This guide has been updated for sails cut after January 2003. Comments, questions or suggestions should be sent to Peter Duncan at sailfaster [at] aol [dot] com. For sails cut prior to 2003, contact Peter for tuning tips.
Elvstrom-Sobstad Albacore Tuning Guide (Rev. 4/1/07)
Centreboard position
Set leading edge within 5 mm of max. aft allowed by rules (2600 mm ahead of aft face of transom). Can allow board to go forward of vertical (up to 5 degrees) in light air. In heavy air (overpowered) be willing to raise board so 3/4 is still in water.
Mast position
Start with it at max forward position allowed by rules (foreside of mast at base should be 3350 mm ahead of aft face of transom). This will place the aft face of mast about be 25.75" ahead of the leading edge of the centerboard a dimension Richard Storer used to claim was optimal for these sails).
Mast Rake
Wind Strength
Bow to sheer*
Tip to transom +
Normal (6-18 knots)
8-9"
264-266"
Light w/flat water
7-8"
266-268"
Heavy (> 25 knots)
10.5-12"
261-258"
* deck at bow to sheerline marked on forestay (with black band at max height)
+ mast tip (with mast step max forward) to deck level at center of transom
Spreaders
- located 9/16th of height from deck crown to hounds (˜ 90-92" above deck)
- deflection for crew weight 280-300 pounds. 1.5" longer than neutral and 1.25" forward of neutral. Add spreader deflection for heavier crews. Reduce for lighter crews. Allowing too much mast bend will reduce pointing and speed.
Wind Strength
Tip to mast*
Chord depth +
Normal (6-18 knots)
16.5"
5.5"
Light w/flat water
17"
6.5"
Heavy (> 25 knots)
16""
6.5"
* deck at bow to sheerline marked on forestay (with black band at max height)
+ mast tip (with mast step max forward) to deck level at center of transom. This is a measurement to a line from gunwale to gunwale at the transom, not to the low point on the scoop of the transom found on newer boats.
Spreaders
- located 9/16th of height from deck crown to hounds (90-92" above deck)
- deflection for crew weight 280-300 pounds. 1.5" longer than neutral and 1.25" forward of neutral. Add spreader deflection for heavier crews. Reduce for lighter crews. Allowing too much mast bend will reduce pointing and speed. Note: I used the "normal" setting (below) for all conditions and all races in 2005. Note: I used the "normal" setting (below) for all conditions and all races in 2005.
Wind Strength
Tip to mast *
Chord Depth +
Normal (6-18 knots)
15.25""
6.0"
Light w/flat water
17"
6.5"
Heavy (> 25 knots)
16"
6.5"
* center of stay wire to near face of mast
Mainsail
- designed for 2 inches of pre-bend in light conditions (under 6 knots)
Jib lead position
Wind Strenght
Centerline to sheet
Transom to sheet
Normal (6-18 knots)
15-16"
96"
Light w/flat water
15-14"
98"
Heavy (> 25 knots)
16-18"
93"
All measurements assume vertical location of sheet vertex is about 1" above seat top.
When carrying jib close to centerline it is important that the jib is not over sheeted (allow sufficient twist). Adjust fore/aft position of fairlead to reduce backwinding of main, however do not eliminate all backwind. Should be some backing of main in area up to 36" above boom and 9" back of mast. Move fairleads inboard and/or aft to increase backwinding of main to achieve desired result.
Barberhaulers
- if still used should be located 6-9" ahead of shroud
Jib luff tension
Rig tension which sets jib luff tension is a critical setting on a high aspect (tall and skinny) jib such as that cut by Sobstad. Aerodynamic theory suggests that high aspect sails are most efficient, however getting the jib luff curve (or sag) correct is necessary to realize full power of these sails. The jib luff tension set by combination of stay position (pin position in chain plate) and jib halyard tension. For a given stay pin position, the mast rake can be used to control jib luff tension.
Initial setting is made by adjusting side stay pin positions such that when jib halyard is tensioned to a rake setting of 8 inches the side stays are just becoming firm (about 20 lb. tension on a wire tension gauge). Once this pin position is established, it is used in most wind conditions.
Here is a general description of how to set jib luff sag for various wind conditions.
Light air considerable slack to allow for fuller more powerful jib. This is particularly important in short chop. At mid height the luff might be > 3" off a straight-line forestay.
Moderate breeze as wind speed increases tighten luff tension to maintain pointing. No need to adjust jib cunningham. Tighter rig for fresh breeze and long waves or flat water. Careful not to take all sag out of luff…sails are cut for about 3-4 inches of sag (from a straight head stay). Taking too much sag out of jib will depower it and kill speed and pointing. Too much sag will also hurt pointing. In most conditions operate with 2-4" of luff sag.
When overpowered ease jib halyard allowing mast to bend and feather off the tip of the mast in puffs. Slack rig to allow rig to "pant" and act as a shock absorber in heavy winds and chop keeps the hull from pounding on waves. (see comments on rake setting). In UK with adjustable stays leave lee shroud slack.