Thank you for all the input to date.
I am reluctant to use the flexi-tanks for the bow, as I am concerned that 1) they will slosh around and keep me awake at night (I have had them on a previous boat in midships, - and not so good; and 2) the constant movement of water in the flexi-tanks in the bow will shorten their lifespan.
I made a cardboard mock-up of a tank to confirm the largest size that I could retro fit with out major modifications of the wood work under the V berth (approx200litres), and then drew this up and sent the drawing to my local SS fabricator for a quote. AUS$1,550.00
I also contact the helpful people at Bavaria Yachts in Queensland, who were able to source a retro fit Poly tank (150 litres). Their email included all dimensions for confirmation that it would fit into the V berth. The tank includes all inlet/outlet fittings & water tank sensor. AUS$ 950.00 plus delivery.
As an aside, the wiring for the second tank is taped up in the V berth ready to connect direct to the poly tank!
I'm off to the boat on the weekend to confirm the poly tank fits!
Cheers,
Steven
SV Konan the Bavarian