The one question that comes up more often than almost anything else is how do you get a round bilged metal hull? The simple answer is with a great deal of design and engineering thought, and careful work by the builder. We’ve got a series of photos here to briefly walk you through the process.
In the photo above you are looking at a 20 foot (6m) chunk of 12mm (15/32″) thick hull plate. It has already been cut on the Circa laser cutter to a predetermined outline.
The plate is lifted by the hoist on the traveling crane and run through the “wheeling” machine in the center of the photo.
Depending on the dies in use and the pressure applied, the plate is stretched into the desired shape, being checked during the wheeling process against shape templates. As you might imagine, this process is very much at the mercy of the operator’s skills.
A big part of getting a fare hull – and there is no hiding problems with fairing compound on a bare hull – is having the correct mix of framing design and plating thickness. We are looking at the skeleton for the fourth FPB 64 above. Framing has to be related to plate size and joints as well as structure and fairness.
A bottom plate after wheeling is routed around the perimeter to provide a groove for welding bead.
The plate is then positioned on the framework, and tack welded into place.
If the curvature is positive, the plates fit very closely to the framing. But the stern of the FPB 64 has a slight tunnel, difficult in the extreme to get right, hence the use of the come-along, chain, and block to force the plate onto the framework.
This is the first plate to port of center.
Looking now from right to left. The vertical element on the centerline is a part of the skeg assembly.
A little later with plate welded into place. You can just make out the tunnel shape. The wedge assemblies are used to align the plate edges during preliminary welding after which they are removed and welding is completed.
Looks easy, right?
Posted by Steve Dashew (February 7, 2010)
