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Garmin GT 51 TM Real World Review

Old 11-22-2015, 02:43 PM
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Default Garmin GT 51 TM Real World Review

Recently I replaced my GT 50 TM with a GT 51 TM due to some testing Gil (Semperfifishing) and I wanted to perform on the higher wattage traditional Chirp of the 51 as well as the 260Khz capabilities in SideVu mode.

Let me start by first stating the 50 performed very well in which I have posted reviews in the past. That said, I found the deeper end of it's SideVu capabilities fading in depths past 100 feet in depth. The 51 looked like a better option for where I look for bottom and I was glad to trade the 800Khz on the shallow spectrum of the 50 for the more depth capable 260Khz of the 51. Each share the 455Khz band and I figured I would use that for the lionshare of my inshore searching duties. I will let the screenshots tell the tail as I was able to toggle between both 455Khz and 260Khz on the same structure so a fair comparison could be observed.

Another thing I will go over is the new SideVu zoom feature that came aboard with the new software update. It does a pretty good job and I really like the splitscreen option to which I will also provide some screenshots and tips.

Ok, to start with is a screen shot running along between 18 and 20 knots. It was pretty bumpy so the images are not like the ones on website or taken on a sheltered lake or bay. Like the title says "Real World" and what you should expect to see on the water on an average day in the eastern Gulf of Mexico out spearing fish and entertaining my obsession with finding new spots. Below is a what a small rock pile looks like when you are running along on your way to the next spot. I spun on this one and found it right where I put the curser. Not a big spot and without SideVu I would have never seen it to check out.
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Last edited by semperfifishing; 03-15-2017 at 10:23 PM.
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Old 11-22-2015, 02:48 PM
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Here is a shot of the traditional chirp doing it's thing when I went looking for the new spot. I have learned a lot discerning the differences between a bottom viewing transducer like my 264n 200Khz ducer and the 51's chirp ducer. The chirp is much more capable of identifying fish while the non-chirp give me a much better ID of the structure composition and size.
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Old 11-22-2015, 02:55 PM
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The next shots show the split screen zoom function. I like seeing both incase something pops up outside of the zoomed area. Note the images seem different in the zoomed area as it appears they have to be scaled differently to run at the same time on the same screen. Still plenty of detail to determine you have something to check out. Remember, it was no pond out there and the fact I have this all mounted to a rocking 23' boat does affect the quality of the imagery.
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Last edited by kmoose; 11-23-2015 at 05:07 AM.
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Old 11-22-2015, 02:57 PM
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One more shot but in 455Khz. Notice any difference in just 56' of water?
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Last edited by kmoose; 11-23-2015 at 05:08 AM.
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Old 11-22-2015, 03:05 PM
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Ok, now here is the trick shot. I passed a structure in 455Khz and spun around and hit it again at the same angle in 260Khz while it was all still on the same screen. This is not a split screen as in the previous shots just a transition between the two frequencies while passing the same object twice on the same side. It took me a few tries but I finally nailed it. So, what do you think did the best job at this depth? 455 or 260? You be the judge...
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Old 11-22-2015, 03:14 PM
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Bottom line, I am pretty happy with performance of the GT 51TM and prefer it over the 50 even in shallower water where you would think it would do a better job. Maybe it would on a better day in better sea conditions but as it stands right now I am happy with the swap.

Here's a pic of what turned out to be a pretty good day with a few new productive spots to add to my collection.
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Old 11-22-2015, 03:24 PM
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My old sled all this new fangled gear is attached to...
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Old 11-22-2015, 03:30 PM
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One last shot of the channel markers on the way in depicting range capabilities on an 18xhd. The returns show the markers out as far 16 nautical miles picked up on the way in at 30 knots. My dome is no more than 8 feet off the water so I'm not sure if it defies the laws of physics for line of sight but seeing is believing and I have been more than thrilled with the 18's performance for its size.

One last note.. The images I have posted are JPEG conversions from the original files and are quite lacking in resolution. If anyone would like to see the raw photos I can send them via email if you are that interested.
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Old 11-22-2015, 03:31 PM
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Great report and when there are real images to view, makes it all the better. You probably remember that I actually had the GT50 at my builders and after more resesrch like you, I switched which was based on reading and theory, not photos. Great job big dawg ! Thanks very much. Once I am squared away with the boat, I am sending u an invite to come to Pensacola for fishing and lessons lol!

Thanks a million !
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Old 11-22-2015, 04:00 PM
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Originally Posted by Badbagger View Post
Great report and when there are real images to view, makes it all the better. You probably remember that I actually had the GT50 at my builders and after more resesrch like you, I switched which was based on reading and theory, not photos. Great job big dawg ! Thanks very much. Once I am squared away with the boat, I am sending u an invite to come to Pensacola for fishing and lessons lol!

Thanks a million !
Thanks brother, I've learned quite a bit on here and I like to pay it forward if I can. Here is a shot from a transducer you don't have... It's pretty old technology called "ActualVu". It's kind of clunky and takes up a lot of space. It does really come in handy and when confirming the imagery of the new Garmin ducers. Maybe you can come down here and give it a try!
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Old 11-22-2015, 04:31 PM
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Hey Moose

Very similar results to my GT51. The 260 khz side vu is heaps better than 455 kHz in all situations. I don't use the 455 any more.

We were out iN horrible conditions and the sidevu and traditional CHIRP held solid bottom the whole time, much better than my SS264 200 could do.

The downvu seems to have no benefit to me, but the sidevu is excellent, much better than I expected.

Big question for me is how deep the traditional GT51 600W mid band CHIRP will go. Next trip out.

Shot of sidevu below showing reef and ripples in the sand channel between the reefs. All depth in meters.

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Last edited by Conquest235; 11-22-2015 at 05:48 PM.
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Old 11-22-2015, 09:19 PM
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Thanks Kmoose, that's a very interesting comparison - I'm sure it will help a lot of people weighing up the difference between the 50 and 51 transducers.

I've just finished installing a GT51 on the weekend. I did a lot of research before selecting it over the GT50 but still wasn't sure I'd made the right decision. It was reassuring to see this today. My problem is that I do a lot of fishing under 100' but I do go out to around 800' now and then. It was obvious the GT51 would perform better on those occasions that I fish deeper but if the performance cost was too much in shallow then I would be better off with the GT50 and perhaps add another transducer for deeper work. It was difficult to try and quantify the performance difference without first hand knowledge but I took the punt with the GT51 and now I'm feeling more comfortable with the decision.

Out of curiosity - the 455kHz on the GT50 is better on paper than the 455kHz on the GT51 but how did you find the difference in practice?

And do you find the 260kHz mode better for rough water or doesn't it make much difference?
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Old 11-22-2015, 10:24 PM
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260 kHz better in the rough water, but then again it is better in all conditions for me.

455 kHz is as disappointing as the 260 is good.
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Old 11-22-2015, 11:50 PM
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Thanks Conquest. That makes sense as the 800kHz on the GT50 and the 455kHz on the GT51 seem to be token features as the bandwidth and beam spread seem to be compromised compared with the primary scan elements in each respectively. I assume these were included as a marketing decision so potential customers don't feel they are getting fewer frequency options than the competition is offering. I expect cost and overall size of the transducer were factors involved in the decision not to put full sized elements in for the higher frequencies.

I'm interested to hear how Kmoose found the comparison between the full size 455kHz in the GT50 with the limited one in the GT51. I expect the GT50 to be better in that regard but interested to know by how much.
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Old 11-23-2015, 04:36 AM
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now compare it to the new gt52
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Old 11-23-2015, 05:04 AM
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Originally Posted by OZFish View Post
.

Out of curiosity - the 455kHz on the GT50 is better on paper than the 455kHz on the GT51 but how did you find the difference in practice?

And do you find the 260kHz mode better for rough water or doesn't it make much difference?
It is hard to say if the 455 was better on the 50 as conditions vary so much from trip to trip. On calm days the 50 worked spectacular on large structure down to 90' but still struggled on smaller targets out any deeper. This was the main reason I switched. Did the 50 do better at 455 than the 51 at the same... maybe slightly but time will tell as I have yet to get the 51 out in any smooth water with the fronts rolling in.

I am pretty convinced the 51 does a much better job in the rough on 260Khz than in 455Khz. I haven't got it out past 85' yet but I am most certain 260 will continue to outperform 455 in deeper water. Hopefully I will be able to find a good day to give it a try and follow up on this report.

For me it is not about the prettiest images but the overall performance in identifying structure targets. The frequency that doe that in less than favorable conditions or at speed the best is the one I want. At this point the 260Khz band on the 51 is it.

Below is a pic of a barge in 90' on a real nice day with the GT50. You can see how much smoother the bottom line is compared to the ones above indicating much smoother seas. Nest nice day I'm out I'll make the same pass with the 51 on both frequencies and post them up.
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Old 11-23-2015, 06:17 AM
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How was the spray between the uprights on the transducer mounting bracket?
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Old 11-23-2015, 06:23 AM
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Thanks man, I think I learned something. Good post.
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Old 11-23-2015, 06:27 AM
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Originally Posted by Hossharris View Post
How was the spray between the uprights on the transducer mounting bracket?
No spray at all with the new deflectors. Made my own right off the bat but Gil sent me a Garmin deflector with the new 51 and it worked great, no issues.
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Old 11-23-2015, 07:07 AM
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Thanks for the great review, nice to see someone who does the same type of fishing/spearfishing that I do. What head unit are you using?
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