 2 pitch sizes(of 2 inches each) is in order.

A good 17 pitch SS prop ought to do it. A Solas HR Titan might be a good choice, but there are others as good(but cost more). You shouldn't lose any speed; should get 44-46 mph.

A 19 pitch would bring your rpm up to about 5300, which is still short of the 5500 rpm your motor needs to develop full power.

 

[mpsyamaha]

Re: Help me pick a prop 130hp Yamaha

Thanks, I picked up this 17p PowerTech SS prop today. Its got a good bit of cup, hopefully it will work better. Ill post results when i get them.

 

[jestor68]

Re: Help me pick a prop 130hp Yamaha

Cupping adds effective pitch to a prop. Even though it's labeled a 17 pitch, aggressive cupping could cause it to act like a 19 pitch. Look for at least 5500 rpm.

The more aggressive design of that prop should produce more bow rise when trimmed out.

 

[mpsyamaha]

Re: Help me pick a prop 130hp Yamaha

Got results for the new 17p prop today. 5600-5700 rpm and 44-46mph on GPS, depending on direction. The boat really feels great with this new prop! The hole shot is downright nasty, the boat is more responsive to trim like i wanted, and the handling on plane is greatly improved... much harder to ventilate this prop! Cruises nicely at 31mph at 4k rpms, and scoots along at 40mph at 5k rpms.

Some more picture whoring...

 

[dazk14]

Re: Help me pick a prop 130hp Yamaha

Time to start raising the motor...

 

[mpsyamaha]

Re: Help me pick a prop 130hp Yamaha

Time to start raising the motor...

Yeah, thats a thought. But the boat performs so nicely right now, I dont know if I can even justify moving it up a hole... Whats the most Ill gain, 2mph?

 

[jestor68]

Re: Help me pick a prop 130hp Yamaha

I'm glad that prop is working so well for you. If your AV plate is even with or slightly above the bottom, I would not waste time fooling with motor height. It could just make it more susceptible to ventilation in turns.

By the way, that's a very nice looking craft! :joyous: I believe that you've got her pretty well dialed in. Enjoy. :joyous:

 

[mpsyamaha]

Re: Help me pick a prop 130hp Yamaha

I'm glad that prop is working so well for you. If your AV plate is even with or slightly above the bottom, I would not waste time fooling with motor height. It could just make it more susceptible to ventilation in turns.

By the way, that's a very nice looking craft! :joyous: I believe that you've got her pretty well dialed in. Enjoy. :joyous:

Thank you sir! Its a real fun ride now!