I have a boomless 21 foot cat. When it gets really windy and gusty I can see that my main is way too "deep". The only way to flatten the sail would be to have a boom or use a smaller sail with a flatter cut? Should I switch my main sheet block to a 10:1 since right now I have an 8:1? In the summer, with predominantly light winds it is no problem but in the fall when the wind is steady 20mph with gusts to 30-35 I can't handle our 265 square feet even double trapped. Any suggestions and advice will be appreciated.

I don't have a good answer for you, but what kind of boat is that?

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Hobie Getaway
Prindle 18 - Sold
South Padre Island, TX
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GForce 21. 265 square feet of sail old style pinhead

The way to flatten your main sail is with your downhaul. It should be at least 4:1, and with that amount of main to flatten I would want 6 or 8 to one.
What do you have now?

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Sheet In!
Bob
_/)_____/)_/)____/)____/)_____/)/)__________/)__
Prindle 18-2 #244 "Wakizashi"
Prindle 16 #3690 "Pegasus" Sold (sigh)
AZ Multihull Fleet 42 member
(Way) Past Commodore of Prindle Fleet 14
Arizona, USA
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Does it have multi places for the mainsheet blocks to attach or does it have an adjustable boomlet on the clew of the main
If so the further forward you attach the mainsheet blocks will depower the sail
It allows the roach of the main to fall away and thus depower the main
If all else fails try and get ahold of Hans the original builder

Cool boat!

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Hobie Getaway
Prindle 18 - Sold
South Padre Island, TX
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I have a 6:1 downhaul which really flattens the luff. There is a clewplate and I always bring the 8:1 main sheet block to the foreward most hole. The problem is that as soon as I sheet in a little tight, even with the traveler almost all the way out (to depower some) the foot of the sail bows out to leeward A LOT and drag/lift becomes bad. I am thinking that the sail cannot be used above a certain wind speed? My options:
1. New smaller main sail cut for High wind with a really stiff lower batten?
2. Start using a boom?

I hate to complicate things with a boom. The nice thing about this boat is that it is simply rigged!

Boomless sails are tricky. I would go ahead and add a boom. There is a reason why all newer boats have a boom.

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David
Nacra 5.5SL
Nacra 5.2 (sold)
San Diego, CA
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Some a class boats are going back to boomless, but I'm thinking that the cut of the sail allows for the downhaul to flatten more in order to make up for that. Most of the newer boats have radial cut sails which I'm sure are patterned to make the downhaul more effective than traditional cut sails.
My suggestion is that when it is really blowing, pick up more girls off of the beach to help hold it down, more fun than buying new sails or having to worry about getting boomed. :)

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Cesar (Cez) S.
Hobie 16 (had a few)
Nacra 5.2 "Hull Yeah"
Vectorworks XJ - A class (not named yet)
West Michigan (Grand Rapids/Holland Area)
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Hello,

Not all fast boats are going to a boom as my F25C class is not going that direction.

Attaching the block further forward not only allows you to spill air off the leech but attaching it further forward on the sail also decreases mast rotation thereby depowering. This is what is done on my Hobie 17. BTW - I am looking for a longer section of the older Harken traveller track so that I can travel the attachment point further forward to depower my square top more.

James

Although there are some modern boomless mains that can be flattened with proper downhaul and a bendy mast, the increased draft that you're experiencing in bigger air, is common with older dacron boomless mains. Adding a boom will help if you want to stay with your current main.

A new main out of newer laminate sailcloth would hold its shape better in a blow than an older dacron one. But that's some serious change, worth it if you have it.

I'm a big fan of using a smaller main for high wind conditions, less heeling moment, and a lot less drag than an overpowered, sheeted out mainsail. But you'd need a boom for that as well, as the foot is likely to be shorter than your current main.

Getting something figured out for your boat will increase your hig wind enjoyment significantly, it'll be worth the effort/investment. Practice your righting skills.

Sorry about the piecemeal input but this is not my focus at this time of the year.

As Dave posted above, yes the sail matters and you can see my H17 sails in my image are Twaron (and I haven't found the time to figure out how to rotate it on this site).

1 more point as the battens on a boomless main become more important. I went with the Aquarius round hollow battens. Using my older stock battens my sail's draft was too deep in heavy conditions. Now should you go with round hollow battens or another high end batten on a boomless rig be careful coming ashore with heavy air from behind as the sail will bend around the shrouds when you hit the beach and you can break the battens.

James
Farrier F25C+
Hobie 17+

Quote

I'm a big fan of using a smaller main for high wind conditions

+1
you can't expect an old dacron sail to be great in 20-30

even if new: in real heavy air you need to reduce area with a smaller rag or reef what ya got