Tuesday, 15 July 2014

When to Change Sails?

Serenity is a small boat, with a LOD of 22' 7". It is also a fairly light wind boat, with the BDR being about 38, and the SADR at 20.5. Considering these bits of information, and my opinion that 15 to 20 degrees of heel is generally what most modern boats require to sail efficiently, I've been pondering when to change sails.

The boat does not have furling, so my sail choices are a 130? genoa, a jib with one reef point, and a mainsail with one reef point.

Here is what I plan to experiment with:

up to 10 knots (up to Force 3) - upwind or downwind - genoa and full main
11 to 16 knots (Force 4) - upwind or downwind - full jib and full main or genoa and reefed main
17 to 21 knots (Force 5) - upwind reefed jib and full main - downwind full jib & reefed main
22 to 27 knots (Force 6) - upwind or downwind - reefed jib and reefed main
28 to 33 knots (Force 7) - upwind reefed main only - downwind reefed jib only
34 or higher knots (Force 8 and above) - be safely docked somewhere protected

The idea is to have the boat heel no more than 25 to 30 degrees in gusts. If it is consistently tipping past 20 degrees, then it is time to reduce sail. This makes things more comfortable for the passengers and crew, and puts less stress on the gear.

When racing, perhaps 5 or 10 degrees can be added to the above heel numbers, but at extreme angles of heel, you will be making more leeway, so probably not getting any benefit from a fraction of a knot speed increase.

When sailing solo, I'll set the sails more conservatively. ie In a force 5, use just reefed main and reefed jib. Winds around here can be very gusty. It is better to go a bit more slowly, than be overpowered, and unable to do much about it.

I'd be interested in knowing what other people's opinions are on this, so if you have any thoughts, please comment.

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