Britain's Maritime and Coastguard Agency detained a registered vessel after it was declared 'dangerously unsafe' following an inspection.
The 250-tonne merchant vessel Seerose1 was going from Germany to Haiti when it sought shelter from bad weather in Poole harbour.
An agency spokesman said the harbour master contacted its Southampton office after an incident involving a crew member occurred when the vessel was attempting to get alongside.
An agency surveyor who then went on board the vessel discovered several deficiencies including water leaks into the main engine, health, safety and fire risks and charts that required correction.
The agency surveyor said: 'This is by far the worst vessel I have ever inspected. The living standards in two of the cabins are uninhabitable. The whole vessel is dangerously unsafe.'
