That is great information and I would only add that I believe one uses a High Quality, Very Fine, Natural Bristle Brush.
Most paint brushes these days are polyester bristle and that is NOT what one wants to use when using Spar Varnish, or any other sort of varnish.
I too varnished a good amount of mahogany on my 30-foot sloop.
The varnish needs to be redone / touched-up each year, but it is THE thing to use if you love your sailing or power craft.
Apropos of wheels, those on my Series 80 have been painted for at least 50-years, and likely much longer.