Crazy Dinghy Ideas

mckenzie.keith

Aspiring Anarchist
674
203
Santa Cruz
No matter how high you pump up your inflatable mast a compressive force component remains. Given that the modulus of elasticity, length and moment of inertia remain unchanged then the tendency to fail by buckling remains (Euler). That is my guess, anyway, after giving it 1 minute of inebriated consideration. Then again, clown-made balloon swords do seem to be more lethal when fully inflated.
Realistically, for a mast with stays, yeah for sure. But in theory, if the inside is pressurized high enough and the diameter is large enough, the closed off ends will be trying very hard to get away from each other and this could keep the entire tube in tension when it is just sitting there, couldn't it?
 
McKenzie said:
" if the inside is pressurized high enough and the diameter is large enough, the closed off ends will be trying very hard to get away from each other and this could keep the entire tube in tension when it is just sitting there, couldn't it?"

That's a good summary. I've been thinking of where else do you find long thin pressurised cylinders? Can only think of aircraft fuselages at the moment. They undergo twisting and bending, so maybe the maths to analyse them could be extended to the pressurised mast idea?
 

El Borracho

Verified User
6,664
2,642
Pacific Rim
Realistically, for a mast with stays, yeah for sure. But in theory, if the inside is pressurized high enough and the diameter is large enough, the closed off ends will be trying very hard to get away from each other and this could keep the entire tube in tension when it is just sitting there, couldn't it?
Yeah, thought provoking. Simply determine if your mast member is isotopic or orthotropic then digest this simple research paper and you will have your answer…
 

Foredeck Shuffle

More of a Stoic Cynic, Anarchy Sounds Exhausting
Many older classes that you sit in not on, have buoyancy bags.. perfect for filling with helium..
Let's stay with hydrogen, better numbers. I could not find the cost of helium versus hydrogen but I'm guessing with global helium shortages and so many efforts to make hydrogen a commercial and consumer fuel it will be less expensive now and into the future. So blow up those bouyancy bags and hulls with hydrogen.

Hydrogen density at 26 degC and 1 bara:
0.081 kg/m3
0.00506 lbm/ ft3
0.000676 lbm/gal(US liq)
0.1571x10-3 sl/ ft3
Hydrogen specific weight at 26 degC and 1 bara:
0.794 N/m3
0.00506 lbf/ ft3

Helium density at 26 degC and 1 bara:
0.1602 kg/m3
0.01 lbm/ ft3
0.001337 lbm/gal(US liq)
0.3109x10-3 sl/ ft3
Helium specific weight at 26 degC and 1 bara:
1.571 N/m3
0.01 lbf/ ft3
 

Steam Flyer

Sophisticated Yet Humble
44,189
9,576
Eastern NC
H2 and H3 are easy to make. All you need is a source of DC current and a funnel.

Keeping it where you want it, that is the more difficult task. It will seep right thru almost anything that is "airtight." I handled elemental hydrogen as an industrial gas and it's the devil even without the explosion thing.
 

nota

Anarchist
balloon airfoil shaped kite floated by H2

no mast no flip cat/kite boat

yes H2 leaks out of anything
but as water is H2O you have an unlimited supply
just move to spin a prop to make el tricks to get H2 free
pump into a gas tank for later use

my crazy idea
 

skslr

Member
217
42
Germany
What ever happened to this? I'm guessing it was great in light air and perhaps not as much in heavy?
Sorry I read about it a long time ago and cannot remember exactly what the article said. I believe the bow was closed later on.

The only thing I could find now was this:


The flaps at the bow on the other picture are also interesting :)

I would think, that in light airs it would not make a lot of difference unless you try to move the weight forward to reduce wetted area at the transom so much that the hole becomes immersed. Then it would create a lot of additional drag...

In heavy airs the extra water sloshing through the cockpit would be extra weight and make the boat less stable I would guess...
 

Dex Sawash

Demi Anarchrist
2,570
796
NC USA
^ maybe with careful rocker distribution, the surge of water through the inside could become propulsive (if that's a word)
 

skslr

Member
217
42
Germany
As I am lazy AND cheap, I would like to see some new building methods "IKEA style" without glueing/sanding for a proper doublehanded dinghy.

Maybe from materials like these?

A German sailing magazine published a huge story about the IKEA dinghy "Seglar" but it turned out to be an well prepared april fool joke.

 

JimC

Not actually an anarchist.
8,171
1,064
South East England
Sorry I read about it a long time ago and cannot remember exactly what the article said. I believe the bow was closed later on.
There have been some odd Nationals. There was one at the dinghy show one year that looked as if a snake had swallowed a selection of geometric solids: lumps and bumps everywhere so as to hit every measurement point but have the bare minimum of boat between. Its debatable whether rule writing is a sufficiently precise art that the measurement points are all that critical.
 

martin 'hoff

Super Anarchist
2,174
1,050
Miami
3 silly ideas.

Pump a Tiwal 3 with helium. A proportion that's calibrated to the sailors weight and overall "all up" weight? If you capsize and lose the mainsheet, you'll have to go catch that stray balloon with a helicopter. Lol.

Screw in a lifting foil from a wingfoiling board – some of those boards are inflatable thanks to a rigid "box" where the foil screws in - so "splice" such a box where the daggerboard trunk is now.

Add a T rudder - or just a long rudder. The wingfoiling foils have a canard setup already.

Ride height control via "weight shift control" (WSC) as done on airliners. The wingfoiling kits with canards are well designed to control ride height with weight/balance. There's no "active" flap – this is way simpler/cheaper/sturdier than a moth/wazsp/ufo foil. They are surprisingly sensitive to operator movement.

Ok, so then how about a moth-like sprit and "wand" with a weight that travels fore-aft – in a "perfectly lubricated tube" – to control pitch and therefore ride height. The sailor still leans aft for takeoff, and might need to scuttle around a bit, but the wave-by-wave action is handled by WSC.

(If it helps, WSC is also how hang gliders are controlled.)
 

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