Fasteners pushing up beneath deck canvas

[Jeff Kelety]

Hi all -

Been a while since I sought your sage advice for Folkboat Nais. I beseech you yet again. I have noticed several small lumps pushing up my deck canvas. As they are in a line, I must assume they are fasteners of some type. Nails more than likely. The canvas has not broken through; it's sound. But I'm trying to prevent furture perferations. My instinct is to take a block of hardwood, lay it atop the lumps and try to carefully pound the fastener back down and hope it stays put. Anyone ever had to do this? Anything else to be done?

Thanks!
Jeff

[Lucky Luke]

Don't do that: you will "perforate" the canvas like if using a punch. Use a small awl instead , whose pointed end will do only a small hole in the canvas, and re-paint after to fill these holes.

[Jeff Kelety]

<Don't do that: you will "perforate" the canvas like if using a punch. Use a small awl instead , whose pointed end will do only a small hole in the canvas, and re-paint after to fill these holes. >

Luke - Brilliant. I knew there was some "boaty" way of handling this. And, of course you're right. My way could have really punched a whole in the canvas. Thanks!!!!

Jeff

[RGM]

You may find that the lumps aren't the suspected nail heads but corrosion from the nail heads pushing up against the underside of your canvas. Or the corrosion pushing putty up against the canvas. Do you know if the fasteners are ferrous in nature? How old is the canvas job we are taking about? How about the last time it was cleaned, prepped and painted? What do you have planned for the up coming Memorial Day weekend? Good luck.

[Wooden Boat Fittings]

.
Jeff, unless you know how the deck is fastened, I'd be inclined to investigate one of these lumps fully before you start bashing any of them flat.

As Roger suggests, they could be caused by corrosion products, either of iron rusting or brass dezincifying. Either case means at least some loss of structural integrity (possibly most of it,) which in turn really means you're going to need to replace all the fastenings.

Against this, any damage to the canvas pales into relative insignificance.

(But I hope the builder wasn't as dumb as this would imply.)

Mike

[SC-Lion]

Sounds like a very similar situation as one I dealt with on my cabin top, canvass over ply. In my case it was corrosion pushing up on the canvas as mentioned above (poor quality “bronze” screws from 1950s Hong Kong). I would seriously consider investigating one of the culprits in detail. If you have such a fastener problem the likelihood is that water is finding its way in and you will only be treating the symptom, not the cause of the problem.

Just my two cents smile.gif .

[Jack Heinlen]

Many boats with planked decks, canvased, have galvanized nails for fastenings. It works well. The nails provide a great grab, in oak especially, are fast to set, and as long as the canvas is maintained they don't corrode much. But if water gets in they can pop their putty. It sounds like that's what's going on here.

I think banging down the offending fastenings with a fine punch will provide a stop-gap measure(not ideal, because the putty is going to be broken up and still lumpy), but I'd inspect the integrity of the canvas carefully, and maybe plan on a re-canvas job sometime in the not-too-distant future. At which point you could reset nails, inspect, reputty and such.

Where's the water coming in?

2 cents.

Jack

[Lucky Luke]

Jeff, all the posters here-above are perfectly right, in that you first have to investigate whether it is nails that, like most fastenings, gradually became a little loose, or the fastenings or even he putty disintegrating.

As well, you must make sure you are hitting the nail (and you got to be GENTLE doing this work, otherwise you will damage the galvanization too) and not a thick putty that has been put over the nail's head.

The suggestion of re-canvassing is certainely good, as this will allow you to fully investigate ply / fastenings....but it is no small job with all the fittings and trims to be removed.... Usually done when the canvas is really dying, and the underneath ply may get deteriorated.

Many other questions could be asked as well: is the canvas coming "off" the deck, is the deck ply or planks, does it leak, a.s.o...

Good luck

[ 05-29-2004, 02:46 AM: Message edited by: Lucky Luke ]