Mk.II Floats - Back to Square 1

by Web FishMay 2, 2014 @ 01:22pm

As we mentioned in our previous post, the new design called for increased displacement and lower weight. Going back to the early days of the project, the original plan was to have the float shells thermoformed / extruded from polycarbonate plastic. This plan proved to be too ambitious and was abandoned early in favor of fiberglass shells (and later on composite wood/foam/fiberglass construction). With the new weight target in place we decided it was worth revisiting the plastic shells idea. Instead of polycarbonate (which, even though very strong, turns out to be less than ideal for thermoforming) it was decided to stick with more traditional polystyrene or ABS floats. The two materials have similar properties with the ABS route adding extra flexibility to the structure (which might or might not be a desire-able feature). Both materials lend themselves very nicely to vacuum forming.

There are two major hurdles when going the vacuum forming route: the cost of the process makes it impractical to run really short series of pulls (we really only need 4 floats for now) and you need a solid (and strong!) plug (positive model). There isn't really much one can do about the former (other than run a larger batch and store the extra shells for future use ;) so we focused on the latter.

Week one results: