I think 3 coats is all I will need if I can get this 3rd coat applied nicely. The epifanes varnish is pretty thick and gives very good coverage. In the photo below I have already applied the 3rd coat to the sides with the roll and tip method thinned 10-12%. I will let this cure then in a couple days I'll tape along the deck/side seam and do the deck seperate this time, that way I wont get another run from the deck onto the sides. The tape line will be on a wood joint line and therefore be invisible especially if the tape is pulled before the varnish hardens. I will apply the 3rd coat to the deck with a foam brush only so I can work from bow to stern and equally along the cockpit coaming to keep the all important "wet-edge" as I work aft around both sides of the cockpit. I think varnishing with the roll and tip methond would be very easy on the deck if the cockpit coaming were left un-installed until after varnishing so you didnt have to try and work around it quickly. If I ever build another wood kayak I think I would do just that.
Varnishing a kayak this size is pretty easy to do by yourself but I can imagine that doing a large boat would be difficult to keep the "wet-edge" going and not have a section skin over before you got back to it. I would think if doing the deck of a large boat it would be nice to have a second experienced varnisher so that each person could start at the bow and tackle one side of the boat working all the way aft. If I decide to sand a re-coat my Glen-L "Zip" Runabout deck, I might have to train a varnish helper by having them do the build up coats with me before the finish coat.
Hopefully I can get the varnish on the deck done and the seat and seatback done by the end of next weekend.