Waterproof deck patches

[fastwave]

Hi guys,

     We had a boat sink the other day because it was running vinyl deck patches. The entire fleet will probably change over to Dacron now.

    Are all Dacron deck patches water proof? Sailsetc state specifically on their website that theirs are leak proof, but are all Dacron ones waterproof anyway?

 

thank you

Chris

[John949]

Best thing to do it to test it since all Dacrons may not be the same.  I leak test my boats using soapy water and a bicycle pump in the bung hole.    I use Dacron from Profabrics and I can't detect it leaking.

[Lester Gilbert]

Two main issues with a deck patch.  One issue is how well it bonds to the deck.  Some glues are better than others and accommodate some surface roughness, others require a mirror finish.  Less obviously, the second issue is resistance to UV.  The real problem with (consumer grade hardware store) vinyl is that it ages quickly (within weeks) under UV and gets brittle.  When launching, it seems secure, but a shock or modest impact in the race will see it disintegrate.  The sticky-backed dacron sold for sailing has glue which is happy with surface roughness and UV inhibitors which take decades to age.

Edited November 15 by Lester Gilbert

[Guzzilazz]

Sticky backed deck patches are generally Vinyl coated polyester on the adhesive side.

[Stephen B]

A sinking… did you get the boat back? You can’t tell us the part story!

[Lester Gilbert]

5 hours ago, Guzzilazz said:

Sticky backed deck patches are generally Vinyl coated polyester

There is all sorts of stuff that is sticky-backed and could be used as a deck patch.  I think the two main ones are Fablon, a sticky-backed vinyl sheet which is PVC, and Dacron with a sticky back which is polyethylene terephthalate, a type of polyester.  I don't know what the stickiness comprises.  I don't know that it matters much whether the material is polyvinyl chloride, polyethylene terephthalate, or whatever.  More important is whether the product has been fabricated for outdoor marine use or indoor home improvement, that is, whether it has a significant UV inhibitor and a coating of industrial strength glue.

[Guzzilazz]

Dacron is a brand name for polyester, and in the time I've been radio sailing I've not seen anything else used other than the woven polyester, vinyl coated self adhesive stuff.

[fastwave]

Thank you guys.

the incident was a port starboard case in upper B-rig conditions. Boats were well heeled and the starboard boat hit the other one on the front deck patch.

deck patch was a relatively thick transparent vinyl.

boat went down on the run within meters. It was retrieved the next day free diving to 6m depth and after drying a couple of days with rice all worked again.