Should I convert from Through Hull to Transom Mount transducer?

[GoneDiving]

Im starting to plan to replace my Sounder so would someome please check my logic.

Converting from Through Hull to Transom Mount seems to make a lot of sense to me:

Cost is several thousand dollars less
Access, repairs and updating are so much easier
Sidescan is included
A wide choice of recreational units and features

I'm a diver not a fisherman so don't need mm resolution of small passing objects. I want to see depth at cruising speed and gross images <100m/300' (shipwrecks, walls, drop offs etc) at dead slow when finding targets. Sidescan is a big plus.

Arguments for better resolution at speed are irrelevant to me. Warp drive for my old girl is 8kn.

The only negatives I have come across are the performance once ~30ft cable extensions are added to suit a 54ft steel vessel and I do get a lot of turbulence and wash from a 42" prop.

Have I missed anything that makes a TM unit the wrong choice?

Thanks

 

[boomerang]

A transducer needs to be ahead of any turbulence to work well. The hi frequency of down & side scan is way more susceptible to interference from prop turbulence than lower frequencies. Transom transducers were designed for outboard & I/O boats. I've seen T/M 'ducers installed on inboard boats & they'll work with limited capabilities, especially if mounted to one side or the other of the boat to stay clear of the prop wash but honestly, it's not correct at all. You can perhaps get by with a single thru hull transducer vs a pair, depending on your boat deadrise, design ,etc. Why not just do it right the first time. If you have a 54' boat, the transducer cost is a drop in the bucket to the $$ you spend elsewhere. Just my opinion.

 

[OldDan1943]

Sounders and turbulence dont like each other.
I would suggest you stick with a through hull sounder.
Just my opinion.

 

[Alaskaflyer]

Also, transom mounted transducers show you what you just struck A slight advantage to a thru hull - at least where they are typically mounted on a displacement boat - is that they are farther forward. It's not a forward-looking sonar or anything, but helps when you are slowly picking your way forward.

 

[boomerang]

The difference between a Garmin (you didn't mention what brand you were thinking of but I'm using Garmin as an example) mid-band side scan transom transducer & the same thing in a thru-hull stainless-housing is just over $300. Yes ,the labor will be a little more involved but maybe you should consider ordering the plotter without a transducer and applying the savings from the one with the transom transducer towards the correct one designed for your boat?

 

[AusCan]

I have my transducer in a PVC tube filled with water mounted on the inside of the hull. This is an option if you have a solid fibreglass hull, but not recommended with cored hulls. It may cause a slight signal loss, but mine seems to operate well.

Installation is easy. No cleaning of transducer required.

 

[boomerang]

I have my transducer in a PVC tube filled with water mounted on the inside of the hull. This is an option if you have a solid fibreglass hull, but not recommended with cored hulls. It may cause a slight signal loss, but mine seems to operate well.

Installation is easy. No cleaning of transducer required.

The OP mentioned he was interested in side scanning capabilities plus he has a steel boat, and while a shoot-through-the hull setup is sometimes a good option on a solid glass boat (We're currently using 2 of those systems on our boat in addition to a through hull for 3 different sounders and they work fine), an in-hull transducer wont work for side-scan or even for conventional sounding on a thicker metal boat.

 

[Fish53]

Airmar makes flush mount transducers with built in angle to match the dead rise of where you want to mount it, I believe the range is from 0 to 22 degrees and 600 or 1000W. On any installation within those parameters you won't need a fairing block and the transducer will be flush with the surface of your hull offering less turbulence, drag and risk of damage. Scanning is a whole different thing, much more expensive in effective equipment and you'll need stainless steel rather than bronze for a steel hull.

 

[Comodave]

Yes they are called tilted array transducers. I have one in my boat and it works great. If you are replacing an old one the hole should already be there. So if you go with a transom mount, I wouldn’t, you would have to patch the old transducers hole. Using a through hull one will be less work. And it will perform better.

 

[GoneDiving]

Thanks guys. All good info. Looks like I'm off to the shop for more research.

For the record, yes 10mm steel hull.

Cheers

 

[KnotYet]

One of the simplest upgrades I did to my steel-hulled boat was the Airmar tilted array.
The only trick was enlarging the existing transducer hole and that was no problem.
3M 5200 sealed it very permanently, too.