OK, now that she's upside down, the plan for August is to fair the chines, prepare the underside of the hull, and cold-mold the second 6mm skin of ply to the bottom.
If I manage that this month, I'll be well pleased!
The trolley now supports the boat using the cockpit sole, so the waterline should be level to the floor for ease of working and painting the antifoul line when we get there.
First task was to trim the well walls back to hull level:
then plane the slight overhang of the sides down to the level of the hull's bottom
Oh, Disaster!!!! Sighting along the chine shows dips something like the Welsh Valleys. Bugger! Time for a beer...
Next Day: A bit of thought led to placing a batten along the chine to assess the real extent of the problem. You can see from the pic below where the darker strips above the batten need to be removed..
In reality, the dips that appeared so drastic on first viewing were only 1 to 1.5mm deep, so judicious use of the belt sander with 80 grit at a low speed allowed for sufficient adjustment to create much smoother chine lines on both sides:
I think the visual impact will also be reduced when the chines are rounded off before glassing, so the remaining slight flat spots don't concern me any more at this point.
After scuffing the hull with 80 grit again, it's time to start the cold molding. I've decided after a trial to use the strapping that comes on pallets of timber to staple through. It's free (thanks to my local building supplier "Meakins"), reduces bruising from the staple bar, and eases removal once the epoxy has set up. It's imprtant to make sure the strap extends about 2-3" past the last staple, or it just rips through. The ooze holes are drilled 4mm on 100mm centres.
So, by 4th August, the first four sections of the second skin are on. Something's got to go wrong !
10th Aug and eveything seems to be on track - now up to around 2/3 of the hull cold molded, and closing in on the well section. About this point, I also abandoned the strapping in favour of the faster speed and tighter clamping achieved without - the extra 1-2mm of bite on the staples seems to hold each piece down much more firmly.
While upside down, the hull also doubles nicely as a workbench for storing/spreading stuff out on.
As an aside, we visited the Wings, Wheels, Speed & Steam show at the weekend, which seemed to be mainly cars, but as it was literally around the corner & a sunny Sunday afternoon, we took a stroll. One small stand was displaying some varnish & sanding/polishing tools, so after a chat, demo & more chat, I ended up with a flexible head sander attachment, sharpening stones, and 0.5 lt of Le Tonkinois Tung oil/Linseed oil varnish for £60.
The discs are claimed to run much cooler than most, and a quick demo seemed to confirm this, with the demonstrator (Brian) cleaning the discs after a while of grinding before starting up again with very good results. The flexibility of the head also stops the drill mounted disc "walking" over the workpiece. I'm all fired up about it at the moment, but will update on whether it does the biz in real life....
The varnish got a great write up in Practical Boat for basically everything except gloss retention, which could have been better. Viewing some examples indicates that this stuff penetrates to 3-4mm (patches have gone clean through the walls of a turned 4mm thick chalice). Also, it apparently flows out beautifully, so I'll be doing a test on my Iroko sample over the next week or so to see how it's UV protection of epoxy works out.There's also a compatible matting agent in case I want to move away from the full gloss look on any sections.
Working towards the front, I wanted to check the vertical alignment of the stem section. There is a slight skew here, probably from the initial stitch-up tensioning problems, but it's only about 2-3mm off centre, so it's out with the sander again before fitting the second skin to this section:
Having got to the pointy end, the curvature required in the panels is now quite extreme, and I don't think staples alone will hold the wider sections down, so I'm going for a strip-planking approach again, with the leading edges of each plank undercut to about 60 degrees to aid holding down the following strip. The ply also seems to conform more easily in this area if turned 90 degrees to the current layout, so the last two flat-ish sections are cut to allow for this:
Despite the change of direction, the compound bend is still too much for tight clamping with staples alone. As I have the kit, steaming to shape seems the best option. A batten stapled to the hull first gives more curve than required, theoretically allowing tighter edge clamping.
In practice, this didn't work out quite as planned: the ends didn't comform as smoothly as I'd hoped. It did, though, allow me to take the cutting angles & trim each strip to its final shape before steaming again & re-fitting prior to gluing.
Had a bit of a lazy week last week, but even so, by 24th August the bottom panels are cold molded onto the hull - a week ahead of schedule.
I'd like to leave a clear 7 days before sanding the hull as the biggest hazard from the epoxy is uncured sanding dust, not the fumes of the wet product, although they're bad enough.
Pulling the inside panels in at the beginning gives a very small overbite to be sanded:
That leaves me with a week to tidy up the edges of the hull and the well, plane the keel flat, and figure out which epoxy to use for the sheathing. Yup, I've run out again!! That's a total of 21kg used to this point of the project. I might well go for the West System 105/207 mix recommended By Ted Moores in Canoecraft, as the hardener has some (albeit limited) U.V. resistance. We'll see...
24 hrs drying is enough to allow removal of staples
before sanding fair (with organic vapour mask - I couldn't wait 7 days in the end!)
Minimal overbite sands down easily to give a fair join which will need only minimal final filling before glassing the hull. Also note the proposed stem shape revision which will accommodate a 30mm wide stem band. It was drawn by setting the vernier to 29mm and tracking the contour.
Final task for the month was to go round the hull with a syringe full of the little LV epoxy I have left filling the drill holes in the cold-molded panels where there has been either some shrinkage, or the panels have lifted enough to suck the epoxy down. So little is required to fill each hole, though, that I'm confident of the integrity of the glue matix.
Running Totals:
|
Building Time so far: |
Costs to Date: |
|
|
|
|
294 hrs |
Workshop Renovation |
Tooling |
Materials |
Consumables |
|
|
£240 |
£392 |
£2179 |
£131 |
|
