Understanding Furuno LS4100 in manual mode

[marzoe]

I'm kind of stuck on how best to get the most out of my new Furuno sounder.
I've been using it in auto mode for about 1 month and after having bought a 'How to better understand your sounder DVD, I now have more questions about the whole thing.
I went out the other day and was fishing in depths up to 75 ft and found it very difficult to set the unit up on manual so that I could make any sense of it at all.
I was using the fastest chart speed as the dvd said, what I thought was a high gain setting and the screen just went to mush.
I read on a previous thread that to increase the gain you go to the minus side on the plus/minus control. I didn't find that out until I got back and I'm not sure if that's correct
I'm also not sure about extra functions such as noise limit, clutter and deep gain in the menu?
Sounding for fish while running at up to 20 knots was totally out of the question.
Would really appreciate it if someone could set me straight on this.
Tim

[MulletMan]

Thats a big topic Mate! I don't have a FURUNO but the principle remains the same for all sounders.

The only two things you normally want to mess about with are the RANGE and GAIN.

GAIN is best set by using the up/down or +/- arrows to the minimum setting and then slowly bringing it up until you start to see small speckles on the screen (called "noise") - more is better in this regard even though the noise may appear distracting. Too little and you may completely cut out any fish returns. The deeper you go, the more GAIN you will need. To answer your Question re which way to wind it up or down, the "+" or "up arrow" will INCREASE the GAIN!

RANGE is worth playing with as powerful sets often have difficulty in AUTO in shallow waters. Remember that when in MANUAL RANGE, if you suddenly drop over the edge then the screen will go blank as your lower limit of the RANGE will be shallower than what you are actually in at the time. AUTO does fix this situation as it follows the ever changing bottom for you.

Salt water is rarely free from squillions of small particles ranging from sand, to seaweed, density/temperature effects, bait fish, jelly fish etc. etc. All of these can be seen by the sounder as "targets" and show up as "noise" on the screen. When you select CLUTTER you are basically telling the sounder to ignore all this crap and wipe it off the screen. Good idea except that it also reduces the normal GAIN setting in the process. With sounders and RADAR, you don't get something for nothing! Reduce the CLUTTER and you also reduce the GAIN indirectly. Just a compromise really. Kinda rare to need to use the CLUTTER control all the same.

NOISE LIMIT is yet another way to suppress what I said above but remember that again you will reduce the sensitivity of the unit and in doing so make any returns more difficult to see.

Don't agree that the fastest screen speed is the best but if the DVD says so then I guess you gotta do it! The set will have a default "normal" value so whatever it says is fine.

DEEP GAIN increases the GAIN automatically to counter for the deeper water and in fact is pretty much the same as you cranking it up manually.

Most decent Furunos have a Simulator mode in them that lets you play with them on the trailer with a couple of tinnies nearby! You usually enter this SIM mode during startup or just check the manual. Great way to get familar with the controls.

The best way to come to grips with sounders is to chuck the pick out somewhere in a reasonable depth of water and muck about with the various buttons - manual nearby!

As a rule of thumb, RANGE and GAIN are inexorably (love that word) linked together, you can't (shouldn't) change one without adjusting the other - Siamese Twins sort of concept.

The more you operate in manual the more proficient you will get! I've got a big old colour CRT Marinetec and have forgotten how to even use it in AUTO!!!

Having said all this though, Furunos are a top set and for most of your average days out, AUTO will do a pretty good job for you so it is not to be ignored!

[onerabbit]

Marzoe,

I have a new 582 which I still stuggle to understand, just no chance to practice with it since I bought it.
The Furuno rep gave me some good info, which I would be happy to copy & send to you, I have tried to scan it but it comes up very fuzzy when small enough to post here.
This info goes into detail of ALL of the functions & how to tune them correctly.
If you would like a copy of this info please PM me with an address that I can mail it to, or an email address & I can try to send them that way.

Muzz

[marzoe]

Thanks a lot guys.
Will give it a try next time I go out with renewed enthusiasm.
Tim

[onerabbit]

After stuffing around for about an hour, ( I'm still not real good with this thing yet) I think I have gotten it right.
Tim, I will also email these to you.

These are the info sheets given to me by the local Furuno rep.

[onerabbit]

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[onerabbit]

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Hope this helps, as I said before , I still dont know how to get the best from mine yet, but given some good weather, I'm sure it's only a matter of practice.

Muzz