Keel offset for 1990 30-2

[BOSSailor]

I know a few of you out there have a 1988-1992 30-2. Does anyone know the keel offset off the top of their head? My transducer is installed forward of the keel under the wooden step plate by the bow berth.
I just replaced my ancient instruments with an i70 and STC-5 (highly recommended if you've got other SeaTalk gear) and forgot to note the offset.
I know the boat drafts 4.25' so I'm using that for the time being just to be safe but would appreciate it if anybody knows the actual number. Not planning on hauling for a bit and it would be nice to get it dialed in.
Thanks

 

[jssailem]

Hi BOS.
First I believe you mean the Raymarine ITC-5 Analog to Digital Transducer Converter.

The offset is based on the distance from beneath the keel too the location of the Transducer. It could be different for every boat as not all transducers are located in the same place. Exact measurements are probably not critical to the safe operation of your boat. The goal is to have an offset that will trigger an alarm when the bottom is getting close to the keel not when it is hitting the keel so you will slow down and proceed with caution.

How about a safe estimate. You know the keel is 4.25' and the rise from the keel root to the location of the transducer is what 1.5' . If you choose 6' as your offset you would be pretty safe.

 

[Ward H]

When I installed my new i70S instruments I backed the boat out of the slip so the bow was over where the keel sits in the slip. Extended my boat hook so I could reach over the bow and touch bottom. Measured the wet length of the boat hook to get the water depth.
Then entered in different offsets until I had the correct, measured, water depth showing on the display.
My draft is 3'10". I set my shallow water alarm to 5'.

Of course in our bay 12' is considered deep and the bottom is all mud and sand with gentle rises and drops in the bottom.

 

[jssailem]

I set my offset to 6 feet. My draft is 4'8".
I figure if the bottom is 6 feet away and the alarm goes off I want to know a little before the keel touches so I can take evasive action or brace myself ...