Humminbird 859 DI transducer issues

[Sideburns]

So I have a humminbird 859ci hd di unit ( http://www.humminbird.com/Products/859c ... Combo-KVD/" onclick="window.open(this.href);return false; ) hooked up to a minn kota w/ ipilot link. We do a lot of kokanee, trout and salmon trolling with the minn kota, and the two units work great together as a high tech auto pilot system.

We've been learning how to use this stuff for about a year now, but I think were getting a handle on it now, and learning the systems deficiencies. The detailed down imaging works great to identify "stuff" sometimes, but is not usually that useful for locating fish. The 2d sonar included in the transom mounted down imaging transducer isnt that great at locating fish either. Not sure why, but the 2d is 200/455khz frequency and doesn't have 83khz at all. The 200/455 is 25/16 degree cone angle and does not show good clean fish arches like most 200/83khz 20/60 degree units do. My transducer is the XTM 9 DI 25 T.

The only officially compatible transducer that adds the 200/83khz frequencies is a trolling motor mounted unit that fits snug to the motor bottom with a hose clamp. It is the XTM 9 WIDE DI 20 T.

I usually like to use the main motor to locate fish and cover a lot of water quickly until we find something that looks fishy. I cant imagine deploying and stowing the minn kota repeatedly to locate fish with 60 degree cone, and locating fish with the minn kota for power alone on a large lake that I haven't been to before doesn't make sense to me either.

So... I'm a bit of a tinkerer... what do you guys think about custom mounting a motor mounted transducer on the transom?
Any reason why I shouldn't? I was thinking of mounting a piece of 90 deg angle aluminum somewhere to the bottom of the transom, kinda like a fixed trim tab, cutting a hole the size of the transducer, and recessing the transducer somehow so that it would be flush with the boat bottom. (this is a 17ft lund alum boat btw). What do ya think?

Thanks for reading, and I look forward to hearing your expert opinions! (opinionated experts?)

[Larry3215]

There is no reason you cant mount that transducer on the transom with the right mount. You could make your own like you said or buy one from HB. It looks like it comes with both mounts when you buy it separately,

http://www.humminbird.com/Products/XNT-9-DI-T/" onclick="window.open(this.href);return false;

You might find you get better arches after its moved. The key to getting nice arches is understanding that the fish have to move into and then out of the cone or you wont get an arch. You also have to have a good enough return signal to get a strong arch. You need to have the boat moving at a reasonable speed (you will not get good arches while drifting) and then you need to adjust the scroll rate of the screen to more or less match the boats speed so the arches get drawn properly. When going slower, slow down the scroll rate. When going faster, speed up the scroll rate. IIRC, Hummingbird recommends setting the scroll rate to the same number as the speed in MPH, so for a speed of 5 mph, set the scroll rate to 5. A higher scroll rate will give wider arches, slower gives shorter arches - just the opposite of what boat speed does. The faster the boat is moving, the shorter the arches.

If your arches look squished, speed up the scroll rate.

You might want to took at this tutorial from Lowrance. Its one of the best introductions to how sonar works I have found. Part way down the page is a whole section on arches with a cool GIF showing how it works.

http://support.lowrance.com/system/self ... LE_ID=2967" onclick="window.open(this.href);return false;

Of course the other thing is your settings for Gain, contrast etc. Im not familiar with that model, so cant help much there, plus its been a long time since I messed with a Humminbird.

You can also get some good help with Humminbird here. Lots of very smart Humminbird guys hang out there including some reps and tech guys that actually work for them. There are separate sections for each model.

http://forums.sideimagingsoft.com/index ... tion=forum" onclick="window.open(this.href);return false;

There are also a lot of users posting on this board:

http://www.bbcboards.net/forumdisplay.php?f=133" onclick="window.open(this.href);return false;

Those are the two most active forums I know of for Humminbird that have good folks that can help.

[Larry3215]

Almost forgot - if that model lets you do screen captures, grab some and post them. They can help a lot with figuring out what might help.

[Sideburns]

This is the one. http://www.humminbird.com/assets/0/88/1 ... c89e8e.png" onclick="window.open(this.href);return false;

It does not come with a transom bracket.

[Larry3215]

Looks like you will have to make your own for that one but....

That transducer isnt designed for transom mounting or moving through the water at hi speeds, so it will likely only work at very slow speeds. There will be too much turbulence causing bubbles to flow over the bottom face at much above idle speeds. Its really intended to only be used on a trolling motor.

[Sideburns]

Thats kinda what I was getting at.. since I think its my only option for adding 83/200, do you think there is any hope of modifying or fabbing a mount to make it work properly?

Ive read that these have different shielding internally, but I think that should be ok?

hope my crappy paint picture come through ok...

[Larry3215]

That may work, but I have my doubts. The problem is the leading edge of the transducer. Its too sharp. The "skimmer" type transducers have a nice rounded front edge so the water can flow smoother around the transducer body when at higher speeds. That sharp front edge will create a lot of turbulence across the face of the transducer and the sonar signals cant penetrate that stuff very well at all.

I would suggest you call customer support to double check if they have any other transducers that might work. Or, even better, ask about it on that link I posted above. The HUmminbird website is know to have issues like that as far as not showing all the transducer compatibility options.

Shortly after I bought my old Humminbird, they came out with the HDSI up-graded transducers. The website said they were not compatible with my unit when they actually were. It might be worth some more research.

On the other hand, you wont loose anything by trying your solution and it might even work just fine. If you do try it, I would angle the rear of the transducer very slightly down so it sits just a hair lower than the leading edge.

[Sideburns]

Well its a 170.00 gamble for that one, and yes I have called humminbird about possible transducers. Its the only option for the wider cone angles.

Another thought on mounting... Maybe a fiberglass plate, instead of aluminum, level with the bottom of the hull, then epoxy the transducer to the top of the plate like a shoot through install? Are there other materials that are shoot through capable?

[TrackerPro16]

If you want to make something fiberglass I may be able to help. I am by SeaTac Airport between Seattle and Tacoma. I also have phenolic sheet.

[Larry3215]

You cant trust Humminbird as far as that being the only transducer option that will work. Like I said, they kept telling me - and everyone else - that the HDSI transducer was NOT compatible with my unit. Technically that was sort of true. The HDSI had features my unit could not use, but it still "worked" much better than the stock transducer. Humminbird will never officially tell you that though. You need to ask the question on that other forum I linked to above.

As far as shoot through, that transducer isnt designed for that, but it may still work. You will have to try it to see. It wont work as well as normal mounting for a couple of reasons, but it may be good enough to get the job done.

Its designed to sit with the bottom face level. If you mount it in a plate like you suggest it will be angled to one side. That will reduce depth range to some degree depending on your hull dead rise. Plus you will be seeing fish off to that side of the boat more than under the boat depending on the depth and angle of the hull.

The other thing is that any shoot through tansducer is less effective than one that is in direct contact with the water. Some of the sonar signal gets absorbed and dispersed (going both ways) in the fiberglass or what ever you shoot through. The losses get a lot worse if the transducer doesnt make a good clean contact with the mounting surface with absolutely no bubbles or air gaps. You will need to epoxy the transducer to the fiberglass plate being very careful not to introduce any bubbles and minimize the gaps. Once you d that, you will likely never get it off if it doesnt work out. Also, if there is a step or gap between the fiberglass plate and the hull, that will also cause turbulence and or air bubbles.

Bottom line - it may work just fine but you probably need to be a little anal about the fabrication and install details.

[Sideburns]

hmmm... I have a feeling that your right about the official vs actual transducer capability, as I have wired transducers from different units to other equipment in the past. And the setup menus of this unit allow me to select a plethora of transducer frequencies that HB says are not compatible.

If glass and epoxy, etc, cause interference at all, I definitely don't want to reduce the strength of returns any more than I have to. I'll "can" the shoot through idea.

I think I'll study the pin out schematics of a few transducers and see what I can come up with.... Almost seems like I could run a separate transducer for 200/83 without effecting the operation of my current transducer.... even though officially incompatible.

[Sideburns]

http://forums.sideimagingsoft.com/index ... pic=6080.0" onclick="window.open(this.href);return false;

Ive been researching this on and off for a year! I think this post answers my question. Just need a y cable and a dual beam 200/83 transducer!

Im waiting for registration approval from the web site, but then I'll verify with these guys. Thanks for your help!

[Larry3215]

That looks very promissing. The guys in that thread are all very sharp and know their stuff when it comes to Humminbird.