The sailing skillcape is very underwhelming. Adding the ability to "teleport to boat" (save the rune cost/inv space for runes from the spell) would be a much welcome bonus.
If you want to just make it slightly nicer, you could add this while keeping the requirement that the target ship for your teleport has the teleport focus facility. If you want to really buff the cape perk, you could allow the teleport without the requirement of the teleport focus facility. Personally, I don't feel that it needs to be quite that strong, but it could definitely use some love by just allowing us to teleport to ships that already have the facility built.