"Do most surfers have a bar of soap with them when they go surfing"?
Good question, but maybe we can change that when windsurfers find
out the many uses soap can have.
1/ Footstrap screws
2/ Lubricant for mast base nuts.
3/ Lubricant for boom adjustments tubes. (Makes them slide really nice like a trombone)
4/ Great for mast ferrules. (Keeps out some of the grit and makes them easier to seperate if they do get stuck.) Use with a wrap of electrical tape over the joint and you will virtually never have a problem with a stuck mast. Keeps the mast much lighter as it seals water
5/ Use soap as a "marking medium" when fitting fin heads. Also serves to make Tuttle and Deep Tuttle fins easier to slide in and out of the board cavitiy.
6/ Lubricant fro fin screws.
7/ Lubricant for camber inducers.
8/ Lubricant/protectant for batten tensioner screws.
9/ Lubricant for centerboard pivots/side plates and gaskets.
So, there are 9 things that a bar of soap can help with.
As far as the IS 121 WC in light winds, you are in for a treat.
It will be great in 10-12 knots with an => 8.5 m2 rig and still very good
in 18-20 knots with a 5.5-6.5. It's a very wide range of use board.
Hope this helps,