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mr-canada · 20-11-2017, 22:13

My Humminbird fish finder which was mainly used as a sounder stopped working. I got a better sounder with 3D bottom reading and tested it out by dumping the two transponders in water in the bilge, it worked - for a while.

I think the problem is likely marine growth or bad bottom paint meaning I have to do the dreaded haul out, clean and paint. I have a curved brush on a long handle and have been cleaning it in the water that way but the time has probably come, although that is another matter.

I'm looking for ideas on a contraption to get the two transponders in the water, but outside of the boat. Ideally it would be removeable so I can stow the things inside the boat. Leaving them in the water permanently may just leave me with the same problem after a while and then I'd have to dismantle the thing to clean them and may attract theives.

I am thinking some wooden hook contraption hanging over the transom with a transponder on either side of the boat to keep them away from engine wash. Wood is easy to build with and pretty light weight. Anyone ever seen something like this or have any ideas?

cal40john · 20-11-2017, 22:38

If you have a solid glass hull just epoxy them to the inside of the hull and shoot through the fiberglass. My Humminbird is supposed to have a 600 foot range. Shooting through the hull I max out at 200 feet. Plenty deep for my purposes.

Cheechako · 20-11-2017, 22:39

Power boats mount theirs on brackets on the stern usually. My fishfinder type shot thru the thick hull fine. (mounted inside with epoxy)

mr-canada · 20-11-2017, 22:41

My problem is either marine growth, or degraded paint. Thru the hull it reads a consistent zero feet. Both sounders are doing it so it's possible that the original one still works.

Sailmonkey · 21-11-2017, 05:23

Are you shooting through the hull on top of the keel?

Are you actually affixed to the hull, or just sloshing around in the bilge?

**skipmac** · 21-11-2017, 05:44

My depth sounder failed before a trip so I tried what you suggest, a sounder on a pole. Only wanted to use it when anchoring or negotiating in a shallow channel so would be a slow speeds. Attached the transducer to a boat hook and tried to hold it in the water while my partner steered but found it was impossible to hold even at a couple of knots.

I think you will find it will take a much stronger, heavier attachment on some kind of removable mount than you think.

Don't see what kind of boat you have. If a power boat the best option outside the hull is on the bottom edge of the transom. There are transducers made just for that.

mr-canada · 21-11-2017, 06:44

The old transponder was mounted aft of the keel and worked well until it went on the fritz, then stopped working altogether.

The new transducers were only in the bilge for testing purposes, and because I could place them in water temporarily to test without messing around with the expoxy for a permanent mount (no sense mounting something that doesnt work from the get go). It worked and saw bottom but after a while it didn't work anymore either (I just wanted to play with it at dock)

This is why I think it is either bottom paint or algae. Where it was originally docked thre was fresh water floating on salt, so "true" marine growth wasnt much of a problem, the growth was more like lake slime. Now its in pure seawater so haulouts are going to be needed.

The wooden or other contraption is merely so I can have a sounder until I get this done and can test it all out again. With the full fin keel it can be a bit hectic being in unknown places, and having depth makes it easier to drop crab traps in the right place the first time without fearing I'm too deep or too shallow.

TreblePlink · 21-11-2017, 07:17

Quote:

Originally Posted by mr-canada

The old transponder was mounted aft of the keel and worked well until it went on the fritz, then stopped working altogether.

The new transducers were only in the bilge [...] .

Are you really using some kind of sonar transponder? (a device that replies to an interrogation) or are we discussing transducers?

Sailmonkey · 21-11-2017, 07:19

It’s possible your marina is just too noisy to allow the sounder to operate.

We have a relatively low powered sounder, some weekends it looses the bottom in the slip.

Squanderbucks · 21-11-2017, 10:03

A transducer for a depth sounder can be mounted inside the hull as others have mentioned - some manufacturers make a special one for that purpose. They do loose some of their power in doing so but not totally. If your depth sounder is registering 0 I would be more suspicious of some other cabling or installation problem.
You need to put it over the side temporarily and see if the signal comes back to normal..If not there is an issue with something else in your installation.
Bottom paint will decrease the signal as well but not make it zero.

There are a lot of reasons to keep your hull clean and smooth that don't have anything to do with the depth sounder functioning but anything permanently mounted in the water will require periodic cleaning and painting with an appropriate paint.

To custom fabricate a bracket that you could lower the transducer into the water when wanted is possible but might put greater wear on the cable attachments with the additional flexing involved with the mount/dismounts.
Also how do you want to run the cable where it is not in the way or exposed to snagging.

Best solution is to either mount inside the hull as mentioned or install as a thru hull and occasionally dive over and clean it's surface.

KidSheeleen · 21-11-2017, 10:12

Here in Florida on our smaller boats we use PVC pipe, run cable through pipe, and attach the transducer to bottom of pipe with kit attachment or make our own out of any scrape materials. Seen guys even use duck tape or Gorilla type tape to secure. Works fine at slow, mid-range speeds for trolling ect. Hardware stores have all kinds of attachments to hold pipe onto the transom. Just a thought.

SouthernPride · 21-11-2017, 10:20

Mount to a pole as others have said.
Lower the anchor to a predetermined depth if not out of the water. Measure and Mark the ideal position of the anchor and where to mount the pole.

Good luck

CHRIS V CLEMENT · 21-11-2017, 10:26

You might want to consider an Airmar transducer, if there is one available for your sounder. It requires drilling a hole in the bottom, but placing it forward of the keel may give you more time to avert a grounding. Once the transducer is installed, if it gets fouled and gives erratic readings, simply unscrew it from inside the hull, insert the dummy fitting, clean the transducer, and re-install it.

billgewater · 21-11-2017, 14:58

I am also having sounder issues. The hull transducer is a single 200 khz unit that has been on my hull since 1978. Over the years I have gone through a number of display units but retained the original transducer.
Recently my Navman Depth 1300 unit suffered from screen burnout and failing digit display, and I am chasing up a suitable replacement as the company, like many, has gone by the way.
In retrospect, I believe that the correct solution is to build a rigid PVC (or other material) tube into the hull that comes well above the waterline internally, something of 60 to 100 mm (2.5 to 4 inches) diameter. A tube is slid down from the inside that has the transducer mounted on the end and is exposed to the water and oriented via a reference mark inside at the top of the larger tube. The internal tube has a standard PVC screw type top to seal it. A snug fitting at the water end or even a coarse screw in assembly may be needed. A blank ended fitting could be inserted for long periods of non use if required. Clearly the placement of such a tube needs careful thought. This can also be done using a large diameter valved skin fitting if needed. The internal tube could be rubber etc. provided it is reasonably straight.
What all this allows is the replacement and or maintenance of the transducer. from inside the boat.
Over the years transducers have changed from single frequency models to multiple frequency models and this approach allows the owner to make changes as needed. On larger vessels, the cost of a single lift out to replace a transducer is usually many multiples of the cost of a built in tube assembly.

It means you can use any transducer (except for the monsters used on deep sea trawlers etc.) and the concept can be applied to other sensors such as speed paddles and temperature sensors.

If I was in the market for a new boat, I would be looking for such a an arrangement. Hulls may last forever, but instruments really don't and usually either become obsolete get damaged or just die, so simple replacement seems like a good idea to me.