Double luff mainsail for cruisers

[Dave_S]

Originally Posted by markpierce

Is one a racer or a cruiser? KISS is for cruisers.

Yeah, I haven't made up my mind yet.

I'm hoping it wont be tricky, looking at it I don't think you will need to rotate the mast to tack just for changes in angle of attack.

[Jim Cate]

Dave,

All this discussion reminds me of a comment from Glenn Nichols (sp?), then a partner at Spar Master in Wynnum. He said they really liked designing and selling rotating masts, reason being that they knew that soon the mast would fall down and they could sell another one. Perhaps a bit jaded and superficial, but there sure were a lot of failures. and not just in their products. This was in 1996, and no doubt lots has changed since then, but the lingering worry of complicated rigging on cruising boats is still there in my mind.

Jim

[Dave_S]

Originally Posted by Jim Cate

Dave,

All this discussion reminds me of a comment from Glenn Nichols (sp?), then a partner at Spar Master in Wynnum. He said they really liked designing and selling rotating masts, reason being that they knew that soon the mast would fall down and they could sell another one. Perhaps a bit jaded and superficial, but there sure were a lot of failures. and not just in their products. This was in 1996, and no doubt lots has changed since then, but the lingering worry of complicated rigging on cruising boats is still there in my mind.

Jim

I take your point Jim. My boat used to have a CF rotating mast and the PO replaced it with a standard aluminium one. When asked why he said it was a PITA, I assumed he meant to use but maybe it didn't work too well. I wish it was still on the boat..... I think.

I get a lot of pleasure playing with these things if they work. I like efficiency but get so annoyed when they don't live up to the hype or break down or require lots of maintenance. To be successful they need to do all of these things.

I'll have a good look before I buy, if I buy. I think the price will put it out of reach anyway.

[Dave_S]

https://m.facebook.com/story.php?sto...73328252750248

I could only find it on Facebook sorry. What do they mean by adjusting the "Slip"

[jmh2002]

Originally Posted by Pauls

Wharram designed sails like this for his cats many years ago, with the exception that they were much simplified by not having a rotating mast. Just a double luffed sail, wrapped around a round aluminum tubing mast. They also employed a short gaff at the sail head, not like a typical gaff rigger but instead hoisted with a single halyard, ie they were square tops.

Wharram builders have used them successfully for decades. Wharram said they were a significant improvement going to weather.

The double luff produces a cleaner air flow, without the break in the flow on the low pressure side which is inevitable with the typical Bermudian mast/sail connection.

Used on a cat, the very wide staying base reduces mast compression loads significantly. This enables a decently long mast without spreaders.

https://www.wharram.com/site/article...m-wingsail-rig

[Redreuben]

Couple of things, a round fronted mast isn’t as aero as could be, secondly the rotating mast can be used to enhance or spoil the sail shape by over or under rotating which the Wharram can’t.
However simplicity is frugality is with the Wharram.

[sailjumanji]

Hmmm, I wonder how much of the performance improvement is due to the rotating mast, and being able to have better airflow across the luff. I know when we used to race Corsair 28R trimaran for years, correct mast rotation made a big difference.