Deck canvas source and fitting?

[Jay]

I have a scull and a four that will need new canvasses. The scull currently has nothing but a lattice to support the fabric, and a load of battening at was fitted around the outside. The 4 has plastic sheet stuck in place with tape.

Can anyone recommend a source for the plastic type material/sheet to make new canvasses?

And is it a heat-shrink fabric? (I use fabric loosely). So you can get best fit, secure it and then run a hot air gun over it to get it really nice and tight?

If not, any suggestions on how best to fit it? Or is it as simple as "cut roughly to shape, tack in place with tape, cut final shape, stretch out with tape tabs, complete taping."?

Many thanks,

Jess.

[Paul]

Get some of the 3m VHB double sides tape for the inside. It seems to stick forever. Stretch the rough canvas shape over by hand, and stick it to the tape. Trim the edges, then attach whatever you like to the outside. You can use just regular duct tape or a wooden type edge nailed to the outside - whatever looks best.

[wmar...@gmail.com]

I was told it was a Dacron. IIRC you would iron it after application, and then apply varnish to seal it, but that's going on very poor memory and not experience. I believe that's the process used by Pocock Racing Shells of Seattle while they still built with wood - the company was started by George Pocock, who learned his craft in the UK before starting out in Vancouver.

I've had success using "backpack fabric" purchased at a local fabric store.

The fabric was, thin, coloured, and had a rubberised coating on one side. We used to rough cut it to shape with about 10 extra inches on either side of the boat. Soak it in the hottest water we could stand, and stretch it from the "bulkhead" (nailed down with a strip of wood and 15 mm long x 1 mm thick silicon-bronze nails (and I'd love to know where to get more of those - mine are all used up)) to the "end" either stern or bow, and c-clamped in place (some locations call this a "g-clamp").

Then - with assistants - "lightly" stretch the fabric down about a foot-long (30 cm) section of one side of the hull, tack it down with the "nailing strip" or wood bead or whatever it's called, then go to the other side, stretch tight against the section you've nailed on the first side, nail it down, and then stretch lightly a foot farther along side 2 - pop across to the first side, stretch tight and secure the foot of fabric you just nailed down, and then do a "loose" foot of fabric...
A lot of prep, pre-drilling nail holes, pre-inserting nails, supporting thin little strips of wood at one end and in the middle while you work your way down, and lots of careful tacking. I used "upholsterer's" 6 ounce hammer with a thin end for starting the nails held between my fingers, and a thick end for sending the little nails home. Try to keep the fabric from drying out while you're working, by sponging hot water over it while you're going.

After it's all tacked down all the way to the end of the boat, carefully trim off all the excess fabric, let everything dry, invert the boat, and apply "varnish" (whatever you're using) to seal the boat/fabric/wood strip...

This is a hastily written rough description of the process I used, as instructed over the phone by one of the boat builders - I can't recall if it was Stan Pocock, Jakob Kaschper, Frank Cunningham, or someone else, but I think I asked each of them for advice, it was a while ago - I think the first time I tried it was about 1984 or so in Vancouver.
Walter

[robin_d...@hotmail.com]

Rubberised Dacron rings a bell although the more recent stuff doesn't need to be doped - I used it when I was in Vancouver around 9 years ago to re-canvas a couple of early 80s Kaschper VIIIs (fibreglass hull, wooden frame) that were being used for learn to row at VRC. After inumerable docking incidents over the years, a few critical bits of the wooden lattice-work under the canvas ends popped out of the glued/tacked joints under the canvas edges. The boat started flexing to a greater degree than normal in Seabus / SeaPlane wakes, the flexing stretched and then detached the edging tape, and then the canvas came loose or ripped at those points. Having stripped the original material off, I then re-bonded the framework joints that had come unstuck to put the rigidity back in, then put double sided-tape (heavy-duty waterproof grade) around the edges and stretched the Dacron over from one side to the other. Once the Dacron was in place, the edges were tidied up with a scalpel, and then I used 3M 471 tape (1.5") with a hair-dryer to secure the edges. Finally, the Dacron was tightened using gentle application of a heat gun to shrink it over the framework. It looked really professional and sounded like a drum skin if you tapped it.

I then did the same with the second boat but ran out of time with the stern canvas before having to leave for home (2am!). In spite of signs advising the contrary, the LTR coaches took the incomplete boat without 471 taping on the water and then wondered why the canvas came off 400 metres away from the dock after being hit by wake. The boat then foundered stern-first and had to be rowed back bow 5 only with 4 people in the coaching launch. Long live fully-enclosed buoyancy!

[sully]

I think Van Deusen still has decking material and the right tape. This is not the dacron decking Walter mentioned, it's a plastic that you fit over and shrink with an iron. They have all the directions, I'm sure, there are still lots of 80s Van Deusens on the water.

If these are wood boats, I'm partial to the dacron decking and varnish. It's a little more tear resistant, and easier to repair if it does get a hole.
The varnished dacron is a bit stiffer, and isn't so heat sensitive (the plastic loosens sometimes in a hot sun.

Pocock may still have the dacron material and instructions.

If theses sources don't work, find out where they got their stuff, and I have directions for doing either.

[Carl]

On 03/07/2014 22:15, sully wrote:
> On Tuesday, July 1, 2014 7:57:54 AM UTC-7, Jay wrote:

<snip>

> I think Van Deusen still has decking material and the right tape. This is not the dacron decking Walter mentioned, it's a plastic that you fit over and shrink with an iron. They have all the directions, I'm sure, there are still lots of 80s Van Deusens on the water.
>
> If these are wood boats, I'm partial to the dacron decking and varnish. It's a little more tear resistant, and easier to repair if it does get a hole.
> The varnished dacron is a bit stiffer, and isn't so heat sensitive (the plastic loosens sometimes in a hot sun.
>
> Pocock may still have the dacron material and instructions.
>
> If theses sources don't work, find out where they got their stuff, and I have directions for doing either.
>

The material for a long time used by shell-builders in the UK for pinned
& beaded decks was iso-varnished Terylene, a woven polyester fabric
impregnated with synthetic varnish. It is still used to insulate
transformer windings & can be bought (probably only by the 100m roll)
from UK Insulations (ukinsulations.co.uk). In decking a shell this was
stretched end to end by being pinned under a beading at the wider end
and then pulled tight to the bow or stern. Next it was symmetrically
tensioned across its width under 1/2-round wooden beads held by thin
copper pins driven through the skin and into the boat's spruce inwales.
The spare edges were very carefully trimmed off & the end result
varnished over.

Then for 20+ years many shells were decked with a clear, opaque or
coloured & Wavelock-reinforced PVC film, held by double-sided tape and
then either beaded over as above, or with the edge covered by cloth
adhesive tape. Modern acrylic-based VHB tapes hold very well on some of
these materials, and the trick is to work along the deck edge in such a
way as not to end up with wrinkles.

Fabric decks contribute little to the structural merits of a shell
beyond keeping the water out. And they are rather easily pierced. So
all modern shells have hard laminated decks which add integrity &
stiffness to the boat.

When we built the replica 1948 doubles for the BBC's "Bert & Dickie"
film we decked them in 60g/sq m Kevlar (a synthetic fibre, the inventor
of which has just passed away), bonding this to the hull (& sealing it)
with epoxy resin. This resembled the original decking (a varnished
calico?) & is another possibility - Kevlar is a bit tougher than Terylene.

Pedants' Corner:
Terylene, invented in the UK, is the original trade name for
polyethylene terephthalate (you can see how they arrived at that name) &
is still used here, but in the US they decided to call it Dacron. It's
known as PET when used to make bottles.

Cheers -
Carl
--
Carl Douglas Racing Shells -
Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
Write: Harris Boatyard, Laleham Reach, Chertsey KT16 8RP, UK
Find: tinyurl.com/2tqujf
Email: ca...@carldouglasrowing.com Tel: +44(0)1932-570946 Fax: -563682
URLs: carldouglasrowing.com & now on Facebook @ CarlDouglasRacingShells

[Henry Law]

On 01/07/14 15:57, Jay wrote:
> If not, any suggestions on how best to fit it? Or is it as simple as "cut roughly to shape, tack in place with tape, cut final shape, stretch out with tape tabs, complete taping."?

I did this, with email assistance from Carl and a couple of others, a
few years ago. It's documented here:
http://www.lawshouse.org/rowing/canvas/ReplacingCanvas.html

--

Henry Law Manchester, England

[Jay]

Good morning all, and thanks for all your help.

I'm based on the South Coast of the UK, which might well have been a relevant bit of info for suggestions for a source of materials!

I have a local sailmaker, who might be a good source of Dacron. So that could be a try.

Carl also raised the point of the lack of structural benefit of the cloth decks. So I could build a timber deck, I have some nice 3mm ply in to repair the hull on the 4, and will have half a sheet of that left over. that could leave a nice varnish finish.
Alternatively, for real stiffness and lightness, I could go composite, and bond in a foam deck, fair it smooth, and then glass sheath it, bonding right across to the top of the hull. Not very traditional, but would add a huge amount of strength and stiffness. Paint it green afterward, and add the varnish timber battens around the outside, and no one would ever know.

Both of these options would make it harder to manage repairs in the future if the hull were damaged though...

Anyway, many thanks for all the help, and do comment if you have any thoughts on any of the 3 options, either soft, timber or composite.

Jess.

[Brian Chapman]

The definitive answer from Carl. PET for bottles comes in fine pellets, Terylene is the fabric.

[Carl]

A couple of thoughts:

It'll be quite hard to get the weight of a foam-core composite much
below that of the 3mm plywood option, & it won't be as robust.

And if you make a neat job of the hard deck, why not omit the beading?

Good luck -

[nowa...@gmail.com]

Check Aircraft Spruce (USA) for heat shrinkable Dacron...

http://www.aircraftspruce.com/catalog/cmpages/peelply3.php?clickkey=4728

[Jay]

Good thoughts Carl.

Yes, the ply would most likely be the easier and lighter of the two hard deck options, and is likely the one I will go with. I may even take the chance to get creative and add in a little decoration at the same time with some veneers or beading set in to the surface.

The beading on the exterior was just a thought if I went with a foam and glass cloth composite, as it would give a suitably traditional looking finish. I'm not planning to race this boat, so an extra few hundred grams would not make much difference. In fact, until I get on the water, I'm not entirely sure whether it will be big enough for me. But yes, the exterior beading would have just been to mimic the look of a canvas deck.

Thanks to all for suggestions, help and advice!

Jess.

[abco...@gmail.com]

For my wife's Pocock, I use 1.8oz uncertified dacron from Aircraft Spruce. Contact Cement is used to glue down the edges. Then trim to shape. I use pinking shears and then the pinked edge is also glued down. Then a light ironing at about 250 degrees F. It doesn't need to be super tight just no sags. You don't want fabric compressing the boat. (fabric covered airplanes will be shrunk at 300 or 325 F). Some tape around the edge to make it look nice, I use 3/4" or 1" wide blue painters fine line edge tape. A few coats of spar varnish and it looks great and is sealed.