Latest News: Forums Technical mainsail size

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  • #21354
    Thomas D McArdle

    Can some kind person please put me out of my misery and measure up his/her mainsail? I am restoring 4558 – Mark II grp – the boat came with a mainsail whose dimensions don’t fit the position of the boom/gooseneck. It’s too long, by about a foot. Someone in times past has repositioned the gooseneck bracket lower, to fit this sail presumably, but changed their mind and gone back to where it ought to be. You can see the cutout and screw holes. The gooseneck is now just below the wider part of the track at the rear of the mast. It’s a Saturn sail, with a big red ‘W’ on it, so was made to someone’s specs. I don’t know if the sail is wrong or the mast is wrong. The mast and boom are gold-coloured with a Proctor plate on the latter, so I suspect they are OK. Total length of sail from head to tack = 5.72 m. Total length of mast = 6.64 m.
    Also request for a jib please, if you have one in reasonable condition. I am not a racer, just a puzzled weekender, so anything considered

    Dave Barker


    According to the spar measurement form the upper edge of the gooseneck black band (just above the actual gooseneck) should be 704 – 710 mm above the centre of the mast pivot hole. (On our boat the centre of the pivot hole is 160 mm above the bottom of the alloy mast section, i.e. where it sits on the plug containing the halyard sheaves. In the photo below the tape starts at the centre of the pivot pin hole – the black band is missing but you can see where the upper edge probably was ~705 mm).

    Likewise the uppermost black band (just below the top of the mast) should have its lower edge 5868 mm above the upper edge of the gooseneck black band. (Part of ours still seems to be intact…)

    These two black bands more or less define the lower and upper limit of the mainsail luff, so 5.87 metres compared with your measurement of 5.72 metres, making your sail a little short, not long (but it’s hard to measure a sail accurately).

    Adding the figures from the measurement form together (ignoring the mast plug and the tip) gives 160 + 710 + 5868 = 6738 mm (6.74 m), whereas yours is only 6.64 m. Your mast is therefore at least 100 mm shorter than a Wayfarer mast – more including the plug and tip, for which you could add a further 100 mm (I estimate).

    Sorry to answer in such an apparently complicated way.

    Have you tried a wanted ad in the classified section?

    Thomas D McArdle

    Thanks for the reply and sorry for no reaction for so long.
    The problem may be the mast. Looking at pictures of other Wayfarer masts I realised that mine may not be one of them! The foot of the mast only has the base spigot to fit the step (which is missing), but the halyard sheaves are further up the mast, at about SSE and SSW if the bow is taken as N. There are no sheaves at the foot. Also, there is no pivot hole, which is probably a clincher.
    If the mast was 30cm taller, the sail would fit nicely. So back to the drawing board


    All you need to know is in the Class Rules & Measurement Forms.

    The extended top side of the boom (= the foot of the sail) should meet the upper edge of lower black band on the mast and the top of the main sail should stay below the upper black band on the mast. The same happens on the boom, the clew of your main should never be aft of the black band on the boom.  The latter black band is measured from the aft edge of the mast. The gooseneck size and position plays no role in the measurements.

    The sail dimensions are part of the rules and the forms as well but they are derived from the black band dimensions.

    The mast, boom and sail measurements are really easy to do but you could of course ask assistance from, a class measurer near you.


    Thomas D McArdle

    Thanks Swiebertje; it would help if there were any black bands left on the mast or the boom! The boat has had some hard use since the 1970s and likewise the fittings. But I am getting there. Cheers.

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