Transom-mount transducer vs. through-hull transducer?

[Colecacola]

I recently installed a Simrad GO5 XSE Fishfinder/Chartplotter Combo with Active Imaging 3-In-1 Transducer and C-MAP Pro Charts on my 2015 Cobalt 220 WSS (see below pics). I’m pleased with the clean install. It sits as good as the factory flush dashboard mounted Garmin 640 GPS.

However, I did not yet install the (large) 3-In-1 transom-mount transducer that offers CHIRP, DownScan and FishReveal. The friend of mine (a marine electronics expert) who helped me install the Simrad, recommends instead purchasing and installing a second through-hull transducer on the port side – adjacent to the existing starboard through-hull transducer (that reads digital dash depth).

He is concerned that the 220s transom angles (see pic), along with the Volvo’s duoprop (V8 270 HP), will cause transducer interference. He also said because I do not use my Cobalt for fishing I will not miss the added 3-In-1 transducer’s features (and it’s more prone to damage and not as clean of an install and more time consuming). However, I’m hesitant to spend more money on another transducer and ideally would prefer the full functions of the transom 3-In-1 transducer.

Cobalt owners, what are you experiences with a transom-mount transducer vs. a through-hull transducer? What are your thoughts on my friend’s recommendation? Thanks in advance for your insight.

[Big Block Power]

You should show us that transducer. I thought about it myself and I didn't want a 12inch black thing sticking out of my transom so I left it in the box.

[tgrace98]

So I put the simrad transom mount one on my 262 and it wouldn’t work over 30mph. Seemed it was more for a fisherman than a bow rider

[AsLan7]

I installed a transom mount on a 24 degree deadrise Donzi. No issues with angles. Just make sure it’s straight shooting (perpendicular to the ground) facing downward. That being said, we did not have an extended plane running surface hull which could cause transducer interference from the outdrive on a Cobalt. Your display will blink at higher speeds as air bubbles interfere with the transducer located aft of the outdrive instead of before it. You could try mounting the transducer next to the drain plug ahead of the outdrive to reduce interference but that also runs the risk of now being too close to it horizontally.

Personally I think it just looks ugly on the transom and I prefer the look of a clean install & protection of a thru-hull installed transducer.

[bruceb58]

I have a transducer hanging of the back of my present Wellcraft boat. I don't notice it since it is in the water. You will almost always have the best performance not shooting through the hull.

[Lockey14s]

listen to you marine electronics expert friend

[Big Block Power]

listen to you marine electronics expert friend

We are marine experts on the internet!
I stayed at the Holiday Inn last night!

[Lockey14s]

listen to you marine electronics expert friend

We are marine experts on the internet!
I stayed at the Holiday Inn last night!

Famous last words right? i read it on the internet, it must be true!

from my experience thru hull transducers always work better.

[Big Block Power]

listen to you marine electronics expert friend

We are marine experts on the internet!
I stayed at the Holiday Inn last night!

Famous last words right? i read it on the internet, it must be true!

from my experience thru hull transducers always work better.

To be perfectly clear. Thru hull means hole in the hull transducer. Shoot thru hull means mounted in the bilge shooting thru the hill no holes.

[AsLan7]

We are marine experts on the internet!
I stayed at the Holiday Inn last night!

Famous last words right? i read it on the internet, it must be true!

from my experience thru hull transducers always work better.

To be perfectly clear. Thru hull means hole in the hull transducer. Shoot thru hull means mounted in the bilge shooting thru the hill no holes.

.
So true.
....and you can test your thru-hull transducer location by putting in in a ZipLoc bag filled with water and placing it over the area in the bilge you wish to test.

.

[Lockey14s]

No shoot thru! get the hole saw out and start drilling!

[Colecacola]

Thanks, everyone, for your feedback and insight. Below is a photo of the transducer. As you can see it’s not petite but does pack in a lot of technology.

My electronics expert friend (who works at West Marine) did recommend that I reach out to you all for your Cobalt/transducer expertise (since many of the boats he works on are deep sea fishing machines (Seattle area). In other words, you are the true Cobalt experts, and this forum, over the years, has been extremely useful.

I do notice that many of the new Cobalts have the Garmin 7607 touch screen – either as an option or standard. For these applications, does the Cobalt factory use the transom-mounted transducer or thru-hull transducer for this Garmin?

[bruceb58]

That doesn't look like a transducer you can shoot thru the hull with but I may be wrong. It shoots sideways as well as down.

This is the transducer right?
https://www.simrad-yachting.com/simrad/ ... qwQAvD_BwE

What some people do is fiberglass a wood box into the bilge at the appropriate angle, filled with water and the transducer mounts to the lid. Oil is added to float on the surface to keep the water from evaporating. probably won't work with that style transducer though.

[Colecacola]

bruceb58, you are correct, that's not the thu-hull transducer. It's the transom-mounted 3-in-1 transducer you linked to (which is rather large) that I currently own.

Short of calling the Cobalt factory this week I'm guessing the Garmin 7607 installs also utilize the thru-hull transducer (mounted through a hole drilled in the fiberglass hull, with the outside of the fitting flush against the exterior hull surface as opposed to a shoot-thru-hull transducers that's mounted in a liquid-filled tank or a transom-mounted transducer). I welcome anyone to correct me if I'm mistaken.

[distinguishedmotors]

I recommend the through hulls to my clients.