Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Excerpted from the “The Mark Eliot C-15 Cookbook Tuning Guide”:
C-15 ASSOCIATION: C15 National Association Home Page
Click on "Tuning Tips"
"Here is a short list of the tuning options for boat speed. They are in order of importance.
“1. JIB HALYARD LOCK - You need a Jib Halyards Lock to control mast rake and sail shape
2. MAST RAKE - Set mast rake between 23 feet 6 inches and 23 feet 8 ...
Jib Halyard Lock and Mast Rake
These are items 1 and 2 on the list, but because they are directly related I will cover them in the same section. If your boat does not have a jib halyard lock you will need to put one on. Buy a jib halyard, a halyard lock and a shroud adjuster. The jib halyard should be 3/32 inch (or 1/8 inch. but be sure you have the right size lock) stainless wire with a swag Ed loop and thimble at one end, a lock ball 36 inches from the loop and another staged loop with NO thimble at the other end. The total length of the halyard should be 226 inches.
With the mast up lay the boat on its side. Attach a tape measure to the main halyard and pull the tape to the top of the mast, putting the main halyard ball in the lock. Space the jib halyard sheave box away from the mast with washers, otherwise the lock ball on the jib halyard won't be able to pass between the mast and the sheave. You can replace the standard jib halyard sheave box with a bale, twist shackle and wire Harken block. (See the Jib Halyard Lock diagram) This will make it much easier to raise and lower your jib but, of course, it is not a factor in boat speed.
To start, pin the shrouds so that there are 2 open holes between the shroud pin and the chain plate. Attach the jib luff wire to one end of the new shroud adjuster. Use clevis pins and ring-a-dings. Attach the jib halyard to the center of the new shroud adjuster. Stuff the halyard through the jib sheave box and run it to the base of the mast. Pull the halyard tight enough so that the shrouds are snug and tie it off at the base of the mast. Make sure that the forestay is hanging loosely and not carrying ANY load.
To measure the mast rake, use the measuring tape attached to the main halyard and determine the distance from the top of the mast to the top of the transom. Fiddle with the shroud adjusters for both the jib halyard and the shrouds until you get 23 feet 8 inches. At this point the shrouds should be just snug enough so that the mast does not move. Mark the position of the jib halyard lock ball on the mast. Install the jib halyard lock there.
Put the boat upright, Move the shrouds down so that you ABSOLUTELY CAN'T put the jib halyard in the lock by yourself. Have an assistant pull hard on the forestay and you should be able to drop the halyard ball in the lock. If you have a rig tension gauge you should get 300-350 Ibs on the shroud. Measure the rake, same as before, with the tape attached to the main halyard and the main halyard in the lock. The distance to the transom should be 23 feet 6-7 inches. You can fiddle with the shrouds and the adjuster on the jib halyard to get it right.
If you have LONG spreaders, site up the mast track with your eye. mast should have about 1 to 2 inches of bend AFT If not, you need to angle your spreaders further back, this will force your mast to bend more. Once everything is perfect mark the shroud positions on the shroud adjusters with a permanent marker.
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"