Hydrofoil fins for a 25hp evinrude on rib

[Huib1965]

Its interesting... my 470Avon has a 60 HP Mariner and when us 2 are on the back seat and coming out of a 10 knot restricted harbor it feels like we will topple backwards as the bow is up that high.... Bought some these so I dont have to drill holes in the engine... Will let you know how I get on....

StarFire | Stingray Hydrofoils by Marine Dynamics - The World's Best Hydrofoil Stabilizers

[derdle]

I used them on a zodiac futura 3.6m sib with a 30 hp. with forward steering and throttle controls.
I could pull a large Ringo with both my daughters on it no problem with fins fitted.
On one occasion when the throttle cable broke I disconnected steering and throttle and went back to the tiller. I did find steering very heavy with fins when using tiller so I removed the fins. After their removal I could not get up on the plane while towing so Refitted them. So I can confirm that for towing they where a must have.

A tip for getting up on the plane i found was..

power forward slowly until tow rope becomes tight.
Then put the boat into a hard turn whilst increasing power.
This lets the speed increase without actually pulling on the Ringo, but the rope stays tight.
as the the boat starts to plane, slowly straighten up and you will start to pull the Ringo without any loss of speed.

[Amcarrapatoso]

I had a 3.5 m with a 25 hp, 2ST, with tiller, and I fitted it with a hydrofoil. The result was impressive, specially when towing rings or knee-boards. It started and went into plane much faster.
I moved to a 4.5 m with a 40 hp, 2 ST, joker seat and when I fitted it with an hydrofoil the result was also impressive. Without the hydrofoil it was hard to pull a skier out of the water being alone in the boat and with no extra weight in the bow.
Now I have a 5.2 m with a 90 hp, 4ST, standing drive position, close to the stern. The result is similar. With the hydrofoil the bow stays low when starting and boat starts planning immediately. Planning speed is also reduced. The only con I found is that starting in a tight turn with the trim low has some strange results (difficult to get it straight).

[Spaco77]

I've got a 25hp on 3.5m, put the SE Sport on there, haven't noticed a top end difference, but really noticed the reduction in bow lift and much "punchier" out of the hole and on the plane. Also planes at lower speed. I'd expect you may notice some difference, but if you're nearing the capacity of your engine/hull, not going to fix that..

[Spaco77]

Also derdles suggested turn works well, we used to pull up 90kg adults on a wakeboard out in the surf using that method, with only a 25hp..