Can you use 2 seperate sounders?

[ChasB]

I've got a Seafarer 300 and am going to buy a second sounder to fit on the flybridge to also act as back-up to the Seafarer down below.

I'm currently looking at the Navman 3100 which is going cheap all over the place.

Q: Can I run both at the same time? or will they interfere with each other? /forums/images/graemlins/shocked.gif

 

[savageseadog]

They will cause havoc to each other. Suggest you use a display repeater, not sure if your model has the option.

 

[longjohnsilver]

Well I've used 2 at the same time for years with absolutely no problems.

 

[savageseadog]

was that 2 of the same model?

 

[ChasB]

Are they the same make? maybe they use different frequencies?

Maybe I should just try it and see. If there's a prob I could just never have both switched on at the same time. I do like the idea of a backup though.

Anyone know the length of cable that comes with a Navman 3100?

 

[Yachtjoy]

I have two sounders (both with shoot through transducers) and have no problem with having both running at the same time. When installing the second I checked the siting of the transducer for interference with the original set up. I was particularly happy about the set up when the first transducer failed!

 

[ChasB]

[ QUOTE ]
When installing the second I checked the siting of the transducer for interference with the original set up

[/ QUOTE ]

Were there any positions that produced a problem? Did you have to hunt around?

 

[fireball]

Is current depth that critical?

We managed for several weeks without a working depth gauge ... /forums/images/graemlins/blush.gif

 

[longjohnsilver]

No, one Furuno and the other was a Garmin

 

[MapisM]

Same here and both same brand (Furuno).
Actually, one of them is dual frequency and the other single, but I never had problems even using both with the same frequency.
Both bronze thru-hull transducers, and separated by a biggish keel, but I guess it shouldn't make a big difference.

 

[savageseadog]

There are circumstances where two sounders on the same frequency won't work.
An explanation:
A sounder will transmit a pulse between 1/3 to 1/2 second or so. Water transmits sound at about 1500 metres per second. The received pulse will be received between about a millisecond and about 200 milliseconds. The 2 sounders will randomly power up and as long as the transmit pulses aren't too close together relative to the depth they will "ignore each other" if the pulses end up closer and in greater depths they will confuse each other. This might happen one in every 10 times they are switched on and the boat was in say 20 metres or more. What the digital readout and processing might hide is skipped soundings. If the sounders are of same frequency and different makes there is a possibility of cyclic intereference as the pulse intervals converge and diverge.

 

[ChrisE]

Err, is this really a problem....

Well, you live and learn. I've spent years on fishing boats that two or even three fishfinders and have never heard of this problem.

Additionally, as one who has a Raymarine depth sounder and fish finder installed on his craft, with transducers about 1 foot apart I have never seen this problem in two years, most of it sailed in waters of over 20 metres. Neither have I seen it on my fishing boat which has two finders.

 

[ChasB]

Re: Err, is this really a problem....

Interesting. Are they designed to not interfere? Or is it just good luck that they don't? Maybe someone will chime in with the answer...

Of course if they did interfere, we would expect havoc in a busy shipping lane with everyone's signals being picked up by everyone else. The sea floor is hardly flat, and signals will hence bounce everywhere.

I suspect this was a problem addressed a long time ago.

 

[DaveS]

I've posted on this before, but I have 3 sounders: the Stowe unit that came with the boat, an Echopilot FLS and a fishfinder - Eagle I think. The Stowe and the FLS have through hull transducers about 0.3 m apart, the fishfinder's is glued on inside, about 2 m away.

The fishfinder operates correctly with either or both of the other units on.

The FLS operates correctly with either or both of the other units on.

The Stowe operates correctly with the fishfinder on, but promptly stops working when the FLS is switched on.

So my answer is a definite "maybe"! /forums/images/graemlins/wink.gif

 

[savageseadog]

Re: Err, is this really a problem....

I think someone should contact a manufacturer. My hypothesis such as it is is only based on some rough working. I imagine that there would be filtering based on the fact that the depth won't vary hugely from sounding to sounding.
The potential is certainly there for spurious soundings.

 

[CliveG]

There is a manufacturing fault with the Navman 3100 series of instruments manufactured over the last few years.
The joint between the circuit board and the LCD Display fails if there is any damp around and sectors of the display disappear.

Navman in New Zealand have stopped production of the range and are redesigning the head units.

I know this as I have a full set of 3100 units that are driving me mad.

Navman in UK are happy to replace them but can't until the redesigned head units arrive from NZ.
Not before late this year I am told. /forums/images/graemlins/mad.gif
A non reading depth gauge is not a good shipmate on the east coast.

 

[gjgm]

just to say, if you didnt mean a fishfinder, then get one of those. Cheap and versatile(and dont worry about the fish part of it)

 

[ChasB]

Wow! And I was just about to order one from mailspeedmarine...

Got any recommendations for a cheap weatherproof unit that is panel mounted? There's a selection <u>here</u>

 

[Yachtjoy]

Started off with two positions fairly well apart. The boat is a 27ft bilge keeler and the original transducer was forward of and pretty much in line with the port hand keel. Place the second transducer about halfway along the boat just to starboard of the centre line (so pointing down between the keels) and had no problem

 

[savageseadog]

Further info Patent

There are probably a number of strategies including this idea for reducing spurious readings. The most important point is do you actually know how many soundings are being rejected before you're made aware of it.