Foot container in position 090202

Position 090202 means that the container is the hold. In Appendix C we must look for the LCG, VCG and TCG of this container (green marked). Remember that the container is in the hold so make sure you’re looking in the right column. As the plan is made for 20 foot containers we only have to read the values.

Foot container in position 320384

Position 320384 means that the container is on deck. Again we look in Appendix C to get the VCG, LCG and TCG for the container (pink marked). Here we must apply a formula to the container which is only applicable for the LCG.

This is because of the plan being only for 20 foot containers. The other 2, VCG and TCG, you just read from the plan.

In our example the LCG for this position will be:

» LCG of bay 31: 38.14 + LCG of bay 33: 32.00 / 2 resulting in a LCG of 35.07 for our 40 feet container.

For any other 40 feet container you must calculate the LCG like explained above.

Break bulk

Break bulk is a fixed weight onboard. This can include the crew and their baggage, the stores and all the equipment such as chairs, tables and so on.

Light Ship

You can find the Light Ship values in the Stability Booklet. For each vessel this is also a fixed value.

Now that we know where to look for the information, let’s continue with our example on a step by step basis.

Step 1: Recalculating to one value

W e’re making this calculation for a density of 1.000t/mі

Our total displacement here is 4054.18 in a density of 1.000t/mі. We must apply the weight correction here, as the Stability Booklet is completely based on a density of 1.025t/mі.

So our corrected weight will be: 4054.18 * 1.025 = 4155.53mt

This Δ: 4155.5mt will be the weight which we will use throughout the example.

Step 2: GM

In the Hydrostatic Particulars (Appendix D) we search for the weight and look for the KM. In the table KM is noted as KMT.

By means of interpolation we find the correct value in the table.

We find for Δ: 4155.5mt a KM of 10.54mtr. We know our KG, because KG is VCG for the Total, giving us 7.55mtr.

KM	10.54mtr
KG	7.55mtr
GM	2.99mtr

We now have our GM but we still need to apply the GM correction. Using the formula:

» GM correction = FSM tanks / weight

» GM correction = 125.33 / 4155.5

» GM correction = 0.03mtr

Continuing with the GM:

GM	2.99mtr
GM correction	0.03mtr
GM final	2.96mtr

Step 3: Draughts

F rom the table we get the following data for Δ: 4155.5mt:

• LCF draught: 3.065mtr
• LCB: 63.0351mtr
• LCF: 63.3700mtr
• MTcm: 102.98mtr
• LCG: 58.44mtr

Let’s calculate the draughts:

A. Trim = (LCG – LCB) * weight / MTcm * 100

Trim = (58.44 – 63.04) * 4155.5 / 102.98 * 100

Trim = -1.86mtr, we must make positive → Trim = 1.86mtr

B. Δt = LCF * trim / Lpp

Δ t = 63.37 * -1.86 / 125.5

Δ t = -0.94, there is no negative Δt, so we must make positive! → Δ t = 0.94mtr

C. Aft d = LCF draught + Δt Fore d = Aft d - trim

Aft d = 3.07 + 0.94 Fore d = 4.01 – 1.86

Aft d = 4.01mtr Fore d = 2.15mtr

D. Md = (Aft d + Fore d) / 2

Md = (4.01 + 2.15) / 2

Md = 3.08mtr

Step 4: List and Wind Surface moments

A) List

W e must calculate our GZ arm with:

GZ = Mtcg / weight

GZ = -416.61 / 4155.5

GZ = -0.100mtr

We must make the table and chart now, to calculate what our list is and afterwards also what our Wind Surface moments are. We make use of Appendix E to get the KNsinφ and put the values in a table together with the calculated KGsinφ.

By subtracting these 2 we get our GZ arm values. We also have to apply a correction on GZ, using the formula:

GZ correction = GM correction * sinφ

So our final GZ value will be: GZ final = GZ – GZ correction

You see that we have a negative GZ arm. Remember what is explained in Step 4 about having a negative GZ arm value.

We’ll write down the note one more time:

Info: If GZ is negative the list is to Portside, if GZ is positive the list is to Starboard side.

Image 40: Table and cross curve chart

Looking in the chart for our GZ value of -0.100mtr we find that we have a list of 2˚ to Portside.

You can also use the interpolating method and calculate the list.

Дата добавления: 2015-11-14