written by Matias Collins on April 19 of 2005 and read by 1248
I have the annual problem of setting up my European boat (I can see the tears being shed in sympathy!) to match my American boat (after spending a year developing the speed of the latter). Those who acquire a new boat or charter a boat or are dissatisfied with the performance of their present boat may find my technique useful and I await your input to assist me:
1. Choose the rake you prefer (see Peter Galloway’s response below as an indication that rake is important - probably because it determines how the jib and the main affect one another): I choose 30 1/2” inches (by the Curtis technique - obtained as follows: Mark the jibstay (detached from the deck) at the point of its intersection with the bottom of the mast, then reattach it (in sailing position) and measure the distance from the mark to the deck)
2. Rake the mast, then release the backstay and pull the mast forward by slowly tensioning the jibstay to a rake 1/2” less than your preferred rake and cleat the jibstay.
3. Tension the backstay until the mast bends 2” (or whatever minimal bend your mainsail requires).
4. Tension the backstay and jibstay alternately until you have both the desired rake and the desired mast bend (in my case 30 1/2” and 2”).
5. Insure that both the jibstay and backstay are free and unrestricted - that nothing is becoming 2-blocked under the deck or in the bow or stern tanks - that the uppers are not too tight (see below) - or anything else is interfering - so that the backstay can be tightened and the jibstay loosened (at least a little from this point)
6. Now check to see whether the mast is flat on the deck or deck pad - so that a knife cannot be inserted under it at any point.
7. If it is not flat, drop the mast and modify the angle of the cut across the base of the mast or shim the deck plate on which the mast rests - so that the bottom of the mast will rest firmly (be flat) without rocking in the optimal rake position.
8. With all three - rake, mast bend, and mast base - correct, tension the jibstay until its tension (Loos Guage measurement) is 25. Mark the jibstay and the backstay for this position which (depending on your sails) is an optimal setting for sailing upwind in about 14 knots.
9. Finally mark intermediate jibstay positions for lighter air (lesser jibstay tension) and intermediate backstay positions for heavier air (greater backstay tension and mast bend).
Advance response from Peter Galloway -
(Example from Spring Bowl racing ) In a breeze we’ve been fine, but our light air speed has been suspect for some time. I discovered on Sunday morning that our uppers were far too tight and with rod rigging, when our shrouds were all the way forward, the mast would not rake sufficiently. Relaxing the headstay would only add sag, not rake, and I’d end up trimming the main too hard, closing down the leech (North mains tend to be fuller in the top). Only adding backstay tension would open it, and we’d end up with a main that was too flat and a headstay with insufficient sag. So on Sunday I added a second top batten with a stiffer trailing end, and loosened the uppers 4 complete turns. Now I found that we could gain rake (might have to go more) and could trim the main without closing down the leech so the sails looked a lot better.
-- Peter E. Galloway, Friendlee Acres
Comments from Joe Van Gieson
Thanks for the article, and especially Peter Galloways' comment. I have been theorizing that my uppers are too tight to achieve the proper rake without undue backstay tension. Peter's description of his mainsail symptoms duplcate mine exactly.
Watch your transom.