Why start here
Nomenclature is the vocabulary with which everything else is explained —the manoeuvres, the lights, the safety—. It is not an eliminating block, but mastering it makes the rest of the syllabus easy to grasp the first time. Let's get to the words that really come up.
Orientation on board
- Bow (proa): the front part, the one that breaks the water as you advance (by extension, the forward third).
- Stern (popa): the rear part (the after third).
- Port (babor): the left side looking from stern to bow. Starboard (estribor): the right.
- Centreline (línea de crujía): the central longitudinal line, from bow to stern.
- Bow area (amura): the area near the bow. Quarter (aleta): the area near the stern. Beam (través): the central area of each side.
- Side (costado): the outer part of the hull; there is a port side and a starboard side.
The hull: underwater body and topsides
The waterline is the one the water marks on the hull and separates two parts:
- Underwater body (obra viva / carena): the submerged part, the one that allows it to float (and where marine growth builds up).
- Topsides (obra muerta): the emerged part, from the waterline up to the gunwale.
Basic structure of the hull: the keel (the «backbone», at the lowest part), the stem (the bow piece), the sternpost (the stern one), the frames (the transverse «ribs») and the beams (the transverse pieces that support the deck).
The dimensions
- Length (eslora): the total length, from bow to stern.
- Beam (manga): the maximum width.
- Depth (puntal): the height of the hull, from the keel to the main deck.
- Draught (calado): the vertical distance from the keel to the waterline (what the boat «draws» below the water).
- Freeboard (francobordo): the vertical distance from the waterline to the deck (the reserve buoyancy that stays out of the water).
A relationship worth remembering: depth = draught + freeboard.
Draughts and trim
The draught can be measured forward, aft and amidships. The mean draught is the half-sum of the forward and aft ones. The trim (asiento) is the difference between the aft draught and the forward one:
- Trimmed by the stern (apopante) (positive): the aft draught is greater than the forward one (the boat sits «down by the stern»).
- Trimmed by the bow (aproante) (negative): the forward draught is greater than the aft one.
- Even keel (neutro): both draughts are equal.
Displacement
The displacement is the weight of the vessel, equal to the weight of the water it displaces. The maximum displacement is the weight of the vessel fully loaded and ready to sail.
Some terms that come up
- To heel (escorar): for the boat to lean to one side; to right (adrizar): to return to the upright position.
- Windward (barlovento): the side the wind blows from; leeward (sotavento): the opposite, where it goes.
How to study it
- Fix the four orientation terms first: bow, stern, port (left), starboard (right) — always looking from stern to bow.
- For the dimensions, anchor the rule depth = draught + freeboard and the rest falls into place.
- Remember underwater body = submerged, topsides = emerged.