Posts: 3514
Location: Elk River, Minnesota | Hi Everyone,
Before I would go out and buy a hydrofoil, I'm curious as to what your "normal load" is when using the boat and what pitch and diameter prop you have currently on it. If you constantly have your rig weighed down with people, gear, livewell, etc, then I would bet going down 2 inches in pitch on your prop would make things perform better at all RPM ranges with maybe a mph or two loss on the top end. If the prop pitch is too high, getting on plane is much harder (especially with heavier loads), can cause porpoising due to too much pitch and not enough "umph" from the motor to keep the bow of the boat up. Going down in pitch is definitely a good move when loaded down....The reason being is that if you have that much load on your motor, you are forcing it to work harder (with the higher pitched prop), which will over time shorten the life of the motor. It is excess strain on all of the parts of the motor...not just the engine..
Many times, when you go down in pitch, you gain diameter...which means you have a bigger "ear" in the water, which results in more thrust (more surface area for water to grab).. It is very similar to what you see with the high-thrust motors like the yamaha T8 kicker, although the high thrust kickers have a very low gear ratio to turn those big ears.
A hydrofoil is designed to help keep your boat on plane at lower speeds. (why the ads always say you gain fuel economy) Many times, you will see them on under-powered boats because the motor on it's own is not strong enough to keep the boat on plane efficiently, and trimming up the motor is not an option due to porpoising (why the ads say you gain speed).
If the motor is reaching it's maximum RPM under your normal load conditions and you are still having issues of getting on-plane and staying there, only then would I consider a foil.
If your boat is a tiller-steered rig, I don't think you are too far off of your max HP range, so when adding people, gear, etc. will definitely slow the whole thing down from hole shot to top end. If the boat is console steering, it is well under-powered...a foil might be your only option in addition to a lower pitched prop.
No matter what you do, there will be a compromise involved of some sort. It is a matter of what you desire to get for performance out of your rig...
Good luck!!
Steve
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