Multihull microcruiser design (capsize approach, vol 2)

[montero]

In answer to my own question ;
a. if no bridgedeck - then probably acceptable ?
b. with bridgedeck - probably pretty poorly. ?

After @magwas "capsize" thread , I started thinking about small cat recovery .
I came up with 7 ways, 3 are worth considering. 1 seems logical to me.

 

[Robert Biegler]

Any idea how fast you would be able to move (with kite) inverted ?

In answer to my own question ;
a. if no bridgedeck - then probably acceptable ?
b. with bridgedeck - probably pretty poorly. ?

I don't think a kite boat needs the form stability of a multihull. Anne Quemere went with a monohull with a voluminous roll bar that makes the boat unstable upside down:

Another good configuration for a kite boat is a proa, possibly with a modest, easily lifted leeward ama. With the weight mostly in one hull, righting becomes easier.

So I think there are easier alternatives than working out how to sail a kite boat upside down.

After @magwas "capsize" thread , I started thinking about small cat recovery .
I came up with 7 ways, 3 are worth considering. 1 seems logical to me.

Would you elaborate?

 

[Will Gilmore]

If you consider kite sails, the control lines would move along a traveler to the leeward hull, on a multi-hull, and the sails, at least, would contribute more to righting while under way.

Of course, if the kite gybed, it might actually pull a multi-hull over. However, a gybe with a kite seems highly unlikely. That kind of wind shift would more likely result in the kite diving into the water instead of a sudden shift of tack.

For righting a sailboat that has gone turtle, maybe the masthead is where the airbags should be deployed. Once a sensor is submerged in seawater, the large balloon bag stuffed inside the mast would eject and inflate to keep the masthead at the surface. Could a kite be used to fully right the boat by pulling upward on the masthead?

I don't think the airbag need be overly heavy. Not expecting the inflated rescue bag to withstand days in the sun or filled with air/CO2, the weight could be kept to a minimum so the apparatus doesn't negatively affect the weight aloft too much. Maybe a reflective mylar foil so it can aid in radar reflection too.

-Will

 

[montero]

I don't think a kite boat needs the form stability of a multihull. Anne Quemere went with a monohull with a voluminous roll bar that makes the boat unstable upside down:

Another good configuration for a kite boat is a proa, possibly with a modest, easily lifted leeward ama. With the weight mostly in one hull, righting becomes easier.
Hug baby wombat. robert heavy weekend.
So I think there are easier alternatives than working out how to sail a kite boat upside down.


Would you elaborate?

 

[montero]

Hug the baby wombat.

 

[rob denney]

I don't think a kite boat needs the form stability of a multihull. Anne Quemere went with a monohull with a voluminous roll bar that makes the boat unstable upside down:
Another good configuration for a kite boat is a proa, possibly with a modest, easily lifted leeward ama. With the weight mostly in one hull, righting becomes easier.
So I think there are easier alternatives than working out how to sail a kite boat upside down.

Too true. A kite boat is very hard to capsize, a kite proa near impossible. All the loads are on the deck. As long as the extension of these loads is equal or above the clr, you can't capsize.
Kites are the future of low cost (no mast, sails, battens, standing rigging, deck gear and the beefing up they require), safe, wind powered boating, but launching, retrieving and keeping them out of the water need to be resolved.
We are playing with them on a couple of boats as tests for the 3,000 kg/6,600 lb 24m/80'/cargo proa, servicing remote Pacific villages. We solve the launch/retrieve/water problems by flying on short lines using a mast. The latest version has reduced the mast to 2m high, which is more elegant and less drama than a 12-15m mast. I hope.
On the 8.5m long tender to the cargo proa.

On a 15m/50' Harryproa
SS_solo.mp4

A long strings kite on a 7.5m Harryproa. The kite is attached to the long, leeward hull. The boat is steered by moving the attachment point along the hull. Works well, as long as the kite is pulling. A paddle is occasionally handy.

 

[montero]

Would you elaborate?

It's 8 ways already.Boat will be only 7.5m long , easy crossbeam disconnet .
1. disconnect one float and use some lift bag.
2.disconnect two floats and as above.
3.hug the baby wombat.
4. use kite and outboards to create opposite force.
5.use kite and portside mast to flip.
6.hug the baby wombat.
7.hug the baby wombat.
8.hug the baby wombat.
Gemerally speaking generally speaking hydrostatic , hydrodynamics , float flooding .
regards

 

[montero]

I don't think a kite boat needs the form stability of a multihull. Anne Quemere went with a monohull with a voluminous roll bar that makes the boat unstable upside down:

Another good configuration for a kite boat is a proa, possibly with a modest, easily lifted leeward ama. With the weight mostly in one hull, righting becomes easier.

So I think there are easier alternatives than working out how to sail a kite boat upside down.


Would you elaborate?

I think the biggest problem is the mast. I distinguish two situations:
1 we sail in strong winds and capsize .
2 we prepare to incoming storm , folding the mast and rely on engines before full storm power.
No1 events are mostly destructive especially when the cat is bigger than hobbie .
Masts are cumbersome in rough weather , lightly speaking.
Maybe this is biggest concern . Maybe some mast-failsafe solution is most difficult. Freestanding ones have more chances to survive .
Applying some controlled brake joint is much easier.

 

[Will Gilmore]

I think the biggest problem is the mast. I distinguish two situations:
1 we sail in strong winds and capsize .
2 we prepare to incoming storm , folding the mast and rely on engines before full storm power.

If you fly the kite from a mast, you can put the control lines through a car that hoists up and down along a track in the mast. Drop the car to the deck so a strong gust isn't pulling from the end of the longer lever arm. You should also be able to fly the kite at a more upward lifting angle to help spill air.

-Will

 

[rob denney]

If you fly the kite from a mast, you can put the control lines through a car that hoists up and down along a track in the mast. Drop the car to the deck so a strong gust isn't pulling from the end of the longer lever arm. You should also be able to fly the kite at a more upward lifting angle to help spill air.

-Will

There is no reason to fly (as opposed to launch and recover) the kite from a mast and several reasons not to. If attached to the deck, capsizing is pretty much impossible with a kite.

 

[montero]

There is no reason to fly (as opposed to launch and recover) the kite from a mast and several reasons not to. If attached to the deck, capsizing is pretty much impossible with a kite.

I think line handling with the hull weight could be a little dangerous. Even bom is a killer sometimes .
Handling with big kite is possible but not by human hands.Capstans are not enough.Maybe new generation of non streched ropes is needed.
Always wonder when people think about kites as propulsion , lets think about kites himself , maybe are some kites more suitable for boat propulsion.
E.g. high altitude kites one mile high ? Ten miles high ?
One rope kite ?

 

[etoimene]

Regarding capsize and recovery, you might find this interesting.

Rob chipped in earlier on kite power.

 

[montero]

I saw this video. Need tests on the ocean in bad conditions. Hello.

 

[montero]

Any capsize /anti capsize ideas for multis ?

 

[gonzo]

To the proponents of kites: How do you recover a kite that fell in the water in heavy weather?