Theres a few interesting points raised here
(a) Many people refer to the country of registration
as determining what paperwork should be carried.This is only true on the high seas and within the country of registrations territorial waters
Outside of that , specifically within a nations territorial waters, any rules can be applied under the laws of that land, including seeking from you paperwork, that you cant actually acquire.
Hence whil UK sailors require no paperwork to sail the high seas or in their own waters, it is quite within Croatias right to demand you have a cert of competency, in order to sail their waters. However most governments practice comity
which mean the recognize each others laws and dont try and repudiate them, but it isn't all persuasive.
of a leisure boat conveys little, it , merely confirms the vessels origin, ie its home state. Local laws may target the skipper
( the person in charge) rathe then the vessel, may purely target the vessel, ( ie French safety
laws) or a combination of both ( croatia)
No country soley demands the ICC
as the only cert
in regards competency. This only applies to open water
, on european canals the ICC is specifically required ( or the relevant National Cert , like the French Permis Plasiance.
Note that contary to what was said , a french boat fitted with an engine
greater 4.7Kw ( 6,5 Hp) is regarded as a motor
boat and licenses are required.
The Op doesnt specifically need an ICC, any cert will do.