Derrick On Ship
You may also like
General Cargo Ship
Uses of Derrick onboard Ship
2.position of inboard and outboard booms;
3. maximum headroom (i.e. permissible height of cargo hook above hatch coaming);
4. maximum angle between runners;
6. length, size and safe working load of runners, topping lifts, guys and preventers;
7. safe working load of shackles;
8. position of derricks producing maximum forces
9. optimum position for guy and preventers to resist maximum forces as at
Precaution and Maintenance of derrick
5.When a single span derrick is being raised, lowered or adjusted, the hauling part of the topping lift or bull-wire (i.e. winch end whip) should be adequately secured to the drum end.
6.The winch driver should raise or lower the derrick at a speed consistent with the safe handling of the guys.
7.Before a derrick is raised, lowered or adjusted with a topping lift purchase, the hauling part of the span should be flaked out for its entire length in a safe manner. Someone should be available to assist the person controlling the wire on the drum and keeping the wire clear of turns and in making fast to the bitts or cleats. Where the hauling part of a topping lift purchase is led to a derrick span winch, the bull-wire should be handled in the same way.
8.To fasten the derrick in its final position, the topping lift purchase should be secured to bitts or cleats by first putting on three complete turns followed by four crossing turns and finally securing the whole with a lashing to prevent the turns jumping off due to the wire’s natural springiness.
9.When a derrick is lowered on a topping lift purchase, someone should be detailed for lifting and holding the pawl bar, ready to release it should the need arise; the pawl should be fully engaged before the topping lift purchase or bull-wire is released. The person employed on this duty should not attempt or be given any other task until this operation is complete; in no circumstances should the pawl bar be wedged or lashed up.
10.A derrick with a topping winch, and particularly one that is self- powered, should not be topped hard against the mast, table or clamp in such a way that the initial heave required to free the pawl bar prior to lowering the derrick cannot be achieved without putting an undue strain on the topping lift purchase and its attachments.