Thwartships -- positioned at right angles to the ship’s keel, to see abeam

Tide -- the regular rise and fall of the ocean current

Tiller -- a bar fixed to the “Rudder” used to steer the ship

Topsides -- the hull’s outer surface above the waterline

Transom -- the cross section of a boat with a square stern

Trim -- a boat’s stem to stern balance
 
Underway -- a boat in motion, not anchored or docked
 
V Bottom -- a ship’s hull with a bottom angled in a “V” shape