Balloon Sail?

[Endy0816]

Any thoughts on the feasibility of using a sail kept aloft by balloons rather than a traditional mast?

[imatfaal]

1 hour ago, Endy0816 said:

Any thoughts on the feasibility of using a sail kept aloft by balloons rather than a traditional mast?

Balloons would act as pretty good "air-anchors".  You also need yardarms .  The sails would need to be different shapes to work - and I don't know this subject well enough but I think they might need to be different shapes depending on where the wind was coming from.  Sails and bits will have a mass between 25-50kg for a yacht - even for that you would need some big balloons; but you woud also need much bigger to provide the tension to keep the line close to vertical when a force is applied through the sail

[beecee]

6 hours ago, imatfaal said:

Balloons would act as pretty good "air-anchors".  You also need yardarms .  The sails would need to be different shapes to work - and I don't know this subject well enough but I think they might need to be different shapes depending on where the wind was coming from.  Sails and bits will have a mass between 25-50kg for a yacht - even for that you would need some big balloons; but you woud also need much bigger to provide the tension to keep the line close to vertical when a force is applied through the sail

Yes, that was my first thought.

[Bender]

If the balloon is large compared to the sail, this would affect controllability of speed and direction.

Likewise, I doubt having the position of the top of the sail out of your control is desirable. 

While perhaps feasible, is there a reason to do this bevond novelty? 

[Damateur]

Also, since the balloons could be at a significant angle to the ship, wouldn't that negatively affect the sail effectiveness?

[imatfaal]

4 hours ago, Damateur said:

Also, since the balloons could be at a significant angle to the ship, wouldn't that negatively affect the sail effectiveness?

Exactly - that was the root of my comment about sail shape.  I don't necessarily think the effect would always be negative but it would be large.  Sails are a shape and are battoned  to work both with the wind and into the wind - this idea would introduce a new variable; the angle of the "mast" with respect to the boat would vary with both the wind direction and with the boat's velocity (magnitude and direction)  with respect to the wind

[J.C.MacSwell]

Kite sails are already in use to propel, or assist in propelling, ships. Some types I believe are in part  inflated.

 

 

https://en.wikipedia.org/wiki/SkySails

 

 

[imatfaal]

19 minutes ago, J.C.MacSwell said:

Kite sails are already in use to propel, or assist in propelling, ships. Some types I believe are in part  inflated.

 

 

https://en.wikipedia.org/wiki/SkySails

 

 

They keep on being suggested but I think they are a novelty item rather than a replacement (or even partial replacement) for the motor.  The consensus is that for very small ships they might make a tiny saving in fuel - but would require extra crew/officers (you don't just assume automatic systems will work in the deep ocean), provide a significant extra danger (super hi tension steel wire rope anyone?), and are untested in real world situations.  BTW - my company currently shells out about 30-40000 dollars a day per ship on fuel; we would happily adopt a decent technology which cut 5% off that expense.  It is just that sails/kites don't pass the test that our maritime architects, naval engineers, and master mariners throw at them.  

[J.C.MacSwell]

1 minute ago, imatfaal said:

They keep on being suggested but I think they are a novelty item rather than a replacement (or even partial replacement) for the motor.  The consensus is that for very small ships they might make a tiny saving in fuel - but would require extra crew/officers (you don't just assume automatic systems will work in the deep ocean), provide a significant extra danger (super hi tension steel wire rope anyone?), and are untested in real world situations.  BTW - my company currently shells out about 30-40000 dollars a day per ship on fuel; we would happily adopt a decent technology which cut 5% off that expense.  It is just that sails/kites don't pass the test that our maritime architects, naval engineers, and master mariners throw at them.  

I wasn't suggesting they were economically viable. Just that they exist. They would only be reliable in limited circumstances, and generally only downwind. But I found them interesting. 

[Endy0816]

15 hours ago, Bender said:

While perhaps feasible, is there a reason to do this bevond novelty? 

I've mostly been thinking about trying this for my kayak. Lots of time to think while paddling and very little else to think about than ways to not have to paddle.

Main benefit would be the zero effective weight of the mast/sail and to avoid some of the issues that a fixed mast imposes.

There are small existing kayak sails and people have even rigged up kite sails, but trying to think of something that hadn't been done before. Hadn't considered the balloons moving relative to the boat as well though. That might be a problem or reduce the speed advantage too much.

 

[Damateur]

I hadn't considered a kite sail which looks like it would be a better choice. But it does suggest that there might be some merit in a balloon supported sail. Maybe put a small inflatable kite sail at the top with a more ordinary sail below?

[Endy0816]

I'm thinking it'd be too difficult to coordinate the two simultaneously. I do like the look of the kite sails though. Smaller but with height and cooperating winds, can reach impressive speeds.

I did price out the floating sail idea and didn't look too crazy price wise, especially assuming a longer trip to make the helium purchases worth it.

[Handy andy]

I had some friends who used a kite from a surf board as a light wind sail to get them across the doldrums. My friend attached himself to the deck and launched the kite, it worked and flew high enough not to be disturbed by the air from the ocean swell as a normal spinnaker can be. https://en.wikipedia.org/wiki/Kitesurfing Flying a kite from a deck is hard work on the arms.

A sail I want to buy in the near future is a parasailer but that requires a mast https://en.wikipedia.org/wiki/Parasailor#Parasail but it has some very  easy to handle features.

A combination of using a helium balloon built into a kite giving the sail some rigidity and buoyancy when the wind drops might be a good idea, and could catch on, I suspect someone has already thought of it.

Edited August 1, 2017 by Handy andy

[Acme]

1 hour ago, Handy andy said:

I had some friends who used a kite from a surf board as a light wind sail to get them across the doldrums. My friend attached himself to the deck and launched the kite, it worked and flew high enough not to be disturbed by the air from the ocean swell as a normal spinnaker can be. https://en.wikipedia.org/wiki/Kitesurfing Flying a kite from a deck is hard work on the arms.

A sail I want to buy in the near future is a parasailer but that requires a mast https://en.wikipedia.org/wiki/Parasailor#Parasail but it has some very  easy to handle features.

A combination of using a helium balloon built into a kite giving the sail some rigidity and buoyancy when the wind drops might be a good idea, and could catch on, I suspect someone has already thought of it.

Ben Franklin pulled himself across a lake using a kite, as well as pulling himself on ice skates.

Quote

I found that by lying on my back and holding the stick in my hands. I was drawn along the surface of the water in a very agreeable manner. Having then engaged another boy to carry my clothes round the pond, to a place which I pointed out to him on the other side. I began to cross the pond with my kite, which carried me quite over without the least fatigue and with the greatest pleasure imaginable.” During the winter Franklin also used kites to pull him along while ice skating. source

Kite/ballon hybrids do exist and are called 'kytoons'.
 

Quote

 

A kytoon or kite balloon is a tethered aircraft which obtains some of its lift dynamically as a heavier-than-air kite and the rest aerostatically as a lighter-than-air balloon.^[1] The word is a portmanteau of kite and balloon.

The primary advantage of a kytoon is that it remains in a reasonably stable position above the tether point, irrespective of the strength of wind, whereas ordinary balloons and kites are less stable.^[1]

The kytoon has been used for many purposes both civil and military. source

 

 

 

[Endy0816]

7 hours ago, Handy andy said:

I had some friends who used a kite from a surf board as a light wind sail to get them across the doldrums. My friend attached himself to the deck and launched the kite, it worked and flew high enough not to be disturbed by the air from the ocean swell as a normal spinnaker can be. https://en.wikipedia.org/wiki/Kitesurfing Flying a kite from a deck is hard work on the arms.

A sail I want to buy in the near future is a parasailer but that requires a mast https://en.wikipedia.org/wiki/Parasailor#Parasail but it has some very  easy to handle features.

A combination of using a helium balloon built into a kite giving the sail some rigidity and buoyancy when the wind drops might be a good idea, and could catch on, I suspect someone has already thought of it.

What kind of speed did your friends get?

I'm hoping to find something I can use to get to or from some of the more distant islands around the state with. At least half of the trip the wind is likely to be cooperating well enough.

 

Looked at kytoons, might be an idea.

 

TIL, Ben Franklin flew kites without his clothes.

[Acme]

1 hour ago, Endy0816 said:

...I'm hoping to find something I can use to get to or from some of the more distant islands around the state with. At least half of the trip the wind is likely to be cooperating well enough.

Looked at kytoons, might be an idea.

TIL, Ben Franklin flew kites without his clothes.

Depending on country and/or state, you should find out what flight rules you have to follow in addition to boating rules. Here are the applicable rules in the US. > PART 101—MOORED BALLOONS, KITES, AMATEUR ROCKETS, UNMANNED FREE BALLOONS, AND CERTAIN MODEL AIRCRAFT