[C320-list] Depth transducer offset

[M K via C320-list]

Hello All,
I have recently installed new RM instruments and did not get around to
measuring the distance between the transducer and the bottom of the keel
when the boat was on the hard. Now it’s in the water, and I would like to
set an offset for my depth to the bottom of the keel.

What offset works best for the 320 with the wing keel?

Thanks,
Matt Knoll
#315 MaryAnne
Dexter, Mi

[Jack Brennan via C320-list]

I set mine to the depth of the water. Just take your boat hook and plunge it to the bottom off your rail. The depth is measured by where the wetness stops on the boat hook.

To set depth under the keel, subtract the designed depth of your keel.

Jack Brennan
Sonas, 1998 Catalina 320
Tierra Verde, Fl.

________________________________
From: C320-list <c320-lis...@lists.catalina320.com> on behalf of M K via C320-list <c320...@lists.catalina320.com>
Sent: Saturday, June 20, 2026 5:47 PM
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Cc: M K <mknol...@gmail.com>
Subject: [C320-list] Depth transducer offset

[ptormey 4square.net via C320-list]

You can just measure the depth at your dock and set the offset to make it agree.

Pat
Pat Tormey
S/V Blue Skies
Newport RI

________________________________
From: C320-list <c320-lis...@lists.catalina320.com> on behalf of Jack Brennan via C320-list <c320...@lists.catalina320.com>
Sent: Saturday, 20 June 2026 21:09:50
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Cc: Jack Brennan <jackbre...@outlook.com>
Subject: Re: [C320-list] Depth transducer offset

[Tony Kalish via C320-list]

my 320 with wing keel draws 4' 3 ". I set my depth finder to 5' It gives
me a little "fudge factor" just in case...

Tony Kalish
"Getting Away"
Pasadena, MD

[Steven Morgan via C320-list]

Wouldn’t the keel offset be the distance from the bottom of the hull, where the transducer is located, to the bottom of the keel ?
Thanks
Steve Morgan
516-680-5829



> On Jun 21, 2026, at 10:12 PM, Tony Kalish via C320-list <c320...@lists.catalina320.com> wrote:
>
> my 320 with wing keel draws 4' 3 ". I set my depth finder to 5' It gives

[Diane Fowler via C320-list]

I do the same; but have run aground with sounder saying 1.8. Thank
God, we have unlimited towing- in Florida- that is a MUST!

Captain Diane Fowler, CRS, GRI, e-PRO

Entrepreneur / REALTOR®
Experience Real Estate Group, LLC
[1]https://dianefowler.eresuccess.com

Cell/Text: (239) 850-4935
[2]dian...@aol.com
"A referral of your friend is the greatest compliment anyone can give
me."

On Jun 22, 2026, at 6:33 AM, Steven Morgan via C320-list
<c320...@lists.catalina320.com> wrote:

Wouldn’t the keel offset be the distance from the bottom of the hull,

References

1. https://dianefowler.eresuccess.com/
2. mailto:dian...@aol.com

[ptormey 4square.net via C320-list]

It depends on how you like it. I like to know how deep the water is, which for me is the waterline to the bottom. Because that agrees with the chart depths.

Easy to set. Drop a weighted line over and measure the wet part then set the offset to match ;-)


Pat

Pat Tormey
Blue Skies S/V
Newport RI
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Sent: Monday, June 22, 2026 7:31 AM
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Cc: Steven Morgan <steve...@gmail.com>; C320...@catalina320.com <C320...@catalina320.com>

[Bob Borelli via C320-list]

I have measured the distance from my C320s water line to the transducer at 1'-6".
The transducer is 1'-6" below the C320s water line.

Bob Borelli 1995 C320 no. 209
________________________________
From: C320-list <c320-lis...@lists.catalina320.com> on behalf of Diane Fowler via C320-list <c320...@lists.catalina320.com>
Sent: Monday, June 22, 2026 9:20 AM
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Cc: Diane Fowler <dian...@aol.com>; C320...@catalina320.com <C320...@catalina320.com>

Subject: Re: [C320-list] Depth transducer offset

I do the same; but have run aground with sounder saying 1.8. Thank
God, we have unlimited towing- in Florida- that is a MUST!

Captain Diane Fowler, CRS, GRI, e-PRO

Entrepreneur / REALTOR®
Experience Real Estate Group, LLC

[1]https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdianefowler.eresuccess.com%2F&data=05%7C02%7C%7C3f2b1bf9405c48cef15508ded063a6db%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C639177323585881513%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=w7BLG6RRS8hETq%2FWZfsiF9jOLyRMtrCIxuhX3Zj8tiM%3D&reserved=0

1. https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdianefowler.eresuccess.com%2F&data=05%7C02%7C%7C3f2b1bf9405c48cef15508ded063a6db%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C639177323585911190%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=%2BwYe5TyokXDh5ltWBJ5M2Ww6hBe%2BuUG4RSD5%2FUelnzM%3D&reserved=0<https://dianefowler.eresuccess.com/>
2. mailto:dian...@aol.com

[ART HARDEN via C320-list]

One thing to remember, is that the depth sounder shows a measurement perpendicular to the boat. If the boat is heeled, then it will show an incorrect depth. So using the draft of the boat as the offset is a good fudge factor.

Remember there are three kinds of sailors, those who say they have never run a ground, those who say they have run ground, and liars. If you haven’t run around, you will!!!

Sent from my iPhone

Art Harden
Catalina 320 "Tortuga" 243
E-42
937.885.9380 (o)
937.477.5544 (m)

> On Jun 21, 2026, at 10:08 PM, Tony Kalish via C320-list <c320...@lists.catalina320.com> wrote:
>
> my 320 with wing keel draws 4' 3 ". I set my depth finder to 5' It gives

[Jack Brennan via C320-list]

Hi Diane:
We were once anchored off Cabbage Key when a sailboat came in and anchored near high tide. The crew dinghied in for a few drinks. When they returned, the sailboat was tilted ominously. The owner couldn't figure it out because the depth sounder showed six feet.

It turned out a storm had created a lump of sand that unfortunately was under the stern of the boat. The depth sounder was forward, so it didn't detect the lump.

Jack Brennan
Sonas, 1998 Catalina 320
Tierra Verde, Fl.

________________________________

From: C320-list <c320-lis...@lists.catalina320.com> on behalf of Diane Fowler via C320-list <c320...@lists.catalina320.com>
Sent: Monday, June 22, 2026 9:20 AM
To: C320...@catalina320.com <C320...@catalina320.com>
Cc: Diane Fowler <dian...@aol.com>; C320...@catalina320.com <C320...@catalina320.com>

[Michael Stumpfoll via C320-list]

I have measured from the scum line to the underside of the wing keel and it is close to 4’-10”. I comment on that in my photo album.
Thanks,
Mike Stumpfoll

On Jun 22, 2026, at 10:15 AM, Bob Borelli via C320-list <c320...@lists.catalina320.com> wrote:

I have measured the distance from my C320s water line to the transducer at 1'-6".