Gl rules 2009 tug

I - Part 1 GL 2009

Section 25

B

Tugs

Chapter 1 Page 25–1

Section 25 Tugs
A. 1. General Scope, application – – – 1.1 The following requirements apply to vessels primarily designed for towing and/or pushing operations or assisting other vessels or floating objects in manoeuvring. Combination with other purposes is possible and will be noted accordingly in the Class Certificate, see2.2. 1.2 Unless specially mentioned in this Section, the requirements of Sections 1 – 22 apply. 1.3 Special designs not covered by the following rules will be considered from case to case. 1.4 For instructions regarding towing operations in general, see VI – Additional Rules and Guidelines, Part 11 – Other Operations and Systems, Chapter 1 – Guidelines for Ocean Towage. 2. Classification,notations – required bollard pull (design value) towrope specification in special cases, intended tow configuration(s) For examination of towing gear with towing winch, the direction of the towrope has to be indicated on the drawings.

The reliable function of the towing gear has 3.2 to be proven during the initial tests on board. 3.3 If a bollard pull test has to be carried out and will be certified byGL, it shall correspond to the procedure given in VI – Additional Rules and Guidelines, Part 11 – Other Operations and Systems, Chapter 1 – Guidelines for Ocean Towage. The test results shall be documented and kept on board together with the certificate of bollard pull testing and the classification documents. 3.4 GL material certificates will generally be required for: – towing hook and attachedload transmitting elements, including slip device towing winch, including frame, drum shaft(s), couplings, brakes and gear(s) towrope(s), including certification of breaking force

2.1 Ships built in accordance with the requirements of this Section will have the Notation TUG affixed to their Character of Classification 2.2 Where towing services are to be combined with other duties such asoffshore supply or ice breaking, corresponding additional class notations may be assigned if the relevant requirements are met. 3. Approval documents, documentation

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Material certificates according to DIN 50049-3.1B may be accepted for standard items, if the manufacturer is recognised by GL.

In addition to the documents listed in the 3.1 rules mentioned under 1.2 above, the following designdocumentation shall be submitted, in triplicate, for approval and/or information: – – general arrangement of the towing gear including winch(es), if provided design drawings and material specifications of towing hook and accessory towing gear, towrope guide and/or of the towing winch including winch drives, brakes and fastening elements slip device(s) including hydraulic/pneumatic systems andelectric circuits, and/or "weak link" for towrope on winch drum

B. 1.

Hull Structures Scantlings, general

For the determination of hull structure scantlings the draught T is not to be taken less than 0,85 H. 2. Deck structure

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2.1 On tugs for ocean towage, the deck, particularly in the forward region, shall be suitably protected or strengthened against sea impact.

Chapter 1 Page25–2

Section 25

C

Tugs

I - Part 1 GL 2009

2.2 Depending on the towrope arrangement, the deck in the aft region may have to be strengthened (beams, plate thickness), if considerable chafing and/or impact is to be expected. See also C.1.5. 3. Fore body, bow structure

coamings shall extend to the lower edges of the beams. 6.2 The stiffeners of the casing are to be connected to thebeams of the casing top and are to extend to the lower edge of the coamings. 6.3 Regarding height of casing and closing arrangements as well as exits see also F.1.1. 6.4 The following requirements have to be observed for superstructures and deckhouses of tugs assigned for the restricted services areas RSA (50) and RSA (200) or for unlimited range of service: – The plate thickness of the external...