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Chris Craft Triple Cockpit, Dumas kit

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SailorGreg:
 Avid readers of the “Who’s building what at the moment?” section might have spotted a post from me revealing that I was about to start the Dumas kit of the Chris Craft Triple Cockpit Runabout.  So having made it public, here we go – the box.





And inside is a whole pile of wood strips and sheets of liteply, with all the parts neatly die cut, fittings, prop shaft and propeller, a full size plan, two similar sized sheets with loads of photos of the build and some very comprehensive instructions. I find Dumas instructions to be very well laid out, well printed and both complete and easy to follow. 10/10 for them.   :-))


The first part of the instructions gives some detailed measurements to lay out the support pieces for the cockpit sides and floors on the various frames.  All the die cut pieces popped out of the sheets with little trouble and no damage. 









Then we glue the two halves of the sheer together as well as the forward part of the keel.





At this point, the instructions suggest pinning the sheer down to the building board, but I decided to fix it differently.  I cut up some of the scrap ply and made a series of clamps to hold the sheer in place, over a sheet of polythene to make sure the building board didn’t become an integral part of the hull.





The frames are then glued into their slots in the sheer.  They are not fixed at 90 degrees to the building board, but rather are given a slight rearward lean.  Dumas provide a simple jig to make sure the frames end up at the correct angle.





I am using Deluxe Materials’ Roket Odourless cyano, which not only glues well but means I don’t finish a session feeling like I have a heavy cold.  I also have a bottle of their ultra-thin to run into any seam which might need a bit of help to stay together.  I can vouch that the ultra-thin, as well as fixing wood very well, is extremely effective should you wish to glue your fingers together.   :embarrassed:


With all the frames and the front part of the keel in place, this is what we have –





Next will be sheeting the hull – what could possibly go wrong?   :}
 
Greg

Capt Podge:
Well Greg, you've made a good start on this one and positive feedback for Dumas.


Looking forward to seeing /reading more soon.
Ray.

ChrisF:
Greg

I like your method for holding the deck in place. I'm also a user of that odourless glue as get similarly affected.

Chris

SailorGreg:
 The rear half of the keel is made with what Dumas call a “butterfly keel”, two pieces that fit into the frames as you can see in the picture.





As you can see, initially I didn’t carry this far forward enough (read the instructions!) and had to add a couple of pieces to extend the butterfly bit.  Next came the chines, which are laminated in place from 3 pieces each side.  The three pieces are glued together for about 50mm then cut to fit against the keel at the front.





Then each strip is glued in place in sequence to give a good, robust chine.








The bottom of the hull is planked with liteply sheets and is fairly straightforward.  A total of 6 pieces cover the whole of the bottom, although the ones towards the bow need a fair bit of twist to get the right shape.











Once the sheets were in place, there looked to be a bit of a discrepancy at the transom.  The wood blocks attached to the transom are due to be sanded to shape to give the elegant curved transom of this boat, but it wasn’t clear to me that there was enough of the bottom sheets to fill the curve.






So I cut a strip from scrap to extend the bottom sheets.  If this turns out to be unnecessary, no problem, but fitting it now is much easier than trying to let a piece into a nearly finished hull.





The edges of the bottom sheets where they meet the chine were planed down to give a flat surface for the side planking.  The section right up in the bow is due to be filled with a block of balsa.









You can see where I added some strengthening pieces to the two frames with large cutouts as they seemed a bit flimsy on their own.  Then the side planking was started.  This is made of balsa strips, although these are shorter than the hull, meaning a joint has to be made along the way.  I followed the suggestion in the instructions by alternating these joints over frames 6 and 7.  The instructions also suggest that once you have 3 or 4 planks on each side, the hull is stiff enough to be removed from the building board.  I did this, and it certainly made fitting the subsequent planks much easier.





I did find that where the planks butted together at the joints there was a discrepancy in how the planks adopted the necessary curve.  Where a plank runs over a frame, it adopts a fair curve, but where it terminates at a frame, the last few inches are straight as there is no bending force beyond the frame.  I didn’t really twig this until I had several planks in place and ended up with a stepped effect like this –






After pondering for a while I opted to leave it alone and allow wood filler and sanding to solve the problem for me.
The instructions do warn that where these balsa planks meet the bow, the sharp curve and twist is likely to cause a few breakages.  They were not wrong.





Rather than worry about this, I decided to ignore the broken bits and later cut them out and form the whole bow section from solid balsa, so planking continued up the hull.  As I got to the planks near the sheer, I could see that as I pushed the tapered pieces into place, the sheer was flexing slightly, so I clamped a stiffener along it to make sure it remained flat as the planking was completed.





That completes the first layer of planking, but as I have said there is now a fair bit of work to get this smooth and fair, ready to take the mahogany planks.  Lots of filling and sanding to come!


Greg
 
 
 
 

Capt Podge:
Hmmm, interesting write up complete with problems encountered and solutions to overcome them.


Good work Greg  :-))


Ray.

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