Forgive me if this has been discussed, but I did a search to no avail. At any rate, after a 10 year hiatus from sailing I just bought a Dart 18. The sails are questionable at best so I'll probably get another set made. Has anyone put a square top on a dart? Advantages? Disadvantages? Sail plans?

Most of the newer catamarans have fat-head or squaretop sails. This is the latest in design. Not that it is a new concept. I can only imagine that if you can find someone that is a great sailmaker you could benefit from a squaretop. If you are racing, even portsmouth, I doubt it would be legal.

Later,
Dan

there are portsmouth rating adjustments for square tops.

See attached pic. The boat is also widened to 8.5' and also has a much larger jib and bridal foil like the Nacras. Also the rudders have been raked under the boat. The boat really sails nicely and is very competitive.

I have a squaretop on my Hobie 17 and I love it. You will see a BIG difference in light air. You can move good even it a light breeze.

Doug

A few people have tried the squaretop.
Another option to getting them made, is to buy used from the UK. There are LOTS of good used sails as it is a huge class in Europe. The cost of shipping is not bad if you do not ship the battens over. Check out www.dart18.com

That looks a really nice job. Did you fit the stronger forestay chainplates, fitted on newer Darts ? The originals have been known to fail. The foil will help to spread the load anyway.
Headhunter: You may not get an answer to your query on the UK Dart 18 website. There are very few modifications made to Dart 18s in the UK, as any changes would hugely devalue the boat.
The Dart 18 is a very strict one design class and they always say "If it did not come with the boat when new, it is not allowed", but that should not matter where there is no class racing - like in Florida.
I know that the Canadians have quite a few Darts and fitted spinnakers to some a few years ago. http://www.dartcatamaran.ca/

Thanks for all the responses thus far. I actually found a UK based agent who sells Dart 18 square tops for the Dutch sailmaker, Landenberger. Prices are competitive, the sail plan looks strong, and they can build in a variety of materials. Check it out - http://www.cat-bitz.co.uk/

They also have dart rudder rebuild kits (thank god).

The only thing I don't know is what (if anything) this will do to my portsmith rating.

After looking at the Portsmouth ratings and taking the sails into consideration I think that the Dart 18 with a couple of modifications could be quite a giant killer.

Take the Rating of a Dart 18: 76.4
Add the Square Top Main (oversized): 0.98
Add Spinnaker: 0.96

Now multiply all that together:
76.4 X .98 X .96 = 71.9 (rounded)

This configuration will still [color:"red"]get[/color] time from a Hobie 18 (w/o chute) at 71.4. I cannot imagine this would not win a handicap race almost everytime.

Anyone have a Dart18 for sale? Kidding, I like Class racing too much I will stick with the Formula 18s, even at portsmouth of 62.4...Ouch! I think there are too many great sailors on this boat.

Later,
Dan

and watch mast fall down - remember it is an unsupported mast (no diamonds) and so (from info gained from the UK fleet) you have to be VERY carefull in anything over about a F3 !

Or if the mast does not fall down, you swim - the D18 has very fine / deep section up front and the rudders are not great - I would not fancy the chances of bearing off in time with a big gust


Not a good plan IMO

The spinnaker that was designed for the Dart 18 is only 12.9 sq. M, because of the unsupported mast section.
Also I agree that, if the bows go down, the shallow rudders loose grip very quickly. Maybe a spinnaker is not the best idea. The Class certainly rejected it after trying it for a while. Still, that Dart with the squaretop looks good.
I have had quite a few dealings with Andy Morse at Cat-Bitz and he is always very helpful.

It's not my boat, so I can't say for sure what he has for the chainplates. Also, the boat has lengthened rudders..probably put 5-6" on them. I think the guys up here have given up on spinnakers.. I personally would think that it would be a bad idea because without a daggerboard or centreboard to pivot around, and since the hulls are quite fine it would be slower to turn downwind.

I am fairly sure that the heavier bow chainplates were introduced at the same time as the spinnaker. I think that there was a pair supplied with the spinnaker kit (about 1997 ?) and have been on all Dart 18s since then. I have also seen sidestay chainplates with cracks. They should be checked regularly on older Darts.