Hey folks
Has anyone had any experience using this BS6349 standard for mooring design of vessels in the neighbourhood of 40,000 DWT?
I am doing a jetty following this standard, and I am having difficulties with the water depth correction factors (figure 30). When I do my calculations as reqd, the lateral vessel forces are insanely high.
We have a longitudinal current of 4 knots (~2 m/s) which is admittedly a bit high. The lateral forces resulting from perfectly aligned current with the vessel is zero. If I consider the current shifting off the bow by only 10 degrees (which is not unreasonable), the forces jump to a ridiculous lateral force of 12,300 kN which seems to be primarily a result of the depth correction factor. According to figure 30, the correction factor should be about 9.5 (for our case d/dm = 1.17).
Ftc = Ctc*Cct*row*Lbp*Dm*Vc^2*10E-4
At 10 degrees
With Ctc = 0.16
Cct = 9.5
Row = 1025 kg/m3
Lbp = 180m
Dm = 10.7m
Vc = 2.06 m/s
If I design as per the OCIMF standard for VLCCs and scale it down to a 40,000 DWT, the design force is about 1000 & 2000 kN for the lateral fwd and aft reactions respectively… which ‘feels’ right. Now what I can’t understand is that the OCIMF is supposedly based on the BS6349 standard.
Following the Canadian Termpol calculation, I only get about 1000 kN lateral.
I was originally following the 1984 version of the BS standard which has been superseded. I naturally suspected that there was an error or an adjustment in the 2000 version… which there was not.
Thanks for any insights
DRW
Has anyone had any experience using this BS6349 standard for mooring design of vessels in the neighbourhood of 40,000 DWT?
I am doing a jetty following this standard, and I am having difficulties with the water depth correction factors (figure 30). When I do my calculations as reqd, the lateral vessel forces are insanely high.
We have a longitudinal current of 4 knots (~2 m/s) which is admittedly a bit high. The lateral forces resulting from perfectly aligned current with the vessel is zero. If I consider the current shifting off the bow by only 10 degrees (which is not unreasonable), the forces jump to a ridiculous lateral force of 12,300 kN which seems to be primarily a result of the depth correction factor. According to figure 30, the correction factor should be about 9.5 (for our case d/dm = 1.17).
Ftc = Ctc*Cct*row*Lbp*Dm*Vc^2*10E-4
At 10 degrees
With Ctc = 0.16
Cct = 9.5
Row = 1025 kg/m3
Lbp = 180m
Dm = 10.7m
Vc = 2.06 m/s
If I design as per the OCIMF standard for VLCCs and scale it down to a 40,000 DWT, the design force is about 1000 & 2000 kN for the lateral fwd and aft reactions respectively… which ‘feels’ right. Now what I can’t understand is that the OCIMF is supposedly based on the BS6349 standard.
Following the Canadian Termpol calculation, I only get about 1000 kN lateral.
I was originally following the 1984 version of the BS standard which has been superseded. I naturally suspected that there was an error or an adjustment in the 2000 version… which there was not.
Thanks for any insights
DRW