Lenticular sails

[sirfbus1964]

Hi guys,

 I take it by the lack of response to my last post you lot also think I'm a crank.

I've been researching building my own boat and noticed what problems everyone has with sails,

or was it because I'm new to this and posted the discussion in news and not here.

As a mechanic I know that simple solutions often work the best, as Bertrand has shown Lenticular shaped sails is the way forward, if  Ship Theory is to be believed then the Vikings could hold the answer, rafting their boats made them more stable at sea, easiest way ship the oars lash them down and together across two boats,you know yourselves a flexible catamaran puts less strain on the hulls,

back to sails, an unstayed  mast in the middle of each hull acts like a biplane or being a kite boarder myself acts like stacking foils.

Bertrand's problem is swapping that shape from one side to the other.

My solution is simple,as I sat by the river looking at the old church I noticed  a sign saying how Turner had painted that same bridge, and realised that art too has advanced down the years, It was the simple drawings of Viking ships that didn't explain why they could sail rings round everybody the answer was they did something we've forgotten, they worked with nature not against it.

Back to Junk rigs at the front we now add a luff flap what if early drawings of these were wrong,

Tai chi tell us the answer; balance.

A double lug rig,same sail either side of the mast, using the wind to flatten one side you then have a perfect Lenticular sail, personally I like the Vikings dimensions of a fully balanced sail 3 times longer than the height looks a lot like a power kite as opposed to the Junks 2/3 the height to length.

Please don't think I'm just a crank I know another Yorkshire man sailors thought that about but eventually captain Cook proved them wrong

[Bertrand FERCOT]

Last month in New Zealand I sailed aboard the cat "Oryx" of Peter Hill who has modified his Split Junk Rig with light wishbones to generate good lenticular profiles in using simple flat sails. The rig with its little jib in front of the masts is very well balanced with a good efficiency, easy to reduce quickly the sails. As with the classical Junk Rigs he has a good control of the sails with the sheets connected to the wishbones and so the stress of the sheets is well spread.

Here are a few photos:

The main advantage comparing with my Swing Wing Rig is that only  flat sails are needed instead double sails and it's possible to adjust the curve before to haul up the sail in adjusting the tension of the sail at each wishbone.

Bertrand

[agur paesüld]

hey, I think that all the rig choices will come to this one conclusion:

a) will you go out to water to experiment, if you finally find the time to leave computations

b) will you go out to sail

if your case is b), then it seems reasonably sound to stick with Wharram rig, or just google around ebay and get yourself some beach cat rig, with full battens.

... as there are literally hundreds of Wharram rigs out there sailing around, you might be doing pretty well trusting Old Master in that point... :)