Anonymous wrote:

We're talking about two different things, Annie.

Peter was talking about the bow transom/forefoot as it narrows down and merges into the bottom panel - I had no difficulty in pulling 6mm ply around the curve on Siblim (but I wasn't there when you added the subsequent layers to see you glueing them on top). I suspect that the ply that Peter used was thicker than it should have been for the scale of the model.

Your problems with adding the middle panels forward stemmed from the error that I made in the shape of the forward bulkheads, which threw out the line of the lower chine. I hope that's corrected now, and indeed, the model stitched up by Peter seems to have fair hull panels forward. 

David

I agree with your analysis of my model.  In truth I probably overtightened the stitcthing at the bow before it was ready.  I was under a bit of pressure due to my sister demanding her dining table back!   

I've added a picture of the failure here.... unfortunately I can't get it to be the correct orientation.  But you get the general idea.  

As you said I had the incorrect thickness of ply, but it wasn't an insurmountable problem and generally the model went together with ease. I also think with hindsight that where the panels converged created a hard point that caused the breakage.... 

I'm now fascinated by your 7m model, and the ease of construction it offers.  

Peter

David Tyler wrote:

On Annie's SibLim, 6mm plywood could be bent around the forefoot area without breaking, so I'm aiming to use it again (three layers rather than four in the smaller boat). Let's see how I get on with 1.5mm plywood in the model.

Well, it didn't break, David, but if you recall, I had tremendous problems around the forefoot, because it is actually a compound curve.  The 6mm plywood wouldn't take the curve and there were huge voids.  I had to cut material out and replace it with smaller pieces, that I could force into place and drill a number of holes so that I could inject resin to fill in the gaps behind the smaller voids.  At the 8m size, the only way you could realistically plank the forefoot would be by cutting the ply into 100 - 150 mm strips and attaching them that way.  Most people were astonished at how I tortured the 12mm ply further up, too.  If I were doing it again, I'd 2 layers of 6mm there.

Gary wrote:

This really should be one of the easiest boats to assemble. 

And one of the quickest. As I was trimming the parts, I was thinking of the many long hours it would take me to mark out and cut these parts by hand. Thank goodness for CNC. For anyone for whom time is money, having to earn a living as well as building a boat, or having to rent a building shed, this has to be the way to go.

Anonymous wrote:

Peter wrote:

David

This looks really interesting.  You may remember that I built a model of the 9m version from CNC cut parts.  I've finally uploaded some pics to my album.

I watch the progress with interest.  

I'd forgotten about this. Did you take it any further than stitching the seams?

I didn't take it any further.  Having established that the CNC cut parts fitted together well enough for stitching, I achieved what I was aiming to. I cut the stitching and put the parts in my sisters attic for a rainy day project.  

The only problem I found with this model was the forefoot.  The curve was too much for the ply and it split athwartship.  I concluded that were I going to build full scale I would have taken a second look at the bow construction method.  A foam/glass forefoot would have worked.

Imagine, if you will, that the old door in the photo is modelling a flat, smooth floor surface in my boatbuilding shed. At full size, it would be 3.23m x 8.415m - large enough to work on the puzzle joints. An actual building shed would need to be wider, to get the topsides on and coated. Maybe 4.5m x 9m would be just about large enough.

It turned out that a craft knife wouldn't cut the tabs, but a multitool made short work of them. 180 grade abrasive paper cleans up the edges easily and quickly. A quick trial fit shows that the puzzle joints will go together with a little pressure, but are by no means too slack. The tabs are a perfect fit in the slots, which is a relief - this is where Gary's model gave problems.