Monday, 24 August 2015

Floatation

Making Betsy unsinkable has been an ongoing project.

Having tabbed in the new bulkhead under the carbon beam I set about filling Betsy, both fore and aft, with polystyrene foam and boxing it all in to create several watertight areas.

The theory goes that buoyancy is most useful and least intrusive to stowage when spread about to the extremities of the boat whilst leaving space for all the weight (water, food, equipment etc.) in the middle of the boat where it impacts least on pitching and rolling.

To that end, no pun intended, here begins the story...

Polystyrene foam has been shaped with a hot wire to fit the bow in an effort to leave as few voids as possible.



A lid laminated from two pieces of foam and fibreglass sandwich was cut to size using cardboard as a cutting template.


An aft end bulkhead made from the same material was tabbed in place using two pieces of 450 gm biaxial glass cloth, the first piece 60mm wide overlaid by a length of 120mm wide tape to give a generous overlap.


With the polystyrene foam back in place the lid was glued on, filleted round and taped in place using the same cloth ratios.


Moving aft, the rather dead space under the cockpit sole has been treated to the same process. First the small void at the root of the rudder keg was filled with a two part polyester expanding foam, pour out equal volumes of each part, mix and pour "quickly" to avoid disappointment!


The excess foam that mushroomed out of the top was cut off with a long arm and a long saw! Various holes in the original plywood either side of the space were filled to create a watertight area. Then, more polystyrene foam...


Various gaps were plugged with wedges of polystyrene and more expanding foam, particularly the awkward space around the old stern tube. A plywood bulkhead was shaped to seal it all in but not before a seacock skin fitting was sealed to the end of the stern tube.


The buoyancy exercise continues with the two relatively shallow spaces beneath the after end of both quarter berths.


More cardboard templates were made, to minimise waste, before sandwich bulkheads and lids cut. All laminated in using the method described earlier.


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