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BS6349

BS6349

(OP)
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I was originally following the 1984 version of the BS standard which has been superseded.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
 

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