add-on kit hydrofoil for average aluminum "fishing boat" or even....

[Barry]

Use of non-OEM parts voids warranties all. the. time.

.

The Magnuson-Moss Warranty Act evidently covers boats as well. In the automotive sector it covers OEM manufacturers from voiding a warranty if you use parts other than OEM parts.
BUT only if the part that you installed/ or another repair shop installed did not cause the subsequent damage.
Say you installed a non-oem engine oil filter and the transmission fell apart. The manufacturer can not deny the warranty coverage on the transmission, or starter, or fuel pump, or etc.
In other words, if the non-OE part did not cause the failure then the manufacturers warranty will stand.

 

[JamesG123]

And you know who the mfg. is going to sic their lawyers on? The people who made that part. Which is why even aftermarket parts keep getting more and more expensive.

In this context (and no offense to Squiddy-Diddy) it would be as if someone sold you a reuseable oil filter that used a roll of toilet paper for its filter element. When you had the seized up car towed to the dealer, what do you think they are going to say?

 

[Squidly-Diddly]

I think you guys have been watching too much Perry Mason. Back in reality, there is a booming "very, very dangerous extreme sports toys" industry that has been thundering along for decades, and recently greatly expanded with WWW, Amazon, Ebay etc. How is at possible, since we know there are 1000s of victims, mostly with well to do legally savvy parents, including many actual lawyers as parents of victims??? Many underage victims will have gotten injured by mfg device without getting parental consent. Ditto ski resorts.

AFAIK, those standard "inherently dangerous, at your own risk" blurbs on the wrapper seem to be holding up 100% in court. Legally, I find that interesting because its SOP to spring that new legal condition on you AFTER you've bought it and spent considerable additional expense related to the purchase, AND I'm pretty sure many of these toys are "no returns".

That and the whole "you can sue my Corporation but you can't sue me".

Obviously, if motorcycles and even bicycles were invented today they would never be allowed on any public roads or sidewalks, and probably not on any private land with public access. But the Jet Ski and PWC industries exist, in spite of high rate of injuries do to dangerous design, and I'm sure if mfg were at all liable, just the deaths and injuries from innocent bystanders would be more than enough to put them out of business.

 

[JamesG123]

They do get sued all the time. Why do you think "very, very dangerous extreme sports toys" and even not so dangerous things, cost so much?

Do what you think you can afford. Just remember to think.

 

[Dejay]

Are hydrofoils really considerably more dangerous than planing boats or speedboats?

 

[JamesG123]

Yes and no, a foil can get on plane at a lower velocity/energy, but all of its lift, control, and stability comes from the foils, which are more vulnerable to failure.

 

[Dejay]

I guess the biggest issue would be some kind of control surface bug which makes the hydrofoil "trip" over itself. If it's designed so that this is possible.

I would assume the much smoother ride flying above the waves translates to less slamming loads and less material fatigue. I'd think you would feel saver on a boat that is just flying along on hydrofoils than on a boat that constantly slams into waves, and for a reason.

If you hit some log that breaks or hit even some weed that increase drag so you crash into the water, I guess it's possible you'd see much worse disasters. Especially as an addon you might rip the hull apart instead of an attachment point. So you might be right there.

But if you'd hit some obstacle, the ideal case the foil would either have some kick up mechanism, slice right through the obstacle or just shear off. So it's possible that the momentum that is imparted on the hull in a crash is much less than what would happen if you hit with the hull itself. If the hull is designed to allow a crash landing without failing catastrophically...

And are foils really more vulnerable to failure than a hull would be? They could be tougher and made out of stainless steel or carbon.

Since they fly higher and are more stable you can also see better what is in front of you.

 

[Doug Lord]

The biggest danger with hydrofoils is poor building and/or design. After that, junk in the water can be a big deal but not just for vertical lifting foils: vertical horizontal lifting daggerboards and rudders are also subject to damage on fast cats or planing skiffs.
----
One bit of nit-picking: most foils do not plane so they do not generically "get on a plane". However, some modern foils like DSS 1 & 2 can plane on the bottom surface of the foil. This is a relatively new phenomenon and does not apply to most lifting hydrofoils.
A couple of general characteristics of DSS foils:
1- one of the only foil systems for sailboats that develops only vertical lift-no lateral resistance,
2- DSS foils tend to be more lightly loaded than other foils. This characteristic allows DSS 2 boats like the Quant 23 to take off in very light air-5 knots. Not bad for a 23' keelboat!
DSS 2 full flying foil system-foil planing:

DSS 1 Foil Assist foil system:

 

[JamesG123]

pick at your nit pick. "on plane" in the context of a hydrofoil is when the entire weight of the craft is being supported by the foils. Not that they are skipping across the surface tension of the water. Or at least that was what I meant while trying to compare foiling and planing.

 

[Squidly-Diddly]

They do get sued all the time. Why do you think "very, very dangerous extreme sports toys" and even not so dangerous things, cost so much?

Do what you think you can afford. Just remember to think.

I've already checked this out, years ago. Presented an underwriter who also did ski resorts and jet ski rentals with a dangerous device and he said I should start with IIRC $5K for million dollar umbrella personal policy. I asked if I could get it in writing that it would cover me when I was operating a "pirate"(on public property without anyone's permission) extreme sports venue, including multiple injuries that might manifest years later, and he said "no problem". He had just written similar policy for a guy who wanted to drag people on their bellies on a piece of sheet steel across the desert behind a 4x4. I asked if there were any requirements for PPE and he said "no". "Would I be covered if I knowingly did something that broke LAWS on PPE, such as renting someone a motorcycle for street use in CA, without a helmet, as sole provider of equip?" "Yes, covered, umbrella means O.J. Simpson's Insurance paid for his lawyers because umbrella includes any liability for any crimes". And that is without any Corporation protections.

So short of a repeat of Nuremberg Trials, its really not a big deal and well sorted, and serviced by of tens of thousands of eager helpful Insurance Agents.

I guess I'd worry about CRIMINAL negligence, because of much greater likelihood of rogue DA/judge/jury, but not too much. I'd most likely be doing what the guy in the 1950s was doing, but with much lighter materials, and maybe even a few computer simulations.

 

[Squidly-Diddly]

One bit of nit-picking: most foils do not plane so they do not generically "get on a plane". However, some modern foils like DSS 1 & 2 can plane on the bottom surface of the foil. This is a relatively new phenomenon and does not apply to most lifting hydrofoils.

DSS 1 Foil Assist foil system:
View attachment 147367

On a diff note, I'd like to try skis attached to long-travel suspension to plane over rougher waters. The suspension would absorb some wave impact, and generally keep surface pressure the ski is seeing moderated. The skis themselves would be able to go deeper into waves without transmitting full force that a full planing hull would.

 

[DCockey]

Professional BoatBuilder No 172, April-May 2018 has an article about hydrofoil boats including the addition of an actively controlled foil system to a 1980's 24' Bayliner cabin cruiser.

 

[Squidly-Diddly]

Professional BoatBuilder No 172, April-May 2018 has an article about hydrofoil boats including the addition of an actively controlled foil system to a 1980's 24' Bayliner cabin cruiser.

I'm predicting that soon a major mfg will produce a mainstream "family" express-cruiser hydrofoil and it be "take the industry by storm" and be "boat of the decade" and "everyone else is scrambling to catch up" and "no one ever dreamed boats to do this", etc.

It will be able to hit a log at certain speeds and have the foils more or less break-away safely. For higher speeds, seatbelts and only sitting inside a safety-cage zone will be recommended.

 

[rnlock]

Seems to me that the real potential is in a softer ride and lower fuel consumption. I suspect going faster than existing motorboats would be much harder to do, and more dangerous.

I've seen video of followers that didn't throw very much spray. Not sure I've seen anything over 20 knots, though.

Seems to me that one way to install foils on a boat would be to put the foils on some kind of form fitting tray that the boat sits on.

 

[tspeer]

Grumman used to sell just such a kit. No form-fitting tray, but it was intended to bolt onto regular boats.