John,don't want to throw a shadow on your repair attempt, but …….

… the reason that i.c. has blown, is most likely a failed component further along the circuit.

Some very nice conversions have been done to the Southampton, that use esc's & radio gear from the more usual makers & make for an improved model.

Its a linear voltage regulator, so it heats with load and supply voltage. If it was the weak link, the replacement will probably do the same eventually. If it was something down the line increasing the load, that would need to be found or it will happen again. Same if it was a voltage supply problem.

Electronic components have two main ways of failing – they either disconnect them selves like a fuse or they short themselves out. A bubbled box indicates heating, so on the way to failure heat was involved. Before finally giving up, it might have presented its load with more voltage than was needed and taken a few other bits with it.

Replacement of the complete electronic installation might be the least fraught way of getting a very nice boat back to full operation.