posted 08-05-2012 10:31 AM ET (US)            

A bit later, after doing some reading on Continuous Wave I raised the engine significantly higher and installed a propeller recommended by Tom Clark. The improvement was incredible.

A couple of years later, just for fun, I removed the fin to see what difference it would make. It made no difference whatsoever.

My conclusion is that a fin provides no advantage to a Dauntless 16's performance if the boat has the right power, propeller, and engine installation. I SUSPECT the result would be virtually the same for just about any boat.

If a boat is underpowered a fin MAY improve performance but so will the proper propeller choice and engine mounting height.

Have we asked ourselves why, if a hydrofoil fin is a universlly wonderful device, outboard engine manufacturers do not incorporate them in their designs?

posted 08-07-2012 11:38 AM ET (US)            

I use them on our Striper 15 also with Evinrude 70.

On both boats, there is no noticeable difference in time to plane or operation at typical 20+ mph crusing speeds with or without the fins. But there is a noticeable difference in how slowly you can run on plane and how the boat handles at pre-plane plowing speeds.

posted 08-12-2012 02:15 AM ET (US)            

quote:

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Have we asked ourselves why, if a hydrofoil fin is a universlly wonderful device, outboard engine manufacturers do not incorporate them in their designs?

Butch

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I've asked this question silently to myself. And until I get a convincing answer, I won't spend hard-earned family treasure on one. My heavy commercial Montauk, (Alert 17) has one, courtesy of the previous owner. I'm thinking of removing it though as the less complex any system is for a given result, the better. If I notice any degradation in performance, I can easily put it back on since the holes in the anti-ventilation plate will still be there.

posted 08-12-2012 10:31 AM ET (US)            

We agree, a hydrofoil is not a "universally wonderful device".

I find fault with those who are quick to recommend a hydrofoil as a solution to everyone who has problems with fuel economy, hole shot, low speeds on plane, and who knows what. I believe they have their place and fill a need.

If a boat is minimally or under powered and a proper propeller, engine height adjustment, weight distribution changes, and knowledge of engine trimming needs do not provide satisfactory operation a hydrofoil may be the best solution.

If all else failed I would certainly try a hydrofoil before buying another engine to add needed horsepower. Trim tabs can also be installed if all else fails but given the cost they would be my last choice.

posted 08-12-2012 10:00 PM ET (US)            

No one has suggested that they should be on every boat from the factory. Once a boat has been fitted with a good prop and the engine height has been optimized, then a fin may be next step for some owners looking for quicker planing and also to help the engine keep the hull on plane across a broader rpm range.

posted 08-13-2012 09:59 AM ET (US)            

A hydrofoil fin does not necessarily provide quicker planing nor keep a hull on plane across a wider RPM range. The positive aspects of a hydrofoil fin do not apply to all applications. Some highly regarded contributors to this forum state in other threads that a hydrofoil fin can be a negative addition to an engine.

posted 08-14-2012 09:53 PM ET (US)            

Since you admittedly have only tried one fin on one hull, you hardly qualify as an authority on the subject.

posted 08-15-2012 10:41 AM ET (US)            

I suggest you read what I've written in this thread. I've clearly stated that a hydrofoil may be of some use on some boats some of the time. How hard is that?

You've just said a foil provides stern lift when water is flowing over it and that assists in planing and remaining on plane. I don't completely disagree. That is why some boaters like to use a foil when they are dissatisfied with hole shot. I'm not sure that a foil is very helpful for keeping a boat on plane. Generally, if a boat's engine is mounted at the best height, when the boat is "on plane" the anti-cavitation plate is at or above water level. In that situation a foil should be out or on top of the water, no? When a boat is plowing a foil may help it to plow at lower speeds. But, plowing speeds should be avoided. Old Salts have told me plowing is the most inefficient speed range in which small craft can be operated. Having a foil attached to the anti-cavitation plate would seem to simply add resistance to forward motion while plowing.

I admit to owning only one foil and to permanently removing it when it no longer served any purpose. That was after ensuring the engine was mounted at the proper height and was using a proper propeller. I've been around a lot of boats over the past fifty years and seen a lot of foils used. I've also see a lot of damaged anti-cavitation plates and a lot of anti-cavitation plates with holes drilled in them.

Having said all that, this is just a discussion and hopefully provides entertainment or possibly even education to participants and lurking readers. I respect your position while agreeing with most of it.