Can I use VS721 instead of Repelin to protect the bottom of my RIB?
Bob McGlashan asked:
I have a RIB with Hypalon Tubes. I bought some VS721 Bottom Coat for anti fouling as the boat sits in the ocean for six months in the summer. Can it be used on both the underside of the fibre glass hull as well as the tubes, or must I use Repelin for the bottom of the tubes?
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VS721 and Repelin have similar properties, but VS721 has superior bonding properties, which is provides greater durability for fiberglass surfaces, but can be too aggressive for fabrics used for inflatable tubes. You can use VS721 on the tube without undesirable effects, providing that the tube is well protected with Poly Guard; a minimum of 2 to 3 coats.
Fiberglass hulls are smoother and more difficult to bond to, typically are heavier which means that there is more hydraulic pressure on the surface and therefore more abrasion from the water when running, especially on planing hulls, therefore require better bonding properties. It has been tested on boat hulls running at up to 145 mph without significant loss of adhesion. VS721 can be stripped from the fiberglass if necessary to perform gelcoat repairs or to paint, etc.
The problem with applying VS721 to the inflatable tube, and even Repelin if applied directly to the tube without Poly Guard, is that it is more difficult to remove. Both products provide a slick surface which makes it more difficult for marine growth to attach and also reduces drag which improves the performance of the boat and reduces fuel consumption. The difficulty is that if either product bonds directly to the surface and a repair is required, it’s more difficult to get the patch to stick. An improperly applied patch can cause leaks, delamination and ongoing maintenance headaches.
It’s important to protect the tube with Poly Guard prior to applying these products as it’s easier to strip from the surface if ever a repair or patch is required. That way the Repelin or VS721 will bond to the Poly Guard and can be safely stripped off if necessary with Speed Clean. After the patch is in place, the area can be protected again with Poly Guard and Repelin and your boat will function as new again.
Thanks for your question,