Second Sounder Option

[R_C]

My trawler has a single through hull transducer (200kHz I believe) connected to the main sounder at the lower helm, which is connected to a remote unit on the flybridge. The remote flybridge unit has become very dim and almost unreadable. I don't want another through hull so what are good options for a sounder on the flybridge?

Are there new units that will work with the existing transducer that also have a remote like my current setup (circa 1988 Sitex)? I doubt this but can two sounders somehow share a transducer concurrently? If I have to install another transducer inside the hull for a new sounder, how far must it be from the existing transducer? Any suggestions would be appreciated.

- Rick

[Mule]

I feel your pain brother, I had 3 old transducers on my trawler, one leaking only one being used. She is on the hard and the holes including speedo wheel have been glassed over and a new Garmon transducer installed.

Weak spots in a hull always have the potential to let seawater into a perfectly good boat, though necessary, make me nervous so the fewer the better. Gotta have some but still again, the fewer the better.

Da Mule..Hobart

[bewitched]

Sounds like you just want to repeat depth information at the fly bridge?

Check the unit at the lower helm. If it has NMEA out facility, all you need is an NMEA repeater at the flybridge

[R_C]

Unfortunately, the lower helm unit does not appear to have NMEA output. There is no mention in the owner's manual and the only connector on the back of the unit is for it's own remote unit.

- Rick

[rustypirate]

While I understand the worry over holes in the bottom of the boat, I have allways liked redundancy in my instrument systems. If you are simply repeating data between displays, then a failure in your main depth sounder will negate any reading on the secondary display. A totally secondary system will still function.

This is just a personal preference of mine, due in part to my desire to travel to remote locations where a single system failure can be disasterous.

[R_C]

I also like the redundancy but I'd rather not add another through hull. There are plenty of discussions in these forums about adding a transducer inside the hull, which is the direction I am leaning. But I haven't been able to find any information about how far apart separate transducers should be installed and whether there are interference issues to consider.

- Rick

[Hollen]

Don’t poke any more holes in your hull. If you are worried about interference, buy a cheap depth sounder with a transom mount (WM has 2 for less than $100). Make a dammed area (not damned area) 3’ away from the other transducer on the bottom of your hull out of duct tape, fill with water, place the new transducer in the lake and watch your new depth sounder give accurate readings of depth (my new Hummingbird works to 400’). Check for interference with your working one. If that works, dry out the dammed area making sure the transducer is relatively level, fill the dammed area with casting resin. This has worked every time I have tried it, on my boat and many others.

[drinky]

I have 2 sounders on my yacht. One is a simple depth sounder which is used most of the time. Then I purchesed a system complete with fish finder sounder. I tested the new transducer in every possible place to mount it and they both read each others echo and didn't work like supposed to. Max distance apart was about 15ft. Finished up with 2 sounders with separate on/off switches so I can use whichever one I need at the time. Good luck.

[rustypirate]

I agree that mounting transducers on the inside of the hull works a trick with GRP hulls, but it just don't do a thing with my steel hull....

go figure

My point was rather the redundant systems in general rather than relying on just a repeater display.

[Fuss]

Just something to think about.
Normally there is a hole for the log and one for the depth.
It is now possible to buy a nmea tri-ducer from Airmar, that means that the log and depth and water temp are all in the one unit.
You could then remove your log and insert the triducer so no more holes are needed. The NMEA output can then be read by an nmea compatible display (navman 3100 is one I think)

[rustypirate]

Just a piece of information to pass along for thise who don't know, nearly all speed and depth transducers in the marine market are manufactured by Airmar.

They make about 3 different models of speed transducers and 5 or 6 different models of depth transducers with different frequency ranges.

The major differences between OEM brands in the same frequency range is simply the connector plug at the end of the wire.

It is possible in an emergency situation to remove the plug from the transducer for brand "A" and wire it to an instrument for brand "B".

Check out some of the schematics for the transducers on the Airmar website and you will see what I am talking about.

[Chief Engineer]

I have my transducer mounted inside the hull.

I don't need to know when I am going off the Continent Shelf

I'm not looking for fish

I'm looking for how far my keel is from the bottom in 10 feet of water.

[roger.waite]

Originally Posted by Hollen

Don’t poke any more holes in your hull. If you are worried about interference, buy a cheap depth sounder with a transom mount (WM has 2 for less than $100). Make a dammed area (not damned area) 3’ away from the other transducer on the bottom of your hull out of duct tape, fill with water, place the new transducer in the lake and watch your new depth sounder give accurate readings of depth (my new Hummingbird works to 400’). Check for interference with your working one. If that works, dry out the dammed area making sure the transducer is relatively level, fill the dammed area with casting resin. This has worked every time I have tried it, on my boat and many others.

Agree with this on GRP boats ... I am getting soundings over 200 metres from my Hummingbird bedded in epoxy on a thin hull. As for steel boats, I thought they just carved a new channel and kept on sailing.

[rustypirate]

Yeah, but I hate to muck up the paint job.....