My experience/problems with a hydrofoil

[michaelsen]

My Regal 1800 with 4.3 Volvo I/O seemed a little heavy to get up of the hole and I added a Sting Ray hydrofoil.<br />My first experience was not good. It was loaded as usual and I expected it to slide right up on plane. I gave it almost full throttle and it started leaning to the right side. It did that until the boat started to plane and the more it cam on a plane the more it straightened up. After it got up I had difficulties trimming it right. It just seemed like I couldn't find the right spot. I reached my top speed (a quiet lake on a quiet day) at around 48 miles and it used to be 55-56 under the same conditions. While we were driving it with top speed, the boat made some strange slow movements from side to side. Everyone was sitting on their seats and there were hardly any waves at all. What the heck is wrong???<br />I have had homemade hydrofoils (aluminum plate) on my older boats and only had good results. I have never felt that side to side movement before. If it weren’t so ugly I would make my own foil again. The installation looks a little weird to me. I will bring my camera home to night and post a picture. The two fins on the hydrofoil are pointing slightly downwards, I guess, because of the shape of the caviation plate. Could that be the reason?<br />Any help and suggestions are appreciated.<br /><br />Regards<br />Mike

 

[sloopy]

Re: My experience/problems with a hydrofoil

you might want to get stronger fins. at that speed they are like paper in the wind, i like the origonal davis one, there nice and strng !!

 

[michaelsen]

Re: My experience/problems with a hydrofoil

Darn... new fins - more holes!!<br />Is that the Doel Finns you are talking about?<br /><br />The stingrays seems pretty hard though, BUT, if they are flexible in the water that will explain that side to side movement.<br /><br />I might try to make a pretty version of aluminum like I use to. That way it could fit the holes, I could paint them in the same color as the outdrive and do some experimenting with size and shape and they would be thinner and not cut as much of the top speed.<br /><br />Still I would like to get any possible input.<br /><br />Regards<br />Mike

 

[bmurray]

Re: My experience/problems with a hydrofoil

I have the SE Sport fin. Great hole shots, and no drag on top end. NOW I'm setup with the fin out of the water when fully trimmed. But never had a problem before this. Good luck.

 

[michaelsen]

Re: My experience/problems with a hydrofoil

I found some good info in a Whaler forum: http://continuouswave.com/ubb/Forum4/HTML/000130.html <br /><br />And I decided to order the SE Sport 300 from Cabelas (the link goes direct to the SE sport)

 

[sho305]

Re: My experience/problems with a hydrofoil

I would be very wary of having a fin that was in the water while on plane due to its shape or your drive height. It should not be in the water on plane, and I think this could be unsafe.<br /><br />Some fins are tilted upwards to the sides, maybe this is why.

 

[flashback]

Re: My experience/problems with a hydrofoil

Do fins make that much difference? seems to me that the manufactuer would just include them in the lower unit casting if the were something that truly enhances performance and speed...

 

[michaelsen]

Re: My experience/problems with a hydrofoil

I got the SE Sport 300 yesterday and installed it right away. It fit in the holes from the Sting Ray. <br />Wow what a difference! If the boat is not moving and I give it full throttle, then it jump right up of the water at 10-12 mph, which is only few secunds. Without any hydrofoil it was 20-25 mph and it took forever to reach that speed. <br />It was a bit wavy on the river yesterday, but I got it up on 55mph anyway and I am not sure I have had it on that speed before. I don't even think I had it trimmed right. (I had to slow down right away because of the waves) One thing is for sure though: that hydro foil does not cut anything of my top speed. No weird behaver either.<br /><br />BMURRAY, thanks a lot for the suggestion, I have a much better boat now.<br /><br />

Do fins make that much difference? seems to me that the manufactuer would just include them in the lower unit casting if the were something that truly enhances performance and speed... <br />

Yes, I have had the same thoughts but the fact is they do help. I guess if the manufacturer made a motor or outdrive for one specific boat they would make it fit, but the drives and motors are made to fit all boats and not all need the large caviation plate.<br /><br />Regards<br />Michael

 

[bomar76]

Re: My experience/problems with a hydrofoil

Have a Stingray on my Baja 184 w/ 140 HP 3.0 Liter Mercruiser.....what a difference! Boat just leaps to plane, is much more controlable while on plane, and trims out so much better. Downside? Lose 2-3 MPH off top end. They work well for my application.

 

[JS2]

Re: My experience/problems with a hydrofoil

I have a Stingray Jr mounted on a 15 hp Merc O/B which I use on an 11-foot inflatable. The hydrofoil works fine in this application.

 

[milklip]

Re: My experience/problems with a hydrofoil

I have a whaler on my boat. It seems to cavitate when you turn sharp at 3/4 speed. could it be causing it or helping. <br />The motor was not at the lowest hole on the mount. To get it there i would have to cut off two small tabs meant to hook over the transom, which is too wide for them. Could 1" make that much difference?