February 08, 2012

Corrections check list

Forward...P & S                aft...P & S               midships...P & S
Mean values, ie. draughts at centreline, forward, aft and midships.
Correct from marks to perpendicular and midships positions.
Misplacement opposite to trim, then positive (+)
Misplacement same as trim, then negative (-)
Hog/sag correction (mean of mean of means, or similar).
negative (-) for hog          positive (+) for sag
CORRECTED MEAN DRAUGHT ... to enter hydrostatic tables.
Displacement from displacement table.
First trim correction or Correction for layer (in tonnes).
LCF same as trim, then positive (+)
LCF opposite to trim, then negative (-)
Second trim correction (in tonnes).
Always positive (+)
List correction (in tonnes).
Always positive (+)
Correction for density.
Less than salt water density, then negative (-)

Information check list

Ship's name                                                      Call letters                                                  Port of registry
Flag                                                                  Year built                                                   Master
Owners                                                            Owner's address                                         Owner's agent
Manager/operator                                             Charterer                                                    Charterer's agent
Shipper                                                            Chief Officer                                              Chief Engineer
Surveyor/s                                                       P&l correspondent                                     Ship's location
Survey requested by:                                       Survey on account of:                                Type of cargo
Weather conditions                                          Date and time of arrival
Length between perpendiculars
Extreme and moulded breadth
Overall and moulded depth
Summer draught and freeboard
Summer displacement and deadweight
Misplacement of draught marks from perpendiculars and midships
Lightship displacement with lightship constant
Hydrostatic particulars:
Displacement, TPC, MCTC, LCB, LCF
Capacity plans and tables
Correction tables:
Position of marks
Hull deflection
General arrangement plan
Profile plan indicating each space in the ship
Sounding tables and corrections for trim
Quantity of bunkers

Check list of reservations

(Not an exhaustive list)
Height of waves / swell
Clarity of draught marks
State of tide - underkeel clearance
Squat effects
Variations in density
Daytime / night-time
Anchors moved, in or out
Ice / snow on deck
Quantity of bilges pumped
Residue in tanks
Suspect calibrations
Ship movements

Documentation and information

Surveyors and ship's officers should discuss documentation details and the location and state of all compartments. The instruction pages of the stability information book and calibration tables should be studied and a check made of the tank capacities with the capacity plan. It should be remembered that the port and starboard tanks may not be the same and consequently have separate calibration tables.
The base for measurement of vertical heights, the reference point for longitudinal measurements, the units and the sign conventions used in the tables must all be verified. The units used in the correction tables should also be carefully noted because there is sometimes a mixture of units and sign conventions contained within the same documentation. The whole survey should be conducted using the units of the ship and the final result changed to a suitable unit, if necessary. When feet and inches are the standard unit, convert to feet and decimals of a foot for the convenience of a calculator.
The full sounding depths of tanks, the summer draught and freeboard and the record of recent tank soundings should be noted.

Equipment check list

Sample jar and water sample bucket with line
Ballast tank dipper with line
Small hand pump with hose for taking samples
Draught survey hydrometer with certificate
Steel sounding tape with graduations in metres and feet
Water finding paste
Draught/freeboard measuring device
Manometer if some draughts are impossible to read, plus a long measuring tape
Plastic tube with plug, to act as sounding pipe extension
Boat available to read inaccessible draughts
Pilot ladder on board ready for obtaining draughts
Pocket computer with draught survey program or calculator