Stowaway incidents may be relatively limited in number, but their consequences can be significant for both the vessel and those involved.
Beyond the immediate security concern, they can create operational disruption, reporting and immigration complications, additional costs and challenging welfare considerations for the crew and company.
Effective prevention therefore depends on access control, situational awareness and careful preparation throughout the port stay.
A stowaway is rarely a problem that begins during the voyage. By the time an unauthorized person is discovered onboard, the opportunity to prevent the incident has usually been missed. The person may have gained access during cargo operations, through an inadequately monitored access point or by exploiting a period when the vessel was particularly busy.
Once the vessel has sailed, what might have been a relatively straightforward prevention issue can quickly become a complex operational, legal and financial matter. For ship management companies and crews, prevention should therefore remain the priority.
Recent industry updates show that stowaway risk remains a persistent concern, particularly in West African ports. A significant number of cases during 2025 and highlighted the continuing exposure of vessels trading in the region, while Skuld also pointed to an increase in incidents despite the wider implementation of the ISPS Code.
More recent safety guidance has reinforced the same message from a different perspective. An IMCA case published in April 2026 involved an unknown person boarding a vessel at anchor during the night, underlining how quickly weaknesses in access control and watchkeeping can result in unauthorized access.
Understanding the risk
Effective prevention starts before the vessel arrives in port. Stowaway risk is not the same in every location. Previous incidents, local conditions, terminal arrangements, cargo operations and the vessel’s trading pattern should all be considered when preparing for a port call.
The Master and SSO should identify when and where the vessel is likely to be most exposed. Cargo operations, crew changes, stores delivery and periods of heavy movement between ship and shore can create opportunities for unauthorized access. Identifying these periods in advance allows attention and resources to be focused where they are most needed.
Closing access gaps
Successful stowaway incidents usually depend on two weaknesses: an opportunity to gain access and a place where the person can remain undetected. Both can be addressed through disciplined shipboard routines.
Access points should be properly controlled and monitored throughout the port stay, particularly during busy operations. Areas not required for normal activities should be secured where appropriate, while security rounds should cover not only normal access routes but also locations where someone could enter or hide.
An unsecured door, overlooked access route or unattended area may be enough to create an opportunity. Depending on the vessel, potential hiding places may include deck stores and lockers, lifeboats, forecastle and mooring spaces, steering gear areas, unused accommodation and cargo-related spaces. Clear responsibility is equally important.
If responsibility for monitoring access points is not clearly assigned, gaps can easily develop.
Pre-departure checks
The final search is one of the most important opportunities to prevent a stowaway from leaving port with the vessel. It should not become a routine exercise carried out simply to complete a requirement. An effective search requires knowledge of the vessel, awareness of the day’s operations and consideration of where an unauthorized person could realistically remain undetected.
The search should take account of cargo movements, shore access, stores and contractor activities, changes in the terminal environment and anything unusual reported by the crew. Particular attention should be given to vulnerable spaces and areas that were open or accessible during the port stay.
The process should be systematic, with clear allocation of search areas to ensure that spaces are neither missed nor unnecessarily duplicated. Findings should be reported and the search properly documented.
Crew awareness
Procedures, lighting, CCTV and access controls are important, but prevention ultimately depends on people. Crew members are often the first to notice something that does not look right. An unfamiliar person, unexpected movement, an unsecured access point, evidence of tampering or activity in an unusual area may appear minor, but could indicate unauthorized access.
Crew members should report concerns promptly, even when they are not certain that a security incident has occurred. Information from agents, terminals and other parties can also be valuable when local circumstances change.
If a stowaway is discovered
If there is reason to suspect that an unauthorized person has boarded while the vessel is still in port, the Master and SSO should be informed immediately. A coordinated search should be conducted as appropriate, and the company, terminal, agent and relevant authorities notified in accordance with established procedures.
If a stowaway is discovered after departure, the situation becomes more complex. Crew safety should remain a priority. The person should be treated safely and humanely, and any immediate medical needs assessed. The Master should inform the company and CSO and establish the person’s identity and circumstances as far as reasonably possible.
The possibility of additional stowaways should also be considered and an appropriate search conducted. The location where the person was discovered, the possible access route and any relevant evidence should be recorded, while access to operationally sensitive or restricted areas should remain controlled.
The company should coordinate with the vessel, agents and appropriate authorities regarding reporting and arrangements for disembarkation. Crew members should avoid making commitments to the stowaway regarding where or when disembarkation will take place.
Effective stowaway prevention is less about adding new layers of security and more about ensuring that existing controls work when and where they are needed most. Port-specific risk awareness, disciplined access control, alert crew members and a thorough pre-departure search can significantly reduce the opportunity for unauthorized boarding.
The most effective response to a stowaway incident therefore remains the one taken before the vessel leaves port.