The New Philosophy

The 1960 design object, “Most fun and highest performance within the strength of a man and a woman to handle in the water and out, with no trapeze, and no spinnaker” was developed against a world-wide background in which from about 1962 stiff spars began to be replaced with “bendy” spars. The steps were:

1. The growing realisation that sail shape could be changed by the degree of bend

2. The development of rig controls to adjust the degree of bend and the sail shape as desired

3. The creation of a logical sail shape philosophy based on aerodynamic principles

4. The development of a datum mark system so that desired sail shapes could be repeated reliably

5. The entirely separate development of an outstandingly efficient “wingmast” rig

6. The optimisation of all of this new technology in the 1975 Tasar design.

I would have preferred that the Tasar alloy mast and topmast assembly were lighter, and that the topmast were more flexible, Regardless, the Tasar design probably represented the common sense high point in this “adjustable rig” process worldwide.

My key point is that the 1975 Tasar design represented my best effort to use the adjustable-rig approach to achieve the design object.

The years 1988 to the present have seen the development of small-diameter FRP topmasts which can now be engineered to whatever flex and distribution of flex is specified. This has enabled us to design progressively more “automatic” rigs in which the degree and distribution of flexibility plus the mast-sail-batten combination enables the rig to do all of the detail work automatically. The crew now select only how easily they want the rig to “work”. (In watching my 59er mainsail through a gust, the top of the leech opens and the top batten flattens first, then the next one down if the gust hits harder, then the sail fills up again from lower toward the top. Sheet movement is trivial. With little downhaul, the leech is tighter and it all happens deliberately. If we approach say a mark under a hill where the wind is rougher, more downhaul makes the whole rig softer and it all flexes much more quickly in the frothy air.) High points in this process would be:

The giant step in the 49er rig design with only one rig to cover the wind range 0 to 25 knots.

My 59er in which I knew at the design stage the sail area needed to make it tack downwind fast at minimum planing speed, so was able to design it to carry this area upwind without stress on the crew in 25kts. (Gunwale beam 20% more; sail area 22% more than Tasar. Mast more flexible. It is easier to hold up in a blow than a Tasar.)

My key point is that a “Revival Through Update” Tasar MkII would express the design object with a simpler, lighter, faster automatic rig, not an adjustable rig.

....continued

Posted 2002-11-03

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