Spinnaker - how do you select what oz?

[cmedsailor]

Hello.
how do you select the most appropriate oz of a spinnaker? Based on the size of the boat or the winds you would like to use it?
Offers for a spinnaker for a 36ft fin sloop (6 tonnes) include all 0.75, 1.0 and 1.5 us-oz variations. So what is happening here if sails manufacturers' offers (for the same boat) are so different?

 

[Quandary]

3/4 oz. is normal weight of working spinnaker, we used a 1 1/2 oz. reacher above about 20 kts. or if closer reaching in 16+when racing. Many cruisers don't spinnaker reach or use kites above about 15 kts. so this weight is best for light weather use if only one is carried. The 1 oz weight would suit heavier weather running and might last longer but would not be favoured for light airs.
If you have not got a kite you probably need a 3/4 oz.

 

[sailorman]

i would go for the 1 oz
it would be more forgiving to cock-ups than the 0.75
the 1.5 might be too heavy & bulky to stow

ask your sailmaker

 

[lw395]

Depends on windstrength as well as boat size/displacement, as other posters have said. Also consider the cut, as a triradial will take more more wind without distortion than a horizontal cut, so may be better value in the long run.
Unless you're intending to use it in strong winds, a 1oz tri-rad might be a good only kite for a 6t boat. A 3/4 oz will be better in the light stuff, but I'm guessing you'll start the motor when a 1oz struggles to fill?
For racing, a 1/2oz makes an amazing difference in the very light stuff, being light enough to get up and catch the breeze at the masthead, you have to decide what will be most useful to you.

 

[bbg]

Quandary is right. 3/4 oz is probably the right one. Light enough to work in quite light winds, strong enough to use in the winds you are likely to fly it in without a full racing crew.

The heavier cloths - esp 1.5 oz - are for stronger winds. You don't need that unless you plan to hoist the kite in 20 knots plus.

Edit - I used to race a lot on a J-36 - so similar size to yours. We had two 0.6 oz and one 1.5 oz spinnaker. We flew the 0.6 up to and beyond 20 knots, and raced the boat hard and frequently. In 5 years we only used the 1.5 two or three times - when the wind was over 30 knots true.

So a 3/4 oz kite, that will be used occasionally on a cruiser, and is not likely to be flown in more than 15-20 knots, should be fine.

 

[matelot]

reversing the question, with an inherited spinny on a second hand boat, how do I find out what the cloth is and therefore get an idea of safe flying conditions.

also have a cruising chute of similar light cloth - how do I determine what weather I can fly that in?

 

[William_H]

Safe flying conditions limiting factors are usually more the helmsman and crews skill and courage rather than cloth weight.

Now my little boat is more than usually light and skittish but last sunday club race I was short of skilled crew. I got a friend who has a heavy 23fter (no spin) to come. He thought he might learn something. (haha)

I elected because it was gusty 20 knots to use tiny spin. It was off a 14ft skiff so pretty tiny. We got it up easily and it pulled the boat nicely in lieu of the tiny jib I had on. (no 3)
Come tme to gybe the spin I felt I wa sthe only one to go onto the foredeck to move the pole. (end for end) I instructed the heplmsman to not gybe unbtil I was ready and moved down the new windward side. He turned the boat a little to get the boom across where upon the boat heeled and kept turning. It spun around to a reach and lay the mast in the water. Me clinging (white knuckles) to the boat side.

I got him to straighten up onto course but he went too far and she gybed the main again with similar effect. It all seemed like a good time to pull the spin down. I wished I had warned him (coached him) on controlling the beast. I must have got complacent myself as I usually helm when gybing. Yes we lost the lead and slipped even further back because I was reluctant to raise that spin again.

So I am sure your boat is not as treacherous as Howzat but the story illustrates that spins can be tricky. good luck and wear a lifejacket.
olewill