To aquire the Barter Routes for Brilliant mats, you have to have 3k Barter count. Ship parts are very important and help make your ship more powerful in battle. In addition, boatmen can also be attached to an Epheria Sailboat to improve boat performance further. Think of it as, the farther you have to travel the more sailing xp you get from the quest. It protects the ship from external collision and corrosion.