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I'm looking for some advice on a good prop for our 1990 Montauk w/ a 1990 Evinrude XP 100 V4. I've read quite a few of the other threads on propping, all w/ other engine models. I currently have a SS 21" pitch. I had a 13" aluminum, which I was somewhat happy with until I took the boat to a new lake and found an unmarked rock shoal. I'm not completely satisfied w/ the 21" b/c we do a lot of waterskiing & it just doesn't have the hole shot to pull me out slalom. I love the top end speed but really hate going back to pick up a dropped ski. The 13" was satisfactory for the hole shot but lost a lot at top end.
I'm a bit hesitant to drop the money on SS just to find out I'm not happy w/ the prop. Maybe if I found the size that worked well I would then be inclined to pick up a good SS prop in the same size.
I'm also wondering if I might benefit from 4 blades vs. 3.

Tom Clark, your advice is greatly appreciated and I know you're in favor of SS. Would you be willing to recommend a good prop in both categories (alum & SS)?

Thanks in advance to anyone w/ advice.

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I have the same engine and use a 13.25 x 17 OMC factory aluminum prop. It performs well for me, although I have not used with skiers/tubes. Hole shot is strong and overall performance seems good to me.

Does a fine job fishing with 3 guys on board running around the Hudson River and inland lakes. Trimmed up tops out around 40mph with me on board and approx 12 gallons of fuel or so. My hull is also the commercial layup and around 300lbs heavier than a standard Montauk 17 set up

Hope this helps.

I also just got a new Solas model, same size on Iboats for under 88 bucks with free shipping last week

Ed

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Sorry I don't have an answer to your question, but I just wanted to say congratulations on owning what will undoubtedly be one of the longest-lasting outboard motors on the planet.

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It would be nice if you also gave us your WOT RPM's with the 21 pitch prop.

I would guess that you aren't getting the RPM's high enough with that prop.

I would also guess that you would have been over revving the engine with the 13 pitch.

Without knowing the WOT RPM's we would all be guessing as that is what you want to go by to insure your engine is running optimally within the manufacturers suggest WOT range.

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Thanks, it does. I'm considering that prop too. I figured it won't break the bank and P me off if I'm not overly satisfied with it.


Thanks, can't take credit for it though. It came with the boat. My wife's uncle bought it new. She hate's the motor because it coughs and spits like a 2 cycle will sometimes. She's always worried it's going to quit and leave us stranded.




The redline is 5500. The range is 4500-5500 (from the original manual). She has to firewall it w/ the 21" just to get me out on 2 and get up on plane quickly. That's w/ 15-20 gallons of fuel under the helm bench, my 50# 7 year old daughter spotting from the helm bench, a modestly loaded cooler forward and anchors stowed in the bow. I'll have to ask her what the RPMs are running w/ it firewalled on the hole shot. The boat WILL NOT pull me out slalom w/ the 21" firewalled or not. I tell my wife when she's towing me not to take it past 5000 once on plane just for a measure of caution. Should I not?

The last time we used the 13" was last year so her recollection of RPMs is vague at best but I know she is hesitant to get it near redline just because she's afraid of giving this motor any reason whatsoever of giving up the ghost and stranding us. She says she does not recall having to firewall it w/ the 13" when pulling me out. From my perspective at the end of the rope I would have to agree. When I originally went from the 21" to the 13" it was like night and day on the hole shot when I was skiing. But it seemed as if maybe I overcompensated.

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I still didn't hear your WOT RPM's ..... ???

I could be pulled out of the water on my 13' Sport with a 35 HP Evinrude on a single ski ...
You really haven't told us much...

When you speak of 13".... let's talk about pitch only............ at this time......
Is this pitch????

I have 3 props....
One for water skiing... 15 pitch
One for top speed... 19 pitch
One for all around... 17 pitch

The lower the pitch, the faster hole shot generally.
The higher the pitch, the faster top end...
You can't have both in one prop...

This would explain why you can hardly get out on 2 skis with the 21 pitch prop... The 21 pitch prop does not have a good hole shot...

Do you have a Tach???
Give us the WOT RPM's if you have a tach...

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If you are referring to pitch, that is a gross range between 21" and 13".

A 21" pitch prop, of any model, is too much pitch.

A 13" pitch prop, of any model is WAY too little pitch for that motor.

Do not use either prop any more; you risk engine damage doing so.

You should be using a 13-1/4" x 17" OMC SST/SSP (old style) or the better yet, the newer style 13-7/8" x 17" SST/Viper or the 13-1/4" x 15" Stiletto Advantage.

Where is your motor mounted on the transom? At what elevation do you typically boat?

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The numbers I'm listing are pitch. I hit 5000 RPMs last week w/ the 21" but I backed off to 4500 for a fast comfortable cruise. I'm sorry I cannot tell you specifically, i.e. 5275, what it would run at constant WOT.



Thanks for the reply Tom. What advantages does the Viper have over the SSP? Do you have a preference between the Viper and the Stiletto?

What kind of damage will the high pitch prop do to a motor? Too much strain at lower speeds? These are the two props that have been w/ the motor since it was purchased 20 years ago. I'm quite sure the 21" stainless has been on it most of it's life though. I switched it out for the 13" because of the poor hole shot.

Sorry I cannot answer where the motor is mounted. I just discovered that thread a week ago and have read some of the cross referenced materials about this issue. Very good stuff. I plan on taking the boat out tomorrow w/ my wife and will see how it looks. There appears to be plenty of room for adjustment either way. The mount can be changed w/out drilling new upper holes. The lower holes are blind. The AV plate on this motor appears to be two part. The larger, wider part being astern over the prop with a much narrower section forward & slightly higher on the unit.

We boat primarily on Youghiogheny Lake which straddles the Mason-Dixon in western MD / PA. Roughly 1450 ft above sea level. During the off-season we'll use Deep Creek Lake which sits at roughly 2450 ft.

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I was also thinking a 21 pitch pro seems a little tall. I'd probably go to at least a 19 if not 17 pitch as the guys above mentioned. Contact your local prop shop and see if they have a demo prop in each size and try it out. I know the shop we deal with will do that. Usually they'll just ask for a credit card for a deposit.

Just remember to keep your WOT rpms in the safe range.

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Duane, thanks for your input. I didn't know that local shops would do demo props and sure enough mine did. They happened to have a 17" pitch SST in stock and were kind enough to lend it for a run. We took it out and I was pretty happy with the performance. But because this is a boat we're talking about of course a different issue came up as soon as we hit the water.... no tach. Of all the instruments on the panel the tach decides to give up the ghost. I pull the engine cover, everything there seems tight. Get under the console everything there seems tight. So we took it for a run anyways. I'm pretty comfortable with what our motor sounds like at different rpms so I felt ok doing this even though I knew I wouldn't get a complete picture of things. My wife gave me a tow on the slalom and the prop lived up to my expectations there as well. I can't justify a $300 SS prop though for everyday boating on freshwater lakes w/ a 100 hp motor. Not when that same $300 can buy me 3 different aluminum ones to provide some choice according to the type of outing we plan to have and allow me a lightweight spare under the console. So I bought an aluminum one, same size/pitch, from them for $90 and ordered a new tach and a 15" pitch prop. I've installed the new tach but that's a different story and thus a new thread.

I did check the height of the motor when on plane and the AV plate appears to be a little deep. How deep I don't know and I am not sure how to measure that accurately and safely. I checked w/ the local Whaler dealer and he said "AV plate 3/4" above the bottom of the transom. No more, no less."

One thing I'm still not clear on, and forgive me for not being a gearhead. Other than over-revving a motor or running it continuously under high load at low rpms, is there some other way that a prop pitched too steep or shallow can have an adverse effect on motor wear and tear?

Thanks again to each of your for your input.

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Just grab a basic aluminum solas as I mentioned above in 13.25 x 17. It is cheap and will work great. I have used this setup on the same engine for 3years now and can't complain