Help me out, guys...

I have a Skeeter SS90 pushed by a Yamaha 80hp with a SS prop. The motor works great, and since the 90 is a short boat, I get up on plane real quick.

A friend of mine gave me an SE Sport Hydrofoil. Will it improve performance? Alter my trim? Just what will its effect be and do you consider one a major improvement on a boat.

I have one on my boat a 20ft Wellcraft center console with 115 Evinrude. However the Wellcraft is VERY heavy..........hydrofoil helps it get up on plane. Dont know if it would help your boat? also regardless of what you hear, it will affect the top speed a little bit, but it also will get the stern out of the water faster. ??? your boat ???

You say your boat gets up on plane really quick, so that is not a reason to install one. The other reason/benefit of using one would be to run on plane at much slower speeds, such as pulling kids on tubes. That was a hidden benefit for me after I put one on mine. The main reason I wanted one is to come out of the hole very quick and it does just that better than I expected. I use a lot less gas when pulling skiers because I don't have to drag them thru the water like before. I notice the gas savings at all times because I don't have to stay full throttle out of the hole, about 2 seconds tops as opposed to 6-8 without it. I still get the same top speed and WOT rpm's my motor recommends with it on also. I am not using the brand you have though. It is an Attwood "V" shaped hydrofoil. Some will say that if you have the right prop, you wouldn't need it. Been my observation that no prop does all things. A perfect prop tuned by a top notch prop man might do it, (but I doubt it cause I aint seen a prop that gives the highest top end speed with top end rpm's that will also get out of the hole in 2 seconds) but it will cost you mucho $. For about $30, mine is fixed. Just my opinion and experiences.
If your motor is still under warranty DO NOT INSTALL ONE! . It will void your warranty.

I have the same boat as Boatman1. I had to install one on my 130 Johnson to stop the nose from porpoising (sp) so bad. Rides much smoother and I get on plane with less speed. I think I lost about 2mph after I installed it, but I rarely run WOT unless I am chasing Don the Angler around Lake Lewisville.

If you have the $$$ Trim Tabs work better and are tunable for any condition. Depending on the boat they may be over kill for the $$$. (I almost forgot you already have the fin. Can't beat the price.)

I have a 189 TSpecial Bluewave tunnel hull. I love the boat, but hated it before I put my turbo lift on it. Turbo lift is a hydrofoil, but it is made of stainless steel and clamps on without having to drill holes. They are made by Grand Island Marine in Florida. I can get my boat and 115 yamaha up in 12" of water as long as I'm not over oysters. I won't ever have another tunnel hull without a turbo lift.