How to design a small spinnaker.

[jonjo]

Given specific rig dimensions does a sail-maker have much latitude to reduce the sail area of a spinnaker from what would be considered normal for the rig?

I ask because the other spinnaker thread has got me thinking whether I need a spinnaker and my current 1100 sq ft asymmetric is too big for single handed sailing.

 

[knuterikt]

Given specific rig dimensions does a sail-maker have much latitude to reduce the sail area of a spinnaker from what would be considered normal for the rig?

I ask because the other spinnaker thread has got me thinking whether I need a spinnaker and my current 1100 sq ft asymmetric is too big for single handed sailing.

It's not uncommon for racing boats to have smaller spinnakers for heavy weather.

 

[jonjo]

It's not uncommon for racing boats to have smaller spinnakers for heavy weather.

If recall the Sigma 33 OOD spi dimensions correctly the light full sized one was 800 sq ft and the heavy was 680. However if looking for a further percentage reduction I have a hunch the only meaningful shaving off of sail area would be from the sheeted side of the sail at which point we are now talking about a slimline polled out asymmetric. Does such a beast have a name in sail making land?

 

[Quandary]

When we had a very tippy Trapper 300 we had one called a 'blast reacher' but it was not asymetric. If you tell the sailmaker what you want he will find a name for it.
It was not really that useful, as by the time it was effective we were reluctant to fly it.

 

[Ingwe]

The best bet is to talk to your sailmaker - if they did not make your current sail it would probably be useful for them if you took along a couple of pictures of it so that they can get an idea of it's design.

To reduce area you can reduce the foot length raise the clew and reduce the area of the shoulders of the spinnaker. The smallest asymmetric is normally designated as an A5 but that is really a reaching sail so you probably don't want to go that far but if you let them know how you think you will use it they can blend the design to suit eg I had a sail made last winter that is a crossover between an A3 and an A4 which is about 20% smaller than our largest spinnaker but is probably the type of thing you are after.

The other thin to bear in mind with sail handling is cloth weight as you see a lot of cruising spinnakers made out excessively heavy cloth designed to be up in 30 knots of breeze, which drastically increases the weight of the thing and makes handling a lot harder.

 

[savageseadog]

You can't reduce area much by reducing the luff and leech lengths, it has to be reduced on the girth and foot.