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cat ketch rig


Guest Stan

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Hi,

I'm new to group and am seriously considering building a CS20. I have a few questions regarding the rig's behaviour that hopefully, some of you out there who have sailed these boats, can answer.

I've heard from someone that cat ketch rigs have a "distressing" tendency to bear away a little before picking up speed when a gust hits, apparently because the static windage of that big mast and sail so far forward pulls the bow off until the boat has steerage way.

Has anyone experienced this? Is it significant and distressing?

Regarding the reefing, is it possible to do away with the sprit boom and reef by rolling up the sail on the spar (the sail would probably need a luff pocket and the mast would need some mechanism to rotate and lock in place)? There's a boat called "Lilli" by Gilles Montaubin (I can't seem to contact the designer) which looks remarkably similar to the CS20 that uses this method.

What would be the drawbacks of being spritless? Can anyone see a problem with rolling up the sail on the mast?

On a different note, has anyone added an outboard well to a CS20? How did you do it?

cheers,

Stan

Tasmania, Australia

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Hello Stan,

I still building so I really can't answer your questions. I've never heard anything about any bad tendencies of this rig. Everything reported on this forum about the sailing tendancies has been very positive concerning the Core Sound designs. Is your concern related to falling off the point and losing speed or falling off the wind and capsizing on next gust?

On the reefing issue if you look back into the older posts from May ("Another reefing question" and "Sail design.. CS20") you will find some interesting information. There was also some posts recently about outboards but I don't think it was on the Core Sound design seems like the posts were about the Bay River. For wells you might look at some of the posts and photos on the Princess.

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Guest Anonymous

There is no doubt that the cat-ketch rig handles a bit differently than the normal main & jib rig. Have you read the article on the cat-ketch rig on Graham's web site?

The main thing to know in a gust is to let the foresail off first to avoid the condition you mentioned. This is opposite to the technique used in a main & jib rig. Sail with the foresail sheet near to hand so you can dump if when needed.

There are ways to handle reefing while keeping the sprits. It depends on which CS you have and whether you use a sleeve luff or sail track. This has been discussed on the forum before. Going to a spritless rig is possible but looses a lot of the versatility of the rig.

Tom Lathrop

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I was hoping that others would respond to this. It appears that your friend is long on bad theory and short on experience with cat ketches. There is no tendency to bear away in a gust, unless you decide to dump the mizzen sheet in a gust and then you would. The mizzen does operate in the backwash of the main, the same as the main operates in the backwash of the jib on a sloop, it is up to the skill and judgement of the designer to balance the hull, rig and appendages to make it all work over the widest range of conditions.

The sprit or 1/2 or full wishbone is what makes this rig really work. By eliminating sail twist, the rig becomes docile especially downwind in strong winds. Upwind the sheet loads are lower because you only pull the sails in rather than in and down.

We have discussed reefing on earlier posts, but if I was building a CS20 I would fit either a sail track and reef the conventional way or use a sleeve luff with a rotating mast that locks. We fitted this to Sam & Earls CS20 Ketchup and Sam called me last week to tell me that it worked fine when he used it last time out.

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Thanks for the informative replies.

One more thing though.......

I'm not experienced enough to look at a hull shape and know how the boat will feel on the water. How do the Core Sounds go in sharp chop (we get this quite frequently where I sail)? Do they slap on the surface a lot or do they cut through?

Graham, at Carla's suggestion ( I e-mailed her last week) I'll probably give you a ring some time this week to talk to you about outboard wells, et al.

cheers,

Stan

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Guest Anonymous

Stan,

Every boat is a compromise. I can say that the Core Sound 17 and 20 excel in some of the choppiest water to be found. Look at the photos on Graham's website. There is one of the CS 20 in a strong breeze of about 20kts making 9kts in fine fashion and in the shallow water of Pamlico Sound.

Tom Lathrop

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Richard,

The way we reef on a sleeve luff is to sew on a reinforcing patch, similar to the tack patch, and then sew on a webbing loop back about 18" (450mm) from the luff on the line of the sprit. The snotter is unclipped from the mast and clipped on to the webbing loop. The mast is rotated, rolling up the sail till the snotter clip is beside the mast. Pin the mast to stop the sail from unraveling, sheet in and sail on.

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