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.

 

[Rayvon]

My experience doing this kind of thing is figure out where you want it mounted from the outside to avoid anything that would cause turbulance/air in front of the TD and then take reference measurements to see where it lands inside. If it's free and clear go ahead and drill a 1/4" hole and check outside if OK. If not adjust accordingly. Drill from the outside using the 1/4" hole to guide your hole saw. Scrape bottom paint off if you have it and grind gelcoat in shape of thru-hull w/a rough disc on mini grinder to roughen it up,clean w/acetone. On inside I like to add a 3/4" 4x4" or 6x6" depending on hole size wood spacer over sanded and cleaned gelcoat or resin. Sikaflex under TD flange and around and under the wood spacer and hand tighten the nut on inside. Always a messy job but I spread sikaflex all over the wood spacer that is chanfered @ 45* at the edges to seal it. An option is to leave it for a day to thicken before tightening with a wrench.You may need someone outside to hold it from spinning while tightening depending on shape etc..

 

[ship happens]

That transducer is most likely made by airmar.

 

[Pineapple Express]

That transducer is most likely made by airmar.

I was thinking the same. Looked on the Airmar site and don't see an exact match but I think Airmar has a lock on manufacturing this type of unit.

 

[wolf]

So im finding this thread intriging... So i have a hds 12 but a very old i think 300 watt airmar thru hull love how it works while crusing and such but I see these new 1 KW ones and yes way more expensive but what are the real benifits.
And i see a variety of ranges low,med,high and all refelcts on price what you order.
As i got a new radar system with a color monitor and can network it all was thinking migh as get the new tranducer as well make it all up to date...
So ill ask the guys in the know here what will i see more of?

 

[ship happens]

So im finding this thread intriging... So i have a hds 12 but a very old i think 300 watt airmar thru hull love how it works while crusing and such but I see these new 1 KW ones and yes way more expensive but what are the real benifits.
And i see a variety of ranges low,med,high and all refelcts on price what you order.
As i got a new radar system with a color monitor and can network it all was thinking migh as get the new tranducer as well make it all up to date...
So ill ask the guys in the know here what will i see more of?

Good question. One I have never been able to answer for myself. All my fish boats have 600 watt standard run of the mill 50/200 thru hulls transducers. Under 500 bucks each. The one I have on the venture is powered from a DFF1 unit and that thing will ping at 2200ft. For myself the sounder is just a tool for proper boat operation. I don't "find fish" with it. So to draw the bottom properly I think it's more important to have a good unit behind it. A 1kw transducer will have the ability to ping down deeper if the unit powering it is good enough, but unless your fishing in that crazy water depths I don't really see the point. My 2 cents. I've installed plenty of 1kw and all the fancy transducers and the cost justification for me personally never clicked. I'd rather spend the money on things that enable your ability to navigate safely and more efficiently.

 

[wolf]

Thanks Ship, I looked it up mines a 600 watt so that sort of answers question but hoping others chime in if they have or were in the same thinking ???

 

[searun]

Agree with you Wolf - probably 600 is all anyone really needs. I did notice the 1 Kw Airmar gave me better fish ID for anything over 100' deep over the other transducer lower power (I have 2). So just thinking after hearing some tips I would get another 1 Kw and go with a thru hull which I have heard from a few folks running those they perform far better than transom mounts. Always good to canvas others who have more experience with thru hull transducers and installation before pulling the trigger - although I just did order one.

 

[ship happens]

Think about it like a speaker and an amplifier down to the basics. The speaker can be 1000 watt rated, but the amplifier running it should have that plus 30 percent headroom. After that it's all software and processing to attain the information back to the user. The transducer is basically a speaker with an input to record back what it pinged out. There's a good joke about why it's called a Trans-ducer

 

[Sir Reel]

I have the B175HW Airmar on my Garmin network. It works very well. Lots of clarity on targets down to 300+ feet.
Got a depth reading of 1122’ in Toba inlet.
Here are a few pics off the screen. The 270’ screen is the hump off Kitty Coleman.

 

[searun]

Beauty imaging - I'm getting pretty excited about doing the thru hull now. Starting to plan for and think about the installation. No one likes drilling big holes in their hull and I'm a little nervous.

 

[Sharphooks]

I bought a pre-owned boat that came with a GT51 through-hull
I’m not a big fan of Garmin but that particular transducer def gets the job done for mid water salmon/bait etc. and I’ve been happy with the results for 3 seasons now
It holds picture at speed and tracks bottom down to about 175 meters .. I had the b175HW on my last three boats and a B75 on current boat so I know my way around the Chirp technology —-the GT51 is in the same league as far as beam angle and the crisp Chirp targets you’d expect
The one caution: it has a fairly large obtrusive footprint (unlike the B175 flush mount)

I mention that because I have had numerous fish go under the boat and break me off on that transducer … it’s more then a nuisance when you get braid broken off on it and know it will eventually end up wrapped on one of your props
I’m considering removing it this winter for that very reason and replacing with a flush mount

I see that the GT17 is a flush mount so no worries about hanging up line but usually the “m” transducers aren’t associated so much with mid water salmon etc because of the narrower beam as mentioned above …some sort of HW (high wide) is what people settle for
Meanwhile I’ll freely admit that the bread and butter transducer on my boat that outshines and out produces all the other high-tech ones I have mounted is the $50 pre-owned 50/200 KhZ 600 watt skimmer transducer I purchased on eBay 10 years ago… that transducer gets removed every time I sell a boat and gets remounted on the new one…it’s really all a salmon guy needs

Need I say more:

 

[Squire]

I’ll chime in that if you don’t already have a hole through your hull you might consider an Airmar P79 shoot-through-hull transducer. I find mine more than adequate although the dealership mounting job left a lot to be desired. They mounted it over the heavy, reinforced keel and didn’t properly orient it to the dead rise. I moved it over from center where the hull is thinner and matched the dead rise and it’s been great since.

I’m not sure if it would be as effective with a dual, cored type hull but that would be a question for the experts.

P79 50/200kHz, 600W, Navico 9-Pin

P79 50/200kHz, 600W, Navico 9-Pin - 600 W Our P79 is a dual-frequency, depth-only, in-hull transducer that easily adjusts to hull deadrise angles up to 22°

www.harbourchandler.ca

 

[Alan Wilson]

one caution
Do not put the Transducer in front of the trolling motor i you do any back trolling for bottom fish the motor wash will kill the reception

 

[TheHurtLocker]

I bought a pre-owned boat that came with a GT51 through-hull
I’m not a big fan of Garmin but that particular transducer def gets the job done for mid water salmon/bait etc. and I’ve been happy with the results for 3 seasons now
It holds picture at speed and tracks bottom down to about 175 meters .. I had the b175HW on my last three boats and a B75 on current boat so I know my way around the Chirp technology —-the GT51 is in the same league as far as beam angle and the crisp Chirp targets you’d expect
The one caution: it has a fairly large obtrusive footprint (unlike the B175 flush mount)

I mention that because I have had numerous fish go under the boat and break me off on that transducer … it’s more then a nuisance when you get braid broken off on it and know it will eventually end up wrapped on one of your props
I’m considering removing it this winter for that very reason and replacing with a flush mount

I see that the GT17 is a flush mount so no worries about hanging up line but usually the “m” transducers aren’t associated so much with mid water salmon etc because of the narrower beam as mentioned above …some sort of HW (high wide) is what people settle for
Meanwhile I’ll freely admit that the bread and butter transducer on my boat that outshines and out produces all the other high-tech ones I have mounted is the $50 pre-owned 50/200 KhZ 600 watt skimmer transducer I purchased on eBay 10 years ago… that transducer gets removed every time I sell a boat and gets remounted on the new one…it’s really all a salmon guy needs

Need I say more:

View attachment 121715

I have the GT51M-THP, very impressed with what it shows. Detailed, fast, and when jigging you can see then coming up or down to your jig.