Hello all, Unfortunately, this model of the the type 7 will not accomodate cells underneath the dive unit as there is no room, the keel is not deep enough. If it were possible to raise the dive unit at all, the best you could do would be to fit 'c' size cells and with that size of battery, even using NiMh types, the best capacity would still only be 4.5Ahr which is what you have with the lead acid battery you have in the boat now. You might be able to sqeeze them into the dive unit but there would be no point and in any case, I personally would'nt recommend putting batteries in there.
I think it may benefit from a new lead acid battery being fitted whilst at the same time accepting the limitations it provides on run time.
Carrying a spare battery in your box is a good idea provided you are prepared for possible discrepencies in weight found between different batteries and the subsequent trim change you may experience when fitting it.
This boat has direct drive motors feeding 35mm,3 blade props and it has been suggested low current motors or motor/ box reduction drives would cut down the current drain but unfortunately, the resultant loss in prop rpm means the boat would have greatly reduced propulsion and would be too slow. I am of the opinion that options on mods are very limited and the boat works fine as it is as long as you accept it has a limited range.
It is for all the above reasons that I addressed all the limitations of the Type7 and created the Type2D.
Very pleased to see you have taken the bull by the horns and gone for the 'plunge' Dino. It looks as though you have had a good day out..... I told you you would!
Kind regards.......... Chris