Running a Hyfrofoil on an older 1970's Merc. To drill or not to drill?

[Roadblock]

Just wanted a quick opinion.

I had a bit of weight in the back of my boat and yes I realize I can move my fuel tank and batteries to the front but my friends all swear by the SE 300 and SE 400 Sport Hydrofoils. I prefer the no drill option simply for not drilling but I have one mounted right now (just bought it lastnight) and the rubber pieces that hold it don't have much bite.

The bolt on option looks MUCH more secure but my concern it drilling into a 1970 Mercury 500 Thunderbolt cavitation plate and having other issues like breakage down the road. Is this a legit concern or am I worried about nothing?

To drill or not to drill?

 

[Georgesalmon]

I have a '79 115 merc with 3/8" holes in it from a previous owner. The lower unit is fine and has no cracks in it. So I think you'll be fine. Though for clarification I am NOT a believer in hydrofoils myself.

 

[Roadblock]

Do you mind if I ask why? Have you ever ran one?

I ask because I was reading another thread where someone mentioned not believing they worked right and about 20 other different people disputed that fact and swore up and down they noticed a huge improvement with one on there. One guy said he never believed in them but had bought a used one with one on there and had taken it out a few times with it on. Then it took it off because he felt they made no difference but after taking the boat out again he wouldn't get the thing back on fast enough and now he has them on all of his boats.

I did not see many people against them actually which is why I'm curious about your reasoning.

 

[Georgesalmon]

Back in the day I did run two different foils on two different boats. One was on a 40 and used it to get the back end up. I guess it worked a bit but when I took it off and used trim tabs I gained top end. On the other boat with a 115 The boat came that way and when I took it off I again gained performance. Just think its not the best idea to add extra strain on my motors that were not designed for that. Good luck to those who like them, Just not my style.

 

[Texasmark]

I never wanted holes in my engine and from a design standpoint, the engine AV plate was not designed to support the pressure imposed upon it by a tail....opinion.....which was the second reason I never ran one. The third is the answer to the question: Are you just adding drag, or does the performance of the addition enhance overall performance to the point where you gain?

Mark

 

[Roadblock]

Well the issue I have is that I just can't plane. I would rather not run one just from the standpoint of they are kinda bulky and in the way.

I'm a pretty big guy and if I go out on my own, it never planes. If I get someone else who is roughly 200 pounds on the boat and get them to sit as close to the dash as possible or climb under into the bow I might get it to plane after a couple hundred feet at WOT.

Even if I shifted my gas tank and two batteries to the front, it wouldn't add enough weight to the bow to help so I thought it might be worth trying.

I picked up an SE Sport 300, figured I would just drill because apparently people loose the non-drill type. Going to give it a try this weekend as if it doesn't help, I'll just pull it and fill the holes with some aluminum filled/mixed West System.

 

[jheron]

I wouldn't hesitate to drill holes and bolt it on if I wanted to try one.
That being said I would not use one, I recommend smart tabs instead. They work great.
Cheers,
Jon

 

[Roadblock]

So I thought I would give an update.

I picked up the SE 300 Sport and ran it for two full day of boating. I definitely noticed a difference. The boat planed quicker and it also planed as expected with a passenger near the back by the splash-well. Guess it worked as it should.

I did drill to install the thing but it was a very simple and clean install.

That said. I then removed the foil and tried just having my passenger sit next to me while I drove and it planed just as fast as with the foil.

So in closing I can plane the boat with both passengers sitting near the dash or I can plane the boat with the foil and anyone can be anywhere they wish.

Due to the increased size of the foil being there I think I'm just going to not run one and make my passenger sit more towards the front.

If I ever want to put one back in, the holes are there and its ready to go.