Re; Top Hat mast height. If you look at
http://homepage.mac.com/clatimer/.Public/TopHat Yachts2/SailPlan.jpg apart from getting all of the measurements for the sails, you will get the lengths of the mast and boom. The mast being 9.4 metres high. As it's the official sail plan, I would like to think that all Top Hats conformed to this. My Sailmaker used this plan. Therefore it's only a matter of measuring from the waterline to mast base to account for variations in the Marks and building for full height.
While on the matter of masts, may I take this opportunity to address the idea put forward by one Poster of putting permanent mast steps up the mast. I have been up there once to replace a blown globe in my masthead light. It is only 30 odd feet up! There is a Roberts 25 with mast steps moored near me. It does not look nice. As a bit of a racer myself, I also wonder about the effect on windage through the slot. Something to think about when you are trying to get your boat to sail as fast upwind as possible! :
John.S
SOMBRERO