Selkie Dancer has a custom made stabilizer sail (also known as an anchor riding sail or steadying sail) to damp down yawing at anchor. The yawing increases the load on the anchor and increases the probability of the anchor of dragging.
It came about after reading an article in PBO, by Paul McBride. The more I thought about it, the more sense it made. You don’t see many aircraft without a rudder! Selkie Dancer rotates about a point through the companionway stair. Any extra windage forward of this point increases her yawing at anchor. Typical culprits are the tender on the foredeck and the raised spray hood. To counter this we need extra windage as far aft as possible – hence the stabilizer sail. It is a 260 cm (backstay), x 240 cm leech, x 220 cm (foot) triangle made of storm jib material with five hanks that attach to the back stay. An Edinburgh sail maker made it up for us for about £200. The halyard runs through a block that is attached above the lower HF isolator. If I did not have the HF isolator I would make the sail a little larger (300 cm on the backstay) and use the topping lift as a halyard. The sheet runs forward to a cleat on the starboard side of the cockpit coaming, this ensures that the sheet is perpendicular to the back stay. The sail is offset from Selkie Dancer’s centre line but this is not a problem.
Do we swing less? Believe me - yes !!
Selkie Dancer steady at her anchor
Sail set and revealing reinforcements at the corners