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1996 Montauk 17' with a 1999 Yamaha 4stroke 100hp. I bought it this past Spring and it came with a 23-K pitch prop (aluminum). When I try to trim up I get a lot of porpoising. When trimmed down it is had to steer at high sppeds. WOT is about 5200 rpms. Dealers I called today said it should have come with a 15' prop. I need the right size and diameter information. Can't find the info anywhere. Is the 23K way too much pitch? Do I need trim tabs? Thanks for any help

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Yes, 23" is W A Y too much pitch for that boat/motor combination.

I suspect your motor is mounted all the way down on the transom. That combined with too much pitch, is the source of your porpoising problems. You do not need trim tabs.

The 1999 Yamaha F100 has a 6000 RPOM redline and a 2.31:1 gear ratio. If the boat is good for 42 MPH then you would probably make good use of a 13-1/4" x 16" Yamaha Performance Series 3-Blade or a 13" x 17" Yamaha Painted Stainless Steel model.

The motor should be mounted three holes up if using either if these propellers and to holes up if you choose the 13-1/2" x 17" Yamaha aluminum model

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No prop expert here but, I would think about a 17 pitch would be about right. I bet that thing will fly with the 23 if it in good shapend you could really turn it, but I have never seen that much pitch on that hull. My 19 montauk zeroed in with a 14 3/8 x 17, mounted 2 holes up and tops out at 46 MPH. Tried a buddies 21 pitch and got it up to 53 and that got a little scary with that hull.
What hole is the motor mounted in?

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The motor is mounted in the third hole from the top. Four holes total. Tom, who would I order these props from or dealers?

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That is what most of us call "2 holes Up" and sounds about right.
http://www.whalercentral.com/articles...cle_id=106

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Thanks Joe, that is good to know for future reference and discussion.

Paul

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That is good. Your motor is mounted two holes up.

o
o
o <-- Mounting Bolts Through the Third Hole
o

It is refreshing to find that a motor dealer has mounted a motor on classic Whaler at a height not all the way down.

You might want to raise it later but for now, leave it as is and focus on a new propeller first.

Yes, any Yamaha branded prop needs to come from a Yamaha dealer, unless you buy off of dBay or some authorized Yamaha parts sources like Boats.net

You can buy Stiletto and Turbo branded props (made by Yamaha) from independent retailers for less money, and here are a lot of those dealers online.

You *might* be able to get away with a 13-1/4" x 17" Stiletto Advantage. You probably won't get all the way to 6000 RPM but you'll be within the upper half of the 5000-6000 RPM range for that motor.

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Thanks Tom. Just the information I was looking for! Much appreciated. Great website for a Whaler newby like myself.

Paul

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Tom, will an aluminum prop work just as well for my needs? I priced the advantage and they are kind of pricey. Thanks

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What are your needs?

What do you think is pricey?

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Price I saw was $350? By needs I meant "to correct my porpoising and steering problems"

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You needn't pay more than $250 for a Stiletto Advantage 4.25, delivered, with hub kit.

In contrast, the aformentioned Yamaha Performance Series 3-Blade (which is the same prop as the Advantage) costs as much a $437, and that is discounted off the >$500 list price

http://www.boats.net/parts/detail/yam...v4-16.html

The stainless steel Stiletto Advantage will be vastly superior to the aluminum Yamaha prop.

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Thanks for that link Tom, I was able to find that 13 X 17 Yamaha Painted stainless steel prop that I posted a need for last week there for about $200 less than direct from Yamaha.