Ok, here is a proper update, I have pretty much got the Hull/chassis built and sealed (gave the inside, mostly joins in plywood, a liberal coating of nail and seal. Before removing the gearbox, wheels etc I did a quick watertest to check it floats which it does albeit a little too low on rear, I did add a motor, esc, battery, servo etc to simulate completed set up. I can sort the rear weight bias fairly easily... instead of the 540 drive motor for wheels I will use a 380/400 as it doesnt need loads of speed it just needs to move. I will also make sure I use a small lipo for power mounted forward in hull/chasssis. The rear boxed area is filled with polystyrene as is the space above where gearbox sits. I appreciate it looks more than a little messy inside but once its painted with stone chip all will be good, looks inside arent important but keeping the lake on outside of hull is important LOL.. plus it still needs a good sand. How I modified wheels using the centre of a Mardave V12 wheel. Working on the hinging for outboard motor.. http://i1253.photobucket.com/albums/hh591/bigguditchus/6-5_zpse08e2c5a.jpg