I'm putting together a 10' beam Nacra 18 Sq Meter, and the traveller track is missing from my rear beam. This seemed a great opportunity to explore a curved track - so, what do I need, and can I buy it, or do I have to make it? Should it be to the radius of the boom length, or a bit tighter to induce twisting (or is it to continue to force rotation?) Or should I just get another straight track? I have a new Ogletree-drawn Ullman-cut squaretop with a 30' luff coming in a month or three, if that makes any difference. Anyway, any information is greatly appreciated.

I have seen the curved tracks on both harken’s site and on ronstan’s site. They both sell the cars that go on tracks as well as the end stops.

Matt

I know Harken will take your specs and create the track for you...but I recommend that you be sitting down when you get the quote!

Just make yourself a Drop Lever on your boom, it does the same thing as a Curved track and is considerably less expense. Plus, your knees will thank you later.
It will still let you have maximum travel on the mainsheet for downwind sailing and still keep the sheeting angle level and the main sheet vertical.

Would it be possible to get a description (preferably a picture) of such an arrangement?

BR

Patrik

I will try and draw one out later today and post a scan. I don't have a picture, but have seen it used mostly on 18sq's.
If anyone has a picture, post one.

Andrew,

I saw a number of 18 Squares in the late 80's that had curved travellers. These had a center of radius behind the mast, so the clew of the sail would be pulled toward the mast as you let out the traveller. This makes the sail fuller and more powerful. The ends of these travellers were higher than the center, inducing twist as the traveller is let out. These tracks were mounted to the top of the rear beam in the center and then a molded track support attached the ends of the track to the hulls. When properly designed, the mainsheet would be set at the start and then the traveller was the only adjustment made as the boat went upwind or downwind or anywhere inbetween. Nice for single-handed boats, however, the traveller is a bit of an obstacle when moving around the boat.

All the systems I saw were purchased from Harken.

P.S. - All the Nacra 18 Squares started as 11' beam. Why reduce it to 10'? I would have made mine 12' beam if I had to change it.

Hi Andrew,

why dincha write to either us or to Palin? Huh? Merry merry, incidentally...

I have a curved traveller, but I ain't givin' it up. Harken will make 'em for you. If you like, I can get measurements of the arc for ya, or other info about the track I've got.

For the drop lever boom, go to
http://www.geocities.com/mec_coleman/18square.htm

This is Mike Coleman's site. Great resource for 18sq cats. Bookmark it, it's useful.

I met a fella at Birmingham recently. He had a Cat II sq rigged up with some interesting stuff, including a boom vang arrangement which is simpler than either the curved trav or the droplever boom.

Why aincha going to 31' mast while you at gettin' a new sail? Not that hard to add the foot to the head of the mast, and mine and Jay's are working out well. Fact, we prolly got some extra extrusion.

And, like the guy said, why 10' beam?

sea ya
tami

Without a jib, I don't think you want twist...

sea ya
tami

Here is picture of one at the back of the boom. The lower travel car on the boom moves freely.

Very cool idea. I wished I'd seen this before I got my curved travelor track installed.

Bill,
It was very popular with many of the 18sq's in the mid to late 80's as an Alt to the curved track. It sure beats having a track beat up your knees!! The 5.2 with the center bar was bad enough!!
CO

Is there any advantage to the curved (flat) track?

Assuming you have a horizontal boom and a free floating car on the boom?

A longer boom is the only penalty I can think of, and the weight of boom track and car.

The mast is a Marstrom Tornado tapered extrusion, probably 1970s vintage, and measures right at 32'; the finished luff of the sail will be 30'.
Why 10'? I have the beams, and at just over 1/8 of a ton (260 lbs) dry weight, I've NEVER "needed" to trap upwind on my 11' Square. The 10' boat will lift a hull sooner, yet the squaretop will allow depowering (if/when it's needed). The drop lever traveler remains a viable option, tho the pics I've seen show it with a beam-mounted boom which angles up sharply. My boom is intended to be nearly horizontal, so I don't know how well it would work. More thoughts tomorrow, thanks y'all.

I used to think that too, till I started using leach telltales.

Eeew... I dunno... maybe you ought to have a conversation with Palin or Charlie about that. My rule of thumb about twist comes from Palin...

sea ya
tami

I'll wrack Charlie's brain as best I can, and probably interview Palin as well. Speaking of Palin, last I heard there was a very good chance that Jon Lindahl's personal LCD Square, pretty much identical to Palin's (or should that be vice versa?), was coming to Texas to stay.

...Bob Young was in process of purchasing the boat when he passed away.

Do please let me know what the boys have to say about twist in unirigs.

sea ya
tami

Hi Andrew,

The mast is a Marstrom Tornado tapered extrusion, probably 1970s vintage, and measures right at 32'; the finished luff of the sail will be 30'.

Great upgrade for a 18 sq.
This brings up some more questions:
Did you use the nacra or tornado rigging?
Or did you make up a complete new rigging?
Did you change anything on the tornado mast foot / nylon mast ball on beam?


Geert Lindemulder
nacra 18 sq sail # 306

New shrouds, Nacra-style (loooong) forestay bridle. I don't think the eggshell hulls would be happy with the stress of a short forestay bridle!

I don't know if it's original, but the half-socket on the mast base fits over the ball fine. It's not captive, but I'm tying off the mast base to the dolphin striker (JUST loosely enough) and haven't had a problem yet.

What's your hull number, out of curiosity? I have two sets; #189 and #12. The new sail and tall rig are going to go with #12. Where are you located, too?