Travelers and Bridles. The purpose of a bridle is to provide a place to anchor the lower boom block and allow the boom to be trimmed to a point between the decks. The closer the boom is trimmed to centerline, the closer a boat will sail to weather. The purpose of a traveler is to pull the boom to the centerline allowing the boat to sail closer to the wind.
The distance that the boom can fall off to leeward can be minimized by having a bridle that is close to the boom and attaching the bridle to the hull as far forward as practical and is Class legal. My bridle is at the maximum limit, 24 inches from the aft face of the transom. (Article XI.3.M.X of the By-Laws). Having the bridle at the maximum limit keeps the boom more on centerline without having to use a traveler to pull it to weather. If my bridle were further aft, I would have to use the traveler much more often.
I do not feel that a traveler is a required item. Until you think you are losing races because you do not have one, I suggest you that you save your money. My traveler stays cleated in the centerline position 80% of the time. Instead, just tie the lower boom block to the center of the bridle and forget it. This will be quite satisfactory and is illustrated in the drawing System A.
Traveler adjustment only becomes useful when racing in light or heavy air. In winds of less than 5, I move the traveler to weather to unload leech tension and put more power in the sail. In winds of more than 15, I want to depower the sail, so I let the traveler off and crank down on the mainsheet to increase leech tension.
I am not arguing against the use of a traveler, only pointing out its function. To win races at the top level they are required. There are at least 10 different variations on travelers. Some are illustrated in the drawings included with in this document. They are labeled System B, C, and D. Estimated cost ranges from $100 to $140.
All drawings by John Harris, #54001) An eye strap bolted through the rail outboard of the tanks. 2) Bridle. 3/16" or 1/4" no stretch line. 3) Lower boom block goes into a knotted loop. Height found by experimentation. I suggest starting with 8 to 10 inches between the block on the bridle and the block on the boom. The more space between the blocks, the more the boom will be to leeward. The more centered the boom is, the closer you will sail to the wind.
1) An eye strap bolted through the rail outboard of the tanks. The Nico Fico brand eye straps are preferred because the loop of the strap is rounded, which eliminates any binding problems when the block is attached, no matter what the mounting direction of the strap. The Nico Fico 1048 eye strap is a good choice. The straps hold Harken #083's single sheave becket blocks. 2) Bridle, using no stretch 3/16" or 1/4" line. Experiment with bridle height as with System A. The simple way is to start is to leave some tail on one end and adjust until you have like you want it. (i.e. don't cut the tail off the first season) The bridle is knotted to the becket of the deck mounted #083 blocks. 3) Harken #083's single sheave block with becket, 4) Mainsheet block, Harken #023, shackled to traveler block. 5) Pinching strings knotted to becket of traveler block, The free ends lead through the 083's on the deck mounted eye straps. 6) Harken #092 cheek block mounted to tank sides. 7) Harken #082 single sheave bullet block, which creates purchase for the pinching strings. 8) Line dead-ends knotted in a hole in aft thwart brace. On Moorman hulls it is recommended that you reinforce the hole with extra fiberglass mat or with a metal plate to spread the load. 9) 3/16" or 1/4" control line leads to side deck as in System D. 10) Friction, a big deal. Boats should have SS or AL tape affixed to the deck to prevent abrasion to the deck.
6) A single line runs to a turning block at the base of' daggerboard trunk and upwards to a swivel cleat that can be adjusted by the crew. Some riggers have terminated the line on a cam cleat mounted on the rear thwart or better to a cam cleat mounted on an SS plate; one end of the plate is bolted to the thwart and the plate extends aft and below the thwart.
 
 
 
 
 
There are all types of bridle and traveler designs. The traveler I use is illustrated as Traveler System D. This traveler is a variation on a design that fell from general favor in the mid-80's. But, I still like it and I have no plans to change to the newer designs. The System D drawing depicts the hardware used and how the lines are lead.
The adjustment line is a continuous loop led to a cleat on both side tanks. The line should be led to a position between the skipper and the crew. This way the skipper can adjust it with his main sheet hand or the crew can play it, depending on who has the upper body strength.
System D - Fixed Length Bridle - Adjustable Traveler1) Wire nico-pressed to a Harken #023 single sheave becket block. 2) 1/8" stainless plastic coated steel wire. The plastic sheath, makes the wire stiff and tangle free. 3) Harken #082 blocks secured to eye straps bolted through the rail outboard of the tanks. The Nico Fico brand eye straps are preferred because the loop of the strap is rounded, which eliminates any binding problems when the block is attached, no matter what the mounting direction of the strap. The Nico Fico 1048 eye strap is a good choice. 4) Harken #084 double sheave bullet blocks. 5) Harken #224 single sheave micro block. This block floats, in that it's position moves fore and aft when the control line is adjusted. It needs to be able to move at least 14 inches forward in order to bring the boom completely to the weather deck. 6) 1/4 inch control line. One end dead ended in a hole in the thwart (or to an eye strap on the side deck or under thwart on McLaughlin boats) The free end leading thorough or under the thwart knees. 7) Harken #092 cheek block mounted on or near the chine. 8) Eye strap or fairlead. Sole purpose to keep the line near the cleat in case you drop it. 9) Harken #200 cam cleat, mounted about three inches below the deck so your legs will not trip it when hiking. 10) The running end does not terminate; but leads to a cam cleat (9) on opposite the deck. See narrative. Important: Layout all parts and lines and be sure the angles are correct before you start drilling holes. If the lines touch any part of the boat the result will be unwanted friction. The wire almost forms a triangle. It leads from (1) thorough (3) and then to the centerline of the boat where terminates in a thimble. A 1/4" line is knotted through the thimble. The line crisscrosses through the double sheave #084 blocks (4) and is then led forward and terminated to a on Harken #224 single sheave micro block. One end of the operating control line (10) is dead ended knotted in a hole in aft thwart brace or to an eye strap under the thwart. (Warning on Moorman hulls it is recommended that you reinforce the hole with extra fiberglass mat or with a metal plate to spread the load. The running end is led forward to a cheek block (7) up through a eye strap (8) and then to a Harken #200 cam cleat. Finally the line drapes down in the boat and leads to the cam cleat (9) on the opposite deck. The controls are identical on both sides of the boat! Having the control line closed allows the line in the lee cleat to be poped out with a light tug from the weather deck, when the length of the line laying in the bottom of the boat is just right. Not too long, it will take too much fussing to pull the line out of the lee cleat. Not too short, or someone's feet will get under it and trip it. I suggest that you cut it long and leave a tail in the knotted ends. Try it and then cut the line until it is Goldilocks right.
The green line is the traveler. Note that it is continious and goes under the hiking straps. [The red, white and blue line happens to be the vang]
 
 
 
My bridle height is fixed and I never move
the traveler from amidships, except in the really light or heavy
air. And that is what I like about my arrangement, the boom
blocks stay centerline without any adjustment and that means one
less control line to fiddle with.
Getting the correct distance between the
block on the bridle and block on the boom is critical to my style of sailing. I
want the blocks fairly close so that the boom is amidships when I trim the
main, without any adjustment to the traveler. I also want the blocks far enough
apart so that I can over trim and depower the sail when necessary. My bridle is
fairly high and when the main is trimmed for a beat in moderate air, there is
only three inches separating the blocks, however there is almost no load on the
leech. The leech is still open. It is not cupped to weather.