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Old 08-01-2009, 04:52   #1
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Suggestions on correct size for spinnaker

Can anyone shed some light on the sort of spinnaker sizes we should use on our Adams 35 cutter rig. Having never flown a spinnaker we are in the dark on that subject.

masthead rig, mast to deck is 12100mm, forestay is 12780 top to bow attachemnt.

We have the choice of 4 spinnakers measuring 10600mm, 12000mm and 2 have 12200mm luffs. The widths are 5800mm, 7200mm, 2 x 7400mm at the widest point respectively.

All are triradial conventional spinnkers.
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Old 08-01-2009, 08:08   #2
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If you are shorthanded and inexperienced get an asymmetric with a sock and not a symetric...a whole order of magnitude easier and safer.

Then go to a sail maker's site like FX sails and they will give you dimensions or go to your local sailmaker.

Phil & Nell who fly a 2000 SQ FT asymmetric with a sock
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Old 08-01-2009, 12:36   #3
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No doubt that an MPS or cruising chute is the top of the list, however we currently have the chance to get a regular spinnaker and just need to make sure that we do not pick one that is too big for the rig. Is a 12000mm luff on a spinnaker too big for a 12780mm forestay ?
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Old 08-01-2009, 15:08   #4
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Quote:
Originally Posted by ribbony View Post
Is a 12000mm luff on a spinnaker too big for a 12780mm forestay ?


I would have thought 1200 mm luffs sound right as they are hanging to deck level when the boat is becalmed and unpoled.

I think its a question for a sailmaker.

Symmetric spinnakers are good in that you can carry them when a cruiser most needs it i.e. when the wind is up the bum! Asymmetric wont hold with the wind too far behind.

A lot of people are scared of spinnakers. Don't be!

They are great sails.

Wool them to put them up and if you are at all worried about the wind coming up make sure you keep a mainsail up too, then you can shadow the kite with the main when pulling it down.

A sock on an asymmetric is a blessing put on cruisers. But a triradial will always be able to be brought down. Sometimes it takes a few minutes and can be tricky (wear a safety harness!) but normally only if you have held it too long in a rising wind. Get rid of it early.

I think an Adams will like the power of a big spinnaker.

By the way, yes kites can pop. If you can't afford to rip one, don't buy it.

In one race series we blew 6 spinnakers including 3 in one day. The skipper wanted to win. But there was no reason - apart from his ego - to have ripped one


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Old 09-01-2009, 00:44   #5
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Thanks Mark. Yes we are scared of spinnakers, through ignorance

We were planing to take one asymmetrical and one conventional. Though it will be many months before we are even tempted to try them, better get a handle on the Main and furling headsail and staysail to begin with.

6 blowouts in a series, ouch ! The sailmaker would be happy with that.
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Old 09-01-2009, 02:15   #6
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First of all I am not an expert or a sailmaker so this is just conversation. The spinnaker is one of my favorite sails. I had angst in the beginning and it can be tough to handle when things are going wrong but I fly it whenever I can now.

If my High School Math is correct we have a 39.7 foot mast, a 41.9 foot forestay and that makes the J dimension about 13.4 feet. I think better in feet.

I have read that about 1.5 times J is a good start point for the spinnaker foot. So 20 feet. Converting back into mm that means about 6,000 mm. The breast will be wider.

There are times when you will want more power and there are times you wish you had less. Depending on the cost of the sail (unable to buy 2) I would try and go sailing with someone who has a similar boat so you can get a feel for it.

Here are some thoughts I would have regarding power -

Crew - Is it just 2 people all the time? If so I would go a tad smaller.
Boat weight - If the boat is heavier I'd go a little bigger
Reaching - A larger sail will be more to handle when reaching*.
Reaching - I agree with mark on luff dimension. I think luff = mast height is about right. You don't want the sail in the water when calmed or when reaching.
Wind - What winds do I expect most of the time. If higher winds I'd go a tad smaller.

(*When reaching you are likely to have the pole low and forward and be sheeting hard)

I think your stated choices are

10600 X 5800
12000 X 7200
12200 X 7400

Given those choices I personally would go with 12000 X 7200. It is bigger than I stated but the 10600 X 5800 might be too small most of the time. We are also talking about the breast dimensions you provided not the foot dimensions - The 7200 (23 feet) will be narrower than that in the foot.

I think with 2 up cruising the 12200 X 7400 is too big. Not so much the foot but the hoist height of 12200.

But I am often wrong...
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Old 09-01-2009, 13:47   #7
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Yeah, once you get used to them they are fun.

Could you reef one by putting a few cable ties (edges soffened with cloth) in the top few feet at the head?

Sometimes when setting a wooled kite in light wind the top few don't break immdeiately, and the sail still sets well. Pole a little higher, thats all.

Could be a thought for early practice?

Mark
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