Hydrofoil

[Morgan320i]

I have a 77 chrysler 65hp 659ha and would like yo put a hydrofoil on it so i can plane quicker, anyone know a model that will fit?

 

[strtbobber]

Re: Hydrofoil

I would suggest doing some research before putting one of those on, then deciding for yourself if you even want one. There's a HUGE debate between the quicker plane and the extra drag it creates. Just sayin'.

I decided not to put one on mine.

 

[fucawi]

Re: Hydrofoil

If there is a huge debate it must be a debate amongst idiots ...the thing should be out the water when you are on the plane ...motor too low if its not ....I always use them the boat can rise onto the plane level non of that nose up rubbish

They are usually a universal fit .

 

[Frank Acampora]

Re: Hydrofoil

Your anti-ventilation plate is smaller than the ones on higher horsepower engines. Try to find a medium sized one designed for engines like an evinrude 50.

They do work well on some hulls, BUT do cause adverse handling on others. So, the thing to do is decide if you want to spend the 30 bucks to experiment on your hull. If it works to your satisfaction, leave it on. If it gives problems, then you simply remove it and there are only four small bolt holes in the anti-ventilation plate.

If you want to spend a little more, you can get an inexpensive set of trim tabs to mount on the transom. I believe Smart Tabs are about 150 for the plastic ones. If interested, search for threads with Smart tabs. There are a bunch of guys on the forum who swear by them.

 

[strtbobber]

Re: Hydrofoil

If there is a huge debate it must be a debate amongst idiots ...the thing should be out the water when you are on the plane ...motor too low if its not ....I always use them the boat can rise onto the plane level non of that nose up rubbish

They are usually a universal fit .

You must be one negative human being. I've never heard you say anything positive since you joined. Always against the grain, eh?!

 

[steveclv]

Re: Hydrofoil

Had one on my 19' Bayliner Capri with 125HP Chrysler - ran it for a few weeks with it on and then took it off - made no noticeable difference to the way the boat got on plane but seems to handle and turn better without it but that may just be psychological. Other hulls may react differently.

 

[fucawi]

Re: Hydrofoil

If we all think the same then somebody is not thinking ..........how can it be negative you learned something about hydrofoils and we are now all using the right term " anti ventilation plate "

To get full benefit from your foil you must trim fully down when you accelerate onto the plane and then trim out as you get to cruise speed. If you dont have electric trim then you dont get the full benefit

 

[tater76]

Re: Hydrofoil

I removed the one that came on my trihull and gained a few mph with no adverse reactions from the boat on plane.

EDIT: My engine was mounted too low when I bought the boat, thus the hydrofoil was dragging at all speeds. I remounted the engine, and use the trim holes to get the boat to do what I need.

 

[surfsalterpath]

Re: Hydrofoil

....


....anyone heard of putting the hydrofoils on a pontoon boat engine?

And thanks for ALL opinions and ideas: positive & negative. We are all humans
and have diff personalities, that makes it a wonderful world!

 

[tater76]

Re: Hydrofoil

I saw a 20 or so foot pontoon with a 150 Merc that had a foil. Fastest pontoon I have ever witnessed. It even had a wakeboard tower! As for the hydrafoil being needed on it, who knows. I would think it would be pretty hard to porpoise a pontoon.

 

[fucawi]

Re: Hydrofoil

A hydro foil is not a cure for porpoise ...just tuck the leg under a little more ...you go faster when you porpoise due to lower contact areas with the water ......

 

[steveclv]

Re: Hydrofoil

Not strictly true .... when you porpoise you reduce the water contact area too much so the boat speeds up until the water contact area is too small to support the weight of the boat which then drops back into the water with a much increased water contact area which increases drag and slows you down.

Your best speed will be when you are correctly trimmed and the water contact area is the minimum that is needed to support the boat's attitude.

But I understand the point you were making

The theory of the plate on a pontoon is not to change the boats attitude in the water - that's very hard to do because of the logs buoyancy - but to increase the thrust energy of the prop. Rather than allowing the water flow to escape upwards and break the surface of the water, it's redirected down/back to allegedly increase water flow rearwards.

However if you are using an appropriate cupped prop on your toon then this shouldn't be a problem anyway.
I've had them on a 24' pontoon but can't tell you if it works or not. It didn't cause any problems but was probably a waste of money.

 

[fucawi]

Re: Hydrofoil

Sounds like you want a Kort Nozzle on your pontoon prop then ....

my racing friends always induce a slow porpoise for max speed