Start hereRules checked 20 October 2026
For years, the most dangerous part of a lifeboat was the device meant to set it free. In the MAIB’s ten-year review, hook failures caused 7 of the 12 lifeboat deaths on UK ships. The investigators described the pattern: on-load hooks had become over-complicated, crews often did not understand how they worked, and once a hook was not fully reset, the weight of the boat itself could drive it open. Sometimes only one hook opened; the attachment at the other end was often torn away, and the boat dropped into the water, sometimes upside down.
The IMO’s answer, adopted in 2011, was the hook rule: a new design standard for release mechanisms and a deadline by which every non-compliant hook on every ship had to be replaced. The deadline passed on 1 July 2019, but the rule still shapes every inspection of release gear today.
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In this lesson
- A release gear question during your first week as chief officer
- In plain words
- In detail
- What the rules say
- Flag and class notes
- Key numbers
- What inspectors find
- Quiz: 6 questions
Try it
A release gear question during your first week as chief officer
In plain words
An on-load release hook has two jobs that pull against each other. It must hold the boat with complete reliability while it hangs, and it must open on command when the crew needs it to, even with weight on it. Older designs often relied on the crew resetting them perfectly, and on parts that did not wear or corrode. When the reset was incomplete, the weight of the boat could push the hook open.
The hook rule fixed this in two steps:
- A new design standard (LSA Code paragraph 4.4.7.6, rewritten in 2011): the hook must stay shut under any load from empty to full until someone deliberately opens it, the boat’s weight must not push on the operating mechanism, locking parts must not be able to turn open under load, and the hydrostatic interlock must reset by itself when the boat is lifted out of the water.
- A retrofit deadline (SOLAS regulation III/1.5): every hook on every ship that did not meet the key parts of the new standard had to be replaced by the first scheduled dry-docking after 1 July 2014, and no later than 1 July 2019.
Manufacturers evaluated their existing designs against IMO guidelines. Designs that passed got a one-time overhaul examination on board; designs that failed were replaced. Either way, the ship keeps a paper that proves it.
In detail
The design rules in LSA Code 4.4.7.6 (as amended by MSC.320(89))
| Paragraph | Requirement |
|---|---|
| .2 | Open only when waterborne, or, if not, by multiple, deliberate and sustained action including removal or bypassing of safety interlocks. Must not open from wear, misalignment or unintended force, with trim up to 10 degrees and list up to 20 degrees, for loads from 0% to 100% of the safe working load |
| .3 | Unless load-over-centre, the moveable hook is held fully closed by locking parts until deliberately opened. Cam designs stay closed through cam rotation of up to 45 degrees from the locked position |
| .4 | Hook stability: when fully reset, the weight of the boat transmits no force to the operating mechanism |
| .5 | Locking devices cannot turn to open from forces from the hook load |
| .6 | A hydrostatic interlock resets automatically when the boat is lifted from the water |
| .7 | Two capabilities: off-load release without manual separation of the ring from the hook, and on-load release with a hydrostatic interlock (or equivalent) and a protected override, broken deliberately, such as a glass cover |
| .8 | Unless the hook is completely reset, either it cannot support any load, or the handle or safety pins cannot be returned to the reset position; indicators must not show reset unless it is (tightened in 2026, see below) |
| .9 | Hook unit, handle unit, cables, links and fixed structural connections of material corrosion-resistant without coatings or galvanising; cables waterproof with no exposed areas |
| .15 / .16 | Hydrostatic interlock factor of safety 6; operating cables 2.5 |
Paragraphs .4, .5 and .6 were the test for existing hooks under SOLAS III/1.5. The full section applies to hooks on ships constructed on or after 1 July 2014.
Since 1 January 2026: MSC.554(108)
For lifeboats and rescue boats with release gear installed on or after 1 January 2026, paragraph 4.4.7.6.8 now says the hook “shall not be able to support any load unless the hook is completely reset”, and requires additional danger signs at each hook station on the proper method of resetting. Paragraph 4.4.7.6.17 was also rewritten for single fall and hook systems used with a painter.
The evaluation and replacement process (MSC.1/Circ.1392)
- Self-assessment by the manufacturer of each type of existing hook.
- Design review by a flag Administration or its recognised organisation.
- Performance test of each type by the manufacturer, witnessed by the Administration or RO.
- Report to IMO by the Administration: compliant, compliant after modification, or non-compliant.
- One-time follow-up overhaul examination on board, of every compliant system, by the manufacturer or its representative, no later than the first scheduled dry-docking after 1 July 2014, ending with a factual statement kept on board. Replacement hooks are accepted by the Administration or RO with a statement of acceptance kept on board.
Steps 2 to 4 were to be finished by 1 July 2013. The IMO also recommended fall preventer devices, under MSC.1/Circ.1327, on existing hooks awaiting evaluation or replacement.
Corroded foundations: MSC.1/Circ.1584 (2017)
When a compliant hook stays on board but its fixed structural connections (foundation, bolts, backing plates) are not made of corrosion-resistant material, the Administration or RO may let them stay if they are in good condition and in a sheltered position inside the boat. The manufacturer assesses them using its manual. Where no manufacturer or manual exists, the circular gives a method:
- 100% visual examination of everything in clear sight
- at least 25% of the bolts of each hook fixation removed and examined; if any is corroded or in bad condition, remove the rest; as a rule, a bolt that has lost 2% of its original dimensions is in bad condition and is replaced with corrosion-resistant material
- where connections show corrosion, ultrasonic thickness measurement and corrosion mapping; a backing plate with 10% or more wastage is replaced
- parts in good condition are cleaned and recoated if necessary
Fall preventer devices today
A fall preventer device (FPD) is a second load path, a locking pin through the hook’s cheek plates or a strop from a strong point in the boat to the fall block, that stops the boat falling if the hook opens. FPDs are not a substitute for a safe hook. Several flags accept their use in drills and maintenance: Liberia if they fully comply with MSC.1/Circ.1327, the Bahamas when the company advocates them, with procedures in the safety management system and the master deciding when they are used.
Material rule, 2026 update
At MSC 111 (May 2026) the IMO approved a revised unified interpretation of LSA Code paragraphs 4.4.7.6 and 4.7.7 (MSC.1/Circ.1529/Rev.1): stainless steel with a pitting resistance equivalent number (PREN) of 22 or more need not undergo the ISO 9227 corrosion test; materials below 22 must be qualified by that test. This affects new approvals, not the checks you make on board.11
What the rules say
- SOLAS regulation III/1.5, adopted by MSC.317(89) and in force from 1 January 2013, required on-load release mechanisms not complying with LSA Code 4.4.7.6.4 to 4.4.7.6.6 to be replaced not later than the first scheduled dry-docking after 1 July 2014, and not later than 1 July 2019.1
- LSA Code paragraph 4.4.7.6.2, as amended by MSC.320(89), requires the mechanism to open only when waterborne or by “multiple, deliberate and sustained action”, and not to open through wear, misalignment or unintended force across 0% to 100% of safe working load.2
- LSA Code paragraph 4.4.7.6.4 requires that, when fully reset, the weight of the lifeboat does not cause any force to be transmitted to the operating mechanism.2
- LSA Code paragraphs 4.4.7.6.5 and 4.4.7.6.6 require locking devices that cannot turn open under hook load, and a hydrostatic interlock that resets automatically when the boat is lifted from the water.2
- LSA Code paragraph 4.4.7.6.7.2 requires the on-load release override to be protected by something deliberately broken, and says “A label or thin wire seal is not considered sufficiently robust”.2
- LSA Code paragraph 4.4.7.6.8, as amended by MSC.554(108) for release gear installed on or after 1 January 2026, requires that the hook cannot support any load unless completely reset, and adds danger signs at each hook station.3
- MSC.1/Circ.1584 lets the Administration or RO accept non-corrosion-resistant hook foundations in good condition and sheltered inside the boat, assessed by removing at least 25% of bolts, replacing bolts with 2% material loss and backing plates with 10% wastage.4
- The HSSC survey guidelines tell the surveyor at each annual survey to confirm the factual statement of the one-time overhaul examination, or the statement of acceptance of a replacement system, is on board.5
- MSC.402(96) paragraph 6.2.4, note 2, forbids any maintenance or adjustment of release gear while the hooks are under load.6
Flag and class notes
- Germany (BG Verkehr ISM Circular 04/2011) explained the evaluation and exchange programme to its fleet: manufacturers’ design review and witnessed performance test by 1 July 2013, the one-time overhaul examination by the manufacturer under MSC.1/Circ.1206/Rev.1 by the first scheduled dry-docking between 1 July 2014 and 1 July 2019, and the factual statement or statement of acceptance carried on board.7
- Liberia (Marine Notice SAF-005) allows FPDs before any drill, test, inspection or maintenance with persons in the boat, but only if fully compliant with MSC.1/Circ.1327, and says they are not a substitute for a safe release mechanism.8
- Bahamas (Marine Notice 82) accepts FPDs when the company advocates them, recognising the master’s overriding authority under ISM Code paragraph 5.2, and recommends carrying a working model of the on-load release gear for training.9
- Class: release gear is type-approved, and the class society or flag performed the design reviews under MSC.1/Circ.1392. If you are unsure whether a hook on board was found compliant, ask the class society for the evaluation result for that type.
Key numbers
| What | Value |
|---|---|
| SOLAS III/1.5 in force | 1 January 20131 |
| Final replacement deadline for non-compliant hooks | 1 July 20191 |
| Load range in which the hook must not open unintentionally | 0% to 100% of safe working load2 |
| Cam rotation the hook must tolerate and stay closed | Up to 45 degrees2 |
| Hydrostatic interlock / operating cable safety factors | 6 / 2.52 |
| Bolts removed for examination (Circ.1584 method) | At least 25% per hook fixation4 |
| Bolt replaced at material loss of | 2% of original dimensions4 |
| Backing plate replaced at wastage of | 10% or more4 |
| MAIB deaths from hook failures, 10 years to 2001 | 7 of 1210 |
What inspectors find
- Missing factual statement or statement of acceptance. It is still on the annual survey checklist.5
- Hooks not fully reset, with indicators that disagree with the hook position, or safety pins that do not engage.26
- Seized or stretched release cables that open one hook and not the other; the MAIB found that crews often did not understand how their hooks worked.10
- Corroded hook foundations in older boats, assessed without removing any bolts.4
FAQ
Our hooks were found compliant in 2014. Do we have to replace them now?
No. Compliant existing hooks may stay in service as long as they are maintained, examined and overhauled under MSC.402(96). Replacement parts and any new installation must follow the current LSA Code.
What is a "load-over-centre" hook?
A design in which the weight of the boat holds the hook closed, so the hook only opens when the load comes off or the mechanism is forced past centre. The design rule in 4.4.7.6.3 exempts these from the locking-parts requirement because the load itself keeps them shut.
Are fall preventer devices still needed?
They are not a SOLAS requirement for compliant hooks. Many companies and flags still use them during drills and maintenance as an extra safeguard. If your company does, follow MSC.1/Circ.1327 and the procedure in your safety management system.
Who may reset the hooks after a drill?
The crew, following the manufacturer’s resetting procedure, which is routine operation. Adjusting or repairing the release gear is certified technician work.
Quiz6 questions
Sources
- 1
IMO Resolution MSC.317(89), Amendments to SOLAS 1974 (adopted 20 May 2011, in force 1 January 2013), Annex: regulation III/1.5. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/MSCResolutions/MSC.317(89).pdf
- 2
IMO Resolution MSC.320(89), Amendments to the LSA Code (adopted 20 May 2011, in force 1 January 2013), Annex: paragraph 4.4.7.6. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/MSCResolutions/MSC.320(89).pdf
- 3
IMO Resolution MSC.554(108), Amendments to the LSA Code (adopted 23 May 2024, in force 1 January 2026), Annex, paragraphs 4.4.7.6.8 and 4.4.7.6.17. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/MSCResolutions/MSC.554(108).pdf
- 4
IMO MSC.1/Circ.1584, Amendments to the Guidelines for evaluation and replacement of lifeboat release and retrieval systems (MSC.1/Circ.1392) (20 June 2017), Annex, paragraph 21. https://wwwcdn.imo.org/localresources/en/OurWork/Safety/Documents/MSC.1-Circ.1584.pdf
- 5
IMO Resolution A.1207(34), Survey Guidelines under the HSSC, 2025, Annex, paragraph (EA) 1.2.1.16. https://wwwcdn.imo.org/localresources/en/OurWork/IIIS/Documents/A%2034-Res.1207%20-%20SURVEY%20GUIDELINES%20UNDER%20THE%20HARMONIZED%20SYSTEMOF%20SURVEY%20AND%20CERTIFICATION%20(HSSC),%202025%20(Secretariat).pdf
- 6
IMO Resolution MSC.402(96), Requirements for maintenance, thorough examination, operational testing, overhaul and repair (in force 1 January 2020), Annex, paragraph 6.2.4. https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/MSCResolutions/MSC.402(96).pdf
- 7
BG Verkehr, Ship Safety Division (German flag), ISM-Circular No. 04/2011, Assessment of on-load release and retrieval mechanism and procedures for the defined exchange program (22 August 2011). https://www.deutsche-flagge.de/de/redaktion/dokumente/ism-rundschreiben/Circ2011_4_engl.pdf
- 8
Liberia Maritime Authority, Marine Notice SAF-005 (Rev. 07/26), paragraph 4.5. https://www.liscr.com/sites/default/files/online_library/SAF-005.pdf
- 9
The Bahamas Maritime Authority, Marine Notice 82, Lifeboat Safety, version 1.1, paragraph 8.4 and section 11. https://www.bahamasmaritime.com/wp-content/uploads/2023/10/MN082-Lifeboat-Safety.pdf
- 10
UK Marine Accident Investigation Branch, Safety Study 1/2001, Review of lifeboat and launching systems’ accidents, sections 1.4 and 2.1. https://assets.publishing.service.gov.uk/media/5a7d8042ed915d2d2ac0954a/Lifeboat_Study.pdf
- 11
American Bureau of Shipping, Brief: MSC 111 (22 May 2026), unified interpretation of paragraphs 4.4.7.6 and 4.7.7 of the LSA Code (MSC.1/Circ.1529/Rev.1). https://ww2.eagle.org/content/dam/eagle/regulatory-news/2026/abs-msc111-brief.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.
