Last summer we restored the roof on our 96 Southwind, 37'. I used Heng's.
It was easy to apply, no primer needed.
I washed the roof with Tide powder detergent before applying. I left it dry overnight and then applied a light coat of Heng's. After the first coat dried a second coat was applied.
It has held up well under the summer sun, wind & rain and snow/ice and freezing temps of a Pennsylvania winter.
It still looks good, eliminated black streaks and is leak free.
I bought 3 gallons and used 2 1/2 gallons to coat 30' of roof.
I'm very satisfied and would not hesitate to use Heng's again.