Depthfinder Transducer Question

In2Deep · 08-08-2009, 01:50 PM

My stock-from-Nordic Hummingbird depthfinder is giving me erratic readings. Not sure if the unit is toast, or maybe the transducer "face" needs cleaning (if that's possible?).

Can anyone tell me where the transducer is located on the Hull? It's on a lift, and a bit hard to get a close look.

Thanks.

I2D

Steve Zuckerman · 08-11-2009, 05:22 PM

It's in the flat pad area under the oil pan.
Mine does the same thing. I replaced the transducer, bedded it properly in epoxy. Works slightly better.
They don't shoot through cored bottoms very well.
Because electronics are very important on fishing boats, most of the hull manufacturers leave a small area (like 2" x 2") in the pad without coring so you could mount the transducer in a "clean" non-cored spot. This works a lot better. External transducer mounts are ugly and prone to damage from debris, but they also work well.
Regards,
Steve

In2Deep · 08-12-2009, 05:42 PM

This helps much.

I won't tell you where I thought it was, since it will make me sound even more dense.

Gracias. Will try.

Steve Zuckerman · 08-12-2009, 10:29 PM

Step hulls can also cause problems because the step is ventilatling/aerating the aft hull surface. Good for performance, bad for on plane transducer connection. Add bubbles to a cored bottom and you have 2 issues to deal with.
Mine only works at idle, and even them it's still erratic. It works best on "hard" (gravel/rock/shallow) lake bottoms because the signal strength is reduced by the coring.
There is a cure for this, but I haven't tackled it yet. You have to use a hole saw (same diameter as the transducer or slightly larger) and slowly, carefully drill through the coring until you reach solid fiberglass. Then rough it up and resin or epoxy the transducer against the glass. Then you have to glass or epoxy around the hole edges so water doesn't get into the coring and migrate laterally and soften the bottom.
Basically you end up with the same mounting area that most fishing boat manufacturers include from the factory.
Regards,
Steve

Linster · 08-13-2009, 05:32 AM

I was going to do the same but I could not get a straight answer a few years back from the factory was the core all along the bottom, so I chickened out on the drill. Mine works the same, good at idle, sometimes takes a minute or so to find something.
I did it on the velocity. Took a hole saw with the pilot bit 1/4" lower than the saw. got the saw going into the top layer. Stopped and removed the polit bit. After I broke through the top fiberglass layer, it went through the balsa core easy and the bottom fiberglass was easy to feel.

In2Deep · 08-13-2009, 01:48 PM

Great ideas. But...
in terms of my non-existent hull-sawing cajones, overall aptitude level at this sort of thing, and previous success rates performing surgery on things best left to professionals -- the day I start cutting into the hull of my beloved Heat is the day before I end up starting the shopping process for a 35' Flame...because I have to.

Damn. Now that I think about it -- that's an interesting and viable strategy to finally secure new boat budget approval from my family CFO.

Where's my post hole digger?

I2D