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APPENDIX "A"
GUIDELINES FOR TUG AND BARGE SYSTEMS USED FOR THE TRANSPORTATION OF OIL IN BULK

Preamble

Section 79 of the Oil Barge Standards requires the owner and the Master of any tug used for oil barge towing to ensure that the tug and towing equipment are in all respects capable of maintaining safe control over the oil barge in all foreseeable conditions during the intended voyage.

Safe tug-barge matching decisions require the assessment of a number of variables related to the characteristics of the vessels concerned, the weather and navigational conditions likely to be encountered, the availability of safe refuge and the experience of the crew. The following guidelines are provided to assist rather than to direct the tug-barge matching process, it being emphasized that operational and environmental safety must be the prime concerns when tug-barge assignment decisions are made.

Primary Towlines ^

1.1 The bollard pull of every tug that tows an oil barge on Foreign, Home Trade or Inland Waters voyages should be determined by a recognized test procedure, and checked by retest whenever changes are made to the propulsion system that affect bollard pull.

1.2 The towline should

(a) comply with the strength criteria given in Table 1, which were derived from successful Canadian towing practice, and

(b) be supplied to the tug with manufacturer's certificates which attest to the strength rating thereof.

TABLE 1

TUG BOLLARD PULL VS TOWLINE BREAKING STRENGTH
for tugs not exceeding 100 te bollard pull

1.3 The breaking strength of chains, bridles, shackles and other gear used in making up the towline assembly should be consistent with the breaking strength of the towline.

1.4 A formal towline inspection schedule and procedure should be established for every tug, to provide for

(a) visual examination of the towline and associated equipment prior to each voyage,

(b) regular towline lubrication,

(c) towline testing, end-for-end rotation, and replacement, and

(d) sign-off by the officer responsible for each towline inspection or maintenance procedure.

Bollard Pull of Towing Vessel ^
2. The following empirical formula is widely used for determining the required bollard pull:

An examination of Canadian Coastal towing practice suggests that in those specific waters, a record of safe towing has been established using the following K values at a towing speed of six knots.

(a) for exposed coastal tows K = 1.0 to 3.0

(b) for sheltered coastal tows K = 0.75 to 2.0

(c) for protected water tows K = 0.50 to 1.5

Two Independent Means of Propulsion ^

3. Every tug used for oil barge towing should be fitted with at least two independent means of forward propulsion, such that any one propulsion system is capable of providing sufficient thrust to maintain safe control of the oil barge in all anticipated navigational conditions.

Single Towing ^

4. Oil barges should be towed singly, except that where particular circumstances make such restriction impractical, a tow may consist of more than one oil barge provided the operational and environmental safety of the intended service is not impaired.

Tug Fenders ^

5. Every tug used for handling oil barges should be thoroughly fendered, with no protruding steel structure.

Emergency Towlines ^

6. Every emergency towline assembly should consist of

a) flexible steel wire rope towline of length not less than the length (L) of the oil barge, and breaking strength not less than three times the required bollard pull of the towing vessel; and

b) messenger and trailing lines of size and length that ensure the safe pick-up and handling of the wire rope towline to the towing vessel, so arranged that the trailing line is

(i) of sufficient length to extend at least 35m astern of the oil barge, and

(ii) provided at its trailing end with a clearly visible marker buoy.

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