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Hi guys- Looking for some help from the Old Montauk crowed. This question is mostly aimed at the guys who have or have had the set up noted below.

I have a 1977 Montauk, with a 1979 Johnson Seahorse 70Hp, 3 cylinder, "Looper" mounted all the way down with the blind holes in use (original install 1979). I am looking for a new prop, 13 spline pleasure craft style. The old one is a 13-3/4 x 15 Michigan Wheel PJ80, discontinued in 1996. It is a bit beat up after 3 previous owners but still did pretty good last season even with the pre-existing dents and dings, on one of the outings I got a little closer to a sand bar than I wanted and took some more paint off, it is off to the prop shop now, but may be relegated to spares duty.

Currently the boat does not have a tachometer (never has had one) WOT is 5500 RPM for this engine, and I will be installing attach soon. The "Looper" is still good and I hope to keep it original for some time to come. The old girl will do 32 mph on flat to 1 ft rippled water with 2 guys (400 lbs), 24 gallons of gas and the tackle boxes and down riggers on board; about what it does with 500lbs of people, 12 gallons of gas and a 200 lb. person on a 5 foot diameter tube 50-75 feet aft. She planes off really fast with 5 adults on board now. We might consider a smaller higher pitch prop for getting places a bit faster but is it worth the effort in the waters I boat, and for what I do?

I live in the North Puget Sound region of Washington state and boat Admiralty and Saratoga Passages with occasional trips outside. Normally conditions are such you do not run WOT, i.e. moderate chop. The boat is used mostly for fishing, whale watching and occasionally pulling a tube (both fresh water lake and salt water).

So guys, I would like to here your recommendations on props, and any recommended changes to the set-up.

I could move things around (up) but that would require a hoist, and plugging/re-drilling the blind holes in the transom, something I am capable of doing, but would prefer not to do. The boat is in great shape after 35 years and I really do not want to mess with it too much if I do not have to. For those wanting to know it is an Idaho and Montana fresh water lake boat that I picked up last year.

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I recommend a 13-1/4" x 15" Stiletto Advantage. Very common prop for these boats.

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Thanks Tom. Anyone else?

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IMO you really should fix the engine height. Like you my engine was blind hole mounted when I bought it. You will gain speed, boat will plane easier, handle better and the engine will respond much better to trim adjustments. Its amazing what a couple inches will do.

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Dave,

Thanks for the input. The thing is the boat handles pretty well right now for what I use it for. I should add to the above post that:
1) The current prop has no cupping, and
2) with the pivot position pin set one hole back and motor all the way down on the transom, the Cavitation plate is 3/4 inch above the keel, also this is a manual tilt and trim setup. Going up too much, especially with NW chop might make it get too loose, i.e. cavitate or break loose.

For those who may have read my initial post, Yes I did read the old mounting article before posting. Joe and Tom know that I am an Engineer and I check things first, measure 2-3 times and drill or cut once.

I also e-mailed with Andy Gere who had a similar setup on his old Montauk.

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Then you don't need a new propeller.

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Tom,

I need a spare anyway, and the quote I had to straighten and file the dings will get me a newer, "used" prop off e-bay or similar location such as Craig's list, then I can take my own time straightening out the dents, and make it a spare.

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If you are shopping for a used propeller, you better know exactly what you are looking for.

What's you budget?

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Lucking out, have lots of coke points, converting to Bass Pro shop gift cards; can now buy new Aluminum, or may add a few bucks and go Stainless.

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I was unaware that Bass Pro sold stainless steel props. Which one will you be buying?

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Tom,
If I'm not mistaken you recommended the same prop (Stiletto Advantage 13.25 x 15) for my Yamaha 90 / Montauk, is it interchangeable?
Unless Yamaha drastically reduces the weight of the F90 my next engine will likely be the F70 so it would be good if I could use the same prop but that doesn't seem logical.

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Yamaha 90 two stroke uses a 2:1 gear ratio. The F70 uses a 2.33:1 gear ratio.

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Thanks, I just ordered one. My 90 I
is mounted all the way down in the blind hole so I intend to change that this spring and will post the results.
When I bought the boat it had an 1989 Evenrude that spared to be mounted at the right height. It makes me wonder if the older engines had the cavitation plate positioned higher than the newer engines.

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There is not strict uniformity between manufacturers and models from a given manufacturer for the distance from the transom bracket to the A/V plate. However, an old OMC mounted all the way down would have had its A/V plate far too low on the transom of a Whaler.