2nd Transducer recommendation for 330 Express

[everwhom]

[Posted this to THT too, will share any useful input here!]

I have a Grady 330 Express, Garmin 7612 xsv and GT-51TH transducer mounted with the full fairing block dead center on the keel (the keel is quite rounded) about 6 feet from the stern. The GT-51 works great below 15kts but when cruising, the sonar image gets completely noisy. I can still usually read bottom, but I could run right over a huge school of tuna or a massive bait ball and never know it.

I primarily fish in < 300ft of water trolling for bluefin tuna, stripers, and bluefish in and around Cape Cod, but I also do a few trips S. of Nantucket to the NE Canyons.

I'm contemplating adding a second flush-mount transducer like the B175 well off to one side of the keel with the hopes of being able to have a clear sonar picture when cruising at 27kts. I want to be able to see fish as we're running to our planned spot if we happen to run over them!

Any thoughts would be welcome, including "forget it -- you'll get the same results as your GT-51"! If folks think the B175 is a good option, which version would you suggest?

(As an aside, my GT-51 was originally mounted without the fairing block, so I tried adding it to move the ducer further from the hull and into cleaner water, but doing so did not have any effect on my problem)

Many thanks,

Joe

 

[SkunkBoat]

Is it just the side view that is noisy or does it look bad in "traditional"(lower frequency) mode also?

On my 265 a have a transom mount GT51 between the motors and it doesn't read well on plane either, especially the sidescan.

I also have an older garmin GS22 sounder with a thru hull AIRMAR transducer that works really well on plane. It is only 2 or 3 ft from the stern.

 

[DennisG01]

Almost all transducers are made by Airmar - even if they get rebranded by Garmin, Lowrance, etc, etc. IF the GT51 is made by Airmar, it might be worthwhile to call them and ask about the differences between the two you are looking at and whether it's worthwhile. Since you mentioned "fairing block", I'll assume you mounted this completely through the hull, but just in case... Is this mounted as a "shoot thru" or is the ducer physically mounted through the hull (hole drilled in hull). Mounted 6' forward, you should have really clean water unless there's another item mounted through the hull in front of it. If it is a "shoot thru", it should be able to read just fine through solid fiberglass. Are you sure you mounted it properly (especially if it's a shoot-thru)?

 

[everwhom]

The GT51 is a thru-hull so hole drilled through and mounted below -- in my case about 4 inches below the keel because of the full fairing block.

The traditional sonar image is quite noisy when I'm up on plane. I do get a correct bottom reading, but I could run over a pod of whales and not see anything distinguishable. The picture is just full of noise...

Skunkboat: when you say your sounder works well on plane, can you see fish?

THX!

 

[SkunkBoat]

The GT51 is a thru-hull so hole drilled through and mounted below -- in my case about 4 inches below the keel because of the full fairing block.

The traditional sonar image is quite noisy when I'm up on plane. I do get a correct bottom reading, but I could run over a pod of whales and not see anything distinguishable. The picture is just full of noise...

Skunkboat: when you say your sounder works well on plane, can you see fish?

THX!

I can see pods of bunker or sand eels between the surface and bottom. I wouldn't say I could see fish unless there is a lot of them.
I've seen enough to make me stop on it at 70' in 200'.

 

[Fishtales]

I like the shoot thru transducers. As Dennis says, it is an Airmar. Sits in a housing and is applied inside the hull over glass.

 

[everwhom]

FWIW I ended up installing a B175HW which folks say is a great complement to the GT51 for the kind of fishing I do (stripers, blues, tuna, and NE Canyons trolling). Boat is still on the hard but will report back with results once I finally get her in the water!

 

[Doc Stressor]

When you are running on plane, bottom tracking is much better if you use a fixed frequency of 200 kHz rather than CHIRP. You should be able to select that on your head unit. Noise and surface clutter is to be expected whenever you're moving fast.

Very few transducer installations will let you see fish when on plane. Your new B175HW will be great for spotting fish in the water column off plane, but it will likely be worse at tracking bottom at speed than your GT51.