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I'm getting ready to install a Garmin TM23 transom mount transducer.
This transducer is almost 11" long including the bracket; somewhat of a torpedo sandwich.

I'm mounting it on the right side of transom about 4" inboard of the sponson channel.

The boat resides in a slip, and though I've been around it on trailer or in water over a thousand times, I never thought to notice this:
At the water line or below, is the outboard section of the transom parallel with the motor mount [center] section surface?
Or, are the outboard sections angled a bit forward relative to the motor mount center section?

I could check it in the water with a 6' straightedge next trip to the marina, but just curious if the two transom surfaces are angled relative to each other, enough to make a difference when mounting the 11" long transducer?
Ultimately I want to be sure the transducer is parallel to the keel line.

Thanks,
'hull'

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Checked it today with a straightedge and tape measure:
over the +/-17" width, the transom angles forward 1-3/4".
That's equivalent to the 11" transducer being a litle more than 1" out of parallel to the hull centerline [keel line].
I'll have to figure out a correction to get it parallel with the keel line.

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Maybe I should have posted to Electrical-Electronics; I'll let admin decide if a move is deemed necessary.

Update :
I haven't yet connected the headunit [Garmin 741xs] to the transducer since that install is still in progress and I was anxious to see how my bracket would work on this mount.

From my original post, the amount of 'skew' turns out to be a bit less than my prediciton, but looks like its enough to require a correction to get it aligned [parallel] with 'Plan Centerline'.
I've attached the best photo I could take over my stern while at 18mph [solo] and if you look closely you can see a bit of rooster tail off of the 'out board' edge of the GT23M. The side of the ducer it's coming from looks like a result of the 'skew'. For the moment, fortunately most spray is directed away from the engine, but it eventually gets the engine [uncertain if getting into the breather ports].
I think the 'skew' is part responsible for the rooster tail spray, but it was much worse before I adjusted the entire assembly up almost 3/4" from whats shown in the 'dry' pics; before that the spray was reaching up about a foot and spraying the engine a lot more.

So, in summation, the current running position has the bottom of the GT23m about 1/2" to 3/4" above the transom bottom. Not visible in the pic, the leading-inner edge of the GT23m looks like it might not be making contact, otherwise I'm making 90% contact with the laminar flow. However, not being connected to the sonar unit, it's a bit irrelevant at the moment. Like I said, I was just anxious to see the transducer motion in the water and curious how the experienced eyeballs out there see it [from the limited pics]. Might go out again w/a crewman steering while I take a few more shots or video.

Thanks for reading and comments/suggestions.

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Hey Hull,

I don't see any pics of the transducer in your personal page.
Am I missing something?

I do have one suggestion for Safety.
Put a cover over the stern sump before someone breaks an ankle. Or worse.
See the last download on this page for the drawing if you don't already have the cover.
http://www.whalercentral.com/download...?cat_id=13
Montauk 17' Sump Cover
http://users.sisqtel.net/~jkriz/Monta...inside.jpg

Everything else looks great.

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Thanks Joe- I cropped them down to <125kb; after populating jpg name field by navigating to jpg file, no other options given.? Got return message " illegal file size/type.
.jpg's, <125kb...whats wrong?

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Best I can do at the moment

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110kb jpg.
keep getting: "Invalid attachment filename or filesize"
??

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What is the name of the file?

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I give up...
anyway, the spray situation is resolvable; was curious if others experienced same and what resolutions other than shields, if really necessary.

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"GT23m skew to transom"

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.jpg of course

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file renamed w/out spaces...

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Stern view

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Profile view

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Thanks Joe-
BTW, I did put a 1/2" starboard cover over the sump a while back.

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Personal Page file names cannot contain any spaces or characters like you have above.
GT23m skew to transom.jpg will not work
I guess you forgot that but your other photos on your personal page do not contain any spaces.
Look at your other photos on your personal page.
GT23m_skew_to_transom.jpg will work

See this Frequently Asked Question and Personal Page Instructions.
http://www.whalercentral.com/faq.php?...p?cat_id=1

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Joe- thanks again; I figured it out after your clues...forgot file naming syntax rules.

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That is a long transducer.

Hopefully someone that has something similar can give you some other tips.