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oft 05-23-2006 07:23 PM

Seafarer 3 Depth Sounder
Does anyone know the frequency of the through hull transducer that would have come with a 1976/77 Seafarer 3? I'm hoping to replace this depth sounder with a fish finder (e.g., Furuno LS 4100 {50/200kHz}) without having to replace the transducer (located on the stbd. side of the hull about a foot to the side, and towards the front, of the iron keel). The Seafarer works well enough but seems a little hard to read. Any comments on this idea? I've checked around but cannot seem to find this transducer frequency anywhere. Thank you.

sailingdog 05-23-2006 08:32 PM

You'll probably need to replace the transducer, as the typical depth sounder will not have the right frequencies for a fish finder. Fish finders and depth sounders are related, but fish finders require much higher resolution than do depth finders, and generally use several frequencies to give better resolution at various depths. I doubt that the depth sounder that you have uses a transducer that the fishfinder will work with.

Are the depthsounder and fishfinder even the same brand?

sailandoar 05-23-2006 09:51 PM

(1) Seems unlikely to me (wild guess on my part) that a 1970's era depth finder would be multi frequency.
(2) Get an O-scope and crack the case on the old sounder and hook to the leads that feed the transducer and look at freq/period of the wave form.
(3) What makes you think the old depth sounder is multi-freq and more than that is a 50/200kHz?
(4) Call tech support of the new depth sounder company and ask them what they think/know.

oft 05-23-2006 11:09 PM

Sorry for the lack of clarity in my post. The Furuno LS 4100 that I hope to replace the old unit with is 50/200kHz. One of the experienced techs that I talked to thinks the old Seafarer 3 transducer is 200kHz, but is not sure. The salesman says that if it is indeed 200kHz then I should be able to use the Furuno.

sailandoar 05-24-2006 08:54 PM

200kHz is a common Freq however you should avoid taking the technical advise of sales folks unless you have some specific reason to think they they are qualified to speak on such matters. Ask the tech if he/she thinks the dual freq Furuno will work on the single freq old transducer.

Does not sound like a good thing to me. Hard to imagine that the dual freq Furuno will be happy with a single freq transducer, or that the plug and the number of conductors will even matchup. Further, the power output of the Furuno may exceed the design power of the 30 year old transducer. Think you need to bite the bullet and swap transducers. I have to do that on my next haul out.
Oh Well!

Will warrenty cover the Furuno if the control head gets smoked by running on the old transducer?

Before the discussion goes much further you need to check the pinout / #conductors on the old vs the new unit, that may decide the question and end the discussion.

Good Luck

sailingdog 05-24-2006 09:49 PM

I've found that many salespeople will blow smoke at you, just to get you to buy... but most are not qualified to give you any technical advice.

Valiente 01-18-2007 05:10 PM

I believe it's a 150 Khz transducer and they are still available in Europe. Google "Seafarer 3 Echo Sounder".

lilledanserboatandbreakfa 03-16-2008 11:13 PM

Seafarer 3 Echo sounder
I have the manual for the Seafarer 3 Echo sounder. It is for sure 150HZ. I see this post was from quite a while ago, but I would like to find the instrument for the Seafarer 3 echo sounder without the transducer. Did you end up switching out your fathometer, and is the instrument still around?


Valiente 03-17-2008 12:36 AM

I have one PLUS a fishfinder. Frankly, I've never bothered to locate the Seafarer's must be directly under the nav station in the old boat.

So I've kept both operational. I find with certain bottoms, the fishfinder isn't quite happy to give a consistent depth, whereas the Seafarer will give, when the gain knob is tweaked, as accurate a measurement in chains or fathoms or drams of sheepfat as it is capable of giving. I enjoy its cathode-lit's easily the most ancient working bit of electrical gear aboard.

julianc 04-15-2008 09:16 AM

I have one, would like to add a repeater output - does the manual have a circuit diagram?

Anyone know the impedance of the transducer in case I want to re-use with a homebrew circuit?


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