Transducer for C-80 on a 22 Cruiser

C-Dawg

Greetings,

I'm on the cusp of being the newest proud owner of a CD 22C (she's being prepped for delivery). I plan on installing a C-80 but not sure which model/type transducer would be best. I do plan to do a lot of fishing in the salt with it.

Suggestions?

Thanks.

Rick
C-Dawg.

Sneaks · Posted: Sun Sep 02, 2007 5:45 pm Post subject:

Well, I use the standard (P65) transom mounted transducer since I don't really want to install a thru hull in the C-22. It works quite well although I would prefer a wider angle in the 200khz crystal. There's a photo of the Jenny B's stern that shows where it's mounted; just to the left of the starboard trim tab.

YMMV

Don

flapbreaker · Posted: Mon Sep 03, 2007 12:12 am Post subject:

I also use the p65 transducer and feel that it's a decent unit. The only problem I have is picking up bottom at about the 700 foot depth and beyond. don't really know what fix there is for that though.

C-Dawg · Posted: Mon Sep 03, 2007 7:43 pm Post subject:

Thanks.

I saw in an archived thread a discussion of mounting the transom transducer when the vessel's got trim tabs. What I took away was mounting just inboard of the trim tab and about 1/4" below bottom. Is that right?

flapbreaker · Posted: Mon Sep 03, 2007 10:47 pm Post subject:

C-Dawg · Posted: Tue Sep 04, 2007 5:24 pm Post subject:

Thanks, that's a great photo explaining a lot.

This being my first 'glass boat I'm a little leary about drilling through the hull below the waterline, so what is the preferred method of attaching the transducer? My other boats were aluminum so I simply used SS screws. But from discussions on other topics I get the impression that I should drill through and use SS bolts and nuts. Is this correct, and should I use some sort of sealant?

Thanks.

thataway · Posted: Tue Sep 04, 2007 6:20 pm Post subject:

I would advise against drilling thru the transom at this level. We have found that the best way to put a transom transducer on is to secure a block of King Starboard on the transom, and then use self tapping screws into the King Starboard. This way you can move the transducer and have no risk of making a piece of swiss cheese of the transom and having water intrustion. The King Starboard is secured by first drilling an over sized hole in the transom, and filling this with an epoxy compound--Marine Tex works well. Then a small pilot hole is drilled in the transom for screws to hold the King Starboard in place--the side of the Starboard which will be next to the hull should be scored so it will allow some adhereance of 5200 (which does not adhere well to plastics). I find that making angled cuts with a Dremmel cutting disc, and shallow holes drilled at an angle work fine and then you get good adherence.

I'll take a photo later this afternoon and post it how we have the Starboard on the CD 25 and TC 255. Often one finds that he has to re-position the transducer or put in a new transducer which screw pattern does not match the old one. With the starboard one can do this with no fear of damage to the transom. The CD 25 had rot around a transducer which was installed as the one in the photo above, even with some sealant.

thataway · Posted: Tue Sep 04, 2007 9:41 pm Post subject:

We have two transducers mounted here. One is a dual frequency Hummingbird, the other is a single fequency 200 khz digital Uniden.

I can run both at the same time, but there is interference if they are on the same frequency. I generally use the Uniden as a back up, and just run the Hummingbird fish finder. You could put bottom paint on the Starboard if you wished. I probably would let some growth occure first, and let that be a "primer" when sanded down for the bottom paint.

C-Dawg · Posted: Wed Sep 05, 2007 2:17 pm Post subject:

Thanks for the pic. I understand the concept and it makes great sense, but I got lost here:

Captains Cat · Posted: Wed Sep 05, 2007 2:35 pm Post subject:

The oversized hole is to protect the core (plywood/Balsa) and waterproof it. The pilot hole is drilled into the filler (Marine Tex) and used to hold the starboard on. No holes are drilled from the inside.

At least that's the way it looks to me!

thataway · Posted: Wed Sep 05, 2007 5:14 pm Post subject:

In this perticular case the entire area, and a little more, is solid glass. The transom had about 10" x 4" thru about 3/4" plywood of rot just from improperly installed transducer in a 4 year old boat, used only two seasons! There are three # 12 screws, plus 5200 holding this piece of Starboard in place. The other two screws can be seen if you look carefully in the lower corners--the left side between the transducer bracket and the right side to the outside and under the transducer bracket.

In the Tom Cat, I drilled 1/2" holes, then routed out about 1/4" of core all of the way around the three holes I drilled. This area of core was replaced with a mixture of epoxy, Cabosil and microlight fairing compound. The new screw hole was drilled in the center of this, and the block put in place with 5200.

The above is a work shop mock up of how one would drill such a hole and fill--but in this case I went from both sides--as one would do with a bolt hole or thru hull. For the screw into the transom, only drill from one side.

The second photo shows a hole drilled from one side of a deck and the under cutting--this is then filled with the compound, or Marine Tex.

chas231 · Posted: Mon Jul 13, 2009 11:54 am Post subject: Transducer mount

I'm getting ready to install a second GPS unit and have a few questions about the transducer mounting. I understand that mounting two transducers beside each other can cause interference, so I'm considering mounting the second transducer on the opposite (port) side of the transom. Should that be far enough away to eliminate interference issues? I'm going to mount the unit on a piece of plastic as suggested in this thread, and will fill and seal the screw holes as recommended. Do the screws holding the cable clips require the same treatment?
Appreciate the good advice!

Captains Cat · Posted: Mon Jul 13, 2009 12:27 pm Post subject:

Chuck, I have two transducers on Captain's Cat. One shoots through the hull on the small uncored portion of the starboard sponson near the bilge pump. The other one is a standard external transducer mounted on the port sponson, probably 7' or so away. The Starboard one feeds the Garmin 545S and it's built in depth sounder, the Port one feeds the E-80 and the DMS300 Sounder from Raymarine. I have noticed no interference, I usually have them set on "auto" and they invariably both go to 200KHz. The external one works much better than the internal one but both are OK.

If the screws holding the cable go into the core, then they need to be "potted" as well.

Charlie

Jazzmanic · Posted: Mon Jul 13, 2009 12:57 pm Post subject:

I just installed a 2nd transducer (Lowrance) on the same mounting board as the 1st (Garmin). They are mounted right next to each other and I haven't had any kind of interference problems, even while using the same frequency. I also followed Dr. Bob's transducer mount plate advice, overdrilling and filling and everything seems to have worked out well. I took pictures but haven't posted them yet. Maybe I'll try to post them tonight. As for the cable clips, where I screwed them, they're well above the water line and I didn't go through the same process for those. I used 5200 to seal those screws. I think I only used no more than 2 screws anyway.

Hopefully others will chime in but I haven't had any problems with mounting the transducers on the same mounting board and I'm really happy with the Lowrance unit I installed, the fish finder is much better.

chas231 · Posted: Mon Jul 13, 2009 2:19 pm Post subject:

Thanks guys. Now I'm thinking of installing both transducers a a piece of plastic about 4" x 12" on the same side, just beside the starboard trim tab. I'll separate them about 10" apart and see how it works. If they interfere with one another I can mount one on the opposite side.