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Texas Boater
05-12-2006, 08:15 AM
While in the process of starting the restoration of my boat's bottom - the "down" time I have been reading, researching and thinking and after all the discussions about materials that could/should be used between the inner plywood bottom and outer planking, I was wondering if anyone has used one of the modern roofing type underlayments (like Bituthene) that provides a water proof barrier, remains flexible and seals around fasteners?

Is there a reason that spreading 5200 is preferred over fitting these membrane products? I assume they both achieve the same end result.

(Remember I am just researching at this point I haven't decided against 5200 yet)

Don Z.
05-12-2006, 12:51 PM
Sounds like what 5200 was made for...

gert
05-12-2006, 02:35 PM
what about this stuff?
I used it around my green house glass roof

http://www.bakor.com/residential_weatherbarrier.asp

pcford
05-13-2006, 12:06 PM
Definitely don't use 5200.

I have used a rubber-like "membrane" between the layers. Also used by one of the major restoration shops in the NW. In this method, polysuphide is applied only around the perimeter of the bottom.

If I had another boat to do, I think I would duplicate the original method exactly.

Yesterday, I was at Jensen Motorboat, perhaps the most historic shops here in Seattle. (They are doing great! Seven boat projects left yesterday!) There are currently doing the bottom of a 42 ft. 30s Chris Commuter. Totally traditional.

Like I've said, if it was good enought to last 75 years, isn't it good enough for you?

Dave Fleming
05-13-2006, 01:05 PM
Ah remember KUHLS Double Planking Cement?

First layer of planking with a coating of KUHLS troweled on, thin sheet of Muslin or fine canvas, some copper tacks to hold it in place, a bit more KUHLS, then the outer layer of planking.

;)

pcford
05-13-2006, 01:48 PM
Ah remember KUHLS Double Planking Cement?

First layer of planking with a coating of KUHLS troweled on, thin sheet of Muslin or fine canvas, some copper tacks to hold it in place, a bit more KUHLS, then the outer layer of planking.

;)

Kuhls went out about the same time I came on board. Petit or Dolfinite used to make a double planking goo. As I recall, just thinned down bedding compound. If I recall correctly, I've made double planking good by just thinning down bedding compound with mineral spirits.

Dave Fleming
05-13-2006, 01:59 PM
Pat, KUHLS DP Cement was also a good screw lube if you had run out or lost yer hunk of Beeswax and Pine Tar.

Chan
05-13-2006, 07:07 PM
Texas Boater,
Ice and water shield or bitch as I like to refer to it is great stuff on a roof. It's so prevalent in new construction now days that contractors don't know how to properly flash a roof. I use it all the time, but I built homes for 15 years before it was introduced, NEVER had a call back.
It doesn't hold up to u.v. Can't imagine it would hold up to s.w.
My experience with it in remodel is it is generally in a deteriorated state, plastic film with some gunk under it, virtually impossible to remove.
All said I have thought about it using it as a cabin to deck sealer, but I don't think I would.