Start hereRules checked 20 October 2026
A ship’s crane works for years at or near its safe working load (SWL). Corrosion in the pedestal, a cracked weld on the jib or a worn slewing bearing can go unseen until the day the crane drops a load or collapses. The two oldest defences in the book are simple: a competent person looks at everything closely every year, and every five years the crane lifts more than it is ever allowed to lift in service, under controlled conditions, to prove the structure still has a margin.
The numbers behind that test are not a matter of opinion. They come from a table that the ILO has used for decades and that IMO copied into the SOLAS guidelines in 2023. Try it below, then read how the cycle works.
Try it
Test load for a ship's crane or derrick
In plain words
Every lifting appliance on a ship goes through a repeating cycle:
- Every 12 months: a competent person carries out a thorough examination: a close, systematic look at the whole crane, with measurements, tests and dismantling where needed.
- Every 5 years, and after any major repair or alteration: a load test. A test load heavier than the SWL is lifted, slewed and luffed, and then the crane is thoroughly examined again.
- Before first use: the same load test and thorough examination when it is new.
The test load is a fixed margin over the SWL: 25% extra for small cranes, a flat 5 tonnes extra in the middle range, and 10% extra for heavy cranes. Loose gear (shackles, hooks, blocks, lifting beams) has its own, much higher, proof test, usually done once by the maker and repeated only after repair.
In detail
The test load table
MSC.1/Circ.1663 table 1, the same figures as the ILO code of practice appendix D and the reverse of ILO Form No. 2:
| SWL of the lifting appliance | Minimum test load |
|---|---|
| Up to and including 20 t | 1.25 × SWL |
| Over 20 t up to and including 50 t | SWL + 5 t |
| Over 50 t | 1.10 × SWL |
The calculator above applies this table. Worked examples:
- 8 t provision crane: 1.25 × 8 = 10 t.
- 30 t cargo crane: 30 + 5 = 35 t.
- 120 t heavy-lift crane: 1.10 × 120 = 132 t.
The bands join up: at 20 t both the first and second rules give 25 t; at 50 t both the second and third give 55 t. The table applies to appliances used in port or sheltered waters. For cranes used in open-sea operations, such as offshore supply transfers, the test load is set by the Administration or the RO taking account of dynamic loads, so it is often higher.
The ILO code of practice adds practical limits. The weight of the test load, including its lifting gear, should be not less than the table figure and should not exceed it by more than 2.5%. For hydraulic cranes where pressure limits make the full 25% impossible, the reverse of ILO Form No. 2 accepts the greatest load that can be lifted, but in general not less than 10% over the SWL.
Loose gear proof tests
Loose gear is tested to a higher multiple because it is small, highly stressed and easily abused. MSC.1/Circ.1663 table 2:
| Item | SWL | Minimum test load |
|---|---|---|
| Single-sheave block | all | 4 × SWL |
| Multi-sheave blocks and hook blocks | up to 25 t | 2 × SWL |
| over 25 t to 160 t | (0.933 × SWL) + 27 | |
| over 160 t | 1.1 × SWL | |
| Hooks, shackles, chains, rings, swivels | up to 25 t | 2 × SWL |
| over 25 t | (1.22 × SWL) + 20 | |
| Lifting beams, spreaders, frames, grabs | up to 10 t | 2 × SWL |
| over 10 t to 160 t | (1.04 × SWL) + 9.6 | |
| over 160 t | 1.1 × SWL |
A note for the careful reader: the circular as printed in 2023 shows 0.993 for multi-sheave blocks. The ILO code, ILO Form No. 3 and Liberia’s corrected marine notice all use 0.933, which is the value that makes the formula meet 2 × SWL at 25 t and 1.1 × SWL at 160 t. Use 0.933.
For a single-sheave block, the SWL is taken as half the resultant load on the head fitting. For a multi-sheave block, it is the resultant load on the head fitting.
What the annual thorough examination covers
The SOLAS guidelines list items that need particular attention:
- corrosion and damage of primary structure: jib, crane housing, pedestal, foundations, welds and bolts;
- wear, corrosion and damage of winches, hydraulic cylinders, slewing bearings, sheaves and pins;
- setting and function of safety, protection and limiting devices (limit switches, overload protection, emergency stop);
- the hydraulic and pneumatic systems, hoses, piping, brakes and drums;
- the means of access, platforms and their brackets and welds;
- certification and identification of ropes.
The ILO code adds that for ship’s gear the examination includes associated fittings such as deck eyes, mast bands and cleats, and that parts are dismantled where the competent person considers it necessary. Blocks will usually be stripped so the pin can be examined. Appliances used to lift persons should be thoroughly examined at least every six months under the ILO code.
When a load test is triggered early
A load test is needed after “repairs, modifications or alterations of a major character”. The guidelines define these as work that changes the SWL; affects the strength, stability or service life; affects the primary load-bearing structure; or modifies the functionality in a way that may affect strength, safety or structural integrity. Renewing a hoist wire with an identical certified wire is normally not in that list; renewing a slewing bearing or cropping and welding a jib section is.
How it fits the survey cycle
Where the thorough examination is not itself part of the annual or renewal survey, the surveyor verifies at that survey that it has been done. Some flags let the 12-monthly and five-yearly dates follow the harmonized survey windows. That suits SOLAS, but ports that apply ILO C152 count 12 months and five years strictly, so plan to the stricter of the two.
What the rules say
- MSC.1/Circ.1663 paragraph 3.2.1.4 says lifting appliances subject to SOLAS II-1/3-13.2.1 and 2.4 should be retested at least once in every five years. 1
- MSC.1/Circ.1663 paragraph 3.2.2.1 requires a thorough examination upon completion of any load test and annually. 1
- MSC.1/Circ.1663 paragraph 3.2.1.5 and table 1 set the minimum test load at 1.25 × SWL up to 20 t, SWL + 5 t from 20 t to 50 t, and 1.10 × SWL above 50 t, for use in port or sheltered waters; open-sea appliances are tested to the satisfaction of the Administration or RO taking account of dynamic loads. 1
- MSC.1/Circ.1663 paragraph 3.2.1.3 defines repairs, modifications or alterations of a major character, which trigger a new load test under paragraphs 3.2.1.1 and 3.2.1.2. 1
- MSC.1/Circ.1663 paragraph 4.2.1 and table 2 require documentary evidence of a proof test for all loose gear, a retest after major repair, and give the minimum loose gear test loads. 1
- ILO C152 Article 22 requires ship’s lifting appliances to be retested at least once every five years, and Article 23 requires a thorough examination at least once every 12 months. 2
- The ILO code of practice, appendix A paragraph A.3.3, says the test load should be not less than the appendix D figure and should not exceed it by more than 2.5%. 3
- The ILO code of practice, section 4.2.4 paragraph 2, recommends that appliances used to lift persons be thoroughly examined at least every six months. 3
- The reverse of ILO Form No. 2 allows hydraulic cranes that cannot lift 25% over SWL to be tested with the greatest possible load, in general not less than 10% over SWL. 4
Flag and class notes
- Liberia (SAF-020) repeats table 1, accepts its authorized ROs’ rules for open-sea test loads, publishes table 2 with the corrected 0.933 factor, and allows the test and examination intervals to be in concert with the harmonized survey dates under SOLAS I/7 and I/10. It warns that C152 port authorities may not recognise those intervals. 5
- Germany (ISM circular 02/2025) states the annual thorough examination and the five-yearly retest plainly, and accepts as competent persons RO surveyors, inspectors authorised by the manufacturer and inspectors of specialist firms recognised by the manufacturer. 6
- Class societies publish their own lifting appliance rules or codes, which their surveyors apply when they act as competent person. Ask your RO for the rule edition and test procedure they will follow before booking test weights.
Key numbers
| What | Value |
|---|---|
| Thorough examination | Every 12 months and after every load test 1 |
| Load test | Before first use, every 5 years, after major repair 1 |
| Test load, SWL up to 20 t | 1.25 × SWL 1 |
| Test load, SWL over 20 t to 50 t | SWL + 5 t 1 |
| Test load, SWL over 50 t | 1.10 × SWL 1 |
| Maximum excess over the test load | 2.5% 3 |
| Single-sheave block proof test | 4 × SWL 1 |
| Shackles, hooks, chains up to 25 t | 2 × SWL 1 |
| Appliances lifting persons, thorough examination | Every 6 months (ILO code) 3 |
What inspectors find
- Five-yearly load test overdue because the date was counted from the last annual survey instead of the last test. 1
- Load test certificates that do not state the radius or boom angle at which the test load was applied, which both the ILO and SOLAS certificate forms require. 4
- Test certificates after a slewing bearing renewal missing, although the work affected the primary load-bearing structure. 1
- Limit switches and overload protection not working, or set wrongly, at the thorough examination. 1
FAQ
Do I need a load test every year?
No. The annual requirement is the thorough examination. The load test is every five years, before first use, and after major repairs or alterations.
Can the five-yearly load test be done with the crane's own load indicator?
The test load should be of verified weight. Lesson 3 covers test weights, water bags and when a dynamometer may be used.
Our crane's SWL is not documented and the maker no longer exists. What test load applies?
MSC.1/Circ.1663 paragraph 3.2.1.6 lets the company nominate an SWL, to the satisfaction of the Administration, and the test load is then calculated from table 1. That SWL is then marked on the crane.
Is a derrick tested differently from a crane?
The table is the same. ILO Form No. 2 says derricks are tested with the boom at the minimum angle to the horizontal for which they were designed, generally 15 degrees, and union purchase rigs have their own certificate, Form No. 2(U).
Quiz6 questions
Sources
- 1
IMO MSC.1/Circ.1663, Guidelines for lifting appliances (28 June 2023), Annex, paragraphs 3.2.1 to 3.2.3, 3.5.1.4, 4.2 and tables 1 and 2 (copy hosted by ABS). https://ww2.eagle.org/content/dam/eagle/Images/rules-and-resources/regulatory-updates/solas-requirements/guidelines-hyperlinks/msc1-circ1663-guidelines-for-lifting-appliances%20%284%29.pdf
- 2
ILO Convention No. 152, Occupational Safety and Health (Dock Work) Convention, 1979, Articles 22 and 23. https://www.ilo.org/dyn/normlex/en/f?p=NORMLEXPUB:12100:0::NO::P12100_ILO_CODE:C152
- 3
ILO, Safety and health in ports, ILO code of practice (2005), section 4.2 and appendices A, C and D. https://www.ilo.org/sites/default/files/wcmsp5/groups/public/%40ed_protect/%40protrav/%40safework/documents/normativeinstrument/wcms_107615.pdf
- 4
ILO model forms under Convention No. 152, Form No. 2 (Certificate of test and thorough examination of lifting appliances), instructions on the reverse, as published by the Danish Maritime Authority. https://www.dma.dk/Media/637721290870425149/Lifting%20Appliances%20-%20Certificates.doc
- 5
Liberia Maritime Authority, Marine Notice SAF-020 Rev. 12/25, paragraphs 2.1.1.3 to 2.1.1.14. https://www.liscr.com/marketing/liscr/media/liscr/online%20library/maritime/saf-020.pdf
- 6
German Flag (BG Verkehr), ISM Circular 02/2025, Lifting appliances: new SOLAS requirements 1 January 2026. https://www.deutsche-flagge.de/de/redaktion/dokumente/ism-rundschreiben/circ02-2025-lifting-appliances-hebezeuge.pdf
Rules checked 20 October 2026. VSL Safety is not an approved training provider and doesn't issue certificates. These lessons don't replace STCW training, or the manufacturer's training and certification that service technicians need.
