Can you test a disconnected transducer

I purchased a Grand Banks 42 woodie last Summer. It has no electronics and 4 transducers. I've read that transducers are made by just a few companies and most operate on a couple of frequencies. Is there a way to test them to see if they work and what brands they may be compatible with?
I have seen mixed opinions on removing old transducers or just leaving them and doing a new install. I just hate the idea of 5 transducers down there. I'm pulling her this Spring for a bottom job and trying to get everything organized.
Thoughts folks?

Transducers usually have an id tag on the cable somewhere. Google search what you find and you will find out what used to be installed. No good way to test without hooking up a like kind DF to the TD.
Personally I would buy a complete DF unit with TD of the same hole diameter of an old TD and swap it out.

Airmar makes a tester. The better marine el outfits have one.

I'd start by eyeballing each of them, taking pictures and getting vendor info.

If you're going to spend money it might be best spent installing new, known-working gear. Because labor isn't free and you may end up spending more money to figure them out than it would have cost to just install a new one. Just a point to consider.

Find whichever existing hole is best positioned to give you a good signal and put a new one there. As for the old units, sometimes it's best to let sleeping dogs lie. But I'd check for moisture intrusion and consider what it would take/cost to have the old holes dealt with.

IMO; each thru hull is a liability. Especially those that might hang out, like a transducer. I would remove ALL the unwanted parts, and fill the holes. I don't have direct experience with u/w plugs on wood hulls, so get a informed opinion on that one. I have done a number of u/w plugs on glass hulls. Up to about 2" dia. BUt that doesn't count for your hull!

diver dave said:

IMO; each thru hull is a liability. Especially those that might hang out, like a transducer. I would remove ALL the unwanted parts, and fill the holes. I don't have direct experience with u/w plugs on wood hulls, so get a informed opinion on that one. I have done a number of u/w plugs on glass hulls. Up to about 2" dia. BUt that doesn't count for your hull!

Click to expand...

Thus my comment. Which is less worse, through hulls not causing problems versus repairs of unknown quality? I'm all for minimizing complications but I'd want to be damned sure about any repairs that eliminated through-hull fittings.

As a side note, when talking to my boat guys yesterday, one of them lamented installing some pretty big through-hulls for sonar, in a Boston Whaler. For two reasons, one being the big-ass holes needed (much more than typical 2" units, apparently) and then discovering the sheer thickness of the foam in the Whaler's hull was longer than the transducer's standard threading. A bit of a scramble with the vendor to get appropriate length solutions and then the open-ended worry of getting a phone call about a leak/sinking episode...

In a glass boat I would recommend removing the ducer and glassing the hole closed. Not sure I would mess with them in a woodie. The repairs would be more complex on a woodie. But I would check the caulking carefully.

Oh, BTW welcome aboard.

Greetings,
Welcome aboard. Agree with removing transducers and replacing with a known working unit. Plug the holes either with a proper wooden hull repair. It CAN be done quite readily. The alternative is "fill" the holes with regular through hulls and cap same.

Congratulations on planning ahead for this job. I hope you have a boat yard that specializes in wood boats. There are still enough old shrimpers around here to support a great wood boat yard. I'm convinced that frequent, short hauls are the best wood boat care. Wishing you many worst plank hauls.

Being the skeptic (cynic) that I am, I would expect poor installation of the older transducers and assess the installations to eliminate the worst ones.

I like the idea of repurposing good ones and keeping new ones for spares.

If the GB is double planked you might need a double plug to allow for movement between planks.

Thanks for the welcome and the opinions. This isn't my first woodie but it is my first Trawler. Previously I restored a 1959 Owens 30' Cruiser. Unfortunately a huge tornado hit Tuscaloosa AL in 2011. Completely destroyed the marina along with my Owens. I finally came out of mourning and this is my new project. Hope to do some cruising in the coming years.
I've been very impressed with the level of interaction and experience on both this and the Grand Banks owners board.
I certainly would like to replace the old transducer with new. My hesitation is that many woodie owners have bad stories to tell about removing and replacing old transducers. They are extra long have faring blocks and who knows what the installer used for adhesive. That may be why there are 4 on the boat now. The airmar tester is a great option. However at a $1500 purchase price I'm going to check with the Marine techs around town and see if anyone has one.
We do have one yard left with an old timer that is great with wooden boats. The boat is in Nashville on the Cumberland River/ Old Hickory Lake.

All trans have a service life whether used or not. They age. Determine model and age from SN on device contact mfr and they can guide you. As to holes in boat....we removed and repaired all old holes. Then installed 2 new xdcrs. This eliminated 3 possible leak points. Good luck with project!