How to fit D2's on a carbon stick?

Charlie - do you mean one of these?

http://www.ldcracingsailboats.co.uk/rs800-lowers-bracket.ir?cName=boat-parts-spars-mast-parts-rs-specific-mast-parts-rs700-mast-parts

This is the bracket the lowers attach to on an rs800 mast, so is designed to be riveted on at gooseneck level. In my old boat the rivets holding this on kept shearing though so be careful! If by D2's do you mean shrouds that go from deck to mast end of first spreaders, this plate probably isnt what you are looking for as the load on rivets might be too much shear due to D2's pulling down too much.

Then yes you will probably need shrouds with t terminals and to put these (the t-terminal backing plate) in to the mast:

http://www.seldenmast.co.uk/fittings/content.asp?Category_ID=4

This is more tricky as you say. You can cut the hole in the mast the size of the small opening, and drill for the rivet holes. You then need to put a bit of string down through it and attach the new terminal plate at the bottom of the mast to the string. Pull it up inside the mast using the string and wiggle it round so it sits in the whole and the rivet holes line up. Then rivet it in place and using the cunning easily untied knot untie it and hey presto.

There is a knot, perhaps igure of eight that is wider than it is long so you can manoeuvre the plate into position, attach it, rotate the knot and it releases. Unfortunately I can't remember which knot it is!
Hope that helps (and makes sense).


Edited by chrisg - 17 Sep 10 at 8:27am

Anything involving rivets should always be a a last resort on a carbon stick. It wouldn't do any harm to mention what boat this is on BTW.
Personally the way I would do it, unless there was something existing to work with, would be to bond a couple of forged shackles onto the spar with mainly unidirectional carbon. Take strips of uni directional carbon about 150mm long and about the width of the shackle pin, wet out in epoxy, wrap round the pin and fan out over the surface of the spar. enough layers that the laminate is as thick as the shackle pin. When all in place put a layer of carbon cloth over the lot, add peel ply and consolidate down with PVC tape. If you make sure the ends of the shackle pins etc are clear the shackles would be just about replaceable at a pinch, but I'd use either hi tech rope for the checks or a lashing to wire on the ends so wear isn't an issue.

Edited by JimC - 17 Sep 10 at 8:46pm

Thanks guys.

Timnoyce - they are metal spreaders. How do you mean 'just rivet them on'? By 'bolt on' do you mean straigth through the mast? Did you find the dynema streached much?

Jim, your way does sound the best engineering wise. Sadly I'm a bit of a bodge it and scarper man... I think I now understand why you tried/contemplated(?) stiffening you mast with some extra carbon though.

Charlie: that sort of thing really isn't that difficult, just a bit painstaking, although I'm not sure it would be the first bit of carbon hacking I wanted to try just from the point of view of confidence, although at least the mast isn't (usually) going to fall over if your checks part company with the stick so its not the highest risk of jobs.

Here's the first one of those I did: as you can see its not that pretty or sophisticated but it did work...




What I've been up to with my mast is a bit different in that I'm attempting to try and reproduce some aspects (but not others) of the behaviour of a multi spreader rig with out any significant extra windage. Its an experiment to learn a bit for the future as, provided I work up the enthusiasm to do it, will be some further de-Nethercotting of 257 I'm mulling over for after Corus.

Edited by JimC - 17 Sep 10 at 9:01pm