Humminbird 981 c side transducer

[Francisco Xavier]

Hello subscribers,
I have aquired a Humminbird Matrix 37 unit with its side 455 KHz transducer, just now I am trying to assemble a Dan two chanels ducer with 4 single 455 KHz transducers each side. I have the information needed about wiring and unit operation to improve that (I hope) gently yielded by Humminbird!
I have read and followed the information about the new excelent 981 c unit. By the info and pictures the sonar beam resolution must be very good (very few degrees or less then one). How they acheive that using a short (in length=large fan horizontal beam shape) and hull fixed ducer (not stabilized)? I think the 981 c unit uses a 455 KHz side ducer too to perform side scan.
I would like to share information with anybody trying the same.

Greetings
Francisco Xavier
AZORES

[ChrisPreece]

Humminbird 981

Hello Franscisco,
Interesting to see so many people building their own sidescans! I'm not...but was, like yourself, very impressed with the Humminbird unit. Quite how they achieve that definition with such a small transducer at 455kHz I don't know either.

However, what I did think was that the pictures on the website were taken in 'ideal' conditions......Many of the sub-surface features suggest fresh water (like the brilliant picture of the swimming pool) and therefore calm surface conditions.....they were also taken over relatively short range and hence the high definition.

I'm not sure what the sea conditions are like in the Azores but here in the UK they are usually quite rough....certainly choppy most of the time and therefore not ideal. Using a hull-mounted transducer over medium to long ranges would certainly result in lower definition and distortion. There is one website picture which suggests this and that is honest enough of Humminbird.

I was interested enough in the 981 though, to consider extending and water-proofing the transducer cable in an attempt to tow the transducer in its own 'fish'. (I did this with an Interphase scanning transducer before I realised the screen definition was so poor I didn't need to bother). This should, together with some clever towing arrangements, de-couple boat motion from the transducer. Humminbird were helpful, which was more than I was expecting. They suggested a low-loss, low-capacitance cable (Belden 9730) to use and wished me well.

Best of luck with your own creation!

Chris Preece
Devon
England

[Charles Oak Island, NC]

Humminbird 981 c side transducer

here is a post you might finding interesting form Treasure net.
http://www.treasurenet.com/f/index.p...c,13640.0.html

[DownUnder]

Just been gathering info on building a SS, and came across this site. Good to see others having a go at home grown. I have a small machine shop at home to fabricate one but my electronic and Electrical knowledge is not quite up to sratch. Hope someone could pass on they're knowledge.
Have read about the Humminbird 987 and 981, they sound great. Could anyone let me know if there would be problems with connecting 4 of they're side transducers in a tow fish.and if any other electronics would be needed to balance them.
Sorry if this sounds a bit dum, if the transducers work like they say on the hummin website, is it possible to have a row of them just mounted in the bottom of a tow fish.
Once finished Will be quite willing to share my project with others if anyone is interested.

Many thanks
Martyn
Down Under

[Unregistered]

I am an owner of a nice new 987C Si sidescan and I love it
for the money it has worked like I expected.
I have a small boat a 16ft Zodak with a 50 hp 4cycle Honda
cirrantly I have my transducer mounted to the transom on the left side of my boat this all but blinds any scanning to the right.
I have made a transducer mount that has a transom clamp at the top and a transducer mount at the bottom with enough length to reach below the outboard, since scanning is done in the 3-6mph range I don't see this as a problem.
when searching you would tend to scan to both sides now you have about 8inches of screen if your like me and keep the data fields on.
so your displaying say 150 feet both left and right in that 8inches which os ok if your searching for a fairly large object like a wreak.
Now that you have found a new wreak you would shift to a one side only screen and make another pass not your using that 8 inch display to show only 150 feet so the objects would be twice there size than before.
the 455Khz seems to go out and down at about a 45deg angle so for 100 foot depth your beem won't hit the bottom till it is 100 feet to the side of the boat, to each side so in effect your missing 200 feet of bottom under the boat.
the 262Khz beem will scan directly under the boat and outward I have not tested this much but i will.
I plan to scan targets with the 455 and the 262 beems to see how they compare.
as for stability the very short range of the system helps reduce the need for a towed array.
here is a link to my web site that has a few scans to give you an idea of real life performance.
http://webpages.charter.net/bhamptonkc7mrp/

brad

[Francisco Xavier]

Hi, brad

I suspect that the 987C 455 KHz transducer can be mounted on a such trowling fish, like I did before with a scanning transducer of SeaScan from Interfase and now, with the Matrix 35.
The Interfase ducer was provided with about 15 m of wiring that was enough for the poupose.
I do not know how long is the Humminbird 987C transducer cable.
My Matrix 35 is provided with 9 m long cable. I acquired another 9 m extension and glued them with epoxi to protect connector from water.
Would be nice from Humminbird to provide a true side scan transducer array, improving the horizontal beam angle and as result, the picture quality, and some meters extension cable, for the 987C series. Doing that they would incrase the 987C unit selling.

Francisco Xavier

[hertsog]

Hello,

can you give some advice, how to put humminbird transtucer to towfish. do you have some pictures of this? Is the cable input to transtucer sufficent waretproof on bigger depths like 30m? Or it need to isolate?
how to make prolongation of cable?
what is best way to join towfish rope and cable