Andrew Softley on the Goat Island Skiff Facebook Group asked about replacing his standard wooden yard for the top of the sail with a piece cut from a windsurfer mast.
The general tendency for stiffness of the yard has been a slight increase in stiffness.
Table of yard weight and stiffness records
We already have a database for yard bend – check this page for any updates (this data July 2014)
Storm Bay Sails 2010 (Tas)
Aluminium 3mm wall
Ian Howick NZ
Clint – Portland
40mm Hollow Box
12kg @ mid-point
SailRite (home sewn)
Old growth Fir
- a – original radiata yard
- b – radiata plus carbon tow – 2 x 1” wide tow top and bottom of yard.
- c – Carbon Yard: C-Tech New Zealand -38mm ID, tapering to 20mm ID at the tip. 1.8mm wall with some reinforcement at either end and the middle where the halyard attaches.
- d – four 15mm x 35mm staves lapped joined; 20mm hollow; end plugs and spacers used to support structure. 50mm x 50mm blank planed to 40mm x 40mm; 10mm walls
- e – Remeasured deflection using 15.9kg (35.05#) at 40% from forward end of yard and at the ¼, ½ and ¾ marks. Deflection at 40% = 33mm.
- f – Some block and leathering included in weight
Duplicating the current yard
Also you have your existing yard which you should measure for bend – we have been using 10kg – usually 10 litres of water in a bucket. Then keep that same distance between the supports and move the windsurfer mast along until you find the section that matches your original bend.
The fat end of the chosen section goes forward at the throat. Also you will need to put a few wraps of 50mm wide glass tape at the ends and any place you want to drill a hole to prevent splitting.
Another important thing is the yard provides buoyancy during a capsize to prevent the boat from turning turtle. The goat just doesn’t want to turtle normally floating on its side. The ends of the yard will have to be sealed with some light ply plugs (they should be a easy fit, hammering will split the carbon) or even some foam with epoxy painted on the end.
If you feel your sail is too flat up top and/or it flattens out too early under the download tension then you need to move the carbon spar until it is maybe 20% stiffer than your original yard. I’d be hesitant to go too far with a stiffer yard as we rely on the flexibility of the yard to make the boat accelerate in gusts rather than stagger.
So if you wanted a yard stiffer than the current I would recommend multiplying the deflection of the current one by 0.80 and then finding the part of the carbon mast that matches that. Or doing the same with an average of the standard yard deflections in the tables if you feel your current yard is too flexible to be a good standard to work from.