96 300 marlin transducer

Capt._Brian

Capt._Brian

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Age
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Location
Chadwick Beach, New Jersey
Model
Marlin
Hey guys I want to upgrade my transducer, I have all garmin electronics I want to upgrade to a b175. I know there’s the 2 spots on the hull for thru hulls but they are already used by older transducers from the previous owner that are no longer used. So I guess my question is do I try to remove one of the old ones or start over ?

Thank you
 
Yes - Decide which one you want to ditch and which one to keep. What Garmin units do you have? If you are using the pads select 0 degree tilt.

www.garmin.com

Garmin AIRMAR® B175M (0° Tilt) | Transducer for Boat

The AIRMAR® B175M (0° Tilt) transducer has a flush-mounted bronze housing that protrudes less than 1/4-inch outside the hull & can sit on the trailer rollers/bunks.
www.garmin.com www.garmin.com
 
There are some treads in THT regarding problems with B175 and the 1234xsv.
Reason for the problems are not really clear to me, some had the transducer tested and found good but still acting up,
others had the transducer replaced under warranty and solved the problem, but it seems that this problems are happening only connected to a 1234xsv. Should you have a 1234XSV I would be careful and investigate well before installing this transducer.
However, the B164 / 175 shape works very well if is installed on the correct location, i have a non-chirp B164 on my RIB and he read up to 32 knots on shallower depths and down to about 1000 ft going slower.

However, if it would be my boat I would pull both old transducers just to free the space, for safety reasons and have less drag,
but that would lead to close correctly the hole from the not used one.
Another option would be to install two thru hulls:
a) not necessary to glass close one of both holes
b) install two same side-scan transducers for side-scan or two different transducers for different purposes

I personally would pull the trigger and install two, either side-scan or two totally different ones if that is needed.


BTW:
I noticed the two "grooves" in the hull on a 2001 306 Bimini and guessed that they are the transducer mounting locations,
is that correct?
Has someone considered to fill and glass even the two transducer mount locations to get a flat hull surface there?
If a B175 transducer is installed on a different location the two unused grooves would be obsolete and a flat hull there may reduce drag?

Chris
 
The B175 has a large diameter. You may need to do a little glass work on the transducer pad to widen it and accommodate the transducer. But that is the best place to put it in my opinion.

See if you can get information off the old transducers before you yank one/both out. There is usually a Airmar tag on one end or the other.

I have a GT51M-TH CHIRP, side scan and downscale. I have not had much success with the side scan. Mine is keel mounted so it can "see" both sides. It otherwise works fine.

I also kept my old B744 triducer. Non-CHIRP, 50/200, speed temp.
 
I belive that the transducer pad is the grooves on both sides of the hull?

I did not tried it but by eye and memory the B165/B175 will not fit inside the "groove"
The "groove" must be filled and glassing over or make a fairing block for the B164/175 to fill the void flush to hull.
I am not sure if that will work because of two reasons:
a) the transducer stem may be too short because the depth of the filled groove/transducer pad
b) unclear is the transducer will pickup bubbles or similar on the closed "groove"

The B164/175 work very well sitting flush to hull as long no turbulence or bubbles disturb reading, this wha I would install this transducer not on(in those transducer pads/grooves), rather left or right of them and obviously where installation can be done without disassembling half boat.
If there are no strakes, water pickups or similar protrusions I would install it between the groove and the keel as usually as deeper a transducer sit, better it will read.

I had the GT51-TM on my Venture 34 and side-scan was working amazing and down to 200ft in murky Costa Rica pacific.
What is the issue that you did not have success with side-scan?

Chris
 
Another option could be a shoot thru (it's in a box with a solution that is attached inside the hull). I have a 1KW in my boat and it works well for me (since 2007).
 
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Sardinia306Bimini said:
I had the GT51-TM on my Venture 34 and side-scan was working amazing and down to 200ft in murky Costa Rica pacific.
What is the issue that you did not have success with side-scan?

Chris
Click to expand...
I use the side scan in Florida Keys in the Winter. Don't really have large wrecks. Use shallow and off the reef in 200 foot of water. All I get are "ink blots" - not very useful. The boat isn't in the water much in Cape May, NJ area but when it was I had better success on the artificial reefs that have a lot of structure.
 
Ah ok, then it makes sense,
if there is nothing else than sand then only sand will be shown, and fishes if there are.

I use side-scan from 2009 on and I like it very much to find structure mainly as new (or lost) scuba diving spot.
But if there is nothing below then any side-scan will show nothing.

Chris
 
Thank you guys all for the replies! I want to use the pads/groves in the back of the hull that seems to be the best place for it I’m gonna have to talk to an electronics guy for the install, having to do glass work is over my head. Has anyone ever moved the transducer forward on the hull and got a 20 degree tilt? Like for reference I was thinking under the aft bunk would be an easier install.
 
Capt._Brian said:
Thank you guys all for the replies! I want to use the pads/groves in the back of the hull that seems to be the best place for it I’m gonna have to talk to an electronics guy for the install, having to do glass work is over my head. Has anyone ever moved the transducer forward on the hull and got a 20 degree tilt? Like for reference I was thinking under the aft bunk would be an easier install.
Click to expand...
The aft bilge is a typical place. You could also try the under the step into the cabin. Both compartments have thru hulls and pickups so you need to be careful about clean water flow.

Talk to the electronics guy. Maybe he can get the pad are reworked or help find a good location.

My GT51M-TH is in aft bilge between the two thru hulls on the centerline.

GT51M-TH6.jpeg
 
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Hookup1 said:
Yes - Decide which one you want to ditch and which one to keep. What Garmin units do you have? If you are using the pads select 0 degree tilt.

www.garmin.com

Garmin AIRMAR® B175M (0° Tilt) | Transducer for Boat

The AIRMAR® B175M (0° Tilt) transducer has a flush-mounted bronze housing that protrudes less than 1/4-inch outside the hull & can sit on the trailer rollers/bunks.
www.garmin.com www.garmin.com
Click to expand...
Hookup1 said:
The aft bilge is a typical place. You could also try the under the step into the cabin. Both compartments have thru hulls and pickups so you need to be careful about clean water flow.

Talk to the electronics guy. Maybe he can get the pad are reworked or help find a good location.

My GT51M-TH is in aft bilge between the two thru hulls on the centerline.

View attachment 31767
Click to expand...


Thank you! Your set up is pretty neat
 
Capt._Brian said:
My hull is cored so I don’t think that’s an option, I wish it was that would make things a lot easier
Click to expand...
Grady White doesn't core the hull. I had a M260 transducer in a wet box under the steps into cabin. Worked fine. You could just epoxy it to the hull if you can get it dry. I wouldn't use an expensive transducer though.

How are you using the transducer/sounder? If you fish the better transducer thru hull is best. If you just need depth for running around you could go cheaper or use old transducers. Did you find out what transducers are installed?
 
Hookup1 said:
Grady White doesn't core the hull. I had a M260 transducer in a wet box under the steps into cabin. Worked fine. You could just epoxy it to the hull if you can get it dry. I wouldn't use an expensive transducer though.

How are you using the transducer/sounder? If you fish the better transducer thru hull is best. If you just need depth for running around you could go cheaper or use old transducers. Did you find out what transducers are installed?
Click to expand...


Hey I have a garmin transom mount on there now. I use the boat for fishing the transducer works fine now but on a recent trip to the canyon I lost my sonar after 300’ of water, we were in 1400’. The old transducers went to the furuno units I’m not sure what the numbers are on them.
 
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Forget the B175. You have to make a huge hole.
Use a B265, B275 or B285 model (very large 1kw) or a B765 model (600w fit exact hole as the old B744). They will mount on the flat areas you mentioned.
look at dimensions of the housing and the diameter of the hole. There are two different sizes. You might match the old hole exactly and its an easy job
https://www.airmar.com/Catalog/Marine/Chirp-ready/Thru-hull

If you want to read 1400ft you will need a 2kw sounder (Garmin GSD24 or 26) and an M422 or R111 or R599 shoot thru hull



Capt._Brian said:
"I would love this as an option but I think it won’t shoot thru my hull is not entirely glass."
Click to expand...
your Marlin hull is not cored, only the sides...
 
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SkunkBoat said:
Forget the B175. You have to make a huge hole.
Use a B265, B275 or B285 model (very large 1kw) or a B765 model (600w fit exact hole as the old B744). They will mount on the flat areas you mentioned.
look at dimensions of the housing and the diameter of the hole. There are two different sizes. You might match the old hole exactly and its an easy job
https://www.airmar.com/Catalog/Marine/Chirp-ready/Thru-hull

If you want to read 1400ft you will need a 2kw sounder (Garmin GSD24 or 26) and an M422 or R111 or R599 shoot thru hull




your Marlin hull is not cored, only the sides...
Click to expand...


I just looked at what’s in there now and I see both of them is the B774 so that being said I think the best option is using one of the models you mentioned. Now the question is which one?
 

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SkunkBoat said:
If you want to read 1400ft you will need a 2kw sounder (Garmin GSD24 or 26) and an M422 or R111 or R599 shoot thru hull
Click to expand...
Sorry to correct you

My TM265LH was reading easily to 1500 ft, calm surface 2500-3000ft and I deep dropped from 2020 till August 2023 with that setup.
With the new GSD26 and the same transducer I reach 5000ft and was not taking time to tweak the settings
The B265LH or the now available B275LHW correctly installed will probably go a bit deeper.

A 2 or 3 kw transducer will get deeper and probably have a better resolution.

Chris
 
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Capt._Brian said:
I just looked at what’s in there now and I see both of them is the B774 so that being said I think the best option is using one of the models you mentioned. Now the question is which one?
Click to expand...
The question is what you want the transducer to show, how deep and wide .
B265LH and B275LH versions will go down to 2000ft if you have a 1Kw MFD 74 - 86 series and have a tight cone for high frequency @ shallow for bottom fishing down to about
B275LHW das same depth at low kHz abut a wider cone at high kHz, great for mid water fish but too wide for less than 100ft
The LHW is very good for trolling or drifting for mid water pelagic to see further around but don't go deeper as 400-500ft for the wider cone and high frequency.

If you wanna see that are cone width and max depth, Airmar has a neat page to play with that

Chris
 
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Capt._Brian said:
I just looked at what’s in there now and I see both of them is the B774 so that being said I think the best option is using one of the models you mentioned. Now the question is which one?
Click to expand...
That is a B744B transducer (re-check your label). Excellent transducer for running around and good down to a couple hundred feet. Non-CHIRP conventional 50/200 kHz with replaceable speed/temp insert. The speed/temp paddle wheel over the years gets banged up. It's on the underside of boat removes with cartridge. Ideally plug it in and test it in the water.

Sometimes there are Vendor variations of the transducer. Furuno, Garmin, Simrad, etc. It could be a different connector or it could be more complicated. Check with your electronics guy. That 525STID-MSD is a Furuno part number. The other tag is a junction box.
 
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