double line reefing

[Barquito]

I am looking into setting up double line mainsail reefing. In looking at diagrams it occured to me that if the line leading from the boom to the base of the mast were off-center the reefing line would be shortened if tacking. ie: if the boom is to port and the mast base block is mounted on the port side, then when the boom moves over to stbd, the line would be tightened (B-C in the diagram). How close to center-line do these need to be?

[sailingdog]

Barquito—

The closer to the mast Block B is located, the less of a difference the angle of the boom will make, since the block will move less. I have the blocks for my three reefs spread across about an eight inch wide plate... and they work just fine.

[Jeff_H]

The "B" block in the illustration actually is part of the gooseneck, boom connection fitting. The reeflines do not exit the boom on center or on the center of the gooseneck pivot. The reef clewline may tighten and loosen slightly as the boom pivots from side to side, but you don't really notice that in the kind of conditions when a reef is necessary. My "C' Block is on the same bail as the vang which also tightens and loosens depending on position of the boom.

I pass the reef tack lines through the reef cringle on the mainsail and tie it back below the gooseneck on the other side of the boom. I pass the active side of the reefline through a shackle at the gooeneck which does does not rotate so the there is not an issue of the reefline loosening and tightening as the boom swings.

[AdamLein]

On my boat the "B" blocks are shackled to a padeye mounted right onto the mainsail track. It probably sits exactly on the gooseneck's axis of rotation.