More than One Way to Sheath a Boat

Better Living on the Milky Way
Borden's ELSIE

Hell has an entire level devoted to... wrapping.
- From the Internet, Somewhere


More Than One Way to Sheath a Boat

Once upon a time, before Epoxy was crowned King of All and took Fibra Glass to be his Queen, there lived a simple lagging compound named Arabol, and his true love, Dynel.

Wait. No. Is this any way to talk about boatbuilding??? Let me start again...

Arabol was once made by Borden, Incorporated, a dairy on steroids. Trademarked in 1905, it was a milk-based  product which was essentially waterproof Elmer's Glue (better known Borden product).

Arabol's main commercial use was as lagging compound.

I know... I had to ask, too. Lagging is the cloth once used to wrap hot water pipes for insulation and protection of those who might otherwise burn themselves. Lagging compound is a latexy substance used to saturate and waterproof lagging, making sort of a softly plasticized cast.

Someone along the way realized that this stuff could be used to sheath boats (generally, but not always above the waterline). BRILLIANT!!!

To apply, lay down fabric - anything from burlap to mosquito netting to fiberglass. Wet it down with water and slap on a first coat of compound. Once dry (which can go quickly on a warm dry day), add another full-strength layer. Repeat until the desired thickness is achieved. Topcoat with flat, latex primer/paint (one among many options).

The result was said to last 15 years or more.

Borden quit making Arabol by the time we built LUNA in 1997, so we tried Childers Chil-Seal (Marine variant CP-50A HV2) over fiberglass cloth. Nineteen rough-shod years later, it's still looking good.

These decks are a bit soft... one can dent it with a fingernail or pierce it with a dropped anchor, but tougher than most traditional canvas. But they're not easy to harm, and easily repaired if you do. Should you want to take up a section for any reason, they have relatively low peel resistance and come up easily with no grinding.

Further alternatives might be other lagging compounds or water-based, concrete sealer?

Recently, we're trying the same approach with TiteBond III, made by Franklin International. It's applied by the same procedure, but finishes to a much harder surface, almost indistinguishable from epoxy. Our new hull's decks are sheathed with it, and it has now survived a year of Southeast Alaskan weather with no sign of trouble.

As noted in the comments by astute readers, it may be that new TBIII won't readily bond to itself after full cure. For multi-layer applications, we've always done 'wet over green (not fully cured), and ditto for any topcoating of primer (though one topcoat test bonded well to fully cured TBIII). My intuition is that, roughed up, the bond should be reasonable to good, but that has yet to be seen.

Dynel is a trade name for woven acrylic fabric once made by Union Carbide. Jamestown Distributors still sells 5oz under that name, and my guess is most any woven, and possibly knit acrylic will do. Alan Jones reports good texture results from acrylic fleece, but that it drinks glue.

Acrylic is highly resistant to abrasion, and often laid over kayak keels to protect fiberglass/resin. It's cheaper, easier to handle and better conforming than glass fabric without those itchy shards. Grinding can 'pill' or 'fuzz' it, but that's easily shaven smooth with a sharp scraper.

So our state-of-the-art is Chil-Seal (proven) or TiteBond III (awaiting further results) with acrylic cloth.

Cheap, easy, pleasant, non(or ver lowly)-toxic, easily maintained...

...Just the thing for the quick and dirty among us!



*****


More on water-based alternatives, here.

By the way...

We used Chil-Seal between LUNA's 2x2, red cedar, strip-planked deck planks, since it was on hand and extra. Turned out to be quite adhesive and filled the gaps easily between the un-bevelled edges as they followed a 6in crown. Undiluted, it was about like gap-filling toothpaste, as I recall. Dried to a sandable solid, like old chewing gum.

We didn't clean up right away with water, and regretted it later. I set up firm enough that we couldn't easily cut it. Burred it away with a Dremel tool along the underside grooves. The things we do for vanity!

I'm thinking Chil-Seal or equivalent would make a very friendly adhesive for general strip-plank construction. It's modest elastomericity would help prevent longitudinal edge failures sometimes seen with epoxy and other rigid glues.

LUNA's deck before sheathing