Home made Hydrofoil Boat, Potential for a Coaching Launch?

[Valgozi]

Just came across this video on Youtube - https://youtu.be/t3eX507Xi_I

Quite an awesome little boat, almost no wake as well once it is up to speed.

Small electric engine on the back could it be an option for very quiet but quite nippy coaching launch?

Just wondering how stable and maneuverable it would be on corners?
The hydro foils seem to be a set angle would this cause any issues?


Carl Douglas what do you think of the construction?

[Valgozi]

This design on the Dyson Awards website of a Quad is quite interesting.

http://www.jamesdysonaward.org/projects/quad-scull-hydrofoils/

It looks to retrofit Hydrofoils on to a rowing boat with reinforcement of the washboard.

[marko....@gmail.com]

Interesting. The crucial question is at what speed it gets up on it's foils, if it is much faster than a rowing shell (I suspect so) how much use will it be? At displacement mode it will create far more wake than the Dart 16 hash-up cats that get made.

I also suspect that it can only go at one speed on it's foils since there does not look to be any manual or auto-trim adjustment. This is why it took the Moth class so long to get it to work: as the boat goes faster and the foils produce more lift that the weight of the boat so they end up popping out of the water and the whole boat topples over. This means they have a 'wand' that floats on the water surface and auto-trims the main foil. Even this isn't enough though and they also constantly play the manual trim on the rudder foil to change the boat pitch.

[Henry Law]

On 04/05/16 10:04, Valgozi wrote:
> Small electric engine on the back could it be an option for very quiet but quite nippy coaching launch?

Would it have enough power? In the film the outboard seemed to be
working quite hard to get the hull out of the water.

But this interested me just as much:
https://www.youtube.com/watch?v=tvlS-4t54cc Motive power just two human
beans, and they don't look to be exerting themselves too much. The
whole thing looks a great deal easier than racing shells with foils.
Because of the start-stop nature of the rowing stroke, I suppose.

--

Henry Law Manchester, England

[marko....@gmail.com]

This foiler design is interesting http://www.dailymail.co.uk/sciencetech/article-2820117/Future-speedboat-Electric-catamaran-flies-water-25mph-without-making-noise.html

C shaped foils have more drag but the faster is goes the less foil is in the water so it self regulates a bit.

[carl]

On 04/05/2016 22:38, marko....@gmail.com wrote:
> This foiler design is interesting http://www.dailymail.co.uk/sciencetech/article-2820117/Future-speedboat-Electric-catamaran-flies-water-25mph-without-making-noise.html
>
> C shaped foils have more drag but the faster is goes the less foil is in the water so it self regulates a bit.
>

Not a bad description of the foiling process except this:
"This turning of the water causes higher pressure on the bottom and
reduced pressure on the top of the foil."
No, there is probably no (or minimal) pressure increase under the foil.

I've been reading about this Slovenian project for a couple of years.
The publicity is excellent but does it actually exist as a product, what
is the speed/power consumption to get it foiling, is it viable (does it
perform to spec?) & what's the sale price?

I guess it'd make short work of any swimmer who was minded to interrupt
a Boat Race.

Cheers -
Carl


--
Carl Douglas Racing Shells -
Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
Write: Harris Boatyard, Laleham Reach, Chertsey KT16 8RP, UK
Find: tinyurl.com/2tqujf
Email: ca...@carldouglasrowing.com Tel: +44(0)1932-570946 Fax: -563682
URLs: carldouglasrowing.com & now on Facebook @ CarlDouglasRacingShells

[sully]

Significant tradeoffs just to get to nearly no wake, where catamaran launches seem to achieve tolerable wake limits. My sense is the cat launches could be built to cut wake a lot more at eights speed with some hull redesigns, but current wakes are a huge improvement over the past tin launch, PT boats, and whalers.

Coaching launches are constantly hitting debris in the water. This would appear to be catastrophic to a hydrofoil boat.

Most launches are selected for their ability to rescue crews in the water, not an option for that tiny boat.

[Henry Law]

On 05/05/16 15:51, sully wrote:
> Most launches are selected for their ability to rescue crews in the water

Esteemed Sully, it's not often that I disagree with you but now is one
of those times. Most of the launches I see are not thus selected,
unless it was assumed (a) the crews to be rescued consist of not more
than two people, and (b) the rescue boat crew is very skilled at getting
them in over the transom and thus avoiding capsizing the launch.

Last regatta I was at the safety launches were plastic affairs about
twelve or fourteen feet long, capable of safely carrying I guess four
people. And they each had a crew of two! I suppose that might be the
regulation, but it makes having a boat that size a bit of a pointless
exercise.

Quis custodiet ipsos custodes?

[sully]

interesting. This has to be a difference between sides of the pond.

[Valgozi]

This is what happens when coaching launches start to try to rescue crews in the UK -
https://www.facebook.com/eveshamrowingclub/photos/a.10151360128406434.1073741825.28464981433/10151360150071434

https://www.facebook.com/eveshamrowingclub/photos/a.10151360128406434.1073741825.28464981433/10151360149791434/

At one point both people on the launch almost went in :-D

Our regatta has proper inland life boats for rescue, from - http://www.sara-rescue.org.uk/

When out training, the river bank is always reached before a safety boat could get to us, and in a lot of the river we could just stand up. The mud stinks as I found out last year.

I was thinking of a coaching launch that could go past moored boats at a speed that would keep up with a rowing boat with no/little more wake than a rowing boat. Currently our twin hulled coaching launch has to slow every time there is a boat moored, so it gets somewhat left behind.

The video I posted seems to have a follow up "coming soon" after he has further engineered it. That first one is just for straight lines it seems.