Assalamualaikum, and weclome back to Orange Shots.
Did you know that seas have their own "mountains"?
Yes, in the depth of the sea,
you only seawater but there are mountains underneath.
These are particularly very dangerous for vessels.
There's one thing that we always do:
we try to measure the depth of the sea.
And how the depth of the sea is measured is a very common question.
Today's video is about these very mountains,
as well as the depth of the sea.
I'll tell you exactly how we measure the depth of the sea,
in different situations, so
let's start.
Just for an example, I'm showing you Luzon Strait,
and there's a depth of around 1000 meters around the island.
800 meters, 700 meters, 200 meters,
and suddenly, there's a peak here with a depth of 10 meters.
Now, this 10-meter peak is
obviously very dangerous for your ship.
A ship's draft is 16 meters long
sometimes 15 meters, 14 meters,
so it's definitely going to end up colliding with that peak,
and it's not going to be a very merciful incident, I must tell you.
So, to mitigate all these situations,
we have equipment on our ship for measuring sea depth.
Obviously, it's all on the ECDIS, that's fine enough,
but then simultaneously, we often need a secondary solution
that can help verify what's on the chart.
One such piece of equipment is the echo sounder.
The echo sounder is based on doppler technology
where radio waves travel and hit something solid,
and the time they take to reach and come back
from the solid object is recorded.
That's how sea depth is calculated.
For example, we're in Dalian right now,
and the water depth here is 50 meters.
5-0 meters.
As you can also see on the chart,
the depth mentioned on our ECDIS is 50 meters,
now let's see what our echo sounder shows.
This piece of equipment here is an echo sounder.
It has continuously been measuring
the depth of the sea (from the bottom).
The figure the equipment is showing right now is around 37 meters.
The ECDIS, instead, shows around 50 meters of depth.
Why is there a difference here?
The difference is there because the ship is 15.4 meters underwater.
The echosounder's transceiver is at the bottom.
That means it's measuring the sea depth from where it is.
Now, the next question is: if we minus 37 meters from 50,
we get 13 meters, where did the remaining 2 meters go?
This thing is, we also have the height of the tide,
because of the moon, tides rise and fall,
then there are different atmospheric conditions,
that can actually cause water to rise and fall.
These are the causes behind such variations
and we're normally aware of them.
We calculate them beforehand
so that we know the actual water depth.
So, in my view, it's okay. It's justified.
But then there's a key problem with echo sounders,
the echo sounder's sensor is at the bottom (of our ship)
but the ship is longer by comparison. It's 274 meters long.
The echo sounder is at the forward of a ship
since, obviously, we're always going forward,
and we need to know the water depth ahead of us
so that the entirety of our ship can safely move forward.
But then, there can be certain conditions, like when you're in congested waters,
ALLAH forbid, it the ship is surrounded on both sides (port and starboard).
I've told you in an earlier video that when a ship turns,
its head doesn't turn, it's the stern that actually swings,
i.e., one-third of the length from the ship's forward.
It is possible when you're in a narrow passage,
for your ship's stern to, ALLAH forbid,
accidentally end up on land.
Besides that, when your ship is approaching a berth,
it is also possible for the berth to not be sounded properly.
By sounding, I mean water depth measurement.
It is possible during loading operations,
for your ship to collide with the bottom of a berth.
Your echo sounder may still show a depth of 0.
This way a ship can end up touching the bottom of a berth.
Then there's one more thing we use,
to sound the port and the starboard side of a ship,
and that is completely "handomatic" manual, not automatic.
this is a word we made up and it means manual.
So that third thing is called a hand lead line.
Now, this is a hand lead line.
It has a lead weight here, and it's actually quite heavy.
It's heavy because when we lower it,
it's supposed to keep the line straight.
It's only used for a certain depth, i.e.,
when we suspect our vessel may be touching the ground.
In an open sea, however, where the depth may be 50 meters or more,
even around 20-25 meters,
we don't use this,
until or unless it's required that we do so.
That's because echo sounders are more reliable in such a case,
since they're already in use
and continuously updating us on the water depth.
But as I told you, there's only one problem with echo sounders.
Some ships have these sensors at the forward and the aft,
but on most ships, the sensor is only located at the forward part,
in which case, if such a ship touches something while turning/swinging,
this is what's used for depth measuring.
And just to demonstrate to you guys, I'm sending my GoPro
underwater with this line.
I hope it comes back safe and sound.
Let's attach it now.
Or maybe we can load from behind, no? That way we can see the propellor also.
What we'll do is try to get a view of the (ship's) propellor.
Your next question might be:
Why is depth measurement required when a ship has already touched the ground?
It's already touched the ground.
And yes I've already told you in one of my videos
that if a vessel ever touches the ground, most times, it's disastrous,
but then some other times, it's not.
If the ground your ship touches is slightly below its draft,
efforts can be made to refloat the ship.
Actually most of the time we do make all sorts of efforts
to refloat the vessel.
In case it can't be refloated, then that's a different story.
If the ships's bottom gets ruptured, it's a different story.
Usually, we use this sounding equipment
when we want to find out which side
has more room so we can manoeuvre our ship out ourselves,
or with the help of a tug (boat).
So, that's the importance of this.
So, basically, these are two things
we have onboard our ship.
There can be extra things onboard a vessel as well
but these are the bare minimum, the necessities.
So that's exactly how we measure the bottom depth of the sea.
I hope you enjoyed today's video.
I hope you got to learn something new.
If you liked today's video, enjoyed it,
and got to learn something new from it,
please do like it, share it,
and subscribe to the channel as well.
Take good care of yourselves.
Remember me in your prayers.
With tons of love to my Orange Shots family,
and to-be Orange Shots family.
Take very good care of yourselves.
This is Orange Shots, I'm Zahid Nisar,
ALLAH Hafiz!