The top picture shows the 13 products used in the test. The bottom photo shows 15 cotton duck 'seals,' shown attached to the clothes pins with which they were suspended for initial drying. The 'seals' were sprayed and dried (and re-coated, if recommended) exactly as specified by each manufacturer.

Breathable material that keeps out water but allows air to circulate is best for helm covers, awnings, hatch covers, ditty bags, seat cushions, bimini tops, boatswain's chairs, life jackets, stowage bags—the list goes on.

The rub is that, being prone to mildew, grime, spiders, mold, stains, moths, water marks, and lady bugs, they get to looking something awful. They also lose their water repellency, partly from wear but also due to the ravages of the sun.

Ipso facto, fabrics need both washing and re-coating with some kind of water repellent. …