I intend replacing my old Autonnic Research combined log and depth-sounder,
both components of which are knackered - I suspect it is the control/readout
unit rather than the transducers (I recently tried a new paddle-wheel and it
was still kaput).

The hassle in getting the present one fixed is not worth it - the company
would send it to an old employee who maybe could or could not fix it - for
£50 deposit and an indeterminate fee. I will use another combined
depth/speed instrument - perhaps a NASA - my question is do these companies
use a standard size through-hull fitting for depth and log transducers?

If so I'll be able to beach the boat near low-water and put the new
transducers in before refloating. If not, I suspect I'll have to lift the
boat out to bed new fittings in. Any ideas?

TIA, Roy