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VirtualTraveller
A way of extending the angle of attack on the boom of a sailboat without a traveller | |
Most sailing boats are fitted with a "traveller" which is a slide that allows the point where the main sheet attaches to the boat to slide athwartship. When a boat is on a port tack and the boom is out the starboard side of the boat, if the main sheet is attached athwartship (in the center of the boat)
it's pulling more sideways than down on the boom and allowing it to rise up which changes the shape of the sail. The boom vang traditionally helps account for this, but the traveller also allows the angle of attack of the main sheet to be modified.
My idea modifying the main sheet line so that instead of attaching to the end of the boom it passes through an eye and down to the gunrail. If the boat is on a port tack, then I'm talking about the starboard gunrail.
This modifies the angle of attack without involving a perhaps awkward or cumbersome traveller.
I haven't completely thought through the implications of tacking. You'd want to be sure you didn't have the main sheet unattached for even a moment else the boom could get away. If perhaps the line was stopped at the end or there were a device that could selectively grip or loose the line.
A Sketch of a Traveler Bar
http://www.catalina...als/mnl87/hb27a.gif
[Amos Kito, Feb 02 2008]
Catalina 22 Handbook
http://www.catalina.../mnl87/handbook.htm
Care and Maintenance of Your Yacht [Amos Kito, Feb 02 2008]
[link]
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Wouldn't the for'd boom vang tend to foul
the mains'l bosun stay between the
yardsheet stunsail reefsheet and the
quarterknot on the starport boardroom
trouserpress? |
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Sorry. I think a picture might be worth
215 words here.... |
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Welcome, [jeremy], and good luck. Not all replies are going to be serious, and few of us are sailors. (If we had any outdoor skills, we wouldn't be here.) |
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I like what I think you are proposing. |
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"He leans to the Left, so draw to the
Right; the wind's in the east, so shoot to
the west." The Paleface 1948 |
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This sounds like you are solving the problem of a boom that is being pulled sideways, by pulling the boom even more sideways. |
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Would anything pull it downwards? I'd imagine the lines would have to be really tight to keep the sail from luffing. Not to mention they would clutter the boat. |
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//modifying the main sheet line so that instead of attaching to the end of the boom it passes through an eye and down to the gunrail// |
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Could you just spell out for us where the two ends of the line would be after this modification? |
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Also, I'd recommend a paragraph break just before //My idea modifying// (just hit return twice, and that will give you one). |
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Don't mind [MaxwellBuchanan]; he hasn't finished his homework yet (deciphering Linear A). |
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//Don't mind [MaxwellBuchanan]// Aye,
me hearty. Don't 'ee pay no 'eed t'yer old
mate Cap'n Maaax. For ee's nought but an
ol' land-dog and 'ee means no 'arm. And
pay no 'eed o' 'is tendency t'drift into
strange accents f'reasons that no maaaan
can fathom. 'Oist the mainsail, me
hearties, and Roger the cabin-boy. |
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From the sketchy image I have, the traveller seems to be the most elegent solution, assuming it is what I think it is; a lateral track with a ring in it that slides to the end where the sail is. |
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The problem as I understand it is that the track is not wide enough as the sail end extends over the side of the boat. A better solution might be to have the track on another track so that it can extend across the walkway and rail on whichever side it is needed, but is sprung to return to centre when not being pulled. |
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I'm new to halfbakery and am not sure how to upload an image. Until I learn I'll try to paint a mental picture. |
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The main sheet currently goes from ship to boom, pulling straight down when the boom is centered by at a steep angle (well over 60 degrees) when the boom is out one side. The steep angle steals the line's downward pull, so ships a) move the point where the line contacts the boat off to the side some (a traveller) or b) use the boomvang (block and tackle from boom to base of mast). |
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In my proposed solution, the line goes from ship to boom (through a block) to gunwale (edge of deck). So the boom is affected by two lines now (one from center and one from far edge) and the net resulting force is between the two. |
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The traveller is a pretty good solution. The only disadvantage is that it takes up a lot of deck space, and on smaller boats (and for the mizzen sheets of a ketch) the traveller is cutting the cockpit in half and making it difficult to tack or move around without spilling beer (obviously unacceptable). |
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[+] You should have said it was to prevent spillage. |
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The traveller on our Hobie catamaran stretches nearly the width of the boat. Any further reach wouldn't be needed as the boat would simply be in irons. |
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