[ken66]

I note the link comes from the esteemed MIT...

It is the sailing club rather than regular MIT research but I like the way they do things. Measure stuff, compare things, share the data and try to explain it. Thanks for further advice and I can see the Davis gauge has things like calibration by screw adjustment, leveling indicators and so on. It certainly looks more professional, but you pay for it.

I couldn't open the attachment which I was curious to do. I don't have Word but Google Docs will usually read Word docs. In this case it couldn't.