Testing a depth sounder

[Seashoreman]

I am never really sure if I am set up for depth below keel (one metre approx.) or depth below sounder. So, any suggestions for a weighted material that I can hang over the side to check this? Most of my rope wont show a colour change and I am sure coloured ribbon is far too expensive. No diving with tape measure suggestions would be appreciated.

 

[VicS]

I am never really sure if I am set up for depth below keel (one metre approx.) or depth below sounder. So, any suggestions for a weighted material that I can hang over the side to check this? Most of my rope wont show a colour change and I am sure coloured ribbon is far too expensive. No diving with tape measure suggestions would be appreciated.

surely you have a lead line ??

 

[Poignard]

Last time I did it I used a ring spanner on the end of a piece of thin cord with knots tied in it at suitable intervals. Lower the weight to the sea bed and keep your eye on the knot that is above the surface as you haul in the line. When that knot comes within reach grip it with your finger and thumb, so you don't forget which one it was, and count the knots from there down.

 

[Seashoreman]

Last time I did it I used a ring spanner on the end of a piece of thin cord with knots tied in it at suitable intervals. Lower the weight to the sea bed and keep your eye on the knot that is above the surface as you haul in the line. When that knot comes within reach grip it with your finger and thumb, so you don't forget which one it was, and count the knots from there down.

This sounds good but how do you know when spanner grounds out? Probably have to try a few experiments up a shallow creek.

 

[VicS]

This sounds good but how do you know when spanner grounds out? Probably have to try a few experiments up a shallow creek.

If you use a proper lead weight you will feel the change in weight on the line when it gets to the bottom.

 

[Poignard]

This sounds good but how do you know when spanner grounds out? Probably have to try a few experiments up a shallow creek.

The line goes slack when the spanner touches the bottom.

ps it doesn't have to be a spanner, any weight will do. I just happened to have one handy at the time. If there's much current you'll need something heavy, eg the lead weight someone has suggested above.

 

[NickRobinson]

surely you have a lead line ??

I keep a redundant set of dome tent poles on board to poke the bottom when I dry out somewhere unknown-

Overheard between Liverpool VTS and incoming tanker- VTS- there's shallow patches ahead of you- Tanker- we've got a man in the bows with a lead line... VTs- lead line? he should have a shovel.....