Hydrofoil/Whale Tail Good or Bad

achris

achris

More fish than mountain goat
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jimmbo said:
...


Many workers have died because of that Ideology. I would like to see management, executives, and owners placed in Prison, for what it is. Premeditated Murder
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Research 'corporate manslaughter'. It's been a thing in the UK since Piper Alpha... (The Cullen report)
 
EZDuzIt

EZDuzIt

Seaman
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Aug 29, 2021
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harringtondav said:
My opinion: Band aid for under powered, or poorly designed boats, waterlogged boats, etc. If you're stuck with one of these, try one. If it helps, keep it. If not, pitch it. ...less expensive than anticavitation plate repair.
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It came with and on the boat when we got it last year and I've never run it without it. My boat is a 76 Apollo tri hull with the Mercruiser 165 straight six so it has plenty of power. I have a 15x17 pitch prop on it too which seems about perfect for how I typically run the boat. I took the hydrofoil off today and we're taking the boat out Tuesday so we'll see how she does without it. Taking it and the bolts with me just in case. Tri hulls hve always had a pretty easy time getting on plain that known of. My buddy has one with way less power than mine has and it has no problem getting out of the hole.
 
harringtondav

harringtondav

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achris said:
"This hydrofoil is designed to be fitted to engines with a minimum increase in installation height of at least 1" above normal."

Why is that important? Because with the increased height, the foil will come out of the water once the boat is planing! And once out of the water it no longer exerts force on the engine/boat. It's no longer generating lift, putting excess pressure on the AV plate or generating bow steer.

Hydrofoils have there place, but it's not on most boats, unless they are specifically set up for one to be installed.
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Stating the obvious here, Chris. This tells me hydrofoils shouldn't be installed on any I/O boat since they're generally set up with the AV plate even with the keel, and the AV plate is under water at planing speeds. Correct?
Seems O/B boats can be adjusted to comply by raising the motor.
 
EZDuzIt

EZDuzIt

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jimmbo said:
In my eyes, they shouldn't be installed on any motor.
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After reading everything in this thread, watching multiple videos and reading reviews I have taken the 'foil of off my outdrive. I'm very interested to see how it performs tomorrow when we take the boat out for some fun on the water for my wife's b day. I'm taking the 'foil and its bolts with me just in case. I'm expecting actually better handling and performance without it after quite a bit of research. My boat has plenty of power so not sure why it was ever put on in the first place. Now I may have holes to fill on my AC plate.
 
achris

achris

More fish than mountain goat
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Messages
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harringtondav said:
Stating the obvious here, Chris. This tells me hydrofoils shouldn't be installed on any I/O boat since they're generally set up with the AV plate even with the keel, and the AV plate is under water at planing speeds. Correct?
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Got it in one!
harringtondav said:
Seems O/B boats can be adjusted to comply by raising the motor.
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Give this man a cupie doll.
 
flashback

flashback

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Achris was being nice, that large foil is helpful on a sailboat known as a keel..
 
harringtondav

harringtondav

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EZDuzIt said:
I was just thinking some two part epoxy and a black Sharpie 🤔
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JB Weld is two part epoxy...with metal dust as a binder. Cosmetics are secondary. Filling the holes to seal the bare aluminum against further corrosion is primary. Tape off the bottom of the holes and fill with a two part of your choice. Wipe off the excess with a rag saturated with acetone or xylene quickly as it will soften the paint. ...worry about the cosmetics when you sell the boat.
 
achris

achris

More fish than mountain goat
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harringtondav said:
... Cosmetics are secondary. Filling the holes to seal the bare aluminum against further corrosion is primary.
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Indeed. And interestingly, small uncovered areas of less noble metals accelerate corrosion on those areas.

It also appears as though suppliers (Merc etc) have place cosmetics above practicality in this case. We see nice shiny stainless props and fully cover (with paint) aluminium housings. Slightest scratch in the paintwork and all the galvanic current pours into it, making a tiny area take all of the corrosion. Ideally the prop should be fully covered and the drive housings left bare... Sounds counter-intuitive, but it's actually the 'right' way to minimise galvanic corrosion. Learnt that on my subsea inspection controller (3.4U) course MANY years ago....

Chris.......
 
EZDuzIt

EZDuzIt

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The verdict is in. I'm putting the hydrofoil back on. Granted my boat is not under powered and it's propped perfectly for its general use but....when towing a tube it worked harder to get up on plane and just didn't handle quite as well. It also took waves quite a bit harder. Running without the 'foil was the roughest ride I've ever experienced since owning the boat. It's a VERY noticeable difference running with and without it. I did gain about 3 mph of top end but I rarely run it WOT. Its cruising speed was pretty close with and without. Fuel consumption was about par. I must say it sounded awesome without it. I can hear the exhaust note a lot more without the 'foil. All things considered I definitely prefer the 'foil being on. I'll be using Lock Tite as well as lock nuts to secure it as I don't anticipate ever taking it off unless I have to. It does have four bolts where I see a lot of others only use two. I'm not too worried about it coming off. My AV plate is also quite thick but my boat is a 76; back when things were made a lot better. I thank you all for your time and opinions. I found them all to be quite valid and helpful. It's definitely a "to each their own" kind of thing. Cheers.
 
Scott06

Scott06

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EZDuzIt said:
The verdict is in. I'm putting the hydrofoil back on. Granted my boat is not under powered and it's propped perfectly for its general use but....when towing a tube it worked harder to get up on plane and just didn't handle quite as well. It also took waves quite a bit harder. Running without the 'foil was the roughest ride I've ever experienced since owning the boat. It's a VERY noticeable difference running with and without it. I did gain about 3 mph of top end but I rarely run it WOT. Its cruising speed was pretty close with and without. Fuel consumption was about par. I must say it sounded awesome without it. I can hear the exhaust note a lot more without the 'foil. All things considered I definitely prefer the 'foil being on. I'll be using Lock Tite as well as lock nuts to secure it as I don't anticipate ever taking it off unless I have to. It does have four bolts where I see a lot of others only use two. I'm not too worried about it coming off. My AV plate is also quite thick but my boat is a 76; back when things were made a lot better. I thank you all for your time and opinions. I found them all to be quite valid and helpful. It's definitely a "to each their own" kind of thing. Cheers.
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That is exactly what I saw on my boat with/without the foil.

I would keep an eye for stress cracks. Your MC1 cavitation plate isnt't any stronger than the one on my alpha one that cracked at the holes. I never thought about it until after my plate cracked off..
 
A

airshot

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There are times when they help, trying one is the only real answer. Get the load balanced as well as you can before adding gizmos, these should be a last result.. Unfortunarely some folks run out and buy one just because they see other people with one. Like anything, therevis a time and place for them. Just adding one when it isnt really needed usually draws negative reviews, however when it is truly needed, they get positive reviews. Like anything they can be abused.
 
EZDuzIt

EZDuzIt

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Scott06 said:
That is exactly what I saw on my boat with/without the foil.

I would keep an eye for stress cracks. Your MC1 cavitation plate isnt't any stronger than the one on my alpha one that cracked at the holes. I never thought about it until after my plate cracked off..
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Did yours have two or four bolts? I see a lot of 'foils that only have two which would create more stress on the cav plate. I gave mine a real good look over and it is free of any cracks.
 
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