Weather routing

A big shout out to Jeremy and Nica on Calypso. He has developed a weather routing website that is most useful! Using it now to make the jump between the BVI and St Martin. Go check it out at

Most interesting. Inquiring minds ask:

What polars and comfort criteria do you use, Gary?

For what sailplan (or sailplans) are your polars relevant?

Who created your polars: did you calculate them yourself from performance? or from a numeric model of the BCC and its sailplan? Or do Jeremy and Nica have a standard BCC polar?

On Z, I had mild success creating a table of target speeds and a polar using both performance data and working through a publicly available spreadsheet. The result was a fairly coarse (i.e. not fine detail) polar which I have used with QTVLM (a publicly available program for wind routing using GRIBs).

I lost my enthusiasm for the project a few years back (and am not certain I can find the polar now - that’s partly also because PCs and harddisks die without adequate backup!).

We usually sail Z in cutter configuration. In light winds and flat water, we fly an overlapping genoa without the staysail. Different performance (but that also might be a product of the state of the staysail, the sailcloth of which seems to age faster than that of the main or jib top - perhaps because of the way it gets handled).