Hi all,

I just got a second hand spi which has some tears I have to repair. I got the PSP spi repair tape. People at our club told me that once the tape is adhered, the sailmaker should sew around once to make the repair more resistant.

Now, the instruction manual says the tape has to be adhered to both sides of the sail. My sailmaker says just one side. So one or two? Would a double sided repair result in a too heavy part in the sail?

How do you guys and ladies repair your chutes?

Thanx for any help!

Both sides not stiched. But my repairs are pretty minor, mostly as a result of line friction while snuffing.

One side only, no stitches. The double sided jobs I have seen have all had problems with stretch. If taped on both sides, the repair will be stronger than the origial cloth and stretch less. This will ruin the shape over time.

If there is something major, one side and stitched. No need to take it to the sailmaker if you are going to tape it together yourself. All domestic machines are up to the job. Just make sure the kite is clean (no salt) and dry. Go over the tape with a soft rag when you have taped it and work the tape so it adheres as well as possible to the cloth.

Have a look at this frankenchute, which Urban used to good effect in this years swedish Tornado nationals.
http://www.borstahusbild.se/nordicweek/mon31/slides/MV6D9375.JPG

Man, now that's a bad case of spinnaker "elephant butt"

But will the adhesive tape last (salt water, uv radiation etc) without stiches?

Rolf: nice term, Frankenchute! Just invented it??

Consider that most new spis are glued today, with only the first meter or so of the main radial seams stitched. As long as the spi is clean (use a hose with freshwater to clean salt from the rifts) and dry, the tape will last as long as the rest of the chute. The exception is if the rifts are in areas with very high shear loads. Then stitching might be a good idea. Eg. if there is a rift in the area where a patch ends, along luff/leech tapes or along the horizontal broadseams. If you are going to stitch two layers of spi-tape, spray both thread, needle, bobbinhouse and bobbing with silicone spray for each bobbin used. If your machine starts to clog with glue, you will have a hard time cleaning it and making it stitch properly again.
If you are in doubt, post some photos of the spi hoisted and circle the areas with rifts.
Do the documentation for the tape you want to use say anything about cloth weight of the ripstop used in it? If it's extra light, doing both sides can be a good move (became a bit uncertain wether there might be different types of spi tape?). The glue will hold tough, just take care to let the spi dry after use. We even used duct tape in a pinch once, and it held up too well. The duct tape was so much stronger than the spi-cloth, that the spi stretched around the tape and ruined the shape..

I must have heard the term Frankenchute used somewhere, but I dont remember where. I certainly did not invent it.


Jake. Picture is of a Tornado (obviously) with a Marstrøm mast, which are notorious for breaking under the new rig according to popular belief. Look at how far out the traveller is, then look at the twist in the mainsail and how much sheet is out. Amazing.. Granted Urban and Helmuth are lightweights, but I dont think I would dare to let out the mainsheet that far even with a sturdier mast. What do you think?

The spi in the picture won the nationals. They were the only boat not to have at least one DNC or DNF due to breakages. We only sailed 5 out of 8 races. Learnt a lesson about maintenance and replacing dogdy gear <img src="http://www.catsailor.com/forums/images/graemlins/frown.gif" alt="" />

Seems I recall this term being applied somewhere also....

In hull flying conditions there's no way we would sheet out that much on the F18 (AL mast) or the I20 (Carbon mast) . Structural support issues aside, I wouldn't think that the main is properly trimmed that far out either.

I think they are badly overpowered and heading down, both spi trim and rudderangle suggest so. But I think they was supposed to pass to the right of the mark in the background, which looks a bit difficult from that angle. Not sure tough..

I am still amazed that the mast could handle it. It suggests that the old alu T's could play more with the mainsheet downwind than I tought sensible. I guess the loads on the mast are much larger going upwind with lots of downhaul, mainsheet and double trapeeze?

To me it looks like crew has just come in of the wire to drop the kite (so needing to bear off) - otherwise crew would be out (and helm if struggling to make a mark)



Different set of loads.

Upwind, yes you have compression from the main sheet, jib halyard and downhaul, but down wind, you have the kite pulling the top of the mast forward (and assuming you had no mainsheet tension, nothing to stop it keeping going. Upwind, you have the DH and mainsheet and jib compressing it. Pull the jib in Max, pull the DH max and sheet in max and then out on the wire and fly a hull. does the mast break - no becasue they are (fairly) static loads (they can only go so far as you can only pull the ropes so hard and then the hull flies). your load is limited by the mainsheet (you can olny sheet in so hard), the DH (you can only sheet in so hard) and the RM of the boat (the hull will fly eventually).

The kite can pull the mast and keep pulling until something fails(the mast), you can only sheet the mainsail in block-to-block and the mast should be strong enough to hold it. I've only ever seen masts break in 3 days

1, Spreader (or fitting) fails, mast folds at the spreaders or at the mounting top or bottom.
2, Mast hits the water in a pitchpole ot wild gybe and breaks from the "impact" load
3, Mast is broken by the kite pulling it too far forward (loose mainsheet).

Why don't cat companies take the stays and move them further aft to help with this problem? I wonder if it would help that much to even move them back 6 inches/foot. Would this help? I guess that might interfere with rotation, but any ideas?

not really - the problem is the spinnaker halyard loads up above where the stays connect and where the mast is unsupported by anything other than the mainsail. The only way to fix would be to support the mast up higher by using baby stays or something - really wouldn't be that hard to do.

I was wondering if the change in the angle would change the loading on that part of the mast, but that is for you engineering types <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" /> .
I guess with the apparent wind running the show all the time on cats the mainsail should be tight anyway, right? I guess it would be more for the "gonzo" days and to protect the mast (esp for those people who have really expensive masts I guess). Like you said though, doesn't seem like it would be that hard to do. Most high end monos have running backstays that would work, in theory, on cats (aside from getting in the way).

Rolf, I attach a schematic drawing of the spi, it is a Hobie 16 spinnaker and it is stiched. Red spots are the rips, blue spots the snuffer patches (approx.).

Actually these rips are already repaired, but in a very rough manner. They used double sided white adhesive dacron and stiched it. So these repairs are much stiffer and heavier than the original material (beside from beeing ugly, white patches on yellow chute). I want to do a "good" repair on this. So where do you recommend stiches?

I don´t know about the weight of the tape, seems more or less the same as the chute.

Thanx for your help!

Claus,

I would have taped all of them, as long as they are in the spi cloth and not the edge tapes.
Abrasion while snuffing might be a problem with the patch close to the retrieval point, but I would try without stitching first. I am too lazy to take out the sewing machine without really needing to.

How long do you expect to have/use this spi? The spi is the first sail to wear out on our boat. It's performance life is just so much shorter than it's mechanical life.

Thanx Rolf! Hopefully I will be able to use the spi two or three years. Besides the rips, the sail cloth seems to be in quite a good shape. Most Hobie 16 races are without spi here, so I will use it only in yardstick type fleets and for training. I´ll post a pic when it´s finished!