[WolfyJames]

Well, that is very interesting, I never played attention to that part of the book. But since there are qabalistic elements on the cards, like the yesod moon on the nines, I did wonder why there are boats on only two cards on the threes.

Maybe it's because Wands are masculine, an outpoor of male energy, that flies in all direction. And the Wands are at the top, they're Atziluth/Chiah, the Life Force itself. On the Three of Scepters (and the Three of Wands on the RWS), the ship is leaving on adventures and business. The threes are binah as well.

As for the Cups, they come right after Wands, they're Briah/Neshamah. As typically seen in the qabalah, it follows balance, male - > female - > male - > female. And Cups are female, receptive, passive, and the ship is coming back.

male - > female - > male - > female

Wands (Atziluth/Chiah) - > Cups (Briah/Neshamah) - > Swords (Yetzirah/Ruach) - > Pentacles (Assiah/Nephesh)