Stern mounted transducer, 28TE

[Norseman]

Got two older stern mounted transducers on the arse end of “Odin”.
They have served their uselful life and will be removed tomorrow and replaced with a single Garmin GT23M-TM with Chirp, Down-vu, Clear-vu whatever capabilities.
I searched the forum for transducer locations, but did not see much or anything about TM transducers.
Does anybody have experience with locations and mounting to keep bubbles to a minimum and depth readings to a maximum at speed?

[Tree]

Port side of the wheel ideally but I have my chirp down vision on the starboard side and it copes perfectly well.

[Norseman]

Port side of the wheel ideally but I have my chirp down vision on the starboard side and it copes perfectly well.

Why Port side....?
Up to what speed do you keep the bottom?

Had same transducer on previous boat, lost the bottom at 15 knots.
Called Garmin, they had no solution, called the boat factory, they knew nothing either.
Hoping for better results on this boat..

[Tree]

Prop wash is on the starboard side - but can’t remember if you have a flush deck and if it’s different on a flush deck.

I lose my signal about 15 knots. If I’m looking for something I’ll be down to sub 7 knots anyway.

[Norseman]

Prop wash is on the starboard side - but can’t remember if you have a flush deck and if it’s different on a flush deck.

I lose my signal about 15 knots. If I’m looking for something I’ll be down to sub 7 knots anyway.

Motor box, left hand turning prop: The downward arc of the propwash should be on the Port side. But the Starboard side will also have a bit of wash I guess.
(Where is a Naval Architect when you need one? )

Aha, so you are loosing the bottom at 15 knots also?
Guess that is the nature of the beast.
Here in the colonies the water is shallow all over so a good depth sounder is worth gold but my plotter also have a data base of the bottom so I should be ok..

[Tree]

If you’re running the navionics software with live updates by users you’re heading in the right direction

[Tree]

Oh and I lose signal with both sounders. One mounted forward of the prop and one mounted aft

[Norseman]

If you’re running the navionics software with live updates by users you’re heading in the right direction

Navionics Software....?
Never heard of it (I must be running in the wrong direction )

[Norseman]

Oh and I lose signal with both sounders. One mounted forward of the prop and one mounted aft

You must be making too many air bubbles.
Seems like the solution is to get the ‘ducer as low as possible.
Will keep that in mind when the new one is being bolted on in a day or two.

If I lose the bottom at 15 knots, not a big deal. I have been using 17 as cruise speed but will probably save a 2 gallons per hour (7.57 liters for ya Limeys:)) by slowing down to less than 15 knots anyways.

[Tree]

One of my ducers is mounted midships so it’s just a hull design - air bubbles are good for a soft ride. I wouldn’t bother slowing down - the 28 pretty much does between 2 to 2.2 mpg from 10 knots to 18 knots anyway!

[Norseman]

. the 28 pretty much does between 2 to 2.2 mpg from 10 knots to 18 knots anyway!

Interesting, have not noticed. Will check it out.

[Pitou]

Here is a link to a discussion that a few of us had back in 2009 on transducer placement on the 28TE in the Electronics Forum:

viewtopic.php?f=27&t=2305&hilit=Transducer&start=15

The crux of the discussion:
1). Left hand props will give you prop wash to the starboard side (Airmar's installation manual shows single left hand prop inboards mounted port side ahead of the wheel).
2). mount forward of the engine and gear close to the centerline.

I did this on my 28 and all drop out issues were eliminated.

Transducer 2.jpg

[Norseman]

Here is a link to a discussion that a few of us had back in 2009 on transducer placement on the 28TE in the Electronics Forum:

viewtopic.php?f=27&t=2305&hilit=Transducer&start=15

The crux of the discussion:
1). Left hand props will give you prop wash to the starboard side (Airmar's installation manual shows single left hand prop inboards mounted port side ahead of the wheel).
2). mount forward of the engine and gear close to the centerline.

I did this on my 28 and all drop out issues were eliminated.
Transducer 2.jpg

Good information, thx.
I am hauled out now and leaning towards an in-hull transducer.
Found this spot on the boat: behind and aft of the batteries and helm seats, Port side, but at angle out instead of down.