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Some people like "Whaletails". Personally I think the DoelFin brand is the best, and I have had one on every boat I owned since 1985. Lower planing speed and less bow rise on acceleration are my reasons for their use.

This year we upgraded to a 2017 150 Montauk. I have read reports that they are under-powered, and some have suggested different props, etc.

For our boating style, she performs just fine. I wouldn't say she is under-powered, but she is not a speed demon either. She is a little slow out of the hole, but not unmanageable. Bow rise is also minimal. My only wish is that she would stay on plane a little easier. In heavy seas I seem to be constantly adjusting the throttle, while that has not been an issue for me before.

I would like her to plane at a lower speed and stay on plane better. My experience with other boats is that a hydrofoil does the trick.

So, my question is....does anyone have any experience with a 'foil on a 150 Montauk?

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Given the limitations you have, I say try it.

It's cheap, compared to a new prop ($400).

If it doesn't work, just remove it.

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What motor do you have? What horse power is the boat rated for?

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The 150 Montauk comes with a 60 hp Mercury standard. It is the only option available and the boat's maximum horsepower.

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I added an SE Sport 400 no drill/bolt on hydrofoil to my 2013 Montauk 150. I changed my prop at the same time so I am unsure of how much help the foil had on its own, but the combo was great for adding bottom end, but it took away from the top. The SE Sport 400 looks good on the engine, almost like it is part of it and not just stuck to the top.

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Here's an update....

I installed a hydrofoil just before vacation, so she got a good week's trial. It was a DoelFin, which is the only one I have ever or will ever use.

To say I was happy would be an understatement. She pops on plane, hold plane better and, to my surprise, all steering torque on plane is completely eliminated.

Best $28 investment I ever made. This is the 4th boat that has shown outstanding results.

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That's good to know. We just purchased a 2017 150 Montauk. So far, I'm happy with performance, but haven't tried it in all conditions yet!

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I'm interested in what you guys did but have a couple of questions.
whaler36340 You mentioned a SE Sport 400 why not 300? and what prop did you replace the standard Vengeance with?
gypsmjim you mentioned Doel-fin can you be more specific as that model you used (part number) as it seams to be 1/3 the price of a SE Sport 400.
I like to try either this weekend but need to know which one.

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Mr Doelscher invented the hydrofoil. The others are reverse engineered copies. In actuality you could bolt a piece of flat aluminum to the motor and get similar results.

The expensive ones with fancy curves and such are merely advertising hype.

Doel makes only 1 model, though they used to have different colors years ago. The best price is on EBay with free shipping and no sales tax.

http://www.davisnet.com/product/doel-...fin-black/

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I chose the $60 400 (jet.c_m) over the $50 300 because it was a no drill application. If you buy the 300 you would still need to buy the $50 no-drill plate to go along with it, unless you want to drill. It is also strong, I stood on it and I am 240lbs. The Davis Doel-Fin looks to be a good fin, but but it is ugly, plus you have to drill.

I used a spitfire 13.8"x1" itch 4 blade prop. This prop is for heavy pulling only and not an every-day prop on a 150 Montauk.

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Drilling 4 small holes is no issue for me. I have had 100% success and have never had to remove one. It sure beats tabs that require drilling 16 holes into the transom....!!!

Beware of the no-drill mounts. There are reports that sometimes they fall off.

There are also reports that foils are prone to break off the anti-ventilation plate. That IS a possibility, but only if they are loose, or improperly installed. SS bolts and nyloc nuts will do the trick.

I speak from 50+ years Doelfin experience with several boats.

I won't debate beauty. Mine is under water so I can't see it.

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Actually, Alexander Graham Bell invented the hydrofoil around 1908... But the Doelfin is a nice adaptation of it.

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Bell's work was with a hydrofoil on a boat hull. Doelsher's adaptation was adding a part to the lower unit of a marine outdrive. Maybe what this thread is about shouldn't be called a "hydrofoil" at all. Nevertheless, back in the early 1980's, the Doelfin was the first I ever saw and early patent protection secured no competition.

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Awesome, nits properly picked! Now give us the meat, what's your Whaler's change in performance as a result of the patented Doelfin?

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I'm recently retired, so I'm not in the mood to collect data any more. I just want to go fishing.....LOL. As a PE, I would have recorded "Time To Plane", "Min Planing RPM", etc. Soooo, you'll just have to make do with my subjective observations.

The Montauk planes faster, at a lower RPM. Bow rise was minimal before - now it is nonexistent. In heavy seas I would have to constantly accelerate to keep her on plane - now I get o plane and she stays on plane with no fiddling required. The performance curve that BW published is spot on and it has not changed. There is no loss it top speed.

The performance for a store-bought setup was awesome before - now it is perfect.

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Congratulations on retirement! A Whaler is the perfect gift to give yourself. Glad it's exceeding your expectations...

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gypsmjim
I did go ahead and bought a Doel Fin set.
The instructions are very vague as they don't tell you where to mount them on your anti cavitation plate.
As an engineer I wanted to know where to put these fins on the plate as the plate on the 60HP EPI 4 stroke is a lot longer than the Doel fins. No where in their mounting instruction do they give this info so I called customer service and was told to center the foils over the C/L of the prop equal to where the foil straight edge angles back to the cav.plate.
That said I did so and ended up with longer out of the hole shot with higher bow rise (engine tucked in all the way) same top WOT speed except much more prone to porpoising.
This was with 4 adults (800+lbs crew and all) the standard 3 bladed Vengeance SS prop. Yes I could plane at slightly lower speed but with two adult women on the bow cushion I felt like the bow was riding to high.
I will remove the $28 "fix" as it didn't really make it "perfect" and I didn't like the way the boat was riding or porpoising.

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Interesting thread. I bought a new Montauk 150 this year and have been considering a hydrofoil as well. Has anyone changed the factory engine mounting up or down? I think mine is on the second from the lowest bolt.

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Bill I thought about it but when you look the cavitation plate it is already at 1" above (at least mine is) bottom which is what we are told is the spot.
As our boats (the 150 Montauks) are basically to new we don't need to repower the nice running Merc. 60 HP 4-stroke yet.
If my Mercury ever bites the dust (which I do not see in near future) I like to try a 70HP (Evinrude/Yamaha) and see what she does.
She's slow out of the hole but for me has enough top speed with the standard 60HP
I played around with 4-bladed merc props which give better torque and slightly quicker hole shot but overall the 3 bladed standard SS Vengeance prop that comes with the boat is the right selection. (see my posts elsewhere on this site for that subject).
Love my boat.

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Love mine too, perfect boat for my location and what I use it for. I have to see where my plate lines up. I've gotten to 31 mph with ~ 360 lbs in passengers and 2 full 6 gallon tanks, seems like I should get a little more on the top end.

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billjnh is that 31 mph at 6,000 rpm? If so yes that is not max. I get 31 knots (36 mph) with the weight load you mentioned. Do you fine trim after WOT.
I assume motor mounted correctly (up) and the stainless Vengeance prop.

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No that's at 5,000 rpm with with motor trimmed. Going above 5000 doesn't seem to increase speed, yes on the vengeance prop. Motor is. Mounted one hole from the lowest hole if you are looking at it.

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Pardon my tardy reply, but we have been on vacation again. Put a lot of gas thru the new Montauk these past few weeks. Our other boats are feeling neglected.....LOL.

As I said before, this is the forth boat to sport a DoelFin. The first 2 were purchased from Mr Doelcher himself. I can't remember what the old installation instructions were, and subsequent installations were done without even reading the new manuals.

ALL my fins were mounted as far back as possible on the anti-ventilation plate. If you have a worse hole shot, more bow rise and porpoising, my guess would be the fin is in the wrong place, since yours got worse and mine got better.

My engine is mounted in the 3rd hole up, and the prop is the std. Vengeance, all as it came from the factory.

As a rule, I don't like WOT. With a 450 lb. load and 2 full tanks our Montauk's sweet spot is about 4000-4500 RPM. With a slight amount of trim this runs at about 23 mph GPS. WOT with a fair amount of trim I get about 5800 rpm and 33 mph, which is close to the published specs. I have NEVER seen porpoising at ANY conditions, with or without the fin.

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Much of the reason for discussing speed performance, WOT rpms, prop model and size and engine height is not for top speed. When all of these pieces are"dialed in" the engine will be performing correctly at all speeds.

We want to avoid a situation where the boat is running like a car racing up a steep hill in either 1st gear or lugging in 5th.

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That's exactly true. As the "experts" suggest, and from my own personal experience, if WOT provides an rpm that is right at the engine's max spec, "performance" will be optimum.

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gypsmjm
i agree with your sweet spot statement that is where I like to run too @ 21knts (23.5 mph)
I also agree with the statement that the installation I did (following Doel factory recommendations) incorrect. I hate to drill 4 new holes but will move them aft, as now they are about 2 " forward of the back end of the plate.
We'll see this weekend.
I ran the boat more than 90 miles during the 2 day weekend and we had a blast in a poker run and just cruising up and down the Eastern Lake Michigan shore.

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During our usual week vacation on the Saint Lawrence River in early July we logged ONLY 127 miles. The weather was iffy (cold some days) and rain was frequent. We usually run a good 300 miles on our jetski in good weather. The wife was glad we took the new Whaler instead...

Sorry about having to drill more holes. At least you are not installing trim tabs in the hull with 16 screw holes. If it turns out you really don't like the tab, filling the holes with small SS or poly bolts will make them hardly noticeable.

Please report back on your performance. I'll be glad to help if I can.

On a side note, the weather was splendid today so we took out our 65 year old wood Lyman, with her 64 year old Evinrude outboard. Had some engine problems (I'm also that age and I too get finicky at times), but she managed to get us home safe as sound.

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Since you didn't reply, I was wondering how things came out. Hope you made an improvement after you moved the fin...