Proa Lug Rig
Using a “track” along the top spar - release (current) sheet, release opposite and sheet in again on other side?
The track could be simple - like a basic dinghy one.
It has to not go right to the ends of the line though - as in pic 2.
To keep the top spar from twisting off too much - a tight line running along the spar and over the mast.
Perhaps brailling lines at the ends.
On smallish proa, it shouldn’t be too much of a handfull.
Scaling up to a larger proa might be easier if it is a schooner.
The idea is that it allows for a central, non moving mast.
Easy to reef and a variety of positions and height options - depending on conditions.
The c of e can be moved around to suit the boat.
Thoughts?
Nice, but you’d need a way to enforce luff tightness and avoid diagonal creases.
I do not see why it is necessary a track along the lug. You simply have to hold the spar from its center. The lug has to be symmetrical and stiff enough, but the boom may be more flexible, since it is tied at both ends.
Fulgencio
The track allows the c of e to move forward, while still holding it tight against the mast - and then to shunt easily too.
Keeping the luff tight may be why “traditional” proa lugs are on the “wrong” side of the mast.
Seems simple enough but there is a lot of devil in the details.
Design wise you have alternating luff and leeches which would probably be a real challenge for a sail maker, but may work OK.
The real demon lurks in the alternating tack and sheet. Tack has to be snugged down tight, really tight, to set well on every shunt. Sooner or later its going to get away from you and having a boom flailing around anchored only at the top of the mast can be terrifying (ask me how I know 😉 ).
I’ve spent a lot of time fiddling with a variation of this biaxial approach and have set it aside for the moment to try a couple of other ideas. One solution to the runaway boom problem is touched on over on the Nomad thread
http://proafile.com/forums/viewreply/892/
Best wishes
Skip
Using a “track” along the top spar - release (current) sheet, release opposite and sheet in again on other side?
The track could be simple - like a basic dinghy one.
It has to not go right to the ends of the line though - as in pic 2.
To keep the top spar from twisting off too much - a tight line running along the spar and over the mast.
Perhaps brailling lines at the ends.
On smallish proa, it shouldn’t be too much of a handfull.
Scaling up to a larger proa might be easier if it is a schooner.The idea is that it allows for a central, non moving mast.
Easy to reef and a variety of positions and height options - depending on conditions.
The c of e can be moved around to suit the boat.Thoughts?
Charming idea with the bridle: You need two downhaulers for the yardarms leading to each bow, otherwise the the whole ensemble is too unstable. The clew of the sail has to be shortened, otherwise it will cut into the water. So the shape of the sail has to be a trapeze, not a rectangle. In light winds the sail will only keep in shape, when the spar in the leech is very light, so you should construct the spar from cable tube mantled with carbon fiber tube.
Regards
Dieter
To keep the top spar from twisting off too much
I expect the yard would twist off in the opposite direction from the boom. The AYRS/Bolger rig had that problem even with a fixed attachment point at the top. You move the attachment point aft on the yard.
The latest Catalyst had an article on a series of three proas. The designer found the tilting mast too scary, and used a similar bridle to move a yard from end to end, but the yard attached to the bow. It did not have to rotate to trim the triangular sail. That doesn’t work for your design.
What apparently hasn’t been tried in multihulled proas is an idea shown on one of the monohull proas recently discussed somewhere here: let a curved mast rotate around a vertical axis. The top of the mast will move. Attach your sail (or spar) to that. Is there a reason not to use a curved rotating mast with either a crab claw or Gibbons sail?
Regards
Robert Biegler
I had a curved rotating mast on my 6m proa as first attempt: The lug sail was a Tornado mainsail, of which I had cut off the top ( approx. 14 sqm ). The boom was running on a bridle to balance the center of effort according to the course to windward. Unfortunately the mast was to weak and in a squall the sail blew up like a parachute and we capsized. So I figured, if I could fix some spreadings to stiffen the mast, but then gave up the idea, as I found no sufficient solution for the interference between spreadings and shroud. A conventional crab claw made from fishing rods reinforced with carbon fiber served much better and reduced the danger of capsizing due to the lower center of effort with the side effect of relieving the strain on the bow by giving lift.
A conventional rotating mast offset in its bearings with a full battened square top sail is another approach,
Luff tension is an issue.
Would battens help - or be more of a pain - breakages and weight etc?
Trying to keep it simple - no sailmaker - DIY and a rectangular piece of sail.
Good, rather than perfect, will do.
Swopping tack and sheet - the sail helps here, as the larger sail area blows off when released. Then through the track, that area is swopped and reverses the process.
Worked on the model - but i realise reality doesn’t always scale well with small models….....
Not seen on the model - a tight line along the top spar, on the inside - to help with the top spar bending off too much.
It passes over the mast, creating (some) tension.
How will it end up in the water - as it will be angled up most of the time - away from the water.
It isn’t reversible if not rectangular.
As for the mast - nothing fancy - a pole….
KISS again.
Perhaps i should mention - it’s for a 3 sheet / 22’ deep v proa.
I still like the crab claw but this would allow for a stationary mast and give more sail area (double!!) and more reefing options.
Even if it works, if the hull is deep V with no boards, you will need to get the COE well ahead of midships to balance.
You can also use the lug as a shunting sail. Have you seen these bad boys?
https://www.youtube.com/watch?v=V5n_UV9IDTQ
-Thomas
I still like the crab claw but this would allow for a stationary mast and give more sail area (double!!) and more reefing options.
You can have a stationary mast with a crab claw by putting a bridle on the upper yard like Monroe did back in 1898 worked rather well in my experience. Reefing is another matter, brailing helps and is a godsend when things go awry. A little reefing is possible by gathering up a small triangle on the boom, try it on the yard and aero goes to hell, at least in my experience. Most effective method I know of but didn’t try was have a couple of rigs, boom yard and sail, raise the one suited for the conditions.
Cheers,
Skip
Why is reefing a crab claw such an issue?
Why is reefing a crab claw such an issue?
Reefed sail either has CE (and mass) way up in the air or way aft, neither a good idea when the whitecaps start blowing off the tops of waves.
Best bet for seeing the pluses and minuses of a crab claw look at Chris Grills blog
http://grillabongquixotic.wordpress.com/2012/04/
He surely has the contemporary record for travelling with a crab claw.
Skip
This method looks like an improvement with a lowering of the CE.
http://outriggersailingcanoes.blogspot.co.nz/2013/09/reef-that-crab.html
Gary
This method looks like an improvement with a lowering of the CE.
http://outriggersailingcanoes.blogspot.co.nz/2013/09/reef-that-crab.htmlGary
Hi, this is my reefing method, Mr. Dierking is re(e)fering to. As yet it has helped me out of two difficult situations. When the wind gets too strong to balance my 11 sq m Crabclaw (5m vaka), I take the yard down, bind in the reef, hook in the (shorter) reef-weather shroud, and hoist the reduced sail again, a bit lower. All this I can do (and have done) in strong conditions on the water. With this reef I still can sail rather safely upwind in 6 Bf singlehanded, bearing not more than 50 degrees off the true wind.
Servus, Reto