I'm trying to add 3 patches to my spinnaker for half pole snuffing system for N6.0. I was trying to use the formula from http://www.guckinc.com/spinnaker_patches.htm but it does not work for me. When I divide luff length by 4 it comes up to be 95.5 inches but spinnaker foot is 228 inches. So when I swing the 95.5 inches radius arc from both the tack and clew those two arks do not intercept.

Here are dimensions for my spinnaker: luff 382, leach 321, foot 228 (inches).

Also, I want to add a bail to the mast. I found some people were using piece of rope attached to the 2 drilled holes in the luff groove. I was wondering if the bail from I20 would feet the N6.0 mast. How is the I20 bail mounted to the mast? Is it attached to the luff groove or to the mast with water tide rivets? What is the distance from the top or bottom of the mast where bail should be mounted?

I would appreciate any help
Thanx
Kris

placing the snuff patches are really pretty simple...basically you want to minimize the distance from the upper and lower snuff points to the corners of the spinnaker so your bag can be as short as possible. You then place the middle one and try and get as far away from the other two as they are from the corners or slightly less. That's a huge freakin' chute but you'll need the snuff points placed at about 114.25" from the clew and the tack (intersecting circle), 114.25" from the head of the sail, and the third 104.75" inbetween the upper and lower.



Bail height is a little tougher. It depends a lot on how your pole is placed. Basically you want to be able to pull your spinnaker luff tight between the end of the pole and wherever the bail is on the mast. Mast rake will affect it so be sure to leave some play.

Answers in reverse order :

Rough position bail : (Mast length - hound height) * 0.6 + hound height

Never go beyond that. If you are really scared that the mast won't hold than use 0.5 instead of 0.6 This halves the bending on the mast. Whatever you do don't believe Bill Roberts reply. He will have you put it 0.33 above the hound which is way to low, the mast can take alot more especially when it is a modern cut spi.

Get the rope spi bail. There is NO reason to fit that metal thing up there. Really no advantage what so ever.

Patches in spi, there is actually a way to discover it yourself.

Lay the spi out on the floor. Grap the spi in the points you think are about right and place these all in one hand. Now lift the spi and stand on a chair or something. have somebody else straighten out the spi towards the floor. If one part of the spi sticks out below from the rest of the spi try to determine which part is it (often it is the top or the tack or part of the leech) and lay the spi on floor and move the nearest point towards the part that is sticking out. Do this a few times and you'll get it right. Then mark the spots and make the patches there.

It helps if you use small pieces of tapes to mark all the spots that you have held at a time.

There are formula's to do this but really just doing is both easier to explain and easier to do and certainly more dependable

Wouter

jake is right but as all sides of the spi are curved outward you can often win a inch or 10 by fine-tune the patch postion with the method I described. I know because I have done it myself at my current spi. Having said this. Jakes positions will provide excellent starting points.

Wouter

Thank you for very fast reply.

One more question for Wouter. In your formula “hound height” indicates the distance from the bracket (where forestay & shroud wires are attached) to the top of the mast. Am I right?

Kris

Hound height = distance base of mast to place where stays (shrouds) are attached to the mast.

I'll give an example :

mastheight = 8.5 mtr
hound height = 6 mtr.

spi gate = (8.5-6.0) *0.6 + 6.0 = 7.5 mtr.

This formula accurately describes the bail heights on F18's ,F20's , F16's and as good as all cat that have been retrofitted with a spi like Nacra 5.5; Hobie 18's, Taipan 4.9's etc. It will hold. In your case as nacra makes rather flexible mast you must remember not to release the mainsheet when blasting along under spi. USe the traveller to depower instead and otherwise choose to go over and go for a swim. Keep your mainsheet sufficiently tight, this is easy to spot, when you top bends forward more than just a little your mainsheet is to loose.

Good luck and have fun.

Wouter

How about patches itself. The source that I provided above suggests to use 12" circle of spinnaker cloth, 9" circle of 3 oz Dacron and 5" circle of 3 oz Dacron.
Do I need all this material for the patches? Would all this material (Dacron) make harder to snuff?

Kris

While on the subject, what are the current thoughts on 2 versus 3 sail patches? While at the Tboat nationals, all boats had 3 patches. This should make the blob of sail material larger and harder to snuff compared to a 2 patch sail. I think the Guck site recommends a 2 patch sail...but I know for a fact that site is several years old now and has not been updated to current trends.

I currently run a 3 patch sail using the Guck Skunk Snuffer. With a well used Dynalite (silicon impregnated) sail, snuffing is great. With a nearly new, 3 patch nylon (cripsy) sail, snuffing is much more difficult. My snuffer bag is likely long enough to handle a two patcher...should I make the change?

Mike.

Krisu13, You might want to reread Jake's advise. Wouter is giving you the optimum number for where to place the bail based on a sail cut specifically for your configuration. All the F18/20/16 etc have specified pole lengths spin size etc.. so yes if your spin is designed to go there it will work fine. But if you are using a spin from a different class and/or a different pole then this might not be the best place for using the sail.
If you want to have the best luck keeping the top of your mast intact though leave it where Wouter specified then recut the sail after you have the boat set up.
This is the reason this height is used. It is the best compromise for not breaking a mast.

What Jake offered was where to put the bail based on the shape of the sail for best sail shape.

Personally I'd place the bale on Wouters advise and then place the blocks where you want them (shroud, rear beam etc..) and have a sail maker look at the chute on the boat and cut the corners to fit the boat right.

I have gone through rigging a spin on a Hobie 18 and this is how I ended up doing it after much trial and more errors.