Using a windsurfer mast for a lug rig yard on a Goat Island Skiff

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 used carbon windsurfer mast. More on the Goat Island Skiff here.

All our articles on setting up and tuning a lug rig are here
From cheap to sophisticated methods through to boat handling in rough conditions.

Windsurfer masts are not normally stiff enough for dinghy masts

Windsurf masts get around being very flexible by being heavily bent by windsurf sails. Also they are supported at shoulder level by the wishbone boom.

On a dinghy they are not prebent and are supported at deck level which increases the highest stress point on the mast by a factor of 4 to 6.

The may work for canoes that are not too beamy. But a regular sailing dinghy will either break them or sail poorly – dumping power by overbending before it is necessary to do so.

However a windsurf mast can be idea for the yard on a lug sail dinghy

This photo is a static test to see the shape of the good value RSS Goat Island Skiff mainsail under normal tension. The yard bend is critical for defining the sail shape.

Yard too bendy and the top of the sail will be too flat and the boat will not accelerate well in gusts. Yard too stiff and the top of the sail will be too full and not depower in gusts.

This is my take on it.

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)

Boat Owner	Yard Diam.	Material	Weight Spar	Deflect	Sail Maker/Yr	Notes
Christophe NH	35mm	Douglas Fir		57mm	Duckworks 2010	a
Christophe NH					Duckworks 2010	b
Woodeneye OZ	40mm	Radiata Pine	2.2kg	47mm	Storm Bay Sails 2010 (Tas)	a
Woodeneye OZ	40mm	Radiata Pine	2.2kg	50mm	ditto	b
Woodeneye OZ	38mm	Aluminium 3mm wall	3.2kg	20mm	ditto
Ian Howick NZ	Taper 38mm -24mm	Carbon	1.15kg	20mm		c
Clint – Portland	50mm	Eastern Spruce		51mm
BobWes Michigan	40mm Hollow Box	Eastern Pine	2.2kg	35mm 12kg @ mid-point	SailRite (home sewn)	d e
George Isted	Taper 40mm-30	Fir	2.56	50mm	Sanders Lymington	f
Paul Hayslett	Taper 38mm	Old growth Fir	2.6	42mm	Duckworks standard

Notes

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 bend

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.

Increasing stiffness compared to your current wooden yard.

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.

Reefing – a different method that is faster, cheaper and simpler than most other methods

The Goat Island Skiff Sail developed by us at Really Simple Sails has one small reef and then two large reefs.

Originally the sail had two or three equal sized reefs but we found that many sailors felt that first step left the boat feeling underpowered. We found that a smaller reef with the combination of making the sail smaller AND bringing the centre of the smaller sail lower in the boat was much more effective that we had imagined. So in boats which are lively we do the same and have a smaller first reef before moving on to larger reefs for when the wind is really strong.

Sometimes in our sailmaking we see either very large reefs all the same size or very small reefs all the same size. But in reality if the first reef is small, then on many boats the second reef should be larger.

We started off using fairly conventional reefing methods, but moved over to a new reefing method using fixed loops which is way cheaper and way faster than tying knots or needing to cleat lines. It was developed by several of us on the Goat Island Skiff Facebook Group, in particular Joost Engelen in the Netherlands, Teo Deus in Portugal and me … wherever.

Faster Reefing Methods for Lug Rigs – developed by the Facebook Goat Island Skiff group. Simpler and faster than most alternatives.