Luff Considerations

Bob Boller of Benicia, Califonia, asks:

"I have three headsails for my 1980 Catalina 30 and their LPs are 85, 110 and 150. As it does on many cruising boats, the bow pulpit interferes with the lower portion of the sails, especially the smaller two. What do you think about slightly raising the tacks of the sails up the forestay? What effect will that have on the performance of the sails?"

Win Fowler replies:

If this bothers you, by all means raise the sail up the forestay. There are both benefits and drawbacks to doing this, but all are relatively minor. The sail’s center of effort will be raised, which produces more heeling moment for the same sail area. Also, when the tack is attached to a luff pendant, there’s a chance the tack might move away from the axis of the forestay under load and that could perhaps damage the luff tape where it enters the feeder for the luff extrusion.

Any added heeling moment, however, will be pretty insignificant, and the risk of a stretched tack position can be handled by keeping sufficient tension on the sail and perhaps lashing the tack ring to the luff extrusion so it remains at the same distance from the extrusion as it would be if the tack were attached to the roller-furling drum.

When done correctly you won’t have any more chafe from the pulpit and you’ll have better visibility under the sail. You will benefit from a bit more apparent wind velocity coming from further aft but you will also have that small amount of increased heel. The effects of both are small, so you needn’t waste time calculating the results.

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