I bought them from Rob at xtremeled.com They are waterproof. They have been in for over a yer and are doing great. They look as good as the day I installed them.i used gorrilla glue to mounth them as the underside was not smooth enough for double stick tape.
Go to eBay and search "SMD 5050 waterproof". About $40 from China with some extra 4 conductor wire. I cut 1" square, 3/8" PVC and drilled a 1/8" vertical hole. Then I used 5200 to glue the PVC in place and small ty-wraps to hold the LED strip after the 5200 set. I used the multicolor 5M string and it was the perfect length for my 36 convertible but you need to cut it in two lengths and meet at the walk thru door. Looks great especially when the colors change automatically. They operate on 12 volts so its an easy connection to the circuit breaker panel. Comes with an IR remote.
Capt. George
FYI, I just replaced mine. After the years they seemed to dim and one side went out. They are cheap enough now, that I don't mind replacing every other year.
The PO had some LEDs plugged into the 120v outlet when I bought the boat. I checked and sure enough they were 12v powered by a step down. I wired them in to the cabin lights circuit on the 12v system and now we have 20+ colors to set the mood! More light and less draw. The next step is to re-wire the ones in the salon.