Transducer installation

I'm looking at installing a Garmin depth transducer in my Mainship 350. I understand the hull is solid fiberglass, correct? I was thinking of installing it midship on stb side near the raw water intake, it looks good and flat in that area. Any thoughts, advice or comments? Thank you.

Plus where can I get wiper arms and blades? The previous owner took them off the boat.

If you have a solid hull you can mount it in the inside. No holes to drill.

I did that (attached to the inside of the solid fiberglass portion of my hull) with an extra transducer I placed inside the hull several years ago and it has worked out fine.

Glen

Greetings,
Mr. D-c. As mentioned your transducer CAN be mounted inside the hull although the literature cautions some loss of "sensitivity" when shooting through the hull.

I mounted 2 transducers inside our hull (upper and lower stations). The maximum adjustment provided by the Airmax/Garmin mounting ring only allowed for 22 degrees of adjustment. I needed about 35 degree offset/angle given the locations I had chosen. I simply cut a piece of PVC pipe (3" I think) at a 20 degree angle and stuck the mounting ring on that. Filled the cavity with mineral oil and I STILL run aground!

Before permanent gluing, if you can stick the mounting ring temporarily onto the inside of the hull with butyl tape, align and fill the cavity with water you should get an accurate reading of your depth. This procedure is to make sure you don't have any voids (air) in your hull lay up.

Years ago I read about doing this by softening up, getting any air bubbles out of a big wad of "toilet ring wax", then stick it on a clean fairly flat spot the inside of the hull, squish the transducer down into it so the face is horizontal, no air bubbles or gaps. I tried it with a Humminbird digital readout unit for a spare on the upper helm. It has worked fine the last 5 years
To locate a spot fill a ziplock bag with water lay it on the hull hold the transducer puck on top of it and see when you get a good readout.

The fluid of choice is poly glycol the pink stuff.

Getting it level required a gauge

The trick is to find a spot where it won't get bumped kicked or knocked around.

Garmin likely has a choice of transducers for the unit you want to install. The cheapest one tends to be the transom mount style, so buy that one, and put it inside a piece of PVC or ABS (cheaper) pipe cut to the angle of the spot you can mount in. I used 10w oil when I put my last one in, about 10 yrs ago and it still works great. Any loss of sensitivity only prevents getting a reliable reading over 600 ft. If I was navigating without GPS, I might want to know where I am on the 1500 ft depth contour, but, really, I can do without that.

Dave-col said:

I'm looking at installing a Garmin depth transducer in my Mainship 350. I understand the hull is solid fiberglass, correct? I was thinking of installing it midship on stb side near the raw water intake, it looks good and flat in that area. Any thoughts, advice or comments? Thank you.

Click to expand...

Dave...
I added a new Airmar transducer to my '08 34HT last season.
The previous in-hull Xducer was digital depth only and I was looking for bottom (anchoring / fish finder) as well sea temp.
I went with the thru-hull type w/ a fairing block.
After searching for a good location I decided on a center compartment where the mid & emergency bilge pumps are located. about mid-ship, near/ small off-set from center line, easy access to the helm for connection to my Raymarine display. Also out of the normal traffic moving around my bilge.

If you go that way and want more info I can provide details of figuring deadrise angle and cutting fairing block as well as installation tips.
Others are absolutely correct re: inhull installations - my original one worked fairly well for what it was designed for but I wanted the additional features. Original installation was somewhat in the traffic bilge flow and was damaged I believe by moving some batteries around. Location should be carefully chosen and tested as others have suggested if you go the in-hull approach.

There are many apps that allow you use your smart phone as a angle finding device.

Download a free one and place your phone where you want to mount the ducer and it will tell you the angle you need to dial into the mount for a straight down shot.

I used the pink water system anti freeze from Walmart, it's about a buck a gallon. I used fish-tank RTV silicone for the glue.

http://themarineinstallersrant.blogspot.com/2014/08/p79-transducer-install-and-repair.html

We have 2 Garmin transducers, one is conventionally fixed thru hull. The other, designed as a transom mount, sits inside the hull and shoots through 1" of f/g(Garmin said I could run 2 sounders off 1 transducer but they erred/lied). The latter takes a little longer to "find" the bottom initially but otherwise works fine. I set it in silicone in an angled piece of plastic drain tube, using a small level.

Avoid putting it too close to any thru-hulls or penetrations in the hull as the turbulence from those can mess with with ducer, and give you false readings.

koliver said:

Garmin likely has a choice of transducers for the unit you want to install. .

Click to expand...

For internal mounting they have both 6 pin and 8 pin. Not expensive either.

Amazon.com: Garmin Plastic In-hull Mount Transducer with Depth (Adjustable, 8-Pin) - Airmar P79 010-10327-20: GPS & Navigation

Greetings,
Mr. H. That is the exact unit I mentioned in post #4 (I mis-described it as Airmax). I used one of these:



to calculate the offset angle.

Thank you for the information on transducers RT, do you know what range is an acceptable angle to read properly?

Dave-col said:

Thank you for the information on transducers RT, do you know what range is an acceptable angle to read properly?

Click to expand...

That is great information that i was not aware of. Thanks for posting the question and thanks for all the replies.
If I need a transducer in the future I won't be held back for fear of cutting thru the hull.

Greetings,
Mr. Dc. I don't quite understand your question (post #14). The bottom face of the transducer must be parallel with the surface of the water for optimum range and sensitivity. That parallelism is adjustable via the mounting mechanism in the link posted by Mr. H (post#12). I used the level instrument to give me a visual reference to the water level.

I'm sure there are others much more qualified than I to be giving you accurate information.

Home Depot has cheap angle gauge I used.
Measure both sides of the boat at the same position on the bottom to see if the boat is crooked to one side before determining the fairing block angle to cut.

I made my own fairing block from some lightweight wood not pine ouf of 2 pieces glued together, maybe Douglas Fir..
Then cut the angle on the table saw.


I modeled it after pictures I found. The fairing should be secured to hull so it can not rotate, I used a couple screws front and back. I sealed this up with Black PL polyurethane roof flashing, similar to 5200 but not as strong a rubber adhesive.