Thanks to a reader comment I have finalised the design and construction of the forward pontoons.
The reader suggested that the original Battlestar Galactica flat top pontoons were made from Bolton Paul defiant fuselages and that lead me to look at other suitable aircraft kit donors. I was originally thinking submarine hulls but couldn't find anything cheap enough or the right length to width ratio. Finally I found some 1/144 scale Kawanishi " Emily" flying boat kits at the right price and importantly the right size for my needs on Hobby link Japan.
The fuselage sides are cemented to a central spine made from two layers of 2mm styrene sandwiching a core of two layers of 1.5mm styrene. The two layers of 1.5mm styrene leave a 3mm wide pocket for the support struts made from heat bent 3mm PVC sheet.
A section of fuselage was cut away for some recessed nurney kit part detail.
Here they are with the first coat of grey primer. There is still a bit of spot puttying required here and there to be done, along with some detail on the struts but for the most part they are done.
And finally here they are in position on the spaceship hull.
Thanks for looking, more soon...