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Author Topic:   Fishfinder transducer location?
Fellatthelast posted 07-20-2005 01:45 PM ET (US)   Profile for Fellatthelast  
I am about to install a Raymarine RS400X Fishfinder onto my Dauntless 160 and I have the option of through hull or transom mounting transducers. Short of stating the bleeding obvious, I would have thought that the best option would be transom mounted? Does anyone have any experience with mounting a transom mounted transducer and cable routing on a Dauntless. I am particularly interested in the location of the transducer as from previous posts, port side is favoured (prop rotation?) but cablie routing is a bit vague.

If anyone can help and particularly with a picture or two, I would be very grateful. Hate to start drilling in the wrong place and make a swiss cheese of my transom!



bsmotril posted 07-20-2005 02:59 PM ET (US)     Profile for bsmotril  Send Email to bsmotril     
if you look at the Ray marine documentation, you will find that Starbord side is favored with a right handed propellor. You want the blades moving down, away from the transducer face, and at least 3 inches away from the swing area of the prop. The documentation goes into detail, and has drawings showing how to measure correctly. Keep it away from strakes, or other hull obtrusions that would aerate the water in front of the transducer. Route the cable up over the transom, and folow the same path the wire harness for the motor uses to the console area. The plastic nut you put onto the transducer cable to hold it onto the back of the fishfinder is delicate, and easily stripped. If the transducer connection on the back of the fishfinder is loose with the fishfinder running, it will damage the fishfinder, transducer, or both. I just went through all this two weeks ago and found out the hard way. BillS
Fellatthelast posted 07-20-2005 05:30 PM ET (US)     Profile for Fellatthelast    
Wow! I never knew there was so much to it. I will certainly look into it further.

Thanks mate.


Marlin posted 07-21-2005 11:51 AM ET (US)     Profile for Marlin  Send Email to Marlin     
As far as I know, there is nowhere to mount a through-hull transducer on the Dauntless, so I think you only have one choice.

Transducer mounting has been a fairly common topic here, and there's a good article in the reference section at .

On my 160 Dauntless, I mounted the Garmin transducer on the starboard side just inboard of the first strake. See , though I apologize that the photo isn't all that great. In this location, the fishfinder reads the bottom well up to about 35 MPH (55 k/h) and 100 feet (30 m) or so. Above that speed (or in deeper water) I still get a good depth reading, but I lose the bottom image. Below that speed, it works well in increasingly deeper water. The sonar works poorly when the motor is in reverse, presumably because the prop is drawing exhaust gas bubbles back toward the transom. This position is also well clear of my trailer bunks, as you can see in the photo.

Many people recommend using a small block of StarBoard or similary material, and mounting that permanently to the transom, then mounting the transducer to the block. This would allow you to reposition the transducer without making more holes in the transom. A good idea, but one that I heard about after I did my installation. In any event, remember to thoroughly seal any transom holes with 3M 4200 or similar below-the-waterline sealant.

I used a plastic cable tie to hold the cable against the motor mount, then one of those screw-down cable ties on the top of the transom. The cable then enters the hull through the boot along with the engine controls, then dives down inside the stern locker and enters the rigging tunnel that leads to the center console.

There should already be a line pulled through the rigging tunnel that you can use to draw through the transducer cable. Just remember to pull a second line through also, so that you have a line in there next time you need to pull another cable.

Unfortunately, the Garmin FishFinder 80 uses a 1" (25mm) or larger plug, so I had to cut a rather large hole in the top of the console. I covered it with a nice piece of mahoghany with a gasket below to minimize water entry into the console. My handheld GPS wiring uses the same hole. See .

Good luck!


florida1098 posted 07-22-2005 12:51 PM ET (US)     Profile for florida1098  Send Email to florida1098     
Just wondering, has anyone tried the portable transducer brackets sold at bass pro shops for about $35. I was walking around there this weekend using their A/C, and thought they seemed like a good idea.
bspencer posted 07-22-2005 02:33 PM ET (US)     Profile for bspencer  Send Email to bspencer     
In my recent pre-whaler days I used a portable suction cup transducer on a Zodiac. It was a pain in the butt and would always slip off. I switched to a transom bracket that was adjustable and clamped to the transom, that worked great. But on my 160 it would not work and would not be any better than the standard installation.
lurkynot posted 07-26-2005 07:24 PM ET (US)     Profile for lurkynot  Send Email to lurkynot     
I have 5 ducers mounted on my 01' 18 Dauntles and they never miss a beat. In my opinion I would not run the ducer cables anywhere near the engine harness wires - in my case the starboard side of the bilge area - I had major interference especially on plane at higher rpms. I switched the first two cables over to the port side and blamo! 99% readings in water as shallow as 3 feet wide open. Hope this helps. Also I would be glad to forward a digital shot of the transom when I use my boat this weekend. And most importantly when hard mounting those ducer brackets make sure you soft bed those fastener holes in the transom with quality marine sealer!
bsmotril posted 07-27-2005 08:49 AM ET (US)     Profile for bsmotril  Send Email to bsmotril     
Now you got my curiosity up. What do you do with the boat that requires 5 transducers? How do you keep them from interfering with each other? Do you work for NUMA? BillS
lurkynot posted 07-30-2005 09:36 AM ET (US)     Profile for lurkynot  Send Email to lurkynot     
I am adding 2 more as soon as the hardware arrives. I run two Large Bottom Line graphs at the helm in the mid to starboard side. An Icom ship to shore ocuupies the port side of the console. One of the graphs has true side finder technology. It incorporates a transducer for the port side and starboard. These ducers have two faces on each, one angled about 5 degrees from horizontal the other at an angle to the first at about 30 degrees. These do not interfere with the main since the system was developed for this setup. The fourth is the one from the Smart Craft setup - a speed sensor - and the fifth is a standard one for the second graph. On the topic of interference it is more dependent on the depth of water. Because I do all my boating locally in the Great Lake area the waters are relatively shallow. In this shallower water there is virtually no interference and the 2 graphs are used to verify false markings and functionality not available on both. If I am trolling for salmon in waters that allow the cones to cross there is some interference, however the both graphs will still read the depth correctly for the most part. Most of that interference is in the water column in the form of false markings related to fish. Hence in this situation I will use one graph for GPS/downrigger control and auto-pilot and the other for sonar applications. I will also switch from one graph to the other frequently while marking fish and structure to confirm the data. Since the graphs are different models from the same manufacturer they exhibit different characteristics and functions as well. I love sonar technology. If I could mount a different graph from a different manufacturer every other weekend I would if it were not for a limited budget of time and money. As for the other 2 ducers I will be mounting, one is actually already on board at the bottom of my electric trolling motor at the bow - just waiting on the cable from Minn Kota. The other is a conventional one with a tighter cone angle which will show better definition and can be toggled back and forth from the other one at the helm.

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