Modified Shoot Thru Hull Installation on 2005 2120 SC

[Luv2fish]

I did a lot of reading on this forum and others on using a trolling motor/transom mount transducer for a shoot thru hull. Some recommended making a "well" and mounting the transducer in some sort of non evaporating liquid. Others recommeded using marine expoy to mount it directly to the transom. I chose a variation of both:

Step 1: I mounted a plastic electric mounting plate purchased from Home Depot in the bilge area where I wanted to put the transducer. I mounted it with 3M 4200 (in case I don't like the project). I gave it 24 hours to set.


Step 2: I used marine epoxy to mount the transducer in the well. I premixed the epoxy. I mounted the transducer in the well and placed a heavy object on the transducer to hold it in place until it sets (about 1 hour). Make sure that you wiggle the transducer to work out any air bubbles.

This is a second transducer for me (I have a transom mount already) and will be used as a backup for depth only. I have two complete systems (I had a new one from a recent boat I traded in). I will be out next week and will update the thread with any "noticable" depreciation of the signal.

 

[Ranger Tim]

The last boat I had, a 17 ft. Key Largo (a wet, heavy, but solid fiberglass boat), had a "shoot-through" transducer that I installed in the bilge. I had great success with this setup and I will probably do the same on my 2120 in the near future. I noticed you used the "skimmer" transducer in your install - this is the same one I had used, except I simply slathered epoxy on the bottom and glued it to the hull. Before doing this I filled the bilge with some water (while underway) and moved it around to find the best spot for optimum signal. I found that it made no difference as to location and that the only difference between in hull and outside the hull (but in the water, of course) was a slight difference in the amount of detail/signal strength. This was to be expected. I estimated the signal loss at around 10-15 percent.

Performance of the shoot through was significantly better than the results I currently have with a transom mount, especially at planing speeds. The only time I ever lost signal was when the hull cleared the water jumping waves. The "hockey puck" style transducers that are sold as shoot-through models appear to be a good fit for the location you have chosen except for the angle of the beam. I know there are models that have an adjustable wedge-type base that would solve this problem.

I will probably keep my transom mount and utilize a helm mounted switch to choose which one to energize. Then I would really have the best of both worlds!

 

[Megabyte]

Nice job. Let us know how it performs when you sea trial her.

 

[Luv2fish]

I was very happy with the results. I had some noise in both systems until I realized they were both sending/receiving on the 200 khz. I put one on 50 and one on 200 and everything cleared up. I did not notice any difference in the systems performance otherwise. The depth was within inches of showing the same thing.

The only real difference was the shoot thru hull never lost signal when running at full speed. This is a GREAT advantage.

 

[Ranger Tim]

I think there is a lot of urban/boat myth about the extent of signal degradation with shoot-through installs. There is only one way to tell and that's to try it! Thanks for the info.

 

[MaxOut]

I have called Air mar on this exact issue and there engineers will tell you a min. of 10-15% loss on any shoot though. Most of the times its more. This was determined in controlled testing environment. You will lose depth and target definition compared to an equal through hull. Like FishFactory said you don't miss what you can't see..Or do you??? :wink:

 

[Luv2fish]

I understand about losing my temp (my second transducer is a transom mount so I do have temp). As far as missing definition, if I lose 10-15% of my fish and only get 85% that still makes me a very happy fisherman.

Seriously, I'll take some pics of my next trip out when I spot some fish. I noted both bait fish and larger fish on both sensors (in about 25 - 50 feet of water) and both looked similar. The Lorwrance (the shoot thru hull) head unit is a better unit so it actually showed the fish better. I'm sure it has to do with the resolution of the display and not the signal of the transducer.

 

[trout21]

Is there anyway you can communicate what 10 to 15 percent means.

I am going to be targeting fish that hold in the water column in less than 100 feet of water. Will I be able to see bait and fish well is the bottom line.

I currently have a Furuno FCV600L and an airmar P79 shoot through. I find my current set up frustrating. The auto setting produces too much noise. I can get what I think is a pretty good image if I modify the gain and the range but since I often fish water that is on a drop that goes from 25' to 150' and since the 600L jumps in range too much, I have to constantly tweak it.

Am I doing something wrong?

 

[samj]

An airmar thru-hull was one of the easiest installation projects performed to our boat. No excuse not to get the performance from your equipment. Get your whole saw, a six pack and get busy.

 

[Luv2fish]

Trout 21,
I never saw any difference between the two units. I fish in water that is 100 feet or less and fish that I saw on one I also saw on the other. I can't give you a comparison, sorry. Others with an electrical engineering degree might be able to but under the conditions that I fish, no difference between the two units as far as definition and finding fish.

The major difference is that the shoot thru hull works while up on plane running WOT. The transom mount does not work.

Hope this helps. I had been told that I would lose 15% (and probably do) but I just don't see it.