Peeling Sheathing

[sea_bee]

I have been the proud owner of a Hartley deep-v bondwood boat for about 8 years. The hull is about 20 years old. The original owner says that it was sheathed in dynel.

After the last use, I put it back on the trailer and have found a patch about 1 metre by .3 where the sheathing has peeled off. It runs along the keel (I mean the bottom of the v as there is no actual keel) from the bottom of the stem, out to the first strake.

I think that it has been caused by years of running the boat into a sandy beach, abrading the sheath along the bottom. I had been patching it with gelcoat putty, thinking that I was keeping it watertight. The last use of the boat was in good calm conditions, and I ran it out to the fishing spot and back at around 35 knots for an hour. I reckon that the water has gotten into the crack at the bottom, and the speed of the flow has peeled the sheath back.

My problem is now how to fix it. To do it properly would mean to invert the hull, but so much work. Remove the motor, tank, fittings, as much as the superstructure as possible - it would take days just removing the fittings.

My question is this, can I patch this upside down? I have been working around the edges, taking it back to secure glass. I now do not think that it is a dynel sheath at all, as the mat looks more like chop-strand than woven. The sheathing is clear underneath, with a white gel coat finish, and would only be a millimetre or so thick. What are your suggestions? Have a go upside down? Using what type of resin and cloth? Should I use pigment, or finish it with white gelcoat? Help, please!

[tattooed john]

You can patch it upside down but it can be messy and frustrating. Maybe practice with some narrow lengths of tape along the keel first before you go full width. The extra cloth could be good if abrasion has been a problem in the past.

Use epoxy for your resin.
Don't use chopped strand mat.

Here's the procedure.
-Wear a hat (very important).
-Lay your cloth out on a piece of plywood under the boat.
-Wet it out completely with resin.
-Turn it over and brush resin on the other side.
-Brush resin on the hull where you want to put the glass.
-Now get your length of wetted out glass and roll it up.
-Unroll it onto the hull. Holding it up and dabbing it with a brush dipped in resin.

Have a piece of plastic under where you work so that if (when) your tape falls off it wont get dirty and you can roll it up and try again.

If you do more than one layer let the first set enough so your next layer cant pull it off if it falls but do it while the resin is still green enough to make a chemical bond.

Don't forget to paint resin on the job as well as the cloth.

I've done a fair bit of upside down glassing this way. It CAN be done. The guy who told me how to do it has done whole boats with full roll widths of cloth (and a team).

You wont enjoy yourself.

When you're done glassing feather the edge of your glass a bit and fair it with the epoxy bog of your choice.

[kc8pql]

Sure you can do it upside down. I roll on a coat of epoxy and then unroll the cloth into it, taping the edges with masking tape as I go and smoothing the cloth into the wet resin. Use several layers of lighter weight cloth rather that one heavy one. when you have it in place, roll on a thin layer of resin, just enough to wet out the cloth and then go over it with a bubble chaser. After it hardens go back with more coats to fill the weave.

http://i4.tinypic.com/6ofyv6x.jpg

http://i3.tinypic.com/6lxz3m8.jpg

[Tom Robb]

What the heck is bondwood?
Interesting. How does one keep the cloth tight to the hull while gravity is pulling it off? Some incantation or other? Vacuum bagging might work. Or how about several coats of epoxy and a solemn promise to never again run it up onto the beach? Cloth failed before didn't it?
They say doing the same thing over and over expecting different results is one sign of mental illness.

[kc8pql]

How does one keep the cloth tight to the hull while gravity is pulling it off?

Surface tension. If you don't use any more resin than necessary to wet the cloth, it stays put nicely. Taping the edges of the cloth to the hull helps a lot too. It seems that if a piece comes loose it always starts peeling off at an edge. Lighter weight cloth helps too. I did the whole bottom in the pics. with layers of 6 oz. cloth with no problems. Nothing fell, no bubbles or voids. It's not as hard to do as it seems it would be.

[Todd Bradshaw]

You can also roll a thin coat of resin on the boat and wait for that point where it's firm, but still sticky and then unroll dry cloth over it. Squeegee it down dry, which gets rid of humps and bumps by altering the weave slightly, getting the cloth down tight on the surface, and then immediately roll and squeegee more resin over it to saturate it. Timing, obviously is fairly critical as you need the cloth to stick to the base coat. It's pretty tricky if it's a huge area, but I know of people who have fiberglassed entire strip canoes that way (not the ideal method for a whole boat in one shot, as they found out, but it did work).

[Bob Adams]

I've often used monel staples to assist the fight against gravity.

[sea_bee]

Thank you for the good advice.

The area to patch is about 3 feet by 1 foot. At the moment it is a pretty irregular shape - kind of oval, but very irregular. Should I be grinding back and trying to make the shape more rectangular? I am planning to use an angle grinder or a sander to taper or bevel the edge of the sheath before applying more. Any suggestions?

So use epoxy resin. What about the cloth? Is this just light weight fibreglass woven rovings?

BTW, bondwood is plywood.

[sea_bee]

... Taping the edges of the cloth to the hull helps a lot too...
What sort of tape? Just masking tape?

And while asking about the edges of the repair, should I be taking the patch right over the bevelled edge of the sheath by a generous margin, and then sand it back?

[sea_bee]

And here's a couple of photos of the boat.
http://gurehlgam.com.au/chris/p.jpg
http://gurehlgam.com.au/chris/8k.jpg

The patch that has peeled is on the port side, but in the bottom photo, it would be a strip between where the keel cuts the water and first strake.
I'll drag it out in the light and get some photos of the damage over the weekend.

[tattooed john]

No no. forget it. I'll keep it to myself.

Nice looking boat BTW.

[sea_bee]

Not sure what you retracted, John, but I appreciated your earlier comments. You made a comment about feathering the edge, and someone else made one about taping the cloth up. These two suggestions seem mutually exclusive - it seems that if you feather the edge, then there will be nothing to hold the tape. I guess I should try this upside down glasswork on some sacrificial material first.

[Gary E]

I have no idea of your facilities, but if in my side yard, you could remove the motor, pump out the gas tank, remove the hard top and all atached. Then stand the boat on it's transom by pulling from the bow with a rope attached high in a tree. This will at least turn an upside down job into one of standing on a stepladder.

Or just roll it onto it's side up aginst the tree...

But working on the bottom while its on the trailer is ..well...just nutz unless it's a small area and you hire a midget... I'm 6'6 so I wont be crawling under there.

Nice looking boat... where do you fish?

[Seagull]

If you "drag the boat out" with a trailer you might consider backing it off the trailer, on to 2, 7-8' heavy timbers whos hight can be adjusted with cement blocks, after which you should be able to cautiously lean the boat to port or starbord giving you reasonably good access to the bottom. By all means feather the edges of the removed sheathing. In fact I would try, very aggressively to remove any surrounding sheathing with a sharp putty knife and also check the surrounding area for spongy, bubbly areas which would indicate sheathing separation. Those areas too should be removed, grinding, scraping, tearing what ever, down to wood. All of the exposed areas should be throughly ground-sanded. I like to use 36, 60 grit to really rough up wood to be sheathed with fabric thus providing a good bit, grip for the resin to adhere to the wood.
You received many good tips on getting the fabric back on to the bottom, so one more shouldent hurt. Since the piece needed for the repair is relatively small you could place the piece of fabric on a larger piece of 4-6 mill plastic film, wet it out with resin as well as the repair area on the bottom then, hopefully, with another pair of hands lift the fabric-film wafer on to the bottom, press on, then use a roller (dry) over the plastic, removing all bubbles etc, before peeling off the plastic film. You should get a fairly even level result.

[ChrisBen]

Working on a boat bottom on a trailer can be awkward at best. If you have unobstructed access then you'll be okay. If not, I'd consider having it blocked at a marina where they have the proper boat stands. A friend took his boat off a trailer to work on the bottom in his driveway and knocked it over when he backed his lawnmower into it :eek:. Don't worry about gravity pulling the glass down, it's a small enough piece and would only happen if you over saturated the piece with resin, let the resin set for a few minutes to tack up. As Seagull mentioned, get down to bare wood and go 4-6" beyond the repair area for good adhesion. This will also give you a clear view to inspect for any possible delamination of the underlying ply. A couple of points about the Dynel, It tends to tear and fluff up when you feather the edges so you'll need a roller like this, Bodi Resin Roller - BoatersWorld.com (http://www.boatersworld.com/product/379940018msk.htm)
available at most marine outlets to force out any air bubbles. The Dynel is typically thicker than the glass cloth so you'll need several layers to equal the same thickness. Do this with increasing larger pieces, smaller first to larger last.

[Nordicthug]

Arrange your hull so the area to be done is in the open and high enough to sit comfortably under it. You do not need to have your hull upside down.

A small area like that, you should be able to do easily and quickly. Yes grind, or sand back to sound glass, feathering about 2 inches. Cut several patches of light glass just larger than the size of the repair rather than one or two of heavier material.

I would likely saturate the area to be repaired with resin well worked in, excess squeegeed off and allowed to cure fully. Bubbles and included suicidal insects can then be sanded fair.

Then.

Lay out a piece of clean cardboard larger than your patches, wet it with resin, lay a pre-cut patch on the wet area, and wet it. Roll it onto a convenient length of clean paperboard tube such as one carpet comes on, then unroll it onto the hull smoothing out bubbles and wrinkles. Squeegee or roll the wet glass from the center of the patch outward, removing excess resin. Repeat until you have duplicated the original fabric thickness. Allow to cure. Fair the raised area around the edge of the repair. Fill weave and any imperfectoin in the surface with whatever fairing compound you feel comfy using, allow that to cure. Sand smooth and fair, then refinish the now perfectly repaired area to match the hull.

When you wet your patches, just wet them, you don't want resin dripping off.

Wear some sort of protection to keep resin off your skin and hair and a good respirator to keep crap out of your lungs. A face shield to keep resin droplets out of your eyes might be nice. The lion's share of the time for the repair is going to be waiting for resin to harden, be very patient.

Pick a moderate day to do this. Too cold and it's like working chilled honey, with cure times seemingly measured geologically, too warm and it's like using water with the cure time measured in seconds.

Stay the hell off gravel beaches.

Have fun.

Gerry

[Tom Robb]

As Gerry said, stay the hell off gravel beaches, and I'd add any beach!
The glass failed before; it's not magic. You tore it up. Quit doing that.