I am terrible at getting my glued-in kneeling pads where I want them exactly without the need to adjust them. I usually use contact cement to glue things to the inside of RX boats, but, of course, there is no ability to re-position things once set in place - it bonds instantly.
What is your recommended adhesive that will give me some (very small amount of time) working time to slide things around before the glue sets up? I like to have me kneeling pads go almost from gunnel to gunnel and long enough to keep my feet off the vinyl. So, it's tough to get these big pieces down in one go. I'd prefer to minimize the patchwork approach and use several small pieces of foam. Besides, no matter how small, I'd get them in the wrong place initially.
I have always been leery of applying still moist contact cement, but it remains my preferred adhesive for minicel adhesion. Getting large pieces perfectly positioned can be a challenge, but some technique tricks can help.
I have a large 4 inch thick foam pad that I use for shop canoe test fittings and locations. I sit in the canoe with the pad on the floor to determine the best placement and then outline the pad(s) in pencil.
With the boat back up on sawhorses at a convenient working height I mask 1/8[SUP]th[/SUP] inch outside the pencil perimeter with blue painters tape, so I have a distinct and easily visible placement area boxed out.
Then, before any contact cement goes on, I do some dry test fits to determine how I am actually going to hold the minicel once the contact cement is on, how I am best able to place, lay, curl or unfurl it in place, which hand goes where and how. . . . .that stuff really matters, like crossing a stream stepping on scattered rocks, where you need to start off the crossing with the correct foot or get halfway across with nowhere to step
With really big pieces the easiest solution is often to have a shop helper (“Oh, son, I need a hand for a minute”) and to dry test fit with their help holding and positioning the minicel at one end while I press down the other. For something like a big piece of minicel with a thwart or yoke positioned above making things even more awkward a helper is almost essential.
After the minicel is in place I remove the painters tape, push it all well down by hand, cover the minicel edges with wax paper and lay sand bag weighs (large Zip-locks full of sand) on top overnight for compression. The next day (or later) I run a bead of Amazing Plumber’s Goop around the pad/floor edge. That little bead of adhesive/sealant is, well, amazing at keeping the edges from lifting and preventing water and sand infiltration under the pad. Same goes for Vyna-bonded or G/flexed D-ring pads.
Other things that help with adhesive durability. I round off any right angle corners on the minicel, and round off the top edge all the way around with Dragonskin to help alleviate any sheer forces pushing or peeling against the pad.
As far as the actual application of contact cement I alcohol clean the area even before sitting in the canoe to make pencil marks. My contact cement routine is one or two coats on the hull and always three on the minicel, letting the coats dry between applications. Once the last coat on the hull and foam is almost dry I hit both the hull and foam with a heat gun (a blow drier will work) and try my damnedest to get it seated inside the painters tape box.
Painter’s tape distinct box outline, dry test fits ‘til I am comfortable with how to lay it in place, shop helper for large pieces. Even the really big pieces of minicel usually hit within the 1/8[SUP]th[/SUP] inch of slop I have left with the tape outline.
Usually; provided I have practiced the test fit. Sometimes I get ahead of myself in the shop and have started with the contact cement before I realize I skipped trying any test fits. Those are the pieces that come out oh-crap cockeyed.
About “one big piece gunwale to gunwale” – I much prefer to use two pieces and leave a water channel down the middle, even if that is only a couple of inch gap in between. A single full size piece of minicel forms a little dam in the boat, holding water (dirt/sand/grit) against the edges of the pad, which doesn’t help with adhesion longevity.
And two medium sized pieces are easier to fit correctly then one giant piece.
