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PostPosted: Sun Jan 09, 2011 8:35 pm 
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All the water has turned hard here in Michigan. Time to do maintenance and tuneups. First on the list: my through-the-hull FF did not perform well last season. I wanted to revise the typical goop mount and try a wet-mounted through-the-hull system. Rather than just drop the transducer into a 4" PVC tube or hollow pool noodle gooped to the inner hull and filled with water, as others have done, I wondered about taking the opportunity to enhance the sensitivity of the transducer by mounting it upside down at the focal point of a parabolic reflector filled with water or acoustic jelly. Theoretically, this should enhance the acoustic pickup in the same manner as the "big ear" listening devices that are used by broadcasters on the NFL sidelines. Now I don't know anything about acoustical engineering, but remember from physics 101 that the diameter of a parabolic reflector should be no less than the longest wavelength to be captured. Knowing the speed of sound in water (1,482 m/s) and the frequency of the transducer (200 KHz) would predict an incredibly small reflector diameter (7.4 mm) I suppose it doesn't hurt to go bigger, but wonder if there is any advantage to this proposal at such high frequencies, especially when the 'ducer itself will probalby cast a significant acoustic shadow.

Anybody have experience with this sort of thing? Worth trying? It would take some doing to fabricate and mount a decent parabolic reflector, so I am looking for practical advice before getting started on a winter project like this.

Jim


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PostPosted: Mon Jan 31, 2011 2:49 pm 
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Joined: Sun Feb 11, 2007 4:17 am
Posts: 55
Location: Pensacola FL
Jim mi,

I went a different route. I mounted my t-ducer to the rudder so it gets better signal and water temp. I run the cable along the top of the gunwale to the head unit. I did this as an experiment and it worked so well I kept it.

Think about it. If interested, I can send you pics via email.


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PostPosted: Mon Jan 31, 2011 6:16 pm 
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I use a Mad Frog Liberator mount with a transducer arm.
Image

Image

Image


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PostPosted: Tue Feb 01, 2011 8:03 am 
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I have pretty much given up on the idea of a parabolic reflector because it would be a real challenge to fabricate and test - time probably better spent on other things. I did remove my transducer and found some bubbles in the marine goop so I am hoping my problems were related to that. Both Theo and Atavuss advocate having the transducer in the water, which is ideal. Several people have described using a simple suction-cup mount which you lean over and stick on the bottom as you are going out, and pull off on the way in. Sounds OK for summer, but I'm not too anxious to lean way over and get my sleeves wet to the shoulder in March or November on Lake Michigan!

Theo - I would be interested in seeing your photos - I PM'd you with my email address. I am concerned that the transducer would keep the rudder from fully retracting when coming into shallow water, or potentially affect your steering. Also, do you find that adjusting the rudder position (as is frequently needed with the pre-2011 steering mechanism) significantly affects the signal or picture you are seeing? When going through weeds, it is easy to clear the rudder by retracting it - does the transducer prevent clearing weeds in this manner?

Atavuss - I consdered the Mad Frog setup, but it seemed kind of awkward, with multiple joints and pivot points and that sort of thing. There is also the potential of getting a fish tangled in the thing when bringing him to the side of the PA for netting.


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PostPosted: Tue Feb 01, 2011 8:52 am 
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Location: Pensacola FL
Jim
I got your PM and will send photos in the next day or so. I need to find them or recreate them.

The transducer is positioned on the back of the rudder and the rudder can retract fully.

I don't fish much in grass but have never had a problem.

Turning the rudder does not affect the image at all.

I have seen the portable unit before and for people who fish multiple yaks and want to move it around it is a great option. For the type of fishing I do (Offshore) having that arm sticking out could cause problems with landing big fish.

Pictures will be sent soon.
Ted


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PostPosted: Tue Feb 01, 2011 7:51 pm 
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I have been using the Mad Frog set-up since spring 2010 with no problems to date. have not had any problems with fish getting tangled up in the transducer arm and I had at least 6 days were I had 40 to 60 rainbow trout each day. the only problem I had is the set up can be in the way if you need to paddle for whatever reason and I had weeds get stuck on the transducer arm, but this was an easy fix, just flip the arm up and clear the weeds. I thought for sure I would snap the arm off but it seems pretty tough.


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PostPosted: Wed Feb 02, 2011 7:08 am 
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Joined: Sun Feb 11, 2007 4:17 am
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Location: Pensacola FL
atavuss: I don't doubt that it works for you and looks like a real good setup.

Fishfinders (like everything else on the yak) are personal preference. I just share ideas and hope it helps.

I find I need the sides of the yak completely clear or the fish I catch will surely break off. Some of these gulf of mexico bad boys can really fight boatside and I don't take any chances.

Good luck.

Ted


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PostPosted: Mon Feb 07, 2011 10:55 pm 
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theo61 wrote:
I find I need the sides of the yak completely clear or the fish I catch will surely break off. Some of these gulf of mexico bad boys can really fight boatside and I don't take any chances.

Good luck.

Ted


Amen brother! Murphy's law of fishing in a kayak, if there is something anywhere near or around your yak for a fish to tangle the line on, it will! Nothing like having to untangle your leader from your bait bucket with a bull red on the other end....


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PostPosted: Thu Mar 17, 2011 1:31 pm 
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Location: Rogers, AR
theo...
I am struggling with my xds 50 ff, in that it never show's me much...I find I am lost though if it doesn't give me depth...
So anyway, I am looking for install advise, and just saw your post that you mounted the TD to the rudder?
Could you let me in on the specific's? The pic's would be great too.
Just an FYI, when I originally installed it with the Hobie kit, it didn't work well, and I thought I had maybe left bubbles in it, so "pried" it off the hull...carefully, and redid it. I just decided I was going to change it, so preparing to have to "pry" it off again, I took hold of it to see how tight it might be, and it came off in my hand..for some reason, the goop didn't hold and I had done it according to the instructions...actually more carefully, to make sure of no air bubbles. Can imagine why the goop would have let go. Just an FYI to all of you hull mount guys.


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