I just repainted my entire C27 this past June. For the Deck I used:
Deck - Pettit Easypoxy Topside & Deck in Gloss White - 1 QT.
Non-Skid - Interlux: Interdeck Beige (Deck Non-Skid Areas) - 1 QT.
Non-Skid - Interlux: Interdeck White (Cockpit & Companion Way sliding hatch) 1 QT.
Primer - Pettit Easypoxy White Undercoater - 1 QT.
4 Rolls of 3/4" Blue 3M 14day Painters Tape
I had old blue non-skid before and the 1 QT Beige was just enough to cover the deck areas with 2 coats. I only used 1/2 of the QT of White Non-Skid. The 1 QT of White Gloss was enough for 3 coats to cover the skid deck areas. I only removed the hatches, teak, cockpit lids, lines and easy accessible hardware from under the 1/4 berths. Make sure you sand and clean the fiberglass before painting on the primer. It took me 2 weeks to prep the deck and just over 1 week to paint it. I did all the work at the dock. If you paint the entire deck, make sure the skid/gloss area's are painted before the non-skid. I was able to get 2 coats of what ever I was painting done in a day, one coat around 7:00am, second coat at 8:00pm. All depends on the weather. I had to tarp my boat due to rain. The damp weather made the paint take longer to dry. I had a couple days where I could only get one coat on. While I waited for pain to dry I redid my teak. The teak was grayed and needed help. I sanded until I got to the nice warm teak color and then cleaned and varnished it with 9 coats.
Let me know if you want a picture. I took lots of them during the painting process and what I did.