In-hull Transducer Installation . Thinking inside the box...

[cbigma]

When I needed to replace my 6-element wide-array transducer for my 3-D depthsounder, I decided to try an in-hull wetbox method instead of direct epoxy or transom-mount.

I had previously mounted the transducer in-hull (shoot-through the glass) using epoxy, but this time wanted to be able to protect it better, and remove it for the cold winter layup. The transducer unit is so large that transom-mounting is less-than-ideal (IMHO).

Here is the link to my original installation Humminbird 946C 3-D Combo

The depthsounder has a separate speed and temperature probe which I mounted to the transom, so mounting the transducer inside the hull doesn’t eliminate the temperature input.

Airmar (noted manufacturer of many OEM transducers) posts some guidelines for transducer mounting inside the hull in a wet-box on their website.

http://www.airmartechnology.com/uploads ... 446-01.pdf

To find the perfect box to protect and fit my transducer I made a cardboard template of the transducer (which has the same shape as a steam-iron) and wandered through the isles of several local supermarkets looking for the perfect plastic food container to use as my “box”

I found a Rubbermaid unit with a perfect fit. Heavy walled construction and tight lid.

A quick trip through the bandsaw to remove the bottom. I used a shim to insure the bottom cut was true. I was careful to leave the cover on, to preserve the shape of the container during the cut.

And then took it for a dance on the beltsander to scarf up the edges and improve adhesion of the sealant.

I used GE Silicone II as the sealant with a bead along the inside and outside bottom edges. I let it cure for three days.

Dropped the transducer in the box, filled with seawater,

I put a divers weight (bag of lead shot) on top to hold it in place.

Cover on… Transducer has the same resolution as the epoxied-in unit. But now I can remove it much easier for winter layup, and it is protected inside its own container during the working season.

It will be interesting to see how this holds up throughout the season.

 

[Megabyte]

Very slick and well documented! 8)

 

[DaleH]

Wow, that'll now give you water temperature too now ... right :?: ?

 

[cbigma]

Dale,

The unit has a separate temp sensor/paddlewheel speed probe that mounts on the transom. Its a very small probe that I was able to attach to a mahogany block glued to the transom.

In my opinion the transducer was just way too big a target to consider mounting on the transom. I would be forever whacking it with flotsam, and it's a huge landing zone for marine growth.

It was a fun experiment, and afterall, that's why any of us do this stuff right? 8) 8) If it holds up well this season, I'll find a smaller container and maybe move it to the port side of the bilge.

I'm going to refill the container with filtered seawater and add a touch of copper sulfate to make sure I don't have any growth going on in there.

...John

 

[MaxOut]

Dale,

The unit has a separate temp sensor/paddlewheel speed probe that mounts on the transom. Its a very small probe that I was able to attach to a mahogany block glued to the transom.

In my opinion the transducer was just way too big a target to consider mounting on the transom. I would be forever whacking it with flotsam, and it's a huge landing zone for marine growth.

It was a fun experiment, and afterall, that's why any of us do this stuff right? 8) 8) If it holds up well this season, I'll find a smaller container and maybe move it to the port side of the bilge.

I'm going to refill the container with filtered seawater and add a touch of copper sulfate to make sure I don't have any growth going on in there.

...John

I would fill it with mineral oil. That is what was used in a through hull transducer I used years ago and worked well. It was sugested by the OEM manufacturer.

 

[cbigma]

I would fill it with mineral oil. That is what was used in a through hull transducer I used years ago and worked well. It was sugested by the OEM manufacturer.

Maxout,

Great suggestion! Mineral Oil is pretty inert stuff, right? Just to be sure it's OK with the Rubbermaid poly container/silicone adhesive combo, I should probably put some in a test container and let is sit for a few days.

I've also seen some literature recommending the use of non-toxic antifreeze. Neither of these two materials have the same viscosity as seawater, so I wonder if there is any effect on the quality of the signal? I guess if the OEMs say it's good to go, then I shouldn't be questioning it.

Probably more a question of which one would I rather be cleaning up in the bilge if I had a breach of the silicone adhesive.

 

[Megabyte]

Probably more a question of which one would I rather be cleaning up in the bilge if I had a breach of the silicone adhesive.

In that case, you might want to try antifreeze first.
Mineral oil could get messy if you experience a leak. :shock:

 

[bigeye2k]

How will the signal be since you are passsing thru the hull first.

 

[cbigma]

How will the signal be since you are passsing thru the hull first.

From what I have read most transducer manufacturers acknowledge that for solid fiberglass hulls less than 1" total thickness, it is acceptable to "shoot thru" the fiberglass without appreciable loss of signal quality. Parker hulls are solid fiberglass. I guess you might lose some signal energy through the fiberglass for very deepwater applications.

This type of mount won't work on boats having a "cored" hull with a layer of plywood, foam, or other compressible material which may contain air. Also, there can't be any air bubbles in the adhesive or liquid layer between the transducer and the floor of the bilge.

I have tested this unit and have seen the same quality of signal with the transducer inside the hull as over the side. Since this transducer is so large, I feel better with it tucked safely inside the hull.

 

[channel_surfer]

How do you like the 946C? I have the Matrix 47 3D with the same transducer. I can paint a good bottom picture but it seems to not pick up fish very well. For example we were out last weekend and boated about 22 little blues up to 22", so we were floating across lots of schools of blues, but I don't remember marking any fish.

Nice job on the thru hull setup. Mine is hanging off the back, so far so good.

 

[cbigma]

Steve...

I love the 946C, it was the right (closeout) price and it delivers fantastic bottom images as promised. 8)

Since my only focus is on diving, and the bottom images, I have never fooled with the fish-spotting capabilities of the unit. I know there are lots of adjustments and options for display and sensitivity of the fish-finder features, but I have never tweaked any of them. :roll:

As for spotting fish, I think of the big stripers (rockfish) as competition, not prey! :shock: ...... A mature striper can eat more lobster in a week than I will see in a year.

I gotta beleive the Matrix 47 3D unit you have probably has all same (and more) tweaky options for finding fish.

It's a couple of months into the season now, and I still have the same original dose of saltwater in the "box", working fine. If this beta version holds up well over the rest of the season, I'll find a slightly smaller container and install it permanently over the winter lay-up.

John