The Merchant Shipping (Official Log Books) Regulations 1981 requires all UK ships > 25 gt to keep an Official Log Book (OLB).
There are exceptions, as the regulations states that the following ships are exempted from carrying the OLB:
- a ship belonging to a general lighthouse authority;
- a ship of less than 25 gross tons; or
- a pleasure yacht.
SI 1981 No 569