Clipper Depth Gauge False Reading

[Pkewish]

I recently fitted a through-hull (I always get confused with these, one which reads through the hull, NOT mounted through the hull) transducer and display. I followed all the instructions to the letter. i.e. mounted away from electrical bits and bobs, in the middle of the boat, pointing down etc etc. I have checked for air bubbles in the caster oil by pushing the transducer down so that oil comes over the top.

The problem is - it only ever reads 1m to 1.2m. The little arrows showing 'getting deeper' or 'getting shallower' ping up periodically, I have reset it etc etc.

The only guess is that it is fitted over an air bubble in the foam between the 2 skins of GRP. Should I replace for an in-hull transducer or does anyone have any other ideas.

Cheers

Pete

 

[tillergirl]

I would have thought that if you have a foam core, it cannot possibly work since the core will inherently have air 'init'. I am afraid I think you need a through-hull.

 

[Pkewish]

Thanks. This was my fear. The price one pays for using cheap on-line retailers who give bad advice hey.

 

[noelex]

Yes an internal transducer will not work on a cored hull.
Before you mount any internal transducer try the position by filling a plastic bag with water and sealing it with no air. The transducer can now be rested on top of the bag that is in contact with the hull. If it does not work find a different spot.
Some boats with cored hulls have solid glass in some areas like along the centreline.
A vey bright torch shone from the outside ( easier if the boat is out of the water) will sometimes show where these spots are.

 

[V1701]

What boat? I have no idea really but wouldn't have thought there'd be core along the centreline...

 

[Pkewish]

It's a 1989 Jeaneau Sunway 21, I can't get directly to the centre line, only a few inches either side. It's 'unsinkable' and has large areas filled with buoyancy foam. That said, I'm not entirely convinced there is foam between the bottom of the aft lockers and the underside of the hull anyway.

Shining a torch through would work is out of the water but there is several layers of epoxy undercoat and 5 layers of copper coat to get through.

I'll try the bag of water trick and see what happens. Also (don't tell the wife) might bunk off work tomorrow (self employed!) as the forecast is good and test the whole lot directly in the water.

I'll keep you posted.

 

[AngusMcDoon]

Foam cored hulls sometimes have a solid layup bit especially for transducers and sea cocks (mine does). Have a poke around. You'll be able to spot it from the inside. It will be indented by about 1cm.