Tuning a Fifteen

The following tuning advice has been generously supplied by Steve Goacher of Goacher Sails, and Alan Bax of Pinnell & Bax.

(See additional tuning guides on the Goacher Sails and Pinnel and Bax websites)

The measurements are those used on the Mk IX Ovington.  You are strongly advised to make a note of  your existing measurements before you alter anything.  If in doubt, consult an expert.

Stepping the mast

The position of the mast foot relative to the keel, and the transom of the boat will vary from model to model.  It is not possible to give a generalised measurement here.

Make sure that the mast is a good firm fit sideways at deck level.  If the mast is loose, then fit packing to stiffen up the mast.  Remember to make sure that any extra packing is applied symetrically, otherwise the mast will lean.

The mast also needs to be a firm fit in the mast step.  Again if the mast is loose, it will move around, and this will result in lost performance.

Make sure that the mast is straight.  With the mast in the boat, and apply rig tension, and then look up the sail track.  If the mast bends off to one side, then ease off the shroud on that side, or tighten the shroud on the other side, then check again.

Goacher settings


Mast Type Length (A) Depth (B)
Epsilon 430mm 165mm
M2 430mm 180mm
Nimbus 430mm 180mm

The spreader dimensions given are for boats where the shrouds are bolted through the gunwales.  If the shrouds are bolted to the hull, then the spreader length will need to be shortened a little.

Rig tension and mast rake

In all conditions, use 24' 10½" for the mast rake.  This is measured with the the mast ram/puller released, and the rig tension set.  measurement is from the top black band to the transom. Assuming 3.0mm Dyform wire, using a Super Spar tension guage set the rig tension at 28½.

Pinnell & Bax settings


Mast Type Length (A) Depth (B)
M2 422mm 175mm
Epsilon 422 197-210mm
Nimbus 422 190mm
M7 422mm 190mm

The length of the spreaders will vary from model to model.  The value quoted is for the MkIX, where the shrouds are attached to U-Bolts outside the sheerline.  Older boats such as the Wyche & Coppock have the shrouds closer inboard.  In this case shorten the spreaders by 15-20mm.

Rig Tension and Mast rake

Wind Speed Kts 1-4 5-10 11-15 16-20 21+
Rake (Metric) 7550 7550 7500 7440 7440
Rake (Imperial) 24'9" 24'9" 24'7" 24'5" 24'5"
Tension (M2/Epsilon) 300LBs Flat Water Choppy 
400LBs     350LBs
Flat Water Choppy 
400LBs     350LBs
300LBs 250LBs
Tension (M7/Nimbus) 400LBs 500LBs 500LBs 400LBs


Mast rake is measured from the top black band to the top of the transom on the centre line
Rig tension should be measured at 1 metre above deck level.