Can anyone tell me the diameter and guage of the stainless steel tube used for square hoops please? I fancy a self-build project.

I've just been looking for the same, and found 19mm to be the O/D, but the wall thickness can be 1.2, 1.4, or 1.6.  The latter seems to be the more widely available in 316 grade stainless - 304 grade is less ressistant to corrosion but seems more widely available. I got a section on e bay, but local stockists might order 3m for you, leaving a bit spare!
Maybe a local fabricator can supply the tube and weld it for you too?

Don't use stainless - carbon is the way forward. 25mm (ish) dia. verticals with a 12mm rod accross the top. Fabricate to shape on the boat and weighs far less. I'll post some pics to Mags now that I have reworked the traveller along the top

Thanks - I would really like to see those pictures of the carbon hoop! I had thought of doing the same but was worried that the "snatch" from a poor gybe or some other such sudden load might cause the carbon to break. I know carbon is very strong but there are some types of stress it doesn't like. However, if you have had good experience of a hoop made of carbon tube, I might feel tempted! Looking forward to the pix.

Not sure that a gybe would snatch at the hoop, unless you have a stopper knot that stops the boom going fully out to the shrouds, or you gybe with the main cleated, both of which sound sub-optimal for racing.

In practice, if you crash gybe letting go of the sheet, the boom hits the shroud - though I have never heard of carbon boom breaking at the shroud. I guess that in reality the boom and sail are relatively light and whilst it may be frightening loosing control the speed isn't that great, so the momentum isnt massive.

Re the momentum, I remember that an ally boom hitting my head in a crash gybe hurts to the extent of seeing stars, whereas a carbon boom I bearly notice :-)

We've been using the carbon hoop for nearly two years without problem (just watch it break now ...). Only issue was head butting the end of one of the uprights at Rutland last year leaving me with a black eye. We have had our fair share of crashes and a fairly breezy Nationals at Looe, so I think we have proven that carbon is OK for this application.

The numbers for the uprights were checked by a pal whom is more able than me on these things and we assumed a 100kg helm falling against it as the worst case.

Go for a carbon hoop - it hurts less when you headbutt it.

Having said that, I have only headbutted the stainless steel sort....

I've got a nice second-hand square hoop if anyone's interested. Email me for details and photos etc

Sorry Mags, the carbon hurts just as much, but is a little softer on the skin so you don't spill ketchup on the varnish. Same colour bruise though.

I had a look at the carbonology web site, their tubess look like they will cost £80.00 before any brackets or platforms are made for the cleats and attachments to the thwart - can the pictures be posted on the web site?

Just finished tidying up the elastic take-aways this evening. Will take the pics first thing then email to Mags tomorrow morning.

Will dig around for the costs when I get the chance, but the bill of materials was: 2 x tubes, 1 sheet of 3mm carbon plate, a few metres of carbon tow, 1 "small" repair pack and a bit of graphite powder - plus the assortment of blocks, cleats and rope. The repair pack included a couple of rectangles of carbon cloth. Definitely worked out cheaper than a stainless one and much lighter. Looks pretty cool too.

Thanks to Mags the pics are now on the site, go to the building and repair section. I have also posted some pics of the one string set up too.

Let me know if further descriptions are required.

Thanks very much Andy. All very interesting (and I would think very satisfying to have done!).

Direct link

So, Andy, what size tubes did you use please, can you give internal and external dimensions please? Thanks.

In reply to Alan's post of 20th July I'd say that I use a stopper knot on the mainsheet to prevent the boom from hitting the shroud.  I've broken 2 carbon spinnaker poles when gybing in strong winds.  The pole is swung sharply against the shroud with the force exerted by the boom, the front end of the pole being hard against the mast.

Measuring the tube (as I cannot remember and it has been a long day) it is 25mm OD. Carbonology only do one 25mm OD tube, so that must have been it. They did put an extra wrap of carbon round it as I thought the standard was a little bit thin.

Thanks for the measurements.

Thanks for the measurements.

New traveller now tested in Plymouth in a F4 plus. Much better than sliding block arrangement. Must now get some T type trapeze handles for the control line ends.