Garmin GT17M-THF Thru-Hull Transducer - thoughts?

[searun]

I'm considering installing a Garmin Thru-Hull transducer in my Grady. The GT17M-THF is a 1 Kw unit, so lots of power.

Wondering if anyone has prior experience regarding how well they function compared to standard transom mount? Any advice, good, bad, ugly would be very appreciated. Also any tips on installation - before I drill a large hole in my hull.

 

[CBsqrd]

What are you planning on using it primarily for? Salmon, bottom fish, all of the above?

I'll preface by saying I haven't used this specific transducer, but have run an Airmar B175HW through hull for several years.

Looks like a great transducer for bottom fishing and an ok one for salmon. The beam angle is fairly narrow which is great for seeing bottom detail, but not ideal for looking for salmon or other fish that are shallow. The 175HW is the standard or pelagic species in up to 1,000' of water and it has a 25 degree fixed beam angle vs the 9 to 18 degrees on the Garmin.

Should give you better performance than a transom mounted transducer. Or rather, it will be less sensitive to installation and setup than a transom mount as long as there is nothing on the bottom the hull in front of the transducer. Probably not going to be seeing bottom running on step, but I never run my sonar then anyway.

Personally, unless you are getting a really good deal on the Garmin transducer, I'd go with the Airmar 175HW which is about the same price.

Oh, and if you do install, be sure to 1) get the right angle version to match the dead rise of your hull; and 2) to install in the correct orientation. On the Airmar through-hulls there is a large arrow that needs to be pointed towards the keel. If someone else installs for you, make sure they do it right (speaking from experience)!

 

[searun]

What are you planning on using it primarily for? Salmon, bottom fish, all of the above?

I'll preface by saying I haven't used this specific transducer, but have run an Airmar B175HW through hull for several years.

Looks like a great transducer for bottom fishing and an ok one for salmon. The beam angle is fairly narrow which is great for seeing bottom detail, but not ideal for looking for salmon or other fish that are shallow. The 175HW is the standard or pelagic species in up to 1,000' of water and it has a 25 degree fixed beam angle vs the 9 to 18 degrees on the Garmin.

Should give you better performance than a transom mounted transducer. Or rather, it will be less sensitive to installation and setup than a transom mount as long as there is nothing on the bottom the hull in front of the transducer. Probably not going to be seeing bottom running on step, but I never run my sonar then anyway.

Personally, unless you are getting a really good deal on the Garmin transducer, I'd go with the Airmar 175HW which is about the same price.

Oh, and if you do install, be sure to 1) get the right angle version to match the dead rise of your hull; and 2) to install in the correct orientation. On the Airmar through-hulls there is a large arrow that needs to be pointed towards the keel. If someone else installs for you, make sure they do it right (speaking from experience)!

Awesome advice on installation - been reading their manual and followed the importance of getting the correct dead rise version and mounting outboard per the arrow. Any special guidance on properly preparing the hole, drilling etc? Wondering if there is anything special to watch out for.
Good tip on looking at the beam angle, thanks!! - they make a few versions so I will investigate further. I'm normally using the sounder for all the above applications with Salmon being obviously the majority of on water use.

Going with the Garmin because the 2 year old Airmar 1 kw transom mount has crapped the bed and no warranty - that was a waste of $2k. At least with Garmin they stand behind their product....and I'm running all Garmin electronics which so far have been bullet proof.

 

[CBsqrd]

Sounds like a good plan! That's disappointing Airmar wouldn't help you out.

I'm guessing you will probably will need the 20-degree version for a Grady.

Here's a good thread on THT with some tips on doing the install yourself: https://www.thehulltruth.com/marine-electronics-forum/857872-installing-thru-hull-transducer.html. In this one the recommendation is to drill from the outside, but I've seen other people recommend going from the inside to out. I think I would do the latter if there was a lot of equipment (bilge pumps, fuel and drain lines, wiring, etc.) on the inside making it a tight fit to ensure the transducer was in the right spot. Measure 5 or 6 times and drill once in this case!

Good idea to have someone give you a hand so you can ensure everything stays in place when you are tightening the nut. I'd dry fit everyone together and make sure you both know the sequence of the steps before you start with the sealant.