Transducer: Shoot-thru-hull vs. transom mounted vs. thru-hull mounted?

[JASinIL2006]

Hi all, the depth sounder on my fiberglass bowrider seems to have flaked out... the gauge is getting power, but the depth reading frequently disappears, or flashes nonsensical depths. After checking for good connections and not finding any problems, I'm thinking it's time to replace...

My question has to do with transducers. The current transducer is a shoot thru the hull type, mounted in the in bilge under the engine. In looking at new transducer models, it seems that my choices are to get another shoot thru the hull model, a transom-mounted model or a thru-hull mounted transducer.

What are the comparative differences between these? The shoot-thru-hull model is attractive because it doesn't involve drilling any holes thru the hull, but trying to get at good spots in the bilge is not easy for me (I'm a fairly big guy and there's not much room back there...). Also, the boat lives on a trailer and it's a 2.5 hour round trip to the nearest boating grounds, so the whole process of fitting the shoot-thru-hull transducer (sandbagging it in place in the bilge, covering with water, testing, etc.) would be a bit of a pain.

I've been following ricohman's thread about installing a transom-mounted unit, and it looks fairly easy, but I don't know much about the plusses and minuses of the different types.

Can anyone help, or point me to a good resource that addresses the differences?

Thanks,
Jim

 

[lrlima]

Re: Transducer: Shoot-thru-hull vs. transom mounted vs. thru-hull mounted?

I have similar problem with my thru hull transducer. I lose the depth reading on the display quite often....so i'm in the same "boat" as you

Im going to install a transom mounted one. I installed one on my last boat it just seems to work the best. Plus, it gave me water temp reading and I matched it with a relatively inexpensive GPS / Fishfinder. SO for me it added a lot of value and worked better.

They are not that hard to install either, once you get over the drilling through your transom anxiety. lol

 

[ricohman]

Re: Transducer: Shoot-thru-hull vs. transom mounted vs. thru-hull mounted?

You don't have to drill. There are a couple of options available to avoid drilling holes.
And you get more versatility in the mount.

 

[JASinIL2006]

Re: Transducer: Shoot-thru-hull vs. transom mounted vs. thru-hull mounted?

Ricohman, when you say you don't have to drill, do you mean for the transducer mount or for the cable, or both? You used some sort of mounting bracket for the transducer, didn't you?

 

[shockrr]

Re: Transducer: Shoot-thru-hull vs. transom mounted vs. thru-hull mounted?

I went to get an depth finder installed at my dealer and was thrilled to hear you could get a thru hull transducer. No more bow mounted transducer. I walked up to the counter and said I want a hummingbird depth finder and one of them thar thru hull transducer. The guy says, we wont even sell you one of those let alone install one. He said if you want bogus readings, readings too late for that impact with bottom etc go find a thru hull. He said transom transducers are all they will install. They did a nice job of the install...but someday it would be nice to have a thru hull setup

 

[OneBadMarine]

Re: Transducer: Shoot-thru-hull vs. transom mounted vs. thru-hull mounted?

My .02 cents. I have boats with transom mounts and with through hull mount/set up, the through hull is the best as it doesn't pick up down riggers and other crap and at speed it does not get air across it like my transom mounts that lose signal over 30 knots...it also sees depth change before the out drive or prop if you are running in shallow water....they are more work but well worth it.

 

[dingbat]

Re: Transducer: Shoot-thru-hull vs. transom mounted vs. thru-hull mounted?

1. A thru hull (hole thru bottom) is the best and most sensitive. Problems with high speed turbulence are rare to nonexistent.
2. Transom mounts and problematic and typically have issue high speed turbulence issues
3. Shoot thru is the least sensitive of all the configurations. The hull causes a frequency shift in the outgoing signal (now 190kHz instead of 200kHz)so those returns are not recognized by the machine, Depending on the thickness of the hull and the frequency your machine operates at, you could lose up to 20% of your sensitivity.

Understand there is a difference between accuracy and sensitivity. Accuracy is a measure of distance. Good if you need to know exactly how deep the water is.

Sensitively is the unit’s ability to detect objects in the water column. The unit’s sensitivity is the bread and butter for a fisherman. Accuracy is irrelevant if you can’t see the object to begin with.

 

[bruceb58]

Re: Transducer: Shoot-thru-hull vs. transom mounted vs. thru-hull mounted?

I would only use a "shoot through" mounting if all you want to know is the absolute depth of the bottom...for example a depth gauge that just displayed the number of feet for the depth.