When my Raymarine equipment was installed I think that the sumlog transducer was left in the bilge (dry but not sure if it works). I should be at the boat next week and I will be able to confirm this
Peter,
Unfortunately I had the same problem 2 years ago the sumlog when working was
superbly accurate. I fitted an electronic Raymarine log which lasts about a month before sea creatures make their home in the impeller and it stops, it also very hard to calibrate.
I have the wire from the impeller and the clock if by chance that part is at fault.
I have a sum log transducer and a short cable to a square connector. No idea if it now works but I can send it to you if you give me your address. This is FOC and I hope that you can make use of it.