Depth transducer location?

[Spike38]

I'm planning to install a Garmin plotter/sounder combination, am deliberating on transducer location and wondering what the arguments are for and against transom mount vs. thru-hull aside from the thru-hull presumably being more effectively located. There's also the "shoot through the hull" possibility but not recommended in cored hulls as I understand it (though I've seen one C-Dory with transducer inside the hull). This last would be ideal - no holes - if it worked, but evidently accuracy becomes questionable. Any and all opinions on transducer location/installation will be appreciated. Also, I note that one member regrets not using a "mounting block" for his transom mount transducer. How would this be used? Should I use this method if I decide on a transom location? Thanks.

[marvin4239]

Theres a thread somewhere on here about mounting transducer to a block rather than directly to your hull. Typically the blocks are made of starboard or cutting board material and attached to the hull with two screws. Mounting holes being overdrilled and epoxy filled. The advantage to this is replacing the transducer from time to time or moving them around or adding a second you don't wind up with mulitple holes in your transom. In my case I added a water speed wheel and may soon change my transducer. I noticed the other day that Gander mountain is selling a piece of material just for this. It's about 9 inches long and maybe three inches wide and 3/4 inch thick and comes with holes in either end plus mounting screws. The starboard I had on hand was only 1/2 thick and I laminated two pieces of it together using 5200 and wasn't happy with the result so I mounted directly to the transom. Advantage to the block is you can adjust, replace or add transducer to the mounting block.

[Jack in Alaska]

When mounting my Hummingbird Matrix 37 transducer years ago I made an adjustable mount that can be controlled/adjusted from inside the boat while on the water. It works very well and also allows the whole thing to slide up out of harms way when beaching the boat if it should set down on a rock etc..
I have the transducer and the temp/speed sensor side by side on it.
Just recently I acquired a Garmin plotter/sonar and it has a separate transducer and want to keep both depth sounders operational. I am contemplating removing the speed/temp sensor and mounting the new transducer in it's place. As there is not enough room I may try "gluing" the speed/temp sensor directly to the hull with 5200.
I made it out of 1/4" Lexan and cut the pieces on a table saw very carefully. Lexan is unbreakable and extremely durable unlike acrylic.
Cut one piece 25" long and 5" wide. mounting piece
Cut 2 pieces 17" long and 3/4" wide. spacer pieces
Cut 2 pieces 17" long and 1" wide. capture strips

The 1" piece goes on top of the 3/4" piece with the excess towards the center "capturing" the wide piece. I drilled through the two pieces top and bottom and into the transom and screwed (using 1 1/4" No.10 stainless screws) them to the boat sealing all with 5200. Put a stainless washer behind the double strips to allow space for the wide piece to go up/down. Keep the double strips approx. 3" from the boat bottom as this will allow the full 5" of the mounting piece to accept sensors and still move up and down.
I drilled 1/8" holes as close together as possible in a vert. line above the top of the transom in the 5" piece so it can be adjusted in small increments and stopped with a small screw in the appropriate hole. I put a handle on top to be able to pull/push it up/down.
It has been on my boat for over 20 yrs. and shows no signs of any deterioration. It works really slick.
Hopefully this is not too confusing as it is really a simple thing.

[Sea Wolf]

Jack-

Sounds like quite an inventive solution!

I found the following photo in your album. Would it be possible to get a close up for all to see?



Joe.

[breausaw]

If I had to do it over I’d seriously look at trying an in-hull transducer mounted in the aft bilge, I believe this section of the hull is solid fiberglass.

[matt_unique]

You'll have to check with C-Dory about the C-25, but the Tomcat is built with a solid square area toward the stern that has no coring for shoot thru hull transducers. I installed one of these and it works great! I would personally avoid drilling like The Plague. There are several good solutions using starboard and such but they also involve drilling.

Good luck.

[Jack in Alaska]

Before I install a 2nd transducer right next to my present one I need to ask............

will they interfere with one another in operation causing both to give bad data????

Thanks

[Doryman]

[Sea Wolf]

Warren's second display unit on the same basic unit is an easy logical solution, providing you don't want two diffeent types of units.

Hee's an edited set of posts from another recent thread:



Posted: Sun Mar 09, 2008 2:37 pm

I've been told that running multiple transducers won't work due to signal interference between the units. Is this not the case? I have thought about adding a second 'ducer, but was concerned that it wouldn't work.
_________________
-Rod



flrockytop wrote:


My cd19 had a Lowrance on it when I bought it. I added a Navman. Both are 50/200 machines. The Lowrance transducer is mounted on the stern I first tried shooting the Navman transducer through the hull. This did not work so well. When running both on 200, the signal from the Lowrance would sometimes overpower the Navman so much that it would not pick up at all. If I turned on the Navman first then, usually, they would both work. Even then I would pickup some sawtooth interference lines in the Navman display. I could run one on 50 the other on 200 and they would work. I moved the Navman transducer to the stern on the other side of the motor (about 2 feet apart). At this location they both will work.

I have used two at the same time on other boats with similar results.

Roger




thataway wrote:

Sometimes they will work and sometimes they won't. When widely spaced in shoal water, they will work OK. If the transducers/sounders are significantly different frequency, they will work.

If they are both the same frequency and close together, they will probably not work.

Unfortunately almost all of the fathometers use 200 mhz transducers currently. There used to be 215, 192, 200 etc...There is a Garmin at 235 (I belive)--but it will cost $500 with the head and transducer.

Bob

Full text HERE

Joe:

[Spike38]

Thanks for the good ideas! Matt and Doryman, how did you discover the solid uncored hull section was there - and its location? I haven't received the 25 manual yet but am not expecting that kind of detail even if such a hull area exists in the boat.

[breausaw]

Something I saw the other day while waiting to go through the Whittier tunnel was the transducer mounted on a trim tab end; was going to talk with the guy but the light went green. I’ve been holding off on mounting the paddle wheel that came with my fishfinder but now thinking of attaching it to one of my tabs.
The boat I saw was a high-end off-shore aluminum class vessel so this retrofit must have work ok for the guy.

[matt_unique]

[starcrafttom]

I would be worried about putting a transducer on the trim tab as it would give a false depth if it is tilted. It has to be pointed straight down to get a correct depth. in a hundred feet of water a twenty degree angle on you trim tab could add 20 ft or more to your depth (just guessing so put the slide rule away joe) Also at speed you will have a lot of air and turbulence coming under the tab from the boat so you will not get a good signal if you get one at all. only at slow speed would you get a reading. Just what I have seen on other boats. I have seen a lot of transducers on trim tabs and it reminds me that "just because you can does not mean you should"

[Sawdust]

Tom,

You are probably right on the 20 degrees - but I ran with the ducer on one of the trim tabs for years. Really liked it and may do it again. Because, using about 200 KC, the transmitted signal is pretty broad I didn't notice much error. Got good arches (dunno why)... and I could easily adjust it to see my balls (Don, no!!)... best drop this !!!

Duster

[Wandering Sagebrush]

I have seen a transducer that was mounted on a sailboat genoa track and car. The owner lifted the transducer out of the water when he was moored. It kept the transducer clean and out of harms way.

Steve