To all.
I forgot toadd that I've had the stainless solar powered vent on the
deck of my 28 ft. Slickcraft for 12 years and never, I repeat, never
have they leaked water into the head, or foward V- berth since I
installed them.
They are very light in weight, and I highly doubt that any roof
distortion is possible.

Later

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Terry 85 GL