Arkon, I looked at your site and it is interesting that this joke is an oldie and has been around a long time.
So, I am going to play devil's advocate. (My apologies to fellow-Canadians)
First, it is obvious that there an element of animosity in the joke against the Americans.
Secondly, it is told in such a way to make the Americans look stupid.
Why is this?
First let me say, that I perceive the American military in general and the navy in particular, as being in the top upper-percentile of professionalism.
So what is going on?
Let's look at the joke first. Assuming the right-of-way rules do not apply, it only makes sense that a lone ship should give way to an armada.
Much easier for a lone ship to change course than a fleet and maybe this is the way Americans sometimes percieve things. It is just logical that a sailing schooner should give way to the fleet rather than the other way around.
Yet many nations perceive the power of the U.S. as kind of a "big brother" and they are obligated to give way.
Someone once described Henry Kaiser as a friendly elephant leaning on him. Nations may view the U.S. in a similar fashion.
However, friendly the elephant, you do not want to make him angry!
So, I suspect there is suppressed anger in having to "give way" to a superior force.
In the joke, the US fleet gives the impression that it is applying its strength to get its way in Canadian waters.
However reasonable it is that the "fishing schooner" should give way to a fleet which is understandably more difficult to maneuver than a fishing schooner, force is still being applied in Canadian waters against a "so-called" Canadian vessel.
And this angers many people of nations who find themselves on the wrong end of the appication of force, however friendly it is applied.
And this is something I think Americans miss. They are often perceived as applying force when they may be just trying to be friendly. Or maybe something in between, friendly force.
So, the joke ends with the Americans making a fool of themselves. And it does is give Canadians a feeling of superiority. An unwarranted feeling of superiority perhaps, but it does relieve the tension which is the purpose of many jokes.
Americans should not take this joke to heart. We can love an older brother but dislike the times when we are pressured by him to do something.
With Canada having at most one-tenth the power of the U.S. it is a way of dealing with the power inequity and thereby relieve the tension.