what best triangle for a sail? (considering lowest CE)

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mussopo
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what best triangle for a sail? (considering lowest CE)

Post by mussopo »

Seeking technical advice for 2 different small triangle sails (same approx. sail area though), in a traditional fixed rig geometry (with mast & boom). For instance, PA sail has variable geometry, i guess.
Question is:
Considering one triangle being equilateral, and the other being isosceles or even scalene shape, what would be the best for overall upwind sailing? (Minding that this is to sail a paddling boat rather than a sailing boat).
My empirical feeling is that the equilateral is best in almost all wind force situations (though with a lower height profile and not so good in a weak breeze...but then who cares?). This is assuming that the equivalent isosceles or scalene shapes, could be positioned in such a way that its vertexes (heads(?) where angles are smaller) should be pointing higher.
Nevertheless i'd appreciate input, if any relevance found on this issue.
Thanks
Last edited by mussopo on Mon Oct 19, 2009 5:44 pm, edited 2 times in total.

Romainpek

Re: what best triangle sail?

Post by Romainpek »

It would be nice if you could draw something, it would help me understand the question

Alm

Re: what best triangle sail?

Post by Alm »

This isn't about pure geometry. There are many other factors to consider - ease of control, camber, stability (without outriggers), possibility to dismantle it fast (or at least - to raise or lower it fast on water). For some people some factors are more important than other. There is a relatively small number of proven types of triangle sales for a small boat as a main sail (if this is what you want), and each design has a recommended aspect ratio (H/W) and other details. There are also triangular designs for auxiliary sails like jib. You should go to Yahoo Sailing Canoes group http://groups.yahoo.com/group/sailing_canoes/ --> Messages (you need to register), and provide list of your needs:
1) Type and size of the boat
2) Need to sail upwind
3) With or without outriggers
4) Semi-permanent or easy to dismantle and to travel with
5) Design for a main sail or other sails.
6) How many sails and masts you plan to carry, or how big total sail area you want.
7) How important for you is the ease of making it yourself (if this is your plan). Some sails are easy to make and difficult to control, or vice versa.

It doesn't matter that your boat is foldable - some people at Sailing Canoes have folders, some not.

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mussopo
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Re: what best triangle sail?

Post by mussopo »

Hello

It may seem some kind of stubbornness from me, but i'm still trying to get something to sail occasionally upwind, and minimizing or eliminating the need for an outrigger at the same time, (in this case, care should be crucial and so i intend to apply for some sort of "lazy-jack" to quickly reef the sail too). I still believe that i can manage this with an equal or less than 2qm sail in my Klep2 (5.2m).
For instance, applying same airplane wing principle... longer, slender ones should be good for soaring while shorter, wider wings are supposed to be best fitted for speed. In my case, when referring to equilateral triangle sail, it's the one with lower center of effort (CE), which might be desirable for stronger breezes.

Alm

Re: what best triangle sail?

Post by Alm »

2 sq,m (22 sq.ft) is just barely-barely enough for upwind sailing on Klepper2, in my opinion. Even without additional resistance caused by an outrigger. You'll need at least 3 sq.m or 4 sq.m sail. But again, you can ask at Yahoo Canoes. There are not too many small boat sailors at the foldingkayaks.org.

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mussopo
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Re: what best triangle sail?

Post by mussopo »

Ok. thanks for that, (i'll give it a try anyway (for the moment i'm idle again for my main mast...can't find an easy way to get some duraluminum 19mm tube here).
Anyway, a bit of paddling whilst "upwind" won't harm with fixed tackle :wink:.

Sorry Romain, but i figure you guessed what i meant about the need for a lower CE (anyhow i can pm to your e-mail if you wish so with sketch...easier for me). Congrats for achievements on your rig.
Last edited by mussopo on Wed Jul 15, 2009 5:48 pm, edited 1 time in total.

Romainpek

Re: what best triangle sail?

Post by Romainpek »

In fact, I did not even know what "scalene" meant.

To go upwind, the best seems to be a narrow shape, while going downwind requires a broader (more "square") shape.

There is no free lunch, each rig is a compromise.

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