I have a 2000 boat that came with a lowrance 3500 depth finder with a
thru hull transducer. Used in fresh water. This past season i started
to get odd readings. On occasion in 3-4' of water I would get a
reading of 235'. Sometimes it would lock onto 3' for a few minutes at
a tiem. While cruising in deep 25' of water sometimes it would lock
into the number for a minute or two, then go back to reading depths.
Sometimes I would be in 25' of water and it would read 175'. It could
go for days and run just fine. I spoke with one lowrance tech and they
said that odds are it was the head unit. I spoke with another and they
said it could be the transducer. They both said that they do not
service the head unit anymore.
The boat is on the hard at the moment. Is there any way to test the
transducer while in the boat. I was able to gead the last new head
unit from my boat manufacturer. I can return it if it didn't solve the
problem. The old head had signs of corrosion around the lense(green
type residue). I was told I could replace the transducer by pounding
out with a rubber mallet. It's glued in with 5200. Unfortunatly the
boat has a genset and I can barley reach the transducer, let alone
have access to hitting it. It is rather difficult to change out. I'm
also a bit scared to whale on it and cause any damage to the outside
of the hull. I hate to launch without the depth finder. It would also
cost a couple hundred to haul the boat out again. Can the head unit go
bad? Or are the transducers the weaker link. Anybody have any
experience trying to free up a transduecer that is glued from the
outside in with out major or any damage?
I appreciate any feedback.

I'm reasonably certain that there is a softener for 5200. Check the 3M web
site or go to your local boat goods store. That should ease the pain of
removing the transducer.

Suggest you replace the transducer using 4200 vice 5200. 5200 is not
intended for anything but permenant installations, IMO.

Butch
wrote in message
oups.com...
I have a 2000 boat that came with a lowrance 3500 depth finder with a
thru hull transducer. Used in fresh water. This past season i started
to get odd readings. On occasion in 3-4' of water I would get a
reading of 235'. Sometimes it would lock onto 3' for a few minutes at
a tiem. While cruising in deep 25' of water sometimes it would lock
into the number for a minute or two, then go back to reading depths.
Sometimes I would be in 25' of water and it would read 175'. It could
go for days and run just fine. I spoke with one lowrance tech and they
said that odds are it was the head unit. I spoke with another and they
said it could be the transducer. They both said that they do not
service the head unit anymore.
The boat is on the hard at the moment. Is there any way to test the
transducer while in the boat. I was able to gead the last new head
unit from my boat manufacturer. I can return it if it didn't solve the
problem. The old head had signs of corrosion around the lense(green
type residue). I was told I could replace the transducer by pounding
out with a rubber mallet. It's glued in with 5200. Unfortunatly the
boat has a genset and I can barley reach the transducer, let alone
have access to hitting it. It is rather difficult to change out. I'm
also a bit scared to whale on it and cause any damage to the outside
of the hull. I hate to launch without the depth finder. It would also
cost a couple hundred to haul the boat out again. Can the head unit go
bad? Or are the transducers the weaker link. Anybody have any
experience trying to free up a transduecer that is glued from the
outside in with out major or any damage?
I appreciate any feedback.