What Size Spinnaker?

[Jeannius]

Having refused to get a spinnaker for my Privilege 435 for many years I'm now re-evaluating things as my departure for the South Pacific and beyond gets ever closer.

As I'm still not sure I want one I'm looking to acquire a used one so that I don't have to spend too much.

So, how to size a spinnaker? The Privilege web site and spec sheets give the area of various sails but not the dimensions. The things for sail on ebay generally give dimensions but not area (I know I can get an approximate idea of area just by calculating area of a triangle and adding a bit).

The spinnakers for sale at the moment with the right sort of luff - my forestay is 56ft so I'm assuming that's about the maximum luff I can use - probably come from half-boats as they all seem to be 28-30ft at the foot.

Is this too narrow for a cat with a 23ft beam?
What sort of weight should I be looking at for what is intended to be used in mainly 10-15 knot true and no more than 15-20 knot true?

[svcattales]

Hi Jeannius, I just went through this process last year for my Privilege 37. Check out my thread "Spinnaker Specs for my Cat" from last year. I got lots of good inputs and ended up with a great chute with sock for $550. After taking a cruise with it last winter, I highly recommend it. We didn't use it much on our mono, but on the cat is much easier to rig and store. Downwinds and broad reaches are a lot faster and we can even carry it on a reach with the apparent wind just forward of the beam. Don't leave home without it!

[Bash]

If we're talking about conventional nylon, a 3/4 oz spinny is ideal for use up to 18 knots apparent.

Realize that just as genoas come in different sizes (150% = "Number 1"; 100% = "Number 3"; et cetera) so do assymetric spinnakers. For cruisers, a G3 (3# Gennaker) is a great chute, highly manageable by a shorthanded crew and far more versatize in reaching conditions, especially in a moderate breeze.

In other words, don't just look at the luff. The foot can be an equally important measurement.

One final thought: a lot of people buy used chutes because they rarely use them. And then end up rarely using them because they don't have an ideal sail. Getting the right sail fit to both your boat and your expected uses, you might find that you use a well-made chute a lot, and the savings of fuel in light airs will soon pay for the initial expense for someone making long passages. I constantly see people motoring downwind in light air because they haven't got the sail they need to do it right.

[Adaero]

Hi Mike,

We have 2 gennakers on Tulliana, the only reason being is that one was free with the boat when we bought it. Unfortunately I don't have the luff sizes etc. Both are currently in socks but I'm looking to put one of them on a bowsprit and furler.

The large one is a 155msq 1.5oz. This is ok up to 15 to 18 knots but trying to get it down in 20 knots is a right hand full and I wouldn't advise it when shorthanded.
The smaller one at 80msq and 2.5 oz we had made in Cape Town after numerous conversations with some of the delivery skippers. The majority advised that on trade wind passages you would have no choice but to drop the 1.5oz one every evening where as we used the 80msq sail day and night in winds up to 26 knots with no problem and it was very easy to handle. Another advantage was that we could use the smaller sail much higher not only giving you better visibility but also lift on the bows.
If you are looking for easy downwind sailing in varying conditions I would recommend the smaller heavier sail, if you want to keep moving in very light winds then get a larger lighter sail. My choice would be the smaller one every time as you still have the choice of main and genny in the lighter winds.

[Jeannius]

Thanks all for the replies so far. I have a 65sq metre furling gennaker that I can use comfortably up to 25 knots so I'm mainly concerned with keeping moving in light winds.

Thanks Greg for the link to your thread. It contains just what I needed to know. I knew I'd seen a thread before but using the search had come up with hundreds of mainly irrelevant threads!