Grand Banks 32 Hull Thickness?

[Oldersalt]

Does anybody know the hull thickness of a 1990 (fiberglass) Grand Banks 32, near the centerline and to one side of the engine? I have installed two in-hull depth transducers and neither works right. They are supposed to be able to shoot through the hull, but either the glass is too thick or there are voids in the glass (Heaven forbid!). I have also posted this query in the Grand Banks Owners Forum but, frankly, I think many more GB owners participate in this forum!
Thanks in advance.
Oldersalt

 

[Gmarr]

Are they the Airmar kind of transducers where you need to have a liquid in the housing? Or, is your hull cored in that area?

 

[kchace]

Many trawlers have cement in the keel. Could that be possible?

 

[Capecodder]

Did you try putting the transducer in a plastic bag filled with water? Try it’s easy to move to find the best spot.

 

[C lectric]

Either a bag of water or Dippity Doo, a hair gel which works well also can be used to try different mounting spots. THe D.D. can be easily cleaned off after testing.
That way you can test before gluing into place.

I think even if the hull is 3/4" where you mounted it the sounder should work if the T.D. is ok and mounted properly. The thicker the hull the less range will be had but its sensitivity should not be affected seriously.
Can't answer about any coring although if memory???? serves properly???? I don't think it's cored.

A question; what did you use to "glue" the transducer into place. The wrong material may stick it into place but may interfere with the passage of the signal. Any air pockets allowed in the "glue" will interfere.

I had that happen, caused a failed T.ducer. Thought it was the sounder head so got a new unit as we were already travelling and troubleshooting was not possible at that time. It had worked for a year or so.

Later
when I was expecting to destroy the T.D. housing to remove it I simply tapped it and it flew out of the epoxy bed. The epoxy was solid on the hull and when I went to install the new one I had to grind the old bed a bit. Nothing wrong with the bed.
I really don't know what I did wrong. I cleaned the face properly, used good epoxy and let it set before using the sounder. The new T.D. is in solidly and the sounder has worked well for the last many years.

Is it possible something was done wrong such an unsuitable adhesive/glue?