In over 10 years of supping, I've only attempted to rail tape a board once, and it was such a disaster with numerous bubbles and creases, that I ripped it off and have been taping the paddle ever since.
It was years ago, can't remember which tape, but I think it may have been a cheapie unsuitable for the job.........
This week purchased a new sup (first in years) with dark rails, the sup retailer/distributor strongly recommended rail tape, "apply wet".
Purchased 3M rail tape from local surf shop, the owner said "apply dry, definitely not wet".........
The plethora of youtube videos on this subject almost unanimously recommend applying wet, not to "activate the adhesion" (as someone suggested), but to facilitate application and placement of the tape.
Jimmy Lewis's tutorial is one of the best:
With conflicting advice (dry, wet??) I decided to follow Jimmy's advice (plenty of other similar videos from Rhino sup etc). I applied two 6-foot long sections on each rail (50mm tape), they were easy to place and adjust into position. The hardest, and most time-consuming part of the whole job, was squeegeeing out the bubbles. Couldn't get 100% of them out, but got close. Concerned that this may eventually cause unsticking, time will tell.
Had some tape left over (two 200mm lengths), so decided to extend the coverage towards the tail (it's a 10' sup). I applied those two pieces dry.
Results and observations: the dry method was also easy, and did allow me a little time to re-position. However, there were several bubbles, and they turned out to be impossible to squeegee out, with no soapy water to assist.
Probably the fault of the inexperienced applicator, perhaps someone with more experience could apply
sans bubbles........that's okay, the pieces are only 200mm long, and I'll remove them with the aid of De-Solv-It (Bunnings) if bubbles get any worse (as undoubtedly they will over time).
If I rail-tape another board, it'll be done using the same method as in the above Jimmy Lewis video.
My 5-year-old Kwad has never been rail-taped, there are maybe 3 or 4 tiny nicks on the whole board. So do I need rail tape? Probably not.
Several of the above correspondents suggested "paddle-tape only"; been doing that for years, but it does require re-taping (with double layer of insulation tape) regularly.
If I can find some helicopter tape (rang 3M, also known as "blade tape", "leading edge tape", and 8671P), for some reason not that easy here in Perth, eBay has a couple, then I'll continue to tape the paddle too using that.
The Kwad's staying virgin