RS800 spreaders

Originally posted by CurlyBen Does anyone know how a datum is established when setting up a new carbon mast?

Like boats (all boats are asymmettric IME) there's not a single master point. Its a question of hitting best compromise. Also of figuring out what you can alter...

The way I do it? As recommended above I'd stick the mast in the boat without the shrouds attached to the spreaders. I'd then roll the boat on her side and work like that. The only trouble with working on the side is you need to put on a load of tension to avoid wire sag throwing you out. The first thing to look at is the relationship between the mast heel and everything else. If the mast heel/boom/majority of the track alignment is pretty good then (you're lucky!) and you have a datum. If not, well investigate. What can you move (if any) most easily of heel and gooseneck? Most likley mast heel. If you can rotate the mast heel and get a better alignment then do so, if not, well, put up with it.

Now wind on up plenty of tension on the shrouds and measure the offsets to the spreaders. If you can take the measurements with the boat rolled on both sides so any sag balances itself out so much the better. Get the two sides as near as you can with available adjustment or whatever.

Don't forget to check the mast is as vertical as it should be. I prefer lining up from the daggerboard case to measuring from the gunwhales - gunwhales might be different heights.. If you have a laser level or similar dig it out, its dead handy for this game.

When the main spreaders are as near as possible symmetrical then repeat with the caps next.

That's really about it. Allow at least a whole afternoon! But offsets from taut wire (or Laser) to spreader are the best thing to work with because you are effectively allowing for all the asymmetries there might be in the boat.

Edited by JimC - 09 Aug 12 at 8:56am

Thanks for all the help and advice - I've just managed to get a new job which will be keeping me pretty busy for the next few weeks but when I've had a chance to get the boat on it's side I'll report back. Getting the boat out does mean disassembling the dog pen which might be interesting with the new pup!

Forgot to mention to tie the lines between each spreader set as this will give you the best gauge for the alignment