The ever popular 'hydrofoil' topic

[needmoremoney]

My waterlogged '76 proline center console with its '90 evinrude 115 is back up & running. I ran it a couple times without its....20 year old....chipped & dinged flat hydrofoil. So i put it back on & it does appear to plane quicker, steer a bit more confidently & well....a question i can't find an answer to....
Which SHAPE is better-FLAT all around like the 'stingray' model hydrofoil OR FOLDED over ends like the 'whale tail' model?

I would imagine working with such a small 'area', difference would be negligible, if measureable at all. But i'm curious if there would, could, or should be any performance difference.

That said...or asked...how 'bout a bit further-the (relatively) THIN stainless steel 'whale tail vs THICKER plastic/composite designs-which would/could provide better performance?

 

[ondarvr]

The only thing a fin, and I call it a fin because the foil shape is just marketing to disguise the fact that plastic needs to be thicker than metal to do the same job, so the foil shape is useless.

​The only thing the fin really does is enlarge the anti ventilation plate on the motor, by making it larger you can possibly raise the motor higher without the prop pulling air from the surface during hard acceleration.

​It may also help by dragging in the water as you first take off, but it should be out of the water once on plane. Since it's supposed to be out of the water on plane the shape shouldn't have much of an affect when running at speed. Some boats slow down, or have scary handling if the foil drags in the water when on plane.

​If the fin curves, or turns down so that it drags in the water it may slow you down or cause odd handling, these are only possibilities though, sometimes that doesn't happen. Many times the actual shape has more to do with being different than the other similar products on the market than any actual performance objective, in other words it's marketing.

​Most of the time tabs are a much better solution to what people want fixed, but fins do have their place.

 

[82rude]

The ever popular waterlogged glass boat responds better using smart tabs.

 

[jimmbo]

If a larger anti-ventilation plate really did any good, the outboard manufacturers would be building the engines with them.

 

[Scott Danforth]

My waterlogged '76 proline center console with its '90 evinrude 115 is back up

Blah....blah..,blah


-which would/could provide better performance?

Restoring your boat and removing 800# of water would be the best performance gain over a gimick like the fin/tail, etc

You are carying your max capacity of weight in your hull without any of your stuff

 

[ondarvr]

If a larger anti-ventilation plate really did any good, the outboard manufacturers would be building the engines with them.

[FONT=&quot]I always chuckle at this response, and that's not a slam at you, it's that a motor manufacturer builds a motor that will do 80% of what people want fairly well, they have no control or idea of every need or desire of each boater, so building something that is perfect for every application is impossible. Why don't the motor manufacturers put hydraulic jack plates on stock, or racing lower units, or a perfect SS prop that will work on every boat made. All of these “aftermarket” products can help to fine tune and improve performance if used correctly, but they don’t come stock either.

​There are so many misunderstandings of what a fin is supposed to do, and actually can do, that it's almost impossible to have any type of informed conversation about them, all it is a "I hate them and they shouldn't exist”" stance from those that feel they don't like them. Those opinions are frequently based on a complete misuse of the product in a way that it virtually guarantee's it will fail, then they say "see, this is proof they don't work". [/FONT]
[FONT=&quot]A fin has a very limited use, and they’re rarely used in the correct way, and it’s just another tool that may help to achieve some goals for certain boaters, the idea that it’s a bolt on and go fix-all for every problem a boater may have is where they get the bad reputation.[/FONT]

[FONT=&quot]The OP asked about the shape of the fin, and if it can affect how it works, and can some shapes work better than others. It’s a good question that deserves to be answered, if people have input please respond.[/FONT]

[FONT=&quot]Signed……not a lover of fins, it’s just another tool in the box that may have some legitimate uses.[/FONT]
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