Association Forum - thru-hull transducer placement

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Catalina/Capri 25/250 Sailor's Forums

Catalina 25 Specific Forum

thru-hull transducer placement

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bradminda
1st Mate

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USA
45 Posts

Initially Posted - 02/21/2008 : 21:00:50

I have a catalina 25 fixed keel and wish to install a depth guage. Any ideas on the placement of a thru-hull transducer.

Edited by - on

OLarryR
Master Marine Consultant

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USA
3467 Posts

Response Posted - 02/21/2008 : 21:42:03

This subject has been discussed a number of times...so you should be able to do a search on the topic and come up w/some good info.

Basically, there is no reason to use a thru-hull for the transducer as long as your hull bottom is solid and there are no voids. Depthfinder and fishfinder mfrs will provide details of epoxying the transducer on the inside of the hull, however, many have found that this too is an overkill and does not allow repositioning the transducer if there is lack of a good signal. What I and some others have used is a glob of the wax from a toilet bowl wax ring. Basically, slap it down near where the original thru-hull transducer is/was mounted. Then take the new transducer (has to be one that indicates it has a flat surface capable of being mounted inside the hull) and smoosh it into the wax to ensure no bubbles underneath the transducer. Then overlap the edges with the wax, hook it up to the depthfinder and see if it is working. You could hang the transducer off the transom first using stick and temporarily tie it to the ladder. Then see how the depthfinder reads. Then mount it inside and see if you get similar readings. My fishfinder instructions indicated the only negative effect mounting the transducer inside the hull vs thru-hull was that instead of being capable of measuring down to 1000 ft it may only read down to 400 ft. That is generally a non-problem for most sailboaters. I have details of my fishfinder installation on my website - Here are some photos:

Edited by - on

sweetcraft
Admiral

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USA
816 Posts

Response Posted - 02/21/2008 : 22:07:28

The wax is a neat idea. Never thought of it when I used the method of a cardboard tube cut to fit on the hull to keep the tube vertical and set and held the depth sounder with duct tape level in a big mound of clear silicone glue/sealant in the tube. Secured the tube to the hull with duct tape until the glue set. This must have been before indoor plumbing.

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OLarryR
Master Marine Consultant

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USA
3467 Posts

Response Posted - 02/22/2008 : 05:25:40

I could see where a glob of silicone glue would work - anyway your installation works...so it's another fine method !

Much better when you can use a method that avoids a potential leak path !

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Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 02/22/2008 : 07:35:12

I used slow cure epoxy, (recommended because it give bubbles time to work out), it was painless.

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Joel37027
Deckhand

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USA
21 Posts

Response Posted - 02/22/2008 : 14:16:24

Larry, I really like the way you have the depth sounder mounted to swing over to the companion way. What make/model sounder did you use for this? Did the mount come with it or was that from a different source?

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OLarryR
Master Marine Consultant

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USA
3467 Posts

Response Posted - 02/22/2008 : 16:55:14

Joe,

First of all, I have to thank Frank for giving me the idea of going with a fishfinder. My mounting is a bit different but this website is great for getting helpful advice.

My fishfinder is a Humminbird Matrix 17. It may be discontinued by now and price-wise fishfinders may currently offer more for same cost as I paid 2+ years ago. In any case, I found a link for it:

http://www.cabelas.com/information/Boating/HumminbirdMatrix17FishingSystem0022977.html

The swing arm is made by a company called RAM. West Marine use to sell (and may still sell) some RAM models but they mostly have swing arms under the WM brand name. I searched the web and found websites with more RAM Models to choose from and then purchased it on-line. These swing arms are fairly pricey...but I went for it once I saw the one that would work well for my application. The RAM Models have a nice look to them. They have a bit of shape to them, not just flat metal welded together. The swing arm knobs effectively increase friction in the joint and lock it in place. Believe this is the website I bought the RAM Swing Arm....they have about 100 different RAM Models for fishfinders, GPSs, cellphones, etc.

http://www.gpszone.com/cgi-bin/shopper.cgi?preadd=action&key=RMRP109V

Some in our Association have made their own swing arms but I went the commercial route and then spent my time crafting the Starboard circle for covering up the 4 1/2" depthfinder hole and for designing/shaping the Starboard mounting support inside the cabin. I used a Craftsman scroll saw to cut the shapes out of the Starboard and then used a router bit to bevel the edges.

Edited by - OLarryR on 02/22/2008 17:00:35

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 02/22/2008 : 17:50:34

Larry, I love toys and the RAM arms continue to bubble up, I think your comment about the quality is the reason. SO, do I want to rethink my system and go with a ram arm set up? I use the bases screwed into the cockpit bulkhead for my Fishfinder and GPS. My fishfinder has a GPS as you can see in the photo, but I like the Garmin 76CS GPS for its magnetic compass function. I store them in a binocular holder as you can see.

Edited by - Frank Hopper on 02/22/2008 17:55:20

ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 02/22/2008 : 19:08:07

" could see where a glob of silicone glue would work -"

As an experiment I tried that on my powerboat... the compound must absorb sound energy as the transducer would not see the bottom. Put it back in a glob of toilet wax... worked again.

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OLarryR
Master Marine Consultant

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USA
3467 Posts

Response Posted - 02/23/2008 : 08:25:02

Frank,

I rememebr back when I was mulling over the options as to what to replace my depthfinder with and your comments at the time helped me finalize how I would go about the replacement. Believe you had a Humminbird Matrix (..Model 12) and also the GPS sensor and you mounted it as your above photo depicts storing the fishfinder in the cabin ...then you attached it to the mount in what was my depthfinder location.

At the time I guess I had a number of things on my mind that I was concerned with and one was that my wife normally would sit with her back on the bulkhead where the knotmeter and depthfinder were located. If I went the fishfinder route and mounted it where my depthfinder hole was, then she could still sit in that position but it would be more limited. That and I like the idea that if I am going to use something everytime I go out sailing, then I would want to minimize connecting and unconnecting wires - rather have the wiring permanently connected....though the downside is you see the wiring when using the swing arm.

So many have come up with their own variations of improving on the original depthfinder. I choose to view it as options to fit everyone's personality/ease of use rather than one way that is definitely better than another. Each method has it's attributes.

By the way.....I have still been procrastinating on getting the GPS option to the Humminbird. A friend gave me a handheld Magellan Marine GPS when his new boat came with a GPS built-in. So...I have been mulling over what benefit the GPS would have over the handheld GPS that has the chart on it of my area. I was also wondering if having the Humminbird GPS and/or the Magellan GPS would be in anyway suitable for use in conjunction with the new VHF radios w/DSC. After the VHF discussion of weeks ago...I have a new VHF radio potential on a backburner for now...just storing some facts for when the time comes that it moves to the frontburner.

Edited by - on

Frank Hopper
Past Commodore

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Pitcairn Island
6776 Posts

Response Posted - 02/23/2008 : 11:21:27

My model Matrix has display options optimized for fishing. As such the unit does not offer a good combination of depth, speed, and compass heading. I looked long and hard a traditional compasses and as we all know the angle of our bulkhead narrows our options. I ended up buying the Garmin 76CS because it has a fluxgate compass that does not depend on motion to function. I just got it at the end of the season but I have it installed the same way as I had the old Humminbird and Garmin 76 on the '82. It really does clutter up the bulkhead.

Edited by - on

OLarryR
Master Marine Consultant

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USA
3467 Posts

Response Posted - 02/23/2008 : 14:48:32

Well... I am impressed ! That is some cluster.... of instruments.

Edited by - on

bigelowp
Master Marine Consultant

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USA
1779 Posts

Response Posted - 02/24/2008 : 15:36:19

I love the idea of mounting a transducer INSIDE the hull. Would I have to use a fishfinder type sounder or could this work with a permanently mounted system from the likes of Raymarine, etc? I need to replace my original electronics and was leaning toward the Raymarine ST40 series for depth (would match the wind system I purchased from a forum member)so if a special transducer is needed would like to start the research.

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OLarryR
Master Marine Consultant

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USA
3467 Posts

Response Posted - 02/24/2008 : 19:21:52

I think it will work with any ultrasonic transducer as long as the bottom has a decent size footprint with using just the wax to hold it. Some Mfrs have the manuals for their products on-line and that may give you some inkling regarding the transducer. Some advertise the transducer can be used for transon and in-hull mounting. That was the case with my Humminbird Matrix 17. I ddi not need the transom config mount but the flat footprint allows it to just sit smooshed in the wax.

Edited by - on

quilombo
Captain

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USA
301 Posts

Response Posted - 03/06/2008 : 21:46:50

I agree with the wax thing, that works fine,, you dont have to cut a hole through your hull with todays technology

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Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 03/06/2008 : 23:16:28

I have ST 60 Bidata wind and depth/speed/log now, but on my Clipper I used a Humminbird
Manufacturers recommend not using silicone because it absorbs energy (elasticity), but that doesn't mean it can't work. Wax is more rigid. Anyway, on my Clipper I made a clay dam slightly larger than the transducer and filled it polyester resin. I tightly stretched Saran wrap around the transducer and pressed it in. That gave me a removable transducer.

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