Range Switch of Echo sounder
- Could be between 0-10M, 0-20M, 0-50M, 0-100M, 0-200M, 0-1000, etc.
- Check the approximate depth in the vicinity of your fix.
- Start at a range which is just little more than this depth. (if the depth is 98M, choose 0-100M)
- Look out for an echo blip or a marking.
- To coax out the echo, you may have to manipulate other controls.
- Once observed, shift to one range scale higher.
- Observe the echo against the enhanced range scale marking.
- It should be the same as the earlier readings.
Draught Setting of Echo sounder
- The E/S Transducer is fitted at the keel of the ship.
- It means that the depth will be measured below the keel.
- To obtain the depth of water, the draft of the ship will have to be added to the measured reading. This can be achieved by setting this control which is known as setting the Zero Line to the ships draught.
- It is safest to keep the switch to 0 setting because there have been instances when the watch keeper presumed that he was reading below the keel reading whereas the zero line was set to the draft of ship. The watch keeper thus over read the depth and ship ran aground.
Feet / Fathom / Meter Selector Switch of echo sounder
- In modern echo sounders, the display automatically adjusts to the chosen scale.
- If your are on Meter scale and the depth shown is 10M,
- It will show 33ft if the Feet scale is selected.
- Or 5.5 Fathoms if the fathom scale is shown
- But in older models, the marking depth will have to be manually read off against the scale and here caution has to be exercised. There have cases, when watch keeper presumed that the Fathom scale was in use, where the echo sounder was set to Meter Scale.
- The watch keeper presumed higher depth which in reality was lower and hence the ship ran aground.
Fix Marker of Echo sounder