Master Yachts | Seamanship Flashcards
Heavy Weather
What are the dangers associated with a Head Sea?
- May cause pounding (slamming), large quantities of water on fore deck
- Violent shocks on board
- Stern lifting from water causing engines to race
- Smashing forward facing windows
What actions can be taken to mitigate head seas?
Put sea slightly to one side of bow, maintain steerage with minimum power, manual steering. The crew should be put on short watches as they will tire easily.
What is synchronous rolling?
When the period of roll of the vessel is equal or nearly equal to the wave period. The result is the vessel rolls with the waves, increasing the angle of roll. The OOW must be alert to this and change course rapidly.
If a vessel is disabled (lost engines) in heavy seas, what action may be taken to keep the bow into the seas?
By partially lowering anchor and cable into the water to act as a sea anchor.
Heavy Weather
What precautions should be taken when launching a rescue boat in heavy seas?
- Vessel manoeuvred to provide lee for launching
- Launch timed so craft lands on wave peak
- Check engine before painter release
Heavy Weather
What water freeing arrangments should be checked before heading to sea?
- Freeing ports, hinges and flaps
- Scuppers
- Deck drains including grid underneath to be flushed and cleared
What tender related items should be considered before heading into heavy seas?
- Tenders secure with lashings
- Remove loose gear
- Empty fuel tanks
- Disconnect batteries
- Test bilge pumping systems
An emergency towing booklet is required under SOLAS II-1, what considerations should be considered before operations take place?
- PPE
- Equipment maintained
- trained crew
- communications
- gear laid out
- crew clear of snap back zones
- minimise time spent in danger areas
- responsible officer in charge
- letting go controlled, tow rope lowered using messenger
- COLREGS complied with
- legal considerations - towage or salvage
- suitability of vessel
- fuel onboard
- weather
When undertaking emergency towage, what manoeuvering considerations are there?
- Ideally tow kept on the quarter
- Length of tow as long as possible to absorb shocks, but will depend on swell length and drag effect - tow should match (multiple) swell lengths.
What does ‘Headreach’ mean?
It is the distance the vessel will travel forward after the engines have stopped.
What does ‘Advance’ mean in reference to ship handling?
Is the distance travelled on original track as it starts a turn, ending once the vessel is 90 degress to original course.
What is the ‘Pivot point’ of a vessel?
- Stationary - normally at the centre of gravity.
- Moving ahead - about 1/4 waterline length from the bow
- Moving astern - about 1/4 waterline length from the stern
What is transverse thrust?
- The helical (spiral) discharge from the propeller creates a larger pressure on one side.
- Looking towards the stern, a clockwise rotating prop will push the stern to starboard whilst running ahead.
- More signifiacnt when going astern as it cannot be countered by the rudder.
How does the ‘bank effect’ impact the navigation of a vessel?
When in close to a river edge or canal bank the bow will be pushed away. The stern initially pushed away but then drawn in, caused by the accelerated flow of water. This can be controlled by helm and adjustment of speed.
How does a vessel interact with another vessel when passing each other?
The bows will be pushed away and the sterns towards each other. Countered by small repulsive force.
What are the signs of squat?
- Increased wash
- Increased vibration
- Loss of speed
- Steering more difficult
Reduce speed to reduce effects of squat.
What does a Pilot card and Wheelhouse poster display?
Manoeuvring data obtained from pre-delivery trials. Including ship dimensions, engine and thruster details and turning circles at different speeds.
What are the specifications to a pilot ladder when rigged correctly?
- Minimum spreader length, 180cm
- 31 to 35cm betwwen steps
- Minimum step width 40cm
- 5th step from bottom must be spreader
- Maximum 9 steps between spreaders
- Man-ropes min diameter 28mm, maximum diameter 32mm
- Handhold stanchions minimum 120cm above bulwark
What methods would you possibly use to clear a fouled anchor?
- Move ahead so the cable ‘grows’ astern
- Drive the vessel around in tight circle
- Bring the cable to the deck, apply slip line and walk anchor out to free
What does ‘foul hawse’ relate to?
When both anchors are in use and the cables cross due to rotation of the vessel
What actions should be taken when dragging anchor?
- Inform Master
- Inform engine room and request engines and thrusters
- Sound general alarm if dragging towards coast
- Veer more cable
- Release other anchor
- Contact other vessel in direction of travel
If, upon receiving a distress message, it is determined that the vessel is unable, or it is considered unreasonable or unnecessary to proceed to their assistance, what must be entered into the official log book?
Master must enter the reason for failing to proceed to their assistance - SOLAS V, reg 33
Why would a vessel purposely beach and if time permits what would be the ideal conditions?
- To avoid collision
- Prevent loss of vessel when damaged and in dange of sinking
- Beach on gently sloping sand, rock free beach
- Little current and surf, appraoched at high tide
- Bow on preferred.
What methods of recovery are there for MOB?
- Williamson turn
- Single or Anderson turn
- Scharnov turn
