New to EU. Where to register and why?

[sepharad]

I am newly an EU citizen. I am a dual US/Portuguese citizen and have just bought a British registered boat, located on the hard in Denmark. Clearly i need to reregister ownership in my name, but where?

There is no VAT owed. The hull was built in 1982 (pre-'86), and 20 horsepower, so no annual Portuguese Tax. Is there any practical reason I should register it elsewhere? My home is in Portugal, but the boat may actually spend most of its time in the med. But will stay in Denmark for at least the next 1-2 years.

I assume one country is cheaper than another to register. Some will surely be less bureaucratic than others, to complete the process. And there are undoubtedly legal requirements as to where I must/may register it.

I would appreciate direction to a clear, concise resource to learn more. Thank you all.

PS. First boat, new citizenship and a new country, make me the ultimate noob, so thank you for your patience.