Monday, December 8, 2014

Mast Specifications by Sail Brand


A while ago I received an e-mail from Giuseppe, a reader from the north of Italy.  He is keen on buying a 2014 GA Vapor and asked whether he should opt for the outgoing GA gold mast or the new blue model.

The easy answer is to say that since the sail would have been designed on the gold mast, this is going to be the best thing to buy.  What I also try to do however, is to think about what is going to happen down the line.  What happens when you replace the sail?  Will the gold mast still be useful?  My advice to Giuseppe was that although the gold mast may (?) be better on the 2014 Vapor, he should opt for the new blue model if possible.  GA tell us that the new masts will work on their older Vapors so he should not have compatibility problems.  He will also have a mast which, in the future, will work with a number of different sail brands and this is the purpose of this post - to give you some mast stats by sail brand.

I wrote a post about mast bend statistics a few years ago.  For those of you who did not read it, here is the short version.  Windsurfing mast bend characteristics are measured as follows:

Suspend the mast from two points (one 5cm from the base, one 5cm from the tip).  Hang a 30kg weight from the point exactly mid way between the two suspension points.  Measure the mast deflection at the mid point when the weight is applied.  For this example assume the deflection is 10cm.
Now mark a point half way between the base suspension point and the mid point and another point half way between the tip suspension point and the mid point.  Measure the deflection at each of these points when the weight is applied.  The tip quarter will deflect more that the base quarter of course. For this example, assume that the tip quarter has deflected 7.8cm and that the base quarter shows a deflection of 6.4cm.  These three figures give us the measures we require.  We take each of the quarter measures (7.8 and 6.4) as a percentage of the mid section deflection (10.0).  So here we have the position of 78% tip deflection and 64% base deflection.  From these two percentages we calculate the curve delta of the mast.  Simply deduct the base deflection from the tip deflection.  In this case the curve delta is 14.  The higher the delta, the softer the mast top.

Here are some deltas you may find interesting:
        GA      Point-7      KA      Maui      North      Severne        Loft          Pryde
460   14        14            14         14           13             13            13              17

490   14        14            14         14           13             13            13              17

These are all stats for SDM race masts.

The above measures show a huge change in some of the brands.  Maui used to have really hard top masts with deltas of 9 or 10.  Gaastra was not far behind them with deltas of between 10 and 12.  Now GA masts are actually softer than both North and Severne.  They are now also compatible with a range of other sails.  Nice!

Pryde and Tushingham are the two brands who persist with very soft top masts.  Antoine certainly gets results out of this approach but I have a feeling he would win on any of the other brands as well.

No comments:

Post a Comment