If we are ever going to have diplomacy implemented, like declaring wars, forming alliences and supporting other nations for port control, we need some sort of barrier regarding nation changing. I'm not saying it should be impossible, but I think it should be costly, and never instantaneous. I believe the game would benefit from people feeling they belong to their nation, and that changing nations should be kind of a big deal. So here is what I suggest (similar limits has been mentioned before, in a post outside suggestions):
1) Whenever you want to leave your nation, you become a pirate.
2) You then lose half of your influence (see this as influence being partly built up for your nation, partly for you personally - this is the price you pay)
3) After becoming a pirate, you have to wait 7 days before you can join any nation
First after this, or a similar, suggestion is implemented, will diplomacy between nations be sensible. I have several ideas for this (wars, blockades, etc.), but without some barrier for changing nation, they don't really make much sense. Oh, and even without diplomacy, these measures would be advantageous to the game, as I'm sure several players have experienced recently.
ABOVE: 1st (OLD) SUGGESTION
BELOW: 2nd EDITION OF THIS SUGGESTION
I present two alternatives. Alternative 1 will, in my opinion, be somewhat helpful in reducing nation changes in a situation with the existing rules, and probably also with a limited form of national diplomacy implemented. If ever things like wars and blockades are to be implemented, however, I think alternative 2 (or some similar form) will be required.
ALTERNATIVE 1:
Whenever a player changes nation, he/she loses 50% if his influence. This is informed in an "are you sure?" box when changing nations. This loss is not applied to players the first time they change nations, to protect newcomers who have chosen an arbitrary nation.
ALTERNATIVE 2:
The concept of "changing nations" is abandoned, and the following options substitute it: 1) Leave nation 2) Apply for citizenship 3) Ask for a royal pardon. These would work as follows: Any player who is NOT a pirate, has the option to "Leave nation" (placed where the current "change nation" is). Whenever a player choses to leave a nation, two things happen: A) He loses half his influence, and B) He becomes a pirate.
Only pirates have the option to apply for citizenship or ask for a royal pardon. These alternatives appear for pirates where the "Leave nation" option is placed for non-pirates. A pirate can apply for citizenship in any nation. It will always be granted, but the process is slow: 30 days after the application, it is granted, and the player is now a citizen of the desired nation.
The faster way is to ask for a royal pardon (of the nation he wants to join). This starts a vote in the target nation. If the vote passes, the player is accepted as a member of the nation as soon as the vote is concluded. If it does NOT pass, he can still apply for citizenship, but will have to wait the 30 days (or he can stay pirate, or apply to another nation). Asking for a royal pardon in a nation with no king will always be accepted, although it will take the same time as an ordinary vote (3 days).
A player who has never changed his nation, may leave a nation without losing influence.