Use of Hydrofoils, Good, Bad?

[Kevinmcm]

I recently purchased a 1985 16' Bayliner capri, Volvo Penta drive 4cy.. I have had it in the shop and had everything checked out, runs like a champ motor wise. I had RPM issues and slow hole shot, found out PO had a prop two pitch sizes too big. Replaced prop and all is well, hole shot is great and cruises about 35 WOT. My question really becomes this.......PO has installed Hydrofoils and was wondering what it benefits, if anything.I dont notice any trouble driving the boat, but was wondering if taking them off was going to drastically change anything. If they wont make a difference, they will stay on.

Just asking for opinions, as I know there are two sides to every story!!

 

[marcortez]

Re: Use of Hydrofoils, Good, Bad?

A hydrofoil will help "lift" the stern...which then lowers the bow, on the out of the hole acceleration.

They will help "pop" the boat on plane quicker and allow planing at a lower speed.

I think they help with side to side rolling/stability also, although you will hear plenty of naysayers grumbling the disadvantages of them.

You say your boat is running well with no issues....I say leave the contraption on.

 

[Bigprairie1]

Re: Use of Hydrofoils, Good, Bad?

I think these things are sort of band-aids. If they have a serious advantage to the performance of a boat...they would be on there from the get go.
Usually, something else is out on the boat or the engine to warrant giving these things a try.
Just my two bits.
BP

 

[MRS]

Re: Use of Hydrofoils, Good, Bad?

I would take them off and see what it does. PO probably had to put on because of the prop pitch being wrong or was trying to get more top end speed. Might run better if it does not, you can always put back on some boats do run better with them, but the right pitch prop you did is the right way to go....

 

[Kevinmcm]

Re: Use of Hydrofoils, Good, Bad?

I had considered making a ten minute run, to determine lake conditions, then take them off, repeat the run, then put them back on, for a final results type of thing. Just dont know if I want to spend that time doing that, or just keep running across the lake

 

[91capri2050]

Re: Use of Hydrofoils, Good, Bad?

had them on both my boats. a 15 foot o/b bass boat, and the current 21 foot bayliner bowrider. they seem to help a good deal to get it on plane.

 

[MRS]

Re: Use of Hydrofoils, Good, Bad?

Kevin, you got to try it without that's the best part of owning a boat you just got to fiddle with stuff. What if it runs faster without you will never know till you try......

 

[mickjetblue]

Re: Use of Hydrofoils, Good, Bad?

I have the same year outfit, but it's a 19', so I'll throw in my 2 cents.

The VP4 is a marvelous engine, but it is not designed to pull a boarder up
out of the hole "right now". Great cruiser at great mileage!

I added an SE sport to the unit, and that actually improved the hole shot and
the fore to aft stability. After a couple of years, I was still not happy with the
low speed wandering from left to right that is said to be typical out the
i/o units. I figured I would try smart tabs. Well, they did more than what I
had been hoping for. The smart tabs stopped the left to right slow speed issue
altogether. Hole shot is still improved, but the biggest difference is that the
overall stability, especially at higher speeds and in rougher water, is better.

The SE sport is on a shelf, maybe will find another use some time.

Much to research on this, so look around with the search feature.

That's my 2 cents worth. Good luck.

 

[dave11]

Re: Use of Hydrofoils, Good, Bad?

There are pros & cons to them. Evaluate your boats handling on and off.

 

[Fishing56]

Re: Use of Hydrofoils, Good, Bad?

I have an 18 ft 1996 Mariah with a 4.3lx. Pretty heavy boat. Wasn't having any problems, just wanted to tinker. Put on a hydrafoil (can't remember the brand), it did help slightly with planning speed, but noticed that top end speed was comprimised. So after a month or two took it off. Regained lost top end speed. Just my thoughts.

Fishing56

 

[dave11]

Re: Use of Hydrofoils, Good, Bad?

Top end speed doesn't mean much for how I use my boats.

 

[Jdeagro]

Re: Use of Hydrofoils, Good, Bad?

Couple of points to make here;

1) lifting the boat from the center of the "V" can not help side to side stability.

2) If the boat runs slower at high speed (full throttle) it simply means that it is not efficient, and although you may be willing to give up the speed, I doubt you are willing to give up the fuel economy. Lift the stern too much and you push the bow down. The boat should run on the last 35% to 40% of the hull. If it runs too flat, with the bow down (as little as 2 to 3 degrees) the additional wetted surface will slow the boat and increase fuel consumption. It is commonly thought that when the hydrofoil slows the top end it is because of extra drag from the hydrofoil itself. This is not the case. The hydrofoil creates more lift as the speed increases. The result is that the boat attitude is off, it is riding bow down. If the boat is opperated at slow to mid speed these effects may not be noticable.

 

[fishingdan]

Re: Use of Hydrofoils, Good, Bad?

I have inherited them on a couple of boats. In general, I have found these types of devices (anti-ventilation plate hyrdrofoils and smart-tabs - I know they are different. Please save the reprimands) beneficial for typical weekend use. Boats increase in weight over time (extra battery, extra on-board gear, etc) and are used for often different purposes throughout the day (cruising, tubing, skiing, fishing, etc). It is too much of a headache to always be planning out your load. These simply give you a much wider range of use for your typical setup.

I especially like them on the 20' bowriders I have owned. With the variability of the load (coolers, guests wanting to ride in back vs the front, changing fuel load, etc), you get up on plane as effortlessly has possible for your boat and can cruise at lower rpms. If installed correctly, they don't take away much from the top end. For me, I'm rarely running at WOT anyways. Losing 2 mph up there isn't meaninful to me.

Just my $.02.

 

[ampcarfan]

Re: Use of Hydrofoils, Good, Bad?

I agree with marcotez, I have had these on 2 of my previous boats and found they do help in planing and bow lift. I ended up removing both as they do cut your wot, trimmed top speed. It's all about your needs for the boat. Remove it and I'll bet you'll see 38mph (wot and trimmed perfect).

 

[ampcarfan]

Re: Use of Hydrofoils, Good, Bad?

Sorry... meant "stern lift" It's a noticable difference.

 

[Kevinmcm]

Re: Use of Hydrofoils, Good, Bad?

Thank You for the many varied responses! Unfortunately, my "sentence" here in Pennsylvania state prison (working, not actual inmate!) has been extended till the end of May, so it will be a few weekends still before a test run can be done. The good news is, boss says I can have a week off when I return home, and I have every intention of being in wake therapy! I will post my result when I run the test and see what works for my boat. Though most applications will be skiing and tubing, the Fiance (she likes that word, funny how women are) says the front deck needs built on top of cushions so she can fish before it sees water again (at which point I reply "whatever you want dear" )

 

[haulnazz15]

Re: Use of Hydrofoils, Good, Bad?

The issue I have with hydrofoils (whale tails, etc) is that they tend to cover up other issues. My boat planes out very quickly (2-3 seconds max) and we don't need one. However, I have seen my same boat model in classified ads with the hydrofoil on it. I just think, why? Now, adding one may make it plane slightly faster, but chances are there are bigger issues at play, like incorrect prop or trim adjustments.

Smart tabs/trim tabs are a different story as they actually extend the running surface of the hull and can be retracted once on plane. Hydrofoils are permanent drag. If the original hull design was that poor to where a whale tail needs to be added, it isn't the type of boat I'd buy anyway.

 

[Summer Fun]

Re: Use of Hydrofoils, Good, Bad?

If they were any good !!. Don't you think that all the boat makers would install them on from the factory ??.
They didn't spent millions in research to not realizes that they are good.

 

[45Auto]

Re: Use of Hydrofoils, Good, Bad?

If they were any good !!. Don't you think that all the boat makers would install them on from the factory ??.

That's kind of like saying that if 19" pitch props were any good, why don't all the boat makers install them from the factory. You could also say the same thing about fuel injection, duo-prop drives, drive lube monitors, GPS speedometers, dual batteries, VHF radios, stainless props, etc, etc, etc.

The answer is that hydrofoils, like 19" pitch props or anything else, are not the answer for every boating situation or price range. In some cases they're good, some they're bad, some they don't make any difference. If you're a manufacturer, are you going to put a $30 hydrofoil (plus cost to install) on all of the 50,000 units you make because it may help 25% of them? That'll take about 2 million dollars straight out of your profits real quick ....

About the only way to find out is to try it on your set up.

I have a friend who many years ago had a 16' trihull with a 50HP outboard that would not plane AT ALL until he put a hydrofoil on it. On his advice I tried one on my 1997 18' Bayliner with a 120HP outboard that was slow to plane. The hydrofoil made it pop onto plane IMMIEDIATLY and it could hold plane about 5 MPH slower than without it. At WOT the hydrofoil was out of the water so it didn't affect the top speed at all. Some people claim that they made their boat handle funny, but I never noticed any difference on mine. In the 7 years that I owned that boat it spent about 90% of it's time zig-zagging back and forth across the river pulling tubes and kneeboarders with no handling problems at all.

I think you'll find the biggest difference on marginally powered boats. And if the height of your motor/outdrive is not correct so the anti-ventilation plate isn't at surface level at WOT, then I can understand how it could cost a few MPH in top speed dragging in the water.

They're easy to put on and take off. Since your boat has one on it already, best thing to do is try it both ways and see which you prefer.