Depth Sounder Setting

[NautiDuck]

I am installing a new depth sounder (ST40). My previous boat did not have a sounder. So, what setting do you folks use? Do you measure the depth at the waterline or the depth at the transducer or the depth under the keel? The transducer one doesn't make much sense to me but the other two both seem to have advantages. I'm leaning to doing the depth at the waterline and then doing the mental math to know if I'm near bottom. What do you do?

 

[Scott]

Waterline

I calibrated mine for the waterline ... I just estimated and didn't even think about measuring it while the boat is out of the water. I just might do that since we are still waiting for spring to arrive! *grr

 

[tom]

Depth at Waterline

The depth at waterline helps with navigation. I then set the depth alarm to warn of shallow water. The alarm depth really depends upon where you are sailing. Steep banks allow a deeper alarm setting. I try to set it where I have time to react before hitting the bottom but where it doesn't go off all of the time. I also allowed a fudge factor in my offset so that when the depth reads 4.5' I am actually about 5.5' giving a foot between the keel and the bottom. Some units have sensitivity settings so that you don't read a soft bottom only harder stuff. Then there is that rock sticking up all by itself!!!! Or in my current lake the tree stumps and trees that weren't cut down before filling the lake.

 

[RickS]

Offset for keel

We have our depth offset for the depth of the keel. If it reads 0 ft, we are in trouble, no second guessing the safe operating depth below the waterline.

 

[Ross]

RandyK, We have ours set from the tranducer

which is about a foot below the waterline. We know that we draw 4.5 feet but we set the alarm at six feet. we will cheerfully sail in six feet but we watch the bottom contours(it is a fishfinder type)and any tendency to show a slope makes us change direction or slow down.

 

[Bill Roosa]

waterline

Makes reading the maps easier. I don't have to do the depth math all the time and only have to remember one number, my draft Also makes reading the tide height a bit easier for the same reasons.The admiral likes the keel setting as then she does not have to remember anything. The setting on our unit is done from the front so it is easy to switch back and forth.

 

[Dick McKee]

We use keel depth

Dont want to do any math if I think I'm in trouble. Our transducer is 3' below the water line and the keel is 8' BLW. I set the offset at 5' and the alarm at 5'.

 

[Seattle Scott]

I mesured the depth of the water

the boat was floating in ( with a leadline) and then used the offset feature to calabrate the sounder for acutal water depth, not water under keel.

 

[sailaway78]

Water depth

I too have mine set for the waterline. This gives you the actual water depth. Unless you are a total mental midget, the math is easy. As stated, it makes the use of charts a little more friendly. But it really boils down to personal preferance. I wouldn't recommend using the transducer depth, as that doesn't read anything exactly. But either the actual water depth, or depth under the keel is just a matter of which you prefer. Different Strokes for Different Folks.

 

[sailortonyb Allied Mis]

Water Depth

Makes chart reading easier without having to do the math. Its not the math thats the problem, its remembering to do the math that i have problems with. The Gulf of Mexico is very shallow near land and it becomes more critical that I be accurate. If I know my keel is 4 1/2 ft. I know that I must stay in water deeper than 4 1/2 feet or in some cases, right at 4 1/2 feet and dredge as you go.I have some friends that use keel depth and I have to remember who does what. Maybe they should pass a law to keep everyone consistant (just kidding). Tony B

 

[Wanderer138]

Waterline/water depth

Makes chart reading that much easier.PeterH23 "Raven"

 

[Stu Jackson]

ND, either way or try this:

slowly run your boat aground on a soft sandbar. Read the depthsounder. That's when you know you'll hit, all the time. Do the math any way you see fit, but anyone, unless he's on a lake, most likely will not be able to compensate for tide changes within a few feet anyway.