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Yamaha 15 prop


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I have just purchased a 15 hp yamaha (2stroke) for my young 780

 

Just wondering what the best option for the prop will be to get the best speed and not over stress the motor

 

Will a standard prop be ok? Or do I need to change it?

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Had a chat to a few Prop shops for the 15hp for Mercenary Royce. Common thoughts were that with a 15 on our sized boats the Barge prop is going to make stuff all difference as you it hull speed so easily with a 15 anyhow. All it will do according to two mercury agents is give me better reverse. And mean that possibly i hit that hull speed with less revs. But as he said you hit hull speed, and probably push hull speed at just over half throttle anyhow so its a good rev range for the motor. And leaves the option to put the outboard on the back of a dinghy etc when its not in cruiser mode?

 

Can try dig out the emails somewhere as they were pretty well explained. You getting rid of the inboard?

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As MM states. You can talk to a prop seller and I recommmend that. But you will find no real benifit changing from what it has. The props are not huge and you get a lot of slip in the water and it tends to balance out quite nicely.

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I had a play with a 15 Evinrude on Ballistic, the correct prop needed to have right amount of thrust to stop it from stalling and overloading the engine and on the other end - over-reving, it took several attempts by a prop expert to get the blade angle correct, we tried a 4 blade type but that didn't work well enough - over-rev. The original prop is built for a little dinghy that accelerates easily and travels at high speed rather than pushing a heavy "barge" along.

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Had a chat to a few Prop shops for the 15hp for Mercenary Royce. Common thoughts were that with a 15 on our sized boats the Barge prop is going to make stuff all difference as you it hull speed so easily with a 15 anyhow. All it will do according to two mercury agents is give me better reverse. And mean that possibly i hit that hull speed with less revs. But as he said you hit hull speed, and probably push hull speed at just over half throttle anyhow so its a good rev range for the motor. And leaves the option to put the outboard on the back of a dinghy etc when its not in cruiser mode?

 

Can try dig out the emails somewhere as they were pretty well explained. You getting rid of the inboard?

 

 

Thanks marsh. Don't want to spend 180 on a prop if I don't have to...

 

I have decided to throw out the old vire 7. I was sick of doing 1.5 knots into 10 knots of wind...

 

On my first outing with the 15 I was doing over 7 knots.

 

Now all I need is a taller rig, square top main, and mast head genny and I'm set. :D

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I tried a std prop on the transom when I launched Supergroove - 8hp Evinrude.

After not being able to stop I went to the big prop - less than a month later. Was then able to reverse in 20 kn and stop when I wanted to. Never regretted it.

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I had a small one on the 9.9, went to the barge prop. Massive difference, knot so much in top end speed but she stays up in speed in all most any nasty weather and when I put it in reverse we do actually stop. Never go back to the small one.

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