I have been waiting for this issue to get resolved and I am amazed that it never has.  Did no one notice?  Did I miss a post somewhere that explained why Epheria Sailboats and Improved Frigates were left out of these two items?  It isn't a text error - these two items genuinely do not work on Epheria Sailboats and Improved Frigates.  Why?  I see no reason for that, and they should.

The UI for boats resource is a bit tricky. You need to open the boat UI and select a special icon to activate the menu that enables the use of this item. 

You cannot simply right click it out of the inventory. 

After mounting the boat and sailing along, open the boat information screen, and look for a little "+" sign. Click that and try again.