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Hydrofins/foils answers for Kusko
Posted by Brian Richardson on May 11 2005
I've used a few brands: the original "Doel-fin", "Cobra Edge" and the "Sting Ray"

The idea on these is to have less fuel consumption with less drag, get quicker out of the hole response by reducing what's called hole slap, reduce to eliminate bow-rising porpoising or bouncing for better ride & visibility, prevent prop blowout, and let you plane or get on step at lower speeds.  

All this from one piece of equipment?  Not exactly... but they do help out particularly w/ trim tabs added for lift on the boats and torque equalizers on the engine for better steering control - also for general tracking.

Hydrofoils/hydrofins are a water "on" water surface accessory.

Your problems sounds like the fin is hanging too low below the water surface or too high...  your motor may not be mounted at the best angle... and possibly you got the wrong sized fin for your HP rating.  

The next thing I'd check into is your prop to see if it corresponds (pitch, diameter, & blade area) to your engine and speeds you run at. Pitch & rpm have an inverse relationship - so you'll have to ask yourself, do you want more pop out of the hole (use lower pitch) or wide open top end speed (use a higher pitch).

One more example that could be your problem... too little blade area can be the cause of what is called blade-loading meaning that your prop may not be able to use the power transmitted from the engine.  

Try a cup-style prop.

Brian Richardson

Next: thanks for the response Kusko May 16 2005

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