WishBone Sailing Rig

Brian,
I think what Steve Clark is referring to by the "less efficient when reaching and running" is that a boomless sail cannot be let out an keep a good shape as easily as one with a boom. Take a nice big genny, and let it out when broad-reaching. Does the shape look or act efficient? Now stick a reaching pole in there (a loooong one) and you will begin to get a better shape. Add a downhaul or two, and you are again improving the shape. The simple way to achieve this is to use a sail with both a boom and a vang It's called a mainsail.... <sorry - couldn't resist that lst one...>

Bipod masts must, by their nature, take more compression. The angle to vertical is narrower, so the resultant tension in the windward 'pod caused by the side force will be much higher than in a conventional spar (OK, "Much" may be a bit far) and thus the compression in the other 'pod will be similarly higher. Take a calculator and check it. I did.

Steve

 

I was refering to the headsail only designs, which have their masts stepped way aft. In order to acheive headstay tension, the backstays have to be set up VERY hard. The difference between the staying base aft and forward works by the old cosine of the angle, so if you have a very long "J" equal to something like 85% of the length of the boat. you arew going to have to wail on the backstays. That turns into compression in the mast, which either grows in diameter or in shrouds and spreaders to take the buckling load.
Mainsails may do many things wrong, but they do hide a mast pretty well from an aerodynamic point of view.
Jibs twist when you ease the sheet. They also camber beyond what is reasonable, so they aren't efficient reaching and running sails without some sort of boom and vang system.
inally, maintaining balance as you shorten sail. As a jib gets smaller it moves further forward. This happens with cat rigs as well, so that once you are well shortened down, the boat has lee helm. In big breeze trying to get to windward, this is very bad and unsafe. One reason to have a little mizzen back there.
I'm not dissing anything, just offering observation based on some experience in the feild.
SHC

 

Brian wrote:
Not exactly 'boomless', rather wishboned-boomed mainsail:
Kind of interesting comments on the shape of this alternately boomed mainsail........Tom Wylie's new ketch rigged vessels....
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* From Chuck Hawley (Regarding Fred Roswold's comments on Randy Repass's new boat, Convergence): I think there may be some misunderstanding on the need to reef this powerful cat ketch. I sailed on Convergence several times with Randy and Sally-Christine before they departed for French Polynesia, and we reefed the main on both occasions, although at higher windspeeds than might have been the case with a conventionally-rigged boat. The winds in Santa Cruz in the early summer are generally around 20-25 knots a few miles offshore, and we saw over 30 knots apparent. I think the point is that the unstayed rigs depower with each puff, bending off to leeward without actually flogging the sail, so that the rig appears to select the correct "gear" for the conditions. Owners of Wylie cats have reported this for years; now Wylie ketch owners are experiencing it!

What's really exciting to me is to see how perfectly both sails set without the intrusion of a boom along their feet (foots?) The wishboom booms create a sail which looks efficient from luff to clew, much more like a genoa than a conventional mains'l. We were able to hit 13.6 knots on a broad reach with excellent control, and with a very broad range of downwind angles that could be sailed without risking an accidental gibe. Truly an innovative and powerful boat.
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Notes:
1)This reference is to a wishbone boom rather than the wishbone mast of the original posting subject.

2)Interested parties might also visit the discussions of 'loose footed mains' at
http://www.boatdesign.net/forums/showthread.php?t=2595

3)Have a look at these two vessels sailing on a reach and tell me whether it appears as though their headsails are working in more unisonal (harmonious)manner than the headsails with the mainsail??
RANGER http://www.boatdesign.net/gallery/showphoto.php/photo/2157/sort/1/cat/500/page/1
WINDROSE http://www.boatdesign.net/gallery/showphoto.php/photo/2158/sort/1/cat/500/page/1

I'll have more to add to this discussion of these photos and this boomed-main subject at a later date, and probably under a different forum subject heading.

 

I remember a review of a Hunter Vision in one of the glossy magazines. They complained that the sagging of the unstayed mast in a puff contributed to weather helm.

They also went out of their way, as I thought, to slam the boat as a 'bay sailor'. Hard to believe they approached the review of an unstayed cat-sloop with an open mind. Hunter responded with a vigorous defense of their rig engineering, as might be expected. No one spoke to my question which was which berth would be suitable for use at sea.

 

Hi, just popped into this site: http://www.barefootsworld.net/windwalker/voyagephotos.html
one of yours Brian ?
rgds O

 

It is not. This fellow picked up on my idea and built one....all the more power to him for being that resourceful. I wish him the best, althought I have some concerns about his rigging arrangement, particularly at the point where the 'aft spreader' pushes forward on the mast.

I have written the fellow asking that he keeps us informed of his trials. I was a bit disappointed that earlier on he copied portions of my website text onto his website without giving me any credits at all. And I have some concerns about his sea experience, and particularly with a 'new' rig.

Lets hope all goes well. I think he plans a transatlantic soon.

 

You´re right, North Atlanic crossin aug/sept might not be the best way to test a new design/boat...not much abot any handeling problems in the log so far. Should be interesting to follow.
Sailing near cost with a lot of tacking and changing winds, how is this rigg to handle compared to a Bertmuda type? "It doesn´t look like a self-tacking type..."

rgds Olle

 

Are you asking about mine or his??

On mine,the mainstaysail and the mizzen on my rig can both be self-tacking. And the mainstaysail can be a battened, hanked on sail as well.

From my discussion on the website;

8) A rig that can be operated without leaving the cockpit. One single person could sail this fairly large rig from anchor up to anchor down. All the sails roller-furl, and the mainstaysail & the mizzen both can self-tack. Only the genoa needs to be tacked over, and this could be delayed until the boat has come about. Even motorsailer folks should appreciate this rig.

....just let the genoa lay against the mainstaysail during the tack, then pull it around upon completion.

....and if you anticipate a lot of tacking and you don't wish to handle 3 sails, just roll up either the mainstaysail or the mizzen.

 

Yes, I asked for yours....thanks for the reply. I´ll check this out further.
rgds
Olle

 

Brian, ´maybe you already looked into this, the documentation from Paasch Marine on "Diomeda Exulans"...the other mans boat....
http://www.bgsu.edu/colleges/library/hcgl/glms0045.html

rgds
Olle

 

I would hate to try helming this running under bare poles. Keep it out of the southern ocean, wouldnt survive.

 

Brian ask:
What specifically are your problems with this rig under bare poles?
And why wouldn't survive?
(Regrettably I may not be able to respond again until I return from Thailand in two weeks)

 

If you were unable to carry sail the windage would be right aft, control would be lost very quickly, the boat would sail backwards pointing into the oncoming seas with no rudder control. Scary thought

 

We have a Manta, Hull #2, in Narragansett Bay. Also have some printed info on the vessel. But, would like to have more info.

 

Brian Eiland

I met a yacht at sea of the azores with a bipod mast it was in the normal ,mast position for a cutter , fabricated from carbon fibre wing section about 300mm wide, italian designer the main was on a luff wire two headsails the mast was canted back by around 15 degrees. We were both becalmed at the time I took photos but the camera was wonky sorry. Designer I think was a gentleman called Sobrero, if this helps.

The crew were delivery crew mostly spanish and french so my interview was shouted and patchy.
Probably not the design you wanted reading back but interesting all the same.

Cheers
Jim