Good board! 

This would take one arrow to create a loop that would cover all four cannons.  An ideal board.

A so-so board.

While it’s possible to create a two cannon loop with only two arrows, I would pass this one by if I had the time to search for a board.  If the captain needed the guns loaded right away though, I would stay here and load the guns.

Another great board. 

Yet again, a one-arrow four cannon board.

A bad board.

While the upper half of the board is workable (three arrows would create a loop that includes both the upper cannons) the lower half is completely unhelpful.  It would take more arrows that you have to keep the loop going.  If pressed for time you might try the basic loop, but you would still have problems loading the odd guns.

Here’s an example of a good board, though it might not seem to be on first glance.

  It would take three arrows to create a loop that would travel past all four cannons.  So we’ll leave the upper guns out of the loop for now.

Instead of a four cannon loop we must make do with a two cannon loop.  This isn’t too much of a problem, as the two guns on the loop are easy to load and the upper left corner gun will be easy to load as well.  For the odd cannon on the board, all we need do is change one arrow.

If we create a variant on the two cannon loop so that the right two guns are covered, then the upper right cannon isn’t so hard to load anymore.  And taa-da! The guns are loaded!   

And here’s another example of a so-so board.

  The lower half can be included in the loop by just one arrow, but the upper half looks like trouble.  Again, if I needed to load the guns right away I would stay here and load them up, but would try to find a better board after I was done.

Another example of a bad board, with both halves containing mish mash that’s hard to work past.  While you could place an arrow before the gun on the lower side to avoid the complicated dead end, it would take two arrows on the upper side to get a loop going past both guns.