Any spring which prevents the ship from moving back (aft) is known as a back spring, and one that prevents a ship from moving forward (ahead) is known as a head spring.
Noluphi utwabuluko luthi lukhusele inqanawa ekusukeni ngasemva, yaziwa njengotwabuluko lwangasemva, olunye olukhusele inqanawa ekusukeni ngaphambili lwaziwa njengotwabuluko lokhokelo.