mounting transducer on Jack Plate (manual)

[motocross269]

I just got through reading how alot of bass pros are going back to mounting their transducers on the transom to avoid signal loss. (an article in Bassmaster Magazine talked about how Zell Rowland did this). Guys in my club are doing the same thing. (versus shoot-thru)
On the Bass cat website they are mounting transducers on the jack plate.  What is your take on this???  Anglers are mounting them on the Jack Plate to keep from drilling holes in the Fiberglass. I think alot of this has came up with the HB side imaging units. 
Here is the link to the Bass cat site.  There are some pretty good pictures and comments about the setup they are running.  As I expected they are having problems with the high speed sonar because the puck is out of the water.
http://p205.ezboard.com/fbasscatownersfrm1.showMessage?topicID=9201.topic

Thanks for any help,
Brian

[Slipkey]

Motocross,

Interesting stuff! I think it would depend alot on your setup.  The Detweiller plate on the BassCats in those pictures is wide enough to mount a transducer.  The Skeeter manual jackplate that comes standard also has a wide triangular spot on the lower corner as well - as I remember from the ZX-202 I owned a few years back.  The Bob's Machine hydraulic plate like Ranger rigs at the factory isn't wide enough to mount aft side of the frame.  You would have to find on the mounting plate itself which could be tricky depending on the motor.   One concern with the side-imaging units would be that, when trimmed down, the motor would be in the 'view' of the transducer side-imaging beams. 

It's clearly a low speed only solution - very low speed.  That location would have alot of noise and turbulence in the water at anything above 2000 RPM's - not to mention it's completely out of the water when you're running.  It seems like when I'm looking for structure on big water, I spend a good amount of time at about 2500 RPM's with the bow up in the air. You would need a second transducer with a switch or another unit for high-speed running.

I have a glassed-in trandsducer and tried the externally mounted transducer for increased sensitivity.  I've given up for the time being after I broke two of them off in rough water.  When it's nasty and you need to keep your bow up, that area gets alot of vertical stress as you come down the back side of a wave.  If you loosen the breakaway up too much it's worthless as coming down the first big wave kicks it up and out of the way.

I didn't, personally, notice too much difference in signal from the glassed in one.  It was just a matter of playing with my sensitivity/noise reduction to get it right.   

With the side-imaging units, though, there might be a bigger difference because of the angles involved.    Humminbird doesn't specify other than that the manuals only include instructions for transom and trolling motor mounting although you would lose the temp sensor if you tried a thru-hull application.  At the very least you'd have to use alot of resin to mount it in the hull since the side imaging transducers require more surface area in the water.  Maybe BryanP can jump in with more info.

[BryanP]

Regarding the side imaging transducers, you cannot epoxy them in hull.  The reason is because the beams are shot straight out of the sides of the ducer.  The SI transducers need to be mounted externally with a non-obstructed view to the sides.

There are quite a few ways to mount that side imaging transducer externally, one of them being on the jackplate.  Skeeter does this at the factory, and I believe Basscat does as well.  The guys rigging this way either accept the fact that the ducer will be out of the water while running on plane, or epoxy a second transducer (standard DualBeam) in hull and run both ducers to a switch.  While running on plane and for high speed traditional sonar readings, flip the switch to the in hull mounted ducer. While idling around, switch to the SI ducer to get both SI and downlooking readings.  SI only works at slower (~10 mph) speeds so this setup works great.  I have a similar setup with my SI unit on my Ranger, only I have my SI ducer mounted above my drainplug so it's completely out of the water while on plane.  Another great way to rig on a Ranger is to mount a plastic Thru Hull (not the same as epoxying in hull/shoot thru hull) ducer under the setback.  I have pictures of various rigging methods that I'll post if I can figure out how!  Also, for 2008, Humminbird is coming out with a Y-cable that will eliminate the need for a transducer switch when rigging an in hull DualBeam/external SI transducer combination.

The only problem with mounting the SI ducer on the jackplate is that you might have to slightly trim up your engine to ensure the ducer has no beam obstruction to the sides, which is realy no big deal because SI works best at idle speed anyway.

For a traditional down-looking sonar only ducer, rigging the transducer on the jackplate isn't the best option IMO, since you're limited to very slow speed use at best.