October 23, 2020

Purchases and tackles

Purchase. A purchase is a combination of blocks or pulleys rove with a rope, wire or chain. Tackle. A tackle is a purchase consisting of a rope rove and through two or more blocks, in such a way that any pull applied to the hauling part, is increased by an […]
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October 23, 2020

Mechanical advantage

All of the above tackles/purchases are designed to increase the power utilised to the effect achieved. Because of friction between the ropes and sheaves, the actual (theoretical) weight lifted can be roughly calculated as being: Weight + (1/10 x weight) for each sheave. The mechanical advantage gained can be found […]
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October 25, 2020

International regulations for the prevention of collision at sea (1972): Part A – General

RULE 1 – Application The abovementioned rules shall apply to all vessels upon the high seas and in all waterways connected therewith, navigable by seagoing vessels. Appropriate authorities may make special rules for harbours, roadsteads, rivers, lakes or inland waterways connected with the high seas and navigable by seagoing vessels, […]
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October 25, 2020

Part B – Steering and sailing rules – Section I

SECTION I – CONDUCT OF VESSELS IN ANY CONDITION OF VISIBILITY RULE 4 : Application. Rules in this section apply to any condition of visibility. RULE 5: Look-out. Every vessel shall at all times maintain a proper look-out by sight as well by hearing as well as by all available […]
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