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Custom solid spinn-chute

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Bramble View Drop Down
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Post Options Post Options   Quote Bramble Quote  Post ReplyReply Direct Link To This Post Topic: Custom solid spinn-chute
    Posted: 08 Feb 19 at 2:33pm
Gentlemen, I'm trying to create a chute for my spinnaker, so it'll be out of the way until needed, and can be hoisted from as close to the bow as possible. No need to suggest alternative ways of launching and lowering, or whose job the kite-handling ought to be. I'm a singlehander in a two-handed class and I've been through it all ad nauseum...

...and I've made on-deck hoops from plumbing-pipe and chutes from old sail fabric, and they were as unsatisfactory as they were unsightly...

...so I want to buy a big piece of solid waste-pipe (solid pipe, I mean, instead of fabric) and install it below the foredeck with a smooth, moulded GRP mouth, and have it leading right back to the middle of the cockpit so the sail is out of sight and mind once it's lowered, and free of snags and tangles.

My only question is, what is the narrowest internal diameter I can select when ordering the pipe?

My spinnakers vary in size from about 90sq ft to double that. I'm hoping an 8-inch (200mm) pipe will be wide enough - it's much cheaper than the 250mm version. But I don't want the sail jamming in the chute.

Any advice?

Thanks for reading.
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mozzy View Drop Down
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Post Options Post Options   Quote mozzy Quote  Post ReplyReply Direct Link To This Post Posted: 08 Feb 19 at 2:50pm
20cm would be pretty narrow for a 180 sq ft kite. But it mostly depends on how many patches your kite has and whether you separate them out with spacer knots. 

A single patch will lead to less bunching, but will need a longer chute. If you need more patches you can alleviate the bunching by putting stopper knots in the down haul. 

The other issue you may have with a solid pipe is it won't drain as easy, which is why most kite socks have a mesh bottom. 
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 08 Feb 19 at 3:29pm
Also be warned that making a moulded chute was the single most unpleasant boat building task I've ever undertaken. Trying to get the reverse curves and everything else mirror smooth was a nightmare. If I couldn't get a suitable commercial cgute, or afford to get one made then I really wouldn't bother!
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Post Options Post Options   Quote Old bloke Quote  Post ReplyReply Direct Link To This Post Posted: 08 Feb 19 at 4:33pm
Might be worth trying to find an old dead plywood spinnaker boat ,such as a fireball, and scavenging the chute from that
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Post Options Post Options   Quote Sam.Spoons Quote  Post ReplyReply Direct Link To This Post Posted: 08 Feb 19 at 11:37pm
The chute mouth is the important bit, the Spice has a mesh sock and the chute is formed by the spaceframe and the bow of the boat, around 8" x 10" at a guess. It's fine for my small kite which is from a Topper Omega and about 13M2 but it is tight for the original Spice 22M2 kite. TBF the Spice kite is pretty well used and not so crispy but the Omega kite is not that much better so my conclusion is that size really does matter.

Edited by Sam.Spoons - 08 Feb 19 at 11:38pm
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Post Options Post Options   Quote Bramble Quote  Post ReplyReply Direct Link To This Post Posted: 10 Feb 19 at 1:44am
I'm grateful for this advice. Reminds me of why I put the chute-idea on the back-burner previously.

Actually a custom chute-mouth may prove even harder to fit than to construct, because the space on my foredeck is limited and there are ribs at close intervals which I don't want to damage.

It occurred to me that I could use the inflated tube from a trolley-tyre (or a slightly bigger one) as a mould for a curved above-deck entry to the chute - so that the kite isn't forced to turn any tight angles as it is hauled back into the chute.

I'm glad the question of patches was brought up - I had even forgotten that bunching is the problem. 

I'm thinking that assuming I can find room on board for about 8ft of the 10-ft pipe, I could make it work by adding a grommet (with a patch of reinforced kite cloth) about 5ft above the foot of the kite, and another grommet, midway between that and the head of the sail...

...then attach a retrieval line to the head of the sail...and follow me closely, here...it'll have a stopper knot above the upper cringle about 4ft from the head, and another stopper, about 4ft below the upper stopper, and below the upper cringle...so that the whole sail will be retracted in two bunches, within the 8ft chute, but the position of the knots won't distort the luff when the sail is hoisted. 

Something tells me that's nicer in theory than it'll be in practice. But looking at the folded kite in the living room, it's no bigger than a plump pillow...surely that'll slide willingly enough inside eight foot of smooth eight-inch dia pipe?

Go on, tell me what I don't want to hear.  LOL
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Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 10 Feb 19 at 12:20pm
I don't think I'd have a retrieval at the head, I think that's going to slow hoists. I reckon the traditional all 3 corners lining up at the mouth is probably best. More important than pipediameter to my mind will be friction and making sure the thing is really well polished. Little bits of roughness have a nasty habit of pulling stitching. Note too risk of the downhaul line scoring ruts in the chute mouth. Needs to be solid enough not to cut with rope burn.
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Post Options Post Options   Quote Rupert Quote  Post ReplyReply Direct Link To This Post Posted: 10 Feb 19 at 6:03pm
Rope seems to cut gelcoat very easily, at least on some classes. It may be as much about angles as materials.
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Post Options Post Options   Quote Riv Quote  Post ReplyReply Direct Link To This Post Posted: 10 Feb 19 at 6:07pm
Friction is worst bit. Our Laser 2 needs a really good spray of silicone all over the chute area and up the tube to make it all work. Whole thing is really too small.
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Post Options Post Options   Quote iGRF Quote  Post ReplyReply Direct Link To This Post Posted: 10 Feb 19 at 6:59pm
I messed about with this concept for ages and the problem with the solid pipe idea was that it messed with the jib slot and got in the way of it, I used a self tacking jib at the time, the best thing I came up with was a massive opening, which i think is the issue, once the kite is in it'll crush down pretty small it's just getting the whole thing in to start with and it can be prety big and bunched up with the head foot and clew all trying to come together almost simultaneously.
So that thing we made for the V twin worked pretty well, it was one of the actual sucesses of that misdaventure, I'll see if I can't find a picture to attach, nothing you can buy I fear it was made for the purpose. But if it helps prompt something from your head then it'll have been worth it.

Edited by iGRF - 10 Feb 19 at 8:14pm
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