Hydrofoils

R

Roy

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Jan 1, 2000
RO Number
114
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186
SE Sport (Sport Marine Technologies) claims their hydrofoils will absolutely improve fuel economy. Anyone with some experience?

Thanks................Roy
 
I cant comment on Sport Marine, but many years ago I installed a hydrofoil on my Carver 2557, 5.7 litre Mercruiser single screw and my fuel economy greatly increased. I can get on plane quicker and can run at lower RPM when on plane, which accounts for the fuel savings..
 
Definitely helped out on my 18 footer with a Mercruiser 3.0. I can't say if there was any fuel economy, but hole shot definitely improved.
 
Used a Doel Fin on my 21' Wellcraft years ago, and loved it! Far better on bow rise and stability, but don't remember any economy.
 
Just try to remember to have a bit of positive trim when backing.
 
I've had experience with a hydrofoil (16' Sylvan) and with self-adjusting trim tabs (on the same boat, and on a 21' ProLine WAC). Tabs are better. Bennett and Nauticus both sell fairly inexpensive, self-adjusting tabs. And they work well on small boats.

Before you add anything, what issue(s) are you trying to solve? If you're just adding 'something' to get better fuel economy I think you'll be disappointed.

My .02
 
Tabs will help you get on plane then they can be retracted to lessen drag. The hydrofoil is with you always and so is the drag. JMO

Padraig
 
There's a difference between hydrofoils and trim tabs or wings on an outdrive. True hydrofoils will actually lift the boat out of the water. I know of large commuter type boats in both Hawaii and Hong Kong. Come to think of it, the americas cup boats all had hydrofoils.
 
Thanks, Charlie, I was talking about the wings mounted on an outdrive or outboard.
 
I am looking for improved fuel economy. It's a 25 footer with a single 5 liter Mercrusier. The boat has Bennett trim tabs.

Thanks.....Roy
 
They will help you plane faster, but that's the only fuel savings you'll get.
 
"I am looking for improved fuel economy. It's a 25 footer with a single 5 liter Mercrusier. The boat has Bennett trim tabs.
Thanks.....Roy"

To achieve greater stern lift and improved economy at mid range speeds I have had great success by switching to a 4 blade prop.
This gives the results without stress and drag on the outdrive/outboard.
In cases where the stern was very heavy adding the 4 blades and then smart tabs as pointed out above made a huge difference in performance.
 
Interesting about the 4 blade prop. Mine is a 3 blade stainless.
 
Have you calculated your prop slip? That will give you an indicator if a new prop or maybe reworking yours will improve fuel useage. You can find slip calculators on line.
 
If the boat has Bennett adjustable trim tabs, used correctly to optimize performance at various speeds and attitudes and sea conditions, I really doubt any new attached "foil"/wing on the lower unit will help enough to make it at all worthwhile.

If you switch from 3 to a 4 blade prop, and all other prop characteristics remain the same, and present prop was optimum size , you would want to go down in pitch about an inch I believe to compensate for the add'l blade drag.
 
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