Thursday 20 June 2013

Model - Turnover celebrations

Well finally I got the planking finished and comes a time when we hold our breath and wonder if the hull will actually come off the jig. I had waxed the ribbands with parafin wax but still wasn't confident of an easy release because I wasn't able to get under the hull during planking to clean up epoxy (I will be able to do so on full scale build). Anyway a few squeezes and tap on planking and eventually she popped off with no damage. The building books say allow yourself a small celebration at turnover stage so I did just that (see below).

You will see in the top right I have managed to save the building jig without any damage so another model like this could be done by me or anyone else interested in the exercise.

Here's a closer view of the hull. There's a few rough spots and short cuts but I am pretty happy with the outcome given the purpose. I didn't cut conventional gains on planks at the bow (because the ply was too thin and brittle to cope with the chiseling) - instead I cut a full thickness rebate in the overlapped plank to give the same effect - I'll fill the air gap with some filleting.  I'm going to try for cutting gains at the stern on the full scale boat - it will be much prettier and avoid having to cut rebates in the transom.


Sunday 16 June 2013

Model - Planking Lessons

As mentioned earlier in this blog, one of my objectives in building a model of Skye Maid before the real boat is to put myself through a DIY boat building school (learn from mistakes cheaply) and get the logical order of doing things sorted in my mind. Despite reading lots of books, I forgot that I needed to allow for the thickness of overlapped plank edge when making patterns - that is until I got to the fifth plank as we round the bilge and plank shapes become their weirdest.  So from there on I moved straight to John How's method of making the plank patterns using two battens stuck together with criss cross sticks stuck with hot stick gun. Ian Oughtred also covers this approach on page 59 of his book but using screws instead of hotstick glue. Some pics and comments follow on my journey so far fitting planks to the model. You can easily ply apart these patterns after copying the plank shape and reuse the battens.

  
 In the above pic you can see the two battens, one clamped to the bottom edge of the last plank glued on, the other is clamped over the top of the next ribband below - this gives top and bottom edge of the next plank to be added. The cross sticks are then stuck on, to preserve the pattern allowing for the exact bent curvature of the plank.  Once unclamped, this pattern can be traced onto planking stock. Remember to mark key locating positions on the pattern (midship mould, bow, transom) before unclamping it and these marks need to be traced onto the planking stock as well as tracing plank edges.

The above pic shows the U shaped clamps I made to hold planks on (an Oughtred idea). The wedges I found at Bunnings for about $10 a box - in a range of different sizes - the wedge gap (plank to clamp) varies from top to bottom of plank because of extra thickness at the laps.



This pic is rather overexposed but it's starting to look like a hull with dry fit of the fifth plank added.