sounder position

[mike thornton]

Hi Guys,
Can anyone tell me whether the sounder on the 336 is calibrated for actual depth or depth beneath the keel as standard.

thanks

Mike

 

[Don S/V ILLusion]

Hi Guys,
Can anyone tell me whether the sounder on the 336 is calibrated for actual depth or depth beneath the keel as standard.

thanks

Mike

Presuming its not a new boat, only you can tell for sure. A previous owner undoubtedly set it baded on their personal preference. Guessing here can be at your peril.

 

[Mulf]

Personal preference and you need the manual

The manual will tell you how to look up what the current offset setting is. Then you can change it if desired. I know people who want to measure it from the bottom of the keel and others who measure from waterline. I have mine set from the waterline because I like to be able to compare it to the chart depth.

 

[Claude L.-Auger]

Re: Personal preference and you need the manual

Like Mulf and for the same reason I like mine set from the waterline. You can check whether yours is set below the keel or at the waterline by measuring the depth at your dock more or less in line with where the sounder is located on board. Use a plumb line to get the real depth then compare with what the sounder tells you. As an example, if the line gives you 10 feet and the sounder only shows 5, assuming your draft is 5 feet, then the sounder is set to read depth below the keel. you can leave it like that or calibrate it to show real depth if you want. Just follow the instructions in the instrument manual.

 

[Stu Jackson]

Philosophical depth sounder offset concepts 101

This is a recurring discussion, in many cases involving How Tos and the like.

I'd considered the two different ways of doing this, i.e., below keel or waterline.

Then I had a "eureka" moment. I found a spot of soft mud and slowly ran the boat over it. When we hit, I noted the depthsounder reading 4.4.

Now I know, for sure, that if the number on the sounder reads more than 4.4 we're OK. Anywhere and everywhere.

The point that it should be set to be used to compare to charted depths, even accounting for tidal differences, I'd also considered. But the depths on charts is either way old and may have changed, and/or is extremely relative, since most charts jump in depths. For that use, I find the contours, and work those.

I anchor regularly, and this has served me well for 15 years. It's the CHANGE in the depth of water one is concerned with in that case.

Your boat, your choice, just another (third) way to do it.

In any event, YOU need to figure out what you have and what you want.