Boating Terminology

boat terminology

Terms for Inflatable Boat

Here are some of the most common terms used to describe inflatable boats and their definitions. You can also find these terms in our glossary.

Inflatable Boat – a vessel constructed with its sides and bow made of flexible tubes containing pressurized gas. On smaller inflatables, the floor and hull beneath it are often adjustable.

Other terms for inflatable boats are “inflatable dinghy,” “rubber dinghy,” “inflatable,” “inflatable rescue boat,” or “rubber duck.”

Hypalon – this is a trademarked name for chlorosulphonated polyethylene (CSPE) synthetic rubber (CSM) which is noted for its resistance to chemicals, temperature extremes, and ultraviolet light. 

PVC – polyvinyl chloride is a robust and lightweight plastic. It is also very flexible and waterproof, making it ideal for inflatable boats.

Anchor Fairlead – device that provides chafe protection on the boat’s bow and through which the anchor rode is lead.

Bench Seat – rigid plank on which to sit while rowing.

Bilge Pump – an electric pump to remove water from the hull.

Bolt Rope (or flange) – a flap of material containing a section of rope that is used to slide into a slot in the hull to hold a buoyancy tube in place (also used in a similar manner for attaching seat cushions).

Bottom of the Hull The part of the hull that’s underwater. Its form is a determining feature in the boat’s navigation capacity.

Cavitation – a situation when the propeller gets air or insufficient bite in the water and loses its power. It can happen due to a motor mounted too high, seas conditions and tight turns.

Choppy Watter – agitated sea due to waves and wind coming from different directions.

Coating – interior and exterior covering of fabric by a flexible sub- stance. The interior layer assures airtightness, the exterior ensures abrasion resistance.

Cockpit – the area of the boat occupied by passengers. Floor drains provide for removing accumulated water.

Cone Reinforcement – rigid caps that protect the ends of the buoyancy tubes.

Decitex – weight measurement of the thread that constitutes the textile strength.

Deck – a horizontal platform on which you may stand. Large boats may have numerous decks.

D-Ring – a ring whose metal part is D-shaped. They were used especially when beaching and towing.

Floor – a surface on which you may stand. Floors may be slats in fabric sleeves, interlocking or hinged sections of wood, aluminum or composite materials, or fibreglass as in Ribs.

Hand Railing – profited grab rail for passengers to hold on to while navigating.

Keel – (for a foldable boat) the inflatable lengthwise part found under the boat, between the boat bottom and the floor. The inflatable keel is an additional safety compartment.

Lacing Cuff – a flap of material (usually positioned on top of the tube) through which lifelines are lead. Lacing cuffs frequently act as upright reinforcements for the buoyancy tube.

Lifeline – line around the boat to help passengers keep steady while navigating and when boarding.

Motor Bracket – the physical part of the boat to which the engine is mounted.

Motor Shaft – that part of an engine goes from below the motor head to the propeller. This height is variable for a given horsepower, and it can be short, long, or extra long.

Oarlock – U-shaped, circular or another shape that holds the oar and secures it to the buoyancy tube, permitting movement for rowing.

Plane – a transitory phase during which the boat goes from pushing the water at low speed to sliding over it. Usually, this phase is accompanied by porpoising as the boat overtakes its bow wave.

Pressure Gauge – measuring instrument that indicates the level of air pressure in the buoyancy tube.

Rubbing Strake – composition of resistant, flexible lateral bands that protect the boat from damage caused by rubbing (i.e. against the dock).

Self Bailer – device that permits accumulated water to exit the boat while not permitting water to enter the vessel. Usually, the plug wilt he used to close the self bailer when the boat is at rest, anchored or not operational.

Stringer – aluminum lengthwise bars that lock the floorboard elements in place when mounted on the boat (foldable boats).

Tiller Arm – a lever with controls used to steer and throttle an outboard motor when a remote helm station is not used.

Transom – a structural component of the boat’s hull on which the motor or motor bracket is mounted.

Trim Tabs/Trim Flaps – an extension of the hull’s bottom beyond the transom that aids in stability and planing.

Water Evacuation Plug – found at the lowest part of hull’s stern. It permits water to evacuate from inside the hull (boat out of the water).

RIB Terms

Breadth – the overall breadth of the vessel in metres, excluding handholds or other outboard side fittings.

Buoyant Volume  the buoyant volume of a RIB is the total volume made up of the following:

a) The volume of all inflatable compartments that form the collars or any other compartment permanently fixed to the hull. 

b) The volume of all sealed rigid compartments that form the hull or any other compartment permanently fixed to the hull. 

c) The volume of any foam buoyancy permanently fixed to the hull but does not fit within any of the compartments that contribute to the buoyant volume included in a) or b).

Collar – the buoyant section of the vessel connected to the hull and runs from the transom to the stem along the vessel’s periphery. 

RIB – an acronym for Rigid Inflatable Boat and an inflatable boat with the lower part of the hull constructed as a rigid unit and the topsides (inflatable hull) achieving its intended shape and buoyancy (or part thereof) by the medium of inflation of a tubular rubber collar such that the inflatable portion constitutes at least one-fifth of the buoyant volume of the vessel. Sometimes but rarely RHIB – Rigid Hull Inflatable Boat. 

Cleat – metal fittings on the boat’s top used when docking a boat and fastening a rope or cable.

Stowage – the amount of room available for stowage materials aboard a boat. It is the storage available to put important boating gear.

Gunwale or Gunnel – the top edge of the hull of a boat. Initially, the gunwale of a boat was the part of the deck where the guns were mounted.

Lifelines – a line or rope for saving a life as one attached to a lifeboat or a lifejacket.

T-top – a T-top is a type of top for center console boats built with a “T” shaped structure when viewed from the side. The top is tall enough to stand under and provides shade and rain protection for two or more passengers at the boat’s helm.

Parts of Boat

Hull – the body of the boat. It is the primary physical part of the boat that sits in the water. 

Deck –  the roof of the hull.

Chine – the sharp change in angle in the cross-section of a hull. “ASIS Boats’ RIBs have unique reverse chines that are sharp and angled, which allows the hull to cut through the waves without getting passengers wet.” 

Console – the area above the deck or cockpit where all the controls are located, including the steering, ignition, GPS and other electronic devices, switches etc. It may have small storage space.  

Bow – refers to the front end of a boat.

Stern – refers to the rear end of a boat. 

Starboard – when looking forward towards the bow of a boat, starboard refers to the right side of a boat. 

Port – when looking forward towards the bow of a boat, port refers to the left side of a boat. 

Transom – a critical part of the hull. The port and starboard sides of your boat are connected by the transom, located at the stern of your boat.  

Propeller – a propeller is a device with a rotating hub that is part of the engine. It has radiating blades set at a pitch to form a helical spiral that performs a rotational motion of the blades when rotated. 

Sterndrive – an inboard/outboard drive (I/O) is a form of marine propulsion that combines inboard power with the outboard drive, so it has an outboard lower unit that connects up through the transom of the boat to an inboard diesel or gas engine. 

Sponson – a sponson is a feature on any watercraft that extends from the hull or other part of the vessel to aid stability while floating or to act as a securing point for additional equipment. 

Berth – a sleeping area on a boat and a place where a boat is tied up

Helm – the area of a boat where the steering and engine controls are located.

Nautical Direction

Underway – when a boat is moving, either by motor or wind, this is called being “underway.” 

Astern – refers to a boat moving in a backwards position (reverse). 

Mooring – a place where a boat may be moored, which means a place where a boat can be tied so it cannot move away, or the object it is tied to.

Boat Measurement

Beam – it’s the width at the widest point; the more narrow it is compared to length generally, the faster the ship was designed to go but with a loss of stability. 

Draft – it is the distance from the waterline to the hull’s bottom. In other words, the draft measure indicates how much of the boat is physically in the water. 

Freeboard – the distance between a boat’s waterline and the top of its gunwales. top of its gunwales

Boating Vocabulary

Down in the Doldrums – stuck in a rut, not making progress.

High and Dry – if you accidentally beach your boat during high tide.

Loose Cannon – unpredictable, spontaneous and potentially dangerous.

Run a Tight Ship – to manage an organization strictly, efficiently and effectively.


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