Hydrofoil Question

[Skeeter]

I have a Mariner 175 HP. Wondering if some of you would give me some pros or cons about Hydrofoils. Do they work and should I have one? OR NOT??? If so which one is best? Thanks in advance.

[Marble Eyes]

The place where I purchased my boat and Motor, told me it would void my warranty if I put one on. When I asked him why he couldn't tell me the reason.

[Box]

You might just need to test some SS props?.. to find one that helps the best. You didnt mention if you have already...

We have dole fin (2 piece) on our 50 hp 16' boat, and it helps lots, but we don't have power trim on that boat.

-Box

[Jeremy]

There are many people who say hydrofoils are just a bandaid for poor weight distibution. I use a stingray, nothing wrong with it, hasn't destroyed my lower unit yet. It sure puts the boat on plane in a hurry

[Phil T.]

It doesn't cost much to find out if you like one. K-Mart used to sell the DoelFin for about $25. The differences between the brands isn't all that much.
If you don't like it, take it off and fill the holes with marine tex patching and paint the repair.
One caution. There have been a number of "watch outs" if your boat will reach 50mph. A hydrofoil will certainly make the effects of trim more pronounced. Be carefull as you learn some new handling quirks.

[stevefellegy]

A few years back, the Doel Fin company sponsored the Pwt events.
I testd them on my tiller boats, which are notorious for beig under powered and hard to see from, when sitting in the back. I thought they were GREAT. I installed one for two years in a row...ya got me wondering why I got away from using one. I surely saw only advantages from this concept, if power was short, planing was hard out of the hole or the like. I especially remember I was on plane longer at slower speeds. Safer.

[Gary]

http://www.cal-nevamarine.com/

Might be of interest.

[Skeeter]

N/m back to top

[Gary B]

It is my experience, I have found the following:

Pro:
1. Your boat will plane sooner at a slower speed with "down" trim.

2. The bow will not rise nearly as high when getting on plane. This works well for slow planing like pulling tubes, etc.

3. The boat will get on plane easier when loaded "aft heavy".

4. Fuel economy may very well increase because the lower unit can be trimmed "up" more at most cruisng speeds. This trimming aligns the prop more with the flow of water, making it more efficient. Trimming usually delivers more speed for a given throttle position.

I may have forgotten a couple other benefits. No others come to mind at the moment.

Con:

1. The boat must be trimmed more and more often. With 175hp (or my 215hp 19ft I/O) You will probably need to start trimming "up" at 25-30 mph, and keep trimming from there.

2.At full "down" trim and 30+ mph, you will probably notice that the boat leans to one side or the other. The fin is lifting the back of the boat too much, but it is not wide enough to balance the boat, so the boat tips to one side or the other(like a wheelbarrow). When this happens.....trim "up". This will level the boat and probably net a little more speed in the process.

3.With "down" trim at cruising speeds, I notice that the boat leans or banks in a turn farther than it would without the fin. This can be un-nerving at times. For example, you tried to get a water skier up, but he fell. You decide to hurry back so you crank the wheel while on plane. You just about put the gunwhale on the surface of the water, but wonder why it still takes such a large area to turn. You have full "down" trim which causes the boat to lean more.

4. To get the most out of a hydrofoil, having and USING electric trim is very important! "Trim more and trim more often"!


For many boaters, these Hydrofoils are great. Like the previous posts say, there may be some considerations. If you try one and don't like it, remove it and fill the holes. It won't cost much to try.

Remember: If the boat leans to one side or the other....TRIM UP.
If the bow of the boat porpoises up and down..TRIM DOWN.


Good Luck.

[Pitts]

Hey guys I do real well with the jackplate on my 1775 Skeeter with a 150 HP but when I want to throttle it back and trim it up to lift the bow in 3' waves it wants to porpoise and makes me trim down.
The boat flys at WOT but you don't always go there and the most economical is about 3800 rpms which if I run there I am really limited on my trim or it will bounce. It balances perfect on the pad way out of the water and I run 5800 rpm's and 55 mph at WOT I just think I need that fin for slower running in waves.
Do ya all agree or not.
I am going to get one this spring and put it on.


Pitts

[Skeeter]

I agree with you Pitts. Thats why I am getting one soon. I see one on the Swap Board for 20 bucks good buy.

[Gary B]

Pitts,
With many boats, you can not trim as much at cruise as you can at top end. Without the fin I cannot trim mine at all below 30-35mph or it will porpoise, yet at top end I can trim any where I want to without porpoising. Adding the fin will almost require you to start to trim shortly after the boat is on plane. You will need to retrim more often with a fin installed.

If you want to lift the nose in waves, you might try lowering the jackplate to stick the prop deeper in the water. The farther it is below the boat, the more leverage it has to lift the bow.

just a thought...........

[Pitts]

Thanks Gary one more question then. If I lower the jack do you think the boat will get up on the pad as well as it does now or will the boat seem like I need to trim just a little more to get the rpms up to 5800 and that last 5 mph that it does at the moment. It seems to me that the tips on the prop are breaking the surface of the water at WOT and the last 1/8 of the trim gauge. The rpms go up 500 to 5800 and the speed increases 5 to 7 mph and she really takes off. Alot more noise and rooster but really goes. If thats the case will the fin be out of the water and not change anything at WOT but enhance my handling at lower speeds.
I appreciate the info.


Pitts

[Gary B]

Pitts,
I'm kinda shootin' in the dark here, but I think it would come out of the hole a little better, maybe??? I am guessing you have a manually adjustable jack plate? It probably will NOT get up on the pad at top end and run as fast. Every inch of lower unit that is in the water is drag that slows you down. If you are after top end, lowering the jack will slow you down(unless you are way too high). I would say that if it comes out of the water OK, handles well, and you like the top end, that you are pretty close to being dialed in. The fin should be out of the water at top end and cause virtually no decrease in performance. To check this, run the trim up to where you get max speed and walk around to behind the boat(on trailer)and compare the position and angle of the anti-ventilation plate and the keel. If your motor is jacked up a bit it should be easily out of the water.

[Pitts]

Thanks Gary:)


Pitts

[Ferny]

Hey Guy's, The StingRay turned my PorpoiseCraft back into an Alumacraft. It's a 16' with 40HP Tiller without trim and tilt.

Later,

Ferny.
Later,

Ferny.