After some info please. Could someone let me know what the length from the top of mast to shrouds, and top of mast to base?  based on deck stepped masts).

Thanks

it's all about based on sheer line. sheerline to gooseneck ( variable) and luff length. It's all in the rules and there is a nice formula that you can use  and it's all in the rules and ther is a link from this site. basically you pick your gooseneck height , then your LL ( up to a max) and foot which in turn gives you max jib area. good luck

Having had to do this last year the upper end of the lower black band (not gooseneck) to sheerline should be between 630 and 730mm.  The lower edge of the upper black band shall not be more than 6180mm above the upper edge of the lower black band.  Thus it is the sheerline is the datum line.

It's all in the link.

Suggest that you call me to discuss this - dimensions will vary according to rig configuration, which is often according to boat age.

GGGGGGGG

As always Garry makes sense, now where are those sheep!

There's a couple of pics about how you measure the shearline and thus mast length

Dear Blackie, I do hope you haven't really changed our dear old Thunderclap's sheerline to a shearline. I'd hate to see that nice sapele deck fall off.

Calm down Mike. No such atrocity has taken place. Spelling was never my strong point although I do know the difference between there and their!!!