Opening
On April 8, 2022, an incident occurred where a barge carrying piles crashed into the underside of the Martadipura Bridge in Kota Bangun, Kutai Kartanegara, East Kalimantan. As a result of this incident, the barge was caught under a bridge which is the main access to the upstream area of Kutai Kartanegara. The cause of the incident was suspected that the ship’s captain had miscalculated the number of barges and at that time the water level of the Mahakam River was high.
Well… Talking about the amount of cargo on the barge, according to my friends, how do you calculate the load of a loaded barge. Let’s see the following explanation…
Discussion
In operating a cargo ship, it is very important to estimate the cargo it carries, this aims to ensure the safety of the ship and ship crew. In calculating the number of shiploads there are several ways, one of which will be discussed this time is the calculation of the draft survey load using the Hydrostatic/Displacement Table method. So, let’s take a look at the following examples.
There is a barge with an empty load, and has the following draft:
Approximately how much is the empty cargo of the ship?
Well, first calculate the average draft from each side of the ship.
| INITIAL | Draft | Mean Draft |
| Forward Left | 0.7 | 0.7 |
| Forward Right | 0.7 | |
| After Left | 0.8 | 0.8 |
| After Right | 0.8 |
Then, we find the overall average draft.
| INITIAL | Draft | Mean Draft |
| Forward | 0.7 | 0.75 |
| After | 0.8 |
From the results of the average draft, we can find the displacement unit in the available table according to the type of barge available. For example, from the 0.75 draft, the following results are obtained:
It can be seen in the hydrostatic draft table that the displacement in tons is 1.010, while the 0.76 draft has a displacement of 1.039. So to find the displacement in the 0.75 draft we do the following calculations:
Displacement =
= 1010 + 14.5
= 1024.5
Then, what if the barge is carrying cargo? how much cargo is carried if the barge has a draft like the one below?
Well, like the way before, we first look for the average draft as follows:
| INITIAL | Draft | Mean Draft |
| Forward Left | 3.6 | 3.6 |
| Forward Right | 3.6 | |
| After Left | 3.9 | 3.9 |
| After Right | 3.9 |
| INITIAL | Draft | Mean Draft |
| Forward | 3.6 | 3.75 |
| After | 3.9 |
Thus, the average overall draft of the barge is 0.75 M.
Then we re-match the draft to get the displacement of the barge in a loaded state, then we get a displacement value of 5.965
The actual load on the barge is:
Total load = displacement of filled barges – displacement of empty barges
= 5,965 – 1,024,5
= 4,940.5 MT
Then, to get the value of the weight of the load, then we multiply by the specific gravity of the load carried. Suppose the load carried is a type of split stone with a specific gravity of 1.5. So the tonnage of the load is:
= load in cubic/ specific gravity of split stone
= 4940.5/ 1.5
= 3,293.6 Tons
Conclusion
So that’s how to calculate the weight of a barge, friends, easy, right?
What do you think friends? Do you have any other calculation method references to solve the above case? try to write your opinion and if there is a wrong discussion, friends can correct it in the comments column..