Sonar transducer question...

[theartfuldodger]

The reason for asking of the use for the device your installing is I have installed a forward looking sonar from echo pilot out of England and the device had to be installed in a particular way and in a particular spot, as it looks forward and down the view is 500 meters forward and ranges down to 10 meters and a depth of 120 meters. This device is very cool and interesting, I use it to find growlers, containers from ships which have fallen off, fish, whales, and what ever might be in the water in front of me.

[sailingdog]

The problem with the lazarette solution, is that the transducer will be pretty far aft, and as such not so useful for fish finding, since you will have passed over the fish before the transducer "sees" them. Probably not too big an issue with running stripers, but for other fish, the boat can often spook them.

[T34C]

If your current depth/fish finder is a Hummin bird you might be able to un-hook and plug it into a new one. I would contact Johnson Outdoors (the manufacture of Hummin bird products) with the current model #. They should be able to tell you if it is compatible with a newer model. The shoot thru the hull option works very well. That is what I have used on my last 3 boats with no problems. I would not use epoxy to secure it in place. I have heard the wax idea before, but no personal experience. I use polysulfite caulk to stick it in place. The polysulfite doesn't flex and distort the signal like silicone yet transducer can be removed in the future if needed.

If your outboard is in a well in the transom, you might be able to use a transducer that is designed to mount on the bottom of the motor shaft. Many fishermen use a transducer mounted on the bottom of their trolling motor. You maybe able to do the same, but mounting inside hull would be a lot easier.

[sailingdog]

Polysulfide sealants will often attack plastics...so you're actually better off using silicone, which is generally harmless to plastics.

[BarryL]

Originally Posted by martsmth

Hey Barry, care to comment on the particular Lowrance units you decided to go with, and a few details on installation of the transducer?

Hello,

My first Lowrance was the M68 C Smap. This is an inexpensive (sub $400) combo chartplotter / Sonar unit. It has a 3.5" high res color screen. It comes with built in high definition charts with all marine Navaids built in.

I installed that unit in my 1986 Newport 28. The transducer was a 'transom' style that I epoxied to the hull near the engine (that was a long as the cable allowed). I first tested the 'ducer in that location by placing it in a bag of water. It worked fine, so I epoxied it there with epoxy provided in the kit.

The M68 C Smap worked fine. I sold the boat last year, and the unit went with the boat. The new owner likes the system.

I bought a different boat in 2006 and needed a new chartplotter. This boat had a working depthfinder, but I like the ability to 'see' the bottom, so I wanted to get another chartplotter / SONAR unit. This time I wanted one with a bigger screen (5"), expandibility, and NMEA intput / output (to connect to a DCS VHF radio).

After doing my research, I decided on a Lowrance 520 series. I was pricing them, when I found a LMS337 CDF (predecessor to the 520) on closeout as West Marine for $500. I bought it (and a detailed Navioncs chart) and installed it.

I mounted the 'ducer for this one forward of the keel in the head, close to the centerline. I wasn't sure if this was the right place to mount it, so I used toilet bowl wax to hold it to the hull. A year later, the wax is still working fine, so I'm going to leave it alone.

Let me know if anyone else wants more info on those units.

Barry

[T34C]

Originally Posted by sailingdog

Polysulfide sealants will often attack plastics...so you're actually better off using silicone, which is generally harmless to plastics.

Except for the minor issue that silicone flexes and can lead to transducer distortion. I have used polysulfite for this application on my last 3 boats over the past 8 years with no problem, including removing a couple of the units and remounting them into other boats.