Example B.6.1 – Frictional securing of round wood on a 6,000 DWT ship
Clasification Society 2024 - Version 9.40
Statutory Documents - IMO Publications and Documents - International Codes - 2011 TDC Code – Code of Safe Practice for Ships Carrying Timber Deck Cargoes, 2011 – Resolution A.1048(27) - Annex B – Samples of Stowage and Securing Arrangements - B.6 Example calculation – frictional securing of transversely stowed round wood - Example B.6.1 – Frictional securing of round wood on a 6,000 DWT ship

Example B.6.1 – Frictional securing of round wood on a 6,000 DWT ship

Figure B.8 Midship section of 6,000 DWT ship frictional secured wood secured

Ship particulars

Length between perpendiculars, LPP: 101 metres
Moulded breadth, BM: 17.5 metres
Service speed: 13 knots
Metacentric height, GM: 0.50 metres

 The deck cargo has the dimensions L x B x H = 65 x 14.5 x 3.1 metres. The weight of the cargo is taken as 1,500 tons.

 Cargo properties

M = 1,500 ton = Mass of the section to be secured in tons, including absorbed water and possible icing
μstatic = 0.35 = Coefficient of static friction between the timber deck cargo and the ship's deck/hatch cover
H = 3.1 m = Height of deck cargo in metres
B = 14.5 m = Width of deck cargo in metres
L = 65 m = Length of the deck cargo or section to be considered in metres
PW = 202 kN = Wind pressure in kN based on 1 kN per m2 wind exposed area, see CSS Code, Annex 13
PS = 130 kN = Pressure from unavoidable sea sloshing in kN based on 1 kN per m2 exposed area, see CSS Code, Annex 13

 Transverse acceleration

With a static friction of 0.35 between the layers of wood and between the wood and the hatch cover the maximum acceptable transverse acceleration can be calculated by satisfying the following equilibrium:

 In this case transverse acceleration cannot exceed 3.2 m/s2 as shown below:

at = 3.2 m / s2

 With vessel particulars as above and considering a stowage position on deck low, Annex 13 of the CSS Code gives the following basic acceleration and correction factors:

at basic = 6.5 m/s2 = Basic transverse acceleration
fR1 = 0.93 = Correction factor for length and speed
fR2 = 1.00 = Correction factor for BM/GM

 The maximum allowed significant wave height HS with this stowage arrangement is calculated as 2.4 m according to the following:

fR = 1 - (Hs - 13)2 / 240

Hs = 13 - = 2.4 m

Parent topic: B.6 Example calculation – frictional securing of transversely stowed round wood
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