Vessel Surface Coating Condition Survey

Adequate surface protection is fundamental in coatings work. The surface finish or coating should have a pleasant appearance and be able to protect the structure against deterioration from its more or less corrosive surroundings and to some degree from mechanical loads and impacts.

The psychologically positive effect of an aesthetically successful coating should not be underestimated, even in ships’ ballast tanks. This is clearly demonstrated by the lengthy discussions about the IMO/SOLAS recommendation of using light-colored coating, 5–6 which basically was introduced to facilitate inspections.

The “market” concerned with protective coatings for ships includes not only ship owners and shipyards but also maritime authorities, ship brokers, the coating industry, the ships’ crew, and really the general public.

In simple terms, shipyards have a fundamental interest in building ships quickly and effectively. The market generally wants ships to be in good shape, nice looking, safe, and economical in operation.

Surface protection, including steel preparation and application of coating materials, adds considerable cost to a ship, so an optimal coating quality at an acceptable cost must be sought.



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Critical areas for corrosion on single hull tankers.


Critical areas for corrosion on double hull tankers.


Typical areas under consideration in the after peak and fore peak ballast tank on a tanker and bulk carrier.



Special Thanks to Capt. Harry González




Container Ship Survey Guide

Container Filled Vessel Survey Guidelines

Container ships are cargo ships that carry their entire load in truck-size intermodal containers, in a technique called containerization. They form a common means of commercial intermodal freight transport.

There are several key points in the design of modern container ships. The hull, similar to bulk carriers and general cargo ships, is built around a strong keel. Into this frame is set one or more below-deck cargo holds, numerous tanks, and the engine room. The holds are topped by hatch covers, onto which more containers can be stacked. Many container ships have cargo cranes installed on them, and some have specialized systems for securing containers on board.

Container Vessel Survey

The hull of a modern cargo ship is a complex arrangement of steel plates and strengthening beams. The hull is built around the keel. Resembling ribs, and fastened at right-angles to the keel are the ship’s frames. The ship’s main deck, the metal plate work that covers the top of the hull framework, is supported by beams that are attached to the tops of the frames and run the full breadth of the ship. The beams not only support the deck, but along with the deck, frames, and transverse bulkheads, strengthen and reinforce the shell. Another feature of recent hulls is a set of double-bottom tanks, which provide a second watertight shell that runs most of the length of a ship. The double-bottoms generally hold liquids such as fuel oil, ballast water or fresh water.

A ship’s engine room houses its main engines and auxiliary machinery such as the fresh water and sewage systems, electrical generators, fire pumps, and air conditioners. In most new ships, the engine room is located in the aft portion of the ship.


Container Ship survey1 Container Ship survey2 Container Ship survey3  Container Ship survey5 Container Ship survey6 Container Ship survey7


Special Thanks to Capt. Harry González



Draft Survey Guide

How to Conduct Bunker Survey
What is Bunker Survey? The survey is carried out to measure and ascertain the quantity of Bunker onboard at the specific time. This survey is produced the report that states the amount of bunker, usually Fuel Oil (FO) and Diesel Oil (DO), and sometimes Lubricating Oil (LO) is included.


In this post limits to how to conduct the Bunker Survey on the ship tanks only.

Survey Tools required for Bunker Surveyor
  • Notes Book,
  • Sounding Tape,
  • Thermometer,
  • Density Meter for Oil (),
  • Oil and Water Paste,
  • Petroleum ASTM Table 54B (for Product Oil) and Table 56,
  • Flashlight,
  • Sampling Can,
  • Bottle or Can for Sampling (if required taken samples).
 Steps for Conducting Bunker Survey

Identify and records the number and Depth of Tank, Reference Height, and Measuring Method recommended to use (Ullage or Sounding) for each Oil Tank. Sounding is determined the level of liquid tank from the bottom of the tank to the liquid surface (typically applied for light liquid).

Ullage means to determine the level of liquid of tank by measured the empty space from top of the Tank (the mouth of Sounding Pipe) to the liquid surface (typically applied for heavy liquid). The both methods will point to the same result.

Record the Last Bunker Report, Time and Place of last Bunker supplied, includes the Oil density.

Records the quantity of bunker onboard when the ship arrives at Port (arrival Condition) as per Engine Log Book.

Checking the accuracy of the Sounding Tape, it is recommended to use your own Sounding Tape. In case we used Ship’s Sounding Tape, please checking the tape.

Sounding each Oil Tank and records the level of Oil on the tank. Attached the sounding Tape with Oil Paste to make easy and clear to show of oil level (recommended for Light Oil).

Check the Ship’s Draft Marks to get the Ship Trim for Trim correction, and check the ship Inclination or Listing for List Correction, that is required to calculate the Tank Quantity Table.

Taken Oil sample, check temperature and oil density, for the accessible tank only. The Service and Settling Tanks are not accessible due to the oil on that tanks were in heating condition at the high temperature. We could records the tank gauging for determining the quantity, the temperature at the thermometer available on each tank, and the Oil Density from the Engine Log Book. If you could not taken the oil sample for checking density, it is recommended to calculate the Density Commingle, by means the Combine Density between two Oils (Old and New Oils) that has mixed on one tanks which they have different in Density. Where it is approaching the actual oil density, the pattern is {(Old Oil Quantity x Oil Density / Total Oil on Tank) + (New Oil Quantity x Oil Density / Total Oil on Tank)}.

Calculations, this stage will involved the Sounding level of each tank, Ship’s Trim and List, Tank Quantity Table (provided by Ship’s Chief Engineer), Oil Density and Temperature, ASTM Table 54B to ascertain the Volume Correction Factor (VCF – to convert from Cubic Meter to Kiloliter) and ASTM Table 54B for Weight Correction Factor (WCF – to convert from Kiloliter to Metric Ton). 

Example to calculate Density Commingle: FO Tank No. 1 C, total oil on tank 400 Cu.M, Old Oil 200 Cu.M with density 0.9870, and New Oil 200 Cu.M with density 0.9720. Density Commingle = {(200 x 0.9870 / 400) + (200 x 0.9720 / 400)} = 0.4935 + 0.4860 = 0.9795.

Issued the Tank Sounding and Bunker Report.

Draft Survey: Procedures and Calculation



The Draft Survey procedures and calculation ascertained as the following series :

  1. Reading the draftmark of the ship, which consist of six (6) points of draftmarks, i.e.; Fore, Midship, and After at both sides of the ship,
  2. Sampling and testing the sea water or dock water density at the place where the vessel floats,
  3. Determining of deductible weights by measuring and sounding of ballast tanks, fuel oil, fresh water that existing onboard at the time of survey,
  4. Using Hydrostatic Table provided onboard to calculation.
Reading the Draftmark of the ship
Commonly, all ship are designed with draftmark for working with Draft Survey to determined their actual weight. The draftmark could be find at six (6) points on the below places:
  • Forward Port Side (FP),
  • Forward Starboard Side (FS),
  • Midship Port Side (MP),
  • Midship Starboard Side (MS),
  • Aftward Port Side (AP),
  • Aftward Starboard Side (AS),
View the Draftmark:
Use the small boat to go around the ship and get as near as possible to the draft mark for best viewing. The surveyor should be read all above marks clearly, because reading the draftmark is the first and most essential process. I am not saying that other processses is not essensial, but this process is hard to do and involves many rules of conduct to gain the correctness and accuracy of Draft Survey itself (I will post it later). The draftmark read is recorded on the surveyor notebook, do not try to remember it or write down in your palm hand. Its useless and un-professional.
Sampling and testing the sea water or dock water density 
After reading the draftmark, directly engage with the sampling of sea water or river water around the ship’s dock.  Why? Because the ship draft will not be the same at different water densities (at the lower density means the ship more sink and at the higher density means the ship more float).  Where as the water density is subject to changes which follow with water tide that carrying different water salinity and temperature on to the ship dock. The sea water density is indeed at density 1.025 and the fresh water at density 1.000. To determine the density of water, we need the instrument named Hydrometer or Density Meter. Inserted the Hygrometer on to the water sample on the Sampling Can or Tube, then we could check the scale pointed on the surface of the sampling water. Records the water dock density as survey data.
Determining of deductible weights by measuring and sounding
Deductible Weight could measure by sounding  the tanks which used the Sounding Tape or gauging the tank level by visual inspection. Any deductible weight such as Ballast Water, Fresh Water, Fuel and Diesel Oil, and Bilges is notify to check. Records all in the survey book includes with the density for Ballast and Bilges, and for Oil complete it with density and temperature . The Fresh Water was at density 1.000.
View the Sounding Pipe:
Using Hydrostatic Table provided onboard to begin calculation, 
I think all necessary data was completed, so we could do calculation. The calculation is uses Displacement Table or usually called Hydrostatic Table. This table is included all data that we need to complete the calculation.
  • Raw Draft Calculation; Fore Mean or Fm = (FP+FS)/2, Mid Mean or Mm = (MP+MS)/2, and Fore Mean or Am = (AP+AS)/2. while Apparent Trim  or AT = Am – Fm. the Apparent Trim is the Trim that visually find.
  • Draftmark posision and correction to perpendicular. As the ship draftmark is not placed at the perpendicular, the Fore and After draft should be corrected with distance from the draftmark to perpendicular. The correction rules is: if the Trim by Stern, the Fore correction should be minus and After correction plus, and if the Trim by Head (stem), the Fore correction should be plus and After correction minus. The Midship correction is parallel with the fore correction with the same pattern. Some Hydrostatic table provided with these correction result. But if not the reference pattern is  for Fore Correction or Fc = (Fd x AT) : LBM and After Correction or Ac = (Ad x AT) / LBM. Where Fd = Fore distance to perpendicular, Ad = After distance to perpendicular, and LBM = Length Between Mark or Length between Fore and After draftmarks  or LBM = LBP – (Fd + Ad).
  • True Draft Calculation / Draft Corrected; Fore draft corrected or Fcd = Fm + Fc, Mid draft corrected or Mcd = Mm + Mc, and After draft corrected or Acd = Am + Ac.
  • True Trim or TT : Actual  Ship Trim after draft corrected or  TT = Acd – Fcd.
  • Fore and After Mean Draft or FAm = (Fcd + Acd)/2, Mean of Mean Draft or MM = (FAm + Mcd)/2, and Mean of Mean of Mean Draft  or MMM or Quarter Mean = (MM + Mcd)/2.
  • The above calculation is similar with : MMM = {(Fcd x 1) + (Acd x 1) + (Mcd x 6)}/8.
  • Coresponding to the MMM or Quarter Mean result, the surveyor could check the value of needed parameters on Hysdrostatic table like; Displacement, TPC, LCF, and MTC. Records them accurately.
  • Get the Displacement or Disp.
  • First Trim Correction or FTc = (TT x LCF x TPC x 100) / LBP. Could be plus or minus depend on LCF.
  • Second Trim Correction STc = (TT x TT x MTC x 50) / LBP. The result always plus (+).
  • Displacement corrected by Trim or DispT = D – (FTc + STc).
  • Density Correction or Denc = DispT x {(Aden – 1.025) / 1.025}. where the Aden is Actual Density that surveyor has taken sampling and testing previously. The density correction commonly in minus (-), due to the Actual Density is usually lower than 1.025 (fresh sea water). In case of at some port where the water salinity is high, the density correction could be plus (+).
  • And we have got the Displacement corrected by Density or DispDenc = DispT + Denc. (after corrected by density we will get the actual ship weight as per shown by Draft Survey).
  • Deductible Calculation. The same as draft, the deductible also need to corresponding to the table that named Tank Table / Tank Capacity Table. Refer to the sounding records that done before, the surveyor could be calculate the total deductbile existing onboard. Total Deductible or Deduct =  Ballast Water + Fresh Water + Bilges + Fuel Oil + Diesel Oil,  this total should be minus to the Displacement corected by Density.
  • The Net Displacement or NDisp = DispDenc – Deduct.
  • The Net Displacement is the actual ship weight after minus with deductible weight. For Unloading, to estimate the quantity of cargo onboard, the Net displacement should be minus withLight Ship and Constant.


Special Thanks to Capt. Harry González



Initial Hull Survey and Annual Hull Survey



Initial Hull surveys

The initial survey, as required by the relevant regulations, should be held before the ship is put in service and the appropriate certificate is issued for the first time.

The initial survey before the ship is put into service should include a complete inspection, with tests when necessary, of the structure, machinery and equipment to ensure that the requirements relevant to the particular certificate are complied with and that the structure, machinery and equipment are fit for the service for which the ship is intended.

The initial survey should consist of:
an examination of the plans, diagrams, specifications, calculations and other technical documentation to verify that the structure, machinery and equipment comply with the requirements relevant to the particular certificate;
an inspection of the structure, machinery and equipment to ensure that the materials, scantlings, construction and arrangements, as appropriate, are in accordance with the approved plans, diagrams, specifications, calculations and other technical documentation and that the workmanship and installation are in all respects satisfactory;
a check that all the certificates, record books, operating manuals and other instructions and documentation specified in the requirements relevant to the particular certificate have been placed on board the ship.

Examination of plans and designs
An application for an initial survey should be accompanied by plans and designs as required by Administration or Class Society, as appropriate, together with:
the particulars of the ship;
any exemptions sought;
any special conditions.


Annual Survey of Hull


The annual survey, as required by the relevant regulations and as shown diagrammatically in the harmonized system of survey and certification, should be held within three months before or after each anniversary date of the certificate.


An annual survey should enable the Administration to verify that the condition of the ship, its machinery and equipment is being maintained in accordance with the relevant requirements.

In general, the scope of the annual survey should be as follows:

a. it should consist of a certificate examination, a visual examination of a sufficient extent of the ship and its equipment, and certain tests to confirm that their condition is being properly maintained;

b. it should also include a visual examination to confirm that no unapproved modifications have been made to the ship and its equipment;

c. the content of each annual survey is given in the respective guidelines. The thoroughness and stringency of the survey should depend upon the condition of the ship and its equipment;

d. should any doubt arise as to the maintenance of the condition of the ship or its equipment, further examination and testing should be conducted as considered necessary.

Where an annual survey has not been carried out within the due dates, reference should be made to re-validation of certificates.


Special Thanks to Capt. Harry González