Help with thru hull transducer placement

[Manny Fish]

Hi Team.
After a long diagnostic process with some of the best in the business down here in New Zealand it seems I have turbulent interference on my thru-hull transducers (B175’s). They are mounted just fore of the pickups either side of the hull. Yes I have checked that they are correctly oriented. No there is nothing on the hull fore of the transducer. Yes the picture is clear until I am doing around 6kts and it gets progressively worse from there.

I’m looking to chat with anyone who has installed thru-hulls on a Grady under 25ft please.

Would be massively appreciative of the help as about to take them out, repair the holes and start again so have to get it right this time.

 

[Hookup1]

I can't tell which side of the photo is forward and aft. It looks like that transducer is mounted forward - not where I would have put it. You may be picking up hull turbulence from the bow. If you are going to relocate it try to install in aft compartment.

You should be on 200 kHz frequency in shallow water. Try dual frequency 50/200 split screen. Start out with auto gain. At 6 knows you should have a cleaner picture. Could also be soft bottom you are over. Screenshot shows 21 knots.

I have 8612xsv and 8610xsv units with different transducers. Have been using it for a few years with great results. GT51M-TH on centerline and B744 transducer on transducer pad on starboard side.



It's also hard to tell how the transducer was angled. The B175 transducers are available for different angle hulls 0, 12 and 20 degree and must be rotated properly to angle down.

 

[DennisG01]

Don't take this as fact, but I'm wondering (after trying the setting adjustment that Hook said) if you're getting some turbulence because the two hull fittings are so close together... thereby not allowing the water to flow smoothly over the ducer fitting. Meaning, there's some turbulence being created between the two fittings which is then backfeeding over the ducer fitting. Try putting some tape over the thru-hull to see what happens. Maybe you can even build up the area between the two fittings with, for example, some tape, to smooth the transition, as well?

 

[Hookup1]

Hard to tell from the photo but from the comments I'm assuming the small thru hull is aft of the transducer. Not sure what that thru hull does (bait well, pump out, etc) but I suppose it could be a source of turbulence (water in, water out or just closed) even if it is aft of the transducer.

Yours transducer is a CHIRP. Mine is a different. I have sounder screens for traditional single frequency, split frequency side-by-side and split zoom side-by-side. Also ClearVu and SideVu CHIRP (2 selectable frequencies). On the options menu for each of the screen types you can select frequencies.

I would recommend you start out at 5 or 6 knot speed, split frequency and take the unit out of auto gain. Increase gain until you get a good solid bottom. Increase speed and see what happens to your bottom picture.

 

[Manny Fish]

Don't take this as fact, but I'm wondering (after trying the setting adjustment that Hook said) if you're getting some turbulence because the two hull fittings are so close together... thereby not allowing the water to flow smoothly over the ducer fitting. Meaning, there's some turbulence being created between the two fittings which is then backfeeding over the ducer fitting. Try putting some tape over the thru-hull to see what happens. Maybe you can even build up the area between the two fittings with, for example, some tape, to smooth the transition, as well?

That’s an interesting idea. I’ll try that - thanks.

 

[Manny Fish]

Hard to tell from the photo but from the comments I'm assuming the small thru hull is aft of the transducer. Not sure what that thru hull does (bait well, pump out, etc) but I suppose it could be a source of turbulence (water in, water out or just closed) even if it is aft of the transducer.

Yours transducer is a CHIRP. Mine is a different. I have sounder screens for traditional single frequency, split frequency side-by-side and split zoom side-by-side. Also ClearVu and SideVu CHIRP (2 selectable frequencies). On the options menu for each of the screen types you can select frequencies.

I would recommend you start out at 5 or 6 knot speed, split frequency and take the unit out of auto gain. Increase gain until you get a good solid bottom. Increase speed and see what happens to your bottom picture.

Thanks I’ve tried that and it makes no difference. Those pickups respectively provide water to the live well and the raw water pump. It makes no difference if they are open or closed.

 

[Manny Fish]

I can't tell which side of the photo is forward and aft. It looks like that transducer is mounted forward - not where I would have put it. You may be picking up hull turbulence from the bow. If you are going to relocate it try to install in aft compartment.

You should be on 200 kHz frequency in shallow water. Try dual frequency 50/200 split screen. Start out with auto gain. At 6 knows you should have a cleaner picture. Could also be soft bottom you are over. Screenshot shows 21 knots.

I have 8612xsv and 8610xsv units with different transducers. Have been using it for a few years with great results. GT51M-TH on centerline and B744 transducer on transducer pad on starboard side.

View attachment 28151

It's also hard to tell how the transducer was angled. The B175 transducers are available for different angle hulls 0, 12 and 20 degree and must be rotated properly to angle down.

No as I said the pickups are aft of the transducer. They are 20 degree transducers and the GW Fisherman 216 has a 19 degree deadrise. It all works fine until you get up to about 6kts.

 

[Manny Fish]

Don't take this as fact, but I'm wondering (after trying the setting adjustment that Hook said) if you're getting some turbulence because the two hull fittings are so close together... thereby not allowing the water to flow smoothly over the ducer fitting. Meaning, there's some turbulence being created between the two fittings which is then backfeeding over the ducer fitting. Try putting some tape over the thru-hull to see what happens. Maybe you can even build up the area between the two fittings with, for example, some tape, to smooth the transition, as well?

That’s an interesting idea - I’ll try that thanks

 

[SkunkBoat]

"I have turbulent interference on my thru-hull transducers (B175’s)'

You have two transducers? one's a 50Khz. There is one on the other side? 200Khz or 150khz?
Both do the same thing at the same speed?

They are brand new transducers?
New Sonar? Which one?

Have you ruled out low power from the sonar?

going slow or stopped Can you cleanly read bottom in 100 meters? 200?300?

A 1kw sonar @ 50khz should read bottom in 300m no problem

 

[Manny Fish]

A M and an L. Yes I have ruled out power. The voltage readings make no difference. I went as far as running the MFD on an independent battery.

I don’t need the diagnostic - I have been through a thorough diagnostic procedure - what I need is people who have installed B175 through hulls telling me where they are positioned.

 

[Manny Fish]

I can't tell which side of the photo is forward and aft. It looks like that transducer is mounted forward - not where I would have put it. You may be picking up hull turbulence from the bow. If you are going to relocate it try to install in aft compartment.

You should be on 200 kHz frequency in shallow water. Try dual frequency 50/200 split screen. Start out with auto gain. At 6 knows you should have a cleaner picture. Could also be soft bottom you are over. Screenshot shows 21 knots.

I have 8612xsv and 8610xsv units with different transducers. Have been using it for a few years with great results. GT51M-TH on centerline and B744 transducer on transducer pad on starboard side.

View attachment 28151

It's also hard to tell how the transducer was angled. The B175 transducers are available for different angle hulls 0, 12 and 20 degree and must be rotated properly to angle down.

Thanks for the photo. Where is this starboard pad you are referring to?

 

[Hookup1]

Thanks for the photo. Where is this starboard pad you are referring to?

On my hull there are flat spots on both sides of the boat for transducer mounting. Inside and out they are like fairing blocks. I don't have a picture of it and the boat is the water. They are on the outside of the port and starboard bunks around the circled area.Not all models came with them. My B744 traducer in mounted there. You would need a 0 degree transducer though for this mounting.



You may want to post your situation on www.thehulltruth.com. Gill of Semperfi is a great resource.

https://www.thehulltruth.com/semperfifishing-marine-electronics-transducer-sales-135/

Also my want to try the generic electronics forum.

Marine Electronics Forum - The Hull Truth - Boating and Fishing Forum

Marine Electronics Forum - Boaters discussion of Radar, GPS, etc.

www.thehulltruth.com

Screenshot B175M and 7612xsv at 30+ knots. Others...

https://www.thehulltruth.com/marine-electronics-forum/801949-anyone-use-airmar-b175-2.html

I would definitely try a few setting if you haven't done them before. Try different frequencies. Manually set depth to 2.5 times to see double echo and set gain. Try it at standstill and again at different speeds.

Beyond that I'm out of ideas!

 

[SkunkBoat]

A M and an L. Yes I have ruled out power. The voltage readings make no difference. I went as far as running the MFD on an independent battery.

I don’t need the diagnostic - I have been through a thorough diagnostic procedure - what I need is people who have installed B175 through hulls telling me where they are positioned.

I hear your frustration. I realize you have done troubleshooting and you are just are asking for someone with the same boat and same transducers to tell you where they put theirs.
You don't want to cut new giant holes in your boat if it isn't going to fix the problem.

I don't have that boat and I don't have those transducers so I will bow out of the conversation.

 

[Manny Fish]

On my hull there are flat spots on both sides of the boat for transducer mounting. Inside and out they are like fairing blocks. I don't have a picture of it and the boat is the water. They are on the outside of the port and starboard bunks around the circled area.Not all models came with them. My B744 traducer in mounted there. You would need a 0 degree transducer though for this mounting.

View attachment 28163

You may want to post your situation on www.thehulltruth.com. Gill of Semperfi is a great resource.

https://www.thehulltruth.com/semperfifishing-marine-electronics-transducer-sales-135/

Also my want to try the generic electronics forum.

Marine Electronics Forum - The Hull Truth - Boating and Fishing Forum

Marine Electronics Forum - Boaters discussion of Radar, GPS, etc.

www.thehulltruth.com

Screenshot B175M and 7612xsv at 30+ knots. Others...

https://www.thehulltruth.com/marine-electronics-forum/801949-anyone-use-airmar-b175-2.html

I would definitely try a few setting if you haven't done them before. Try different frequencies. Manually set depth to 2.5 times to see double echo and set gain. Try it at standstill and again at different speeds.

Beyond that I'm out of ideas!

That’s really helpful thanks.

 

[Manny Fish]

On my hull there are flat spots on both sides of the boat for transducer mounting. Inside and out they are like fairing blocks. I don't have a picture of it and the boat is the water. They are on the outside of the port and starboard bunks around the circled area.Not all models came with them. My B744 traducer in mounted there. You would need a 0 degree transducer though for this mounting.

View attachment 28163

You may want to post your situation on www.thehulltruth.com. Gill of Semperfi is a great resource.

https://www.thehulltruth.com/semperfifishing-marine-electronics-transducer-sales-135/

Also my want to try the generic electronics forum.

Marine Electronics Forum - The Hull Truth - Boating and Fishing Forum

Marine Electronics Forum - Boaters discussion of Radar, GPS, etc.

www.thehulltruth.com

Screenshot B175M and 7612xsv at 30+ knots. Others...

https://www.thehulltruth.com/marine-electronics-forum/801949-anyone-use-airmar-b175-2.html

I would definitely try a few setting if you haven't done them before. Try different frequencies. Manually set depth to 2.5 times to see double echo and set gain. Try it at standstill and again at different speeds.

Beyond that I'm out of ideas!

That’s really helpful thanks. I tried posting this question on THT but I think I can’t post pics as I have not had 10 posts - at least I got an error message saying I couldn’t post a URL until I’d had 10 posts (no URL in my post). Yeah I am not getting anything like that quality of image at 10kts. I am going to stick a go-pro under the boat while underway and try to see what is going on.
Appreciate your help

 

[Hookup1]

I don't use TheHullTruth that much but it is a resource. Good Luck is your search.

 

[muddypuddle]

Just confirming, many months later, I have multiple thruhull on a recent model 22ft grady and they run well. A 175hw, 175m and garmin gt56th on the keel. Fishing in 30m to 140m most the time. Cruise at about 50kph.

Still got bottom at wot most days, obviously not perfect at this speed, but gives an idea. Really clear at lower speed. They go into a gsd26 but still only run at 1kw, just better target separation.

Gt56 is a bit useless for off shore IMHO, no depth penetration. Panoptix ps30 is average but useful. Pulling these two off and putting on a new ps70th in a fairing. Can't wait. Also giving livescope xr a test, once garmin give me a loan to confirm it is worth the investment. Garmin rep gone AWOL recently.

Don't struggle finding the fish with this gear, just encouraging them to leap in the boat is a little tricky, I find. Dogs are much more obedient. Watching the footy on the garmin while fishing is pretty nice, sound through the factory ra770.

 

[Ryhlick]

I have a 228 and installed a 175hw and it reads most things at any speed. I will take pictures tomorrow of where I installed it and post them.

 

[Ryhlick]

Here is a picture of where my transducer is placed it is about 7” up from the center of the hull and placed in front of the intake so it has clean flow going over it.