Common Abbreviations in Boat Listings

Boat listings are packed with industry shorthand. Once you know the code, you can assess a vessel at a glance — but until then, the alphabet soup of abbreviations can make listings feel impenetrable. This guide decodes the most common ones you will encounter when browsing boats for sale.

For broader context, see the how to read a boat listing guide and the full nautical terms glossary. Where an abbreviation relates to specific technical topics, links to dedicated guides are included below.

Dimensions & Performance

These abbreviations describe the physical size and sailing performance characteristics of a vessel. Understanding them lets you compare boats objectively and find vessels suited to your intended use. See also the understanding boat dimensions guide.

LOA: Length Overall. The total length of the vessel from the foremost fixed point of the bow to the rearmost fixed point of the stern, including any bowsprit, swim platform, or fixed overhangs. This is the number marinas use to allocate berths and the figure most commonly quoted in listings when a single length is given.
LWL: Length at Waterline. The length of the hull measured at the surface of the water. LWL determines theoretical hull speed for displacement boats. A longer LWL relative to LOA indicates less overhang and is generally associated with better sea-keeping. Often listed alongside LOA on bluewater cruisers and performance sailboats.
LOD: Length on Deck. The length of the hull measured along the deck centreline, excluding removable fittings such as a bowsprit or anchor roller. LOD is sometimes used in older European listings and can differ from LOA by half a metre or more on boats with pronounced overhangs.
BOC: Beam Overall (Centreline). The maximum width of the vessel at its widest point. BOC affects interior volume, stability, and marina berth requirements. On catamarans, BOC is often dramatically larger than on monohulls of equivalent LOA.
DLR: Displacement-to-Length Ratio. A dimensionless number that classifies a sailboat as ultralight, light, medium, heavy, or very heavy. A DLR below 100 indicates a racing boat; above 300 indicates a heavy bluewater cruiser. Buyers looking for offshore passage-making capability generally prefer a higher DLR for sea-kindly motion.
SA/D: Sail Area to Displacement Ratio. A measure of a sailboat's power relative to its weight. A higher SA/D means more sail power for a given displacement — the boat will be livelier in light airs but may require more reefing in a blow. Racing designs typically exceed 20; comfortable cruisers sit between 14 and 18.
kts: Knots. The standard unit of speed at sea, equal to one nautical mile per hour (approximately 1.852 km/h). Boat listings quote hull speed, cruising speed, and top speed in knots. One knot is not the same as one mile per hour.
nm: Nautical Miles. The unit of distance used in marine navigation, equal to one minute of arc of latitude (approximately 1,852 metres). Range figures in listings — "600 nm at cruising speed" — use this unit. Do not confuse with nm (nanometres) in other contexts.
gal: Gallons. Used for fuel and water tank capacities. Be alert to whether US gallons (3.785 litres) or Imperial gallons (4.546 litres) are intended — American listings use US gallons; UK and Australian listings typically use Imperial or litres.
lt: Litres. The metric unit for tank capacities (fuel, water, holding). European listings almost always quote in litres. When comparing a US listing in gallons with a European one in litres, divide litres by 3.785 (US) or 4.546 (Imperial) to convert.

Engine & Propulsion

Engine specifications are critical for assessing the mechanical condition of a vessel. See the engine types explained guide for detail on specific power plant configurations.

HP: Horsepower. The traditional unit of engine power output. Most marine diesel auxiliaries for cruising sailboats range from 20 to 75 HP; motorboat engines are rated from under 100 HP up to several thousand HP on larger vessels. HP figures in listings refer to continuous rated output, not peak output.
kW: Kilowatts. The metric unit of engine power. European listings increasingly quote kW rather than HP. To convert: 1 kW ≈ 1.34 HP. A 40 HP auxiliary is approximately 30 kW.
RPM: Revolutions Per Minute. Engine speed. Listings may specify rated RPM (the maximum continuous speed the engine is designed to run at) or cruising RPM (the typical operating speed for fuel efficiency and longevity). Running consistently above rated RPM accelerates wear.
hrs: Engine Hours. The total number of hours the engine has run, recorded by an hour meter. Engine hours are a primary indicator of wear and remaining service life — broadly analogous to mileage on a car. What constitutes high hours depends on the engine type and maintenance history. See the reading engine hours guide for context.

Navigation & Electronics

Modern boats carry a wide range of electronic navigation aids. The abbreviations below appear in equipment lists and in the descriptions of what a vessel is fitted with. See also the electrical systems on boats guide.

GPS: Global Positioning System. The US-operated satellite navigation system providing position, speed, and time data. In common usage, "GPS" is often used loosely to mean any satellite positioning system. See GPS on Wikipedia.
GNSS: Global Navigation Satellite System. The collective term for all satellite positioning systems, including GPS (USA), GLONASS (Russia), Galileo (EU), and BeiDou (China). Modern chartplotters and AIS transponders receive multiple constellations simultaneously, improving accuracy and reliability. A listing noting "GNSS" rather than just "GPS" typically indicates a more capable multi-constellation receiver.
AIS: Automatic Identification System. A VHF radio-based system that broadcasts a vessel's identity, position, speed, and course to other AIS-equipped vessels and shore stations. Class A transponders are mandatory on commercial vessels; Class B transponders are common on recreational boats. A listing noting "AIS transponder" (transmit and receive) is preferable to "AIS receiver" (receive only). See AIS on Wikipedia.
VHF: Very High Frequency. The radio band (156–174 MHz) used for short-range marine communication. A fixed-mount VHF radio with DSC is standard safety equipment. Listings may note "fixed VHF" and/or "handheld VHF". See Marine VHF radio on Wikipedia.
DSC: Digital Selective Calling. A feature built into DSC-capable VHF radios that allows a vessel to transmit a digital distress alert (including GPS position if the radio is interfaced with a GPS) to the coastguard and nearby vessels at the press of a button. A DSC-capable VHF requires registration with an MMSI number to function correctly.
SSB: Single Sideband Radio. A high-frequency (HF) radio system used for long-range offshore communication when VHF is out of range. SSB is found on bluewater cruisers and offshore passage-makers. It can also receive weather fax transmissions. SSB is increasingly supplemented or replaced by satellite communication systems.
MMSI: Maritime Mobile Service Identity. A unique nine-digit number assigned to a vessel's DSC-capable VHF radio and AIS transponder, used to identify the vessel in digital distress alerts and AIS broadcasts. The MMSI must be registered with the national maritime authority. It should transfer to the new owner on sale — verify this during the purchase process.
UTC: Coordinated Universal Time. The global time standard used in navigation, weather broadcasts, and official maritime records (log entries, incident reports). Listings for international deliveries or offshore races reference UTC to avoid ambiguity caused by local time zones.
ETA: Estimated Time of Arrival. Used in passage planning, delivery documentation, and AIS data. When buying a boat that requires a delivery passage, the seller or delivery skipper will typically provide an ETA for the destination port.
ETD: Estimated Time of Departure. The planned departure time for a passage or delivery. ETD appears in passage plans, port clearance documents, and delivery schedules.

Safety Equipment

Safety equipment abbreviations appear in the "equipment included" section of listings. Verify service dates and certification status for all safety items during the survey and pre-purchase inspection. See the marine survey guide for what to check.

EPIRB: Emergency Position Indicating Radio Beacon. A device that, when activated (manually or automatically on immersion), transmits a distress signal via satellite to the international COSPAS-SARSAT system, alerting search and rescue authorities with the vessel's position. EPIRBs must be registered and have their battery and hydrostatic release replaced on schedule. See EPIRB on Wikipedia.
PLB: Personal Locator Beacon. A smaller, personal version of an EPIRB, worn by crew members. PLBs transmit a distress signal via satellite when activated manually. Unlike an EPIRB, a PLB is registered to a person, not a vessel. Listings for offshore boats may note the number of PLBs aboard.
SART: Search and Rescue Transponder. A radar transponder that, when activated, responds to 9 GHz radar signals from ships and aircraft, displaying a distinctive pattern on the rescuer's radar screen to assist in locating a survivor. SARTs are typically carried in the grab bag or mounted near the life raft.
AIS-SART: AIS Search and Rescue Transponder. A combined device that transmits an AIS distress signal when activated, making the survivor's position visible on the AIS displays of nearby vessels and on vessel traffic services. AIS-SARTs are increasingly preferred over traditional radar SARTs because AIS coverage is broader and the position data is more precise.
MOB: Man Overboard. A critical safety event — a crew member has fallen into the water. MOB also refers to the dedicated button on chartplotters that marks the overboard position with a single press. Listings for well-equipped offshore boats may note MOB equipment such as MOB lights, MOB poles, or dedicated MOB modules.
GMDSS: Global Maritime Distress and Safety System. The international framework of communication equipment and procedures required on commercial vessels. Recreational boats are not required to comply with full GMDSS, but GMDSS-compliant equipment (DSC VHF, EPIRB, SART) is standard on well-found offshore cruisers and is referenced in offshore race safety requirements.
MSD: Marine Sanitation Device. The holding tank and/or treatment system for sewage. US listings frequently note whether the vessel has a Type I, II, or III MSD, as overboard discharge of untreated sewage is regulated or prohibited in US waters. A listing noting "holding tank" or "MSD fitted" is relevant to coastal and inland cruising regulations.

Hull & Construction

Construction material abbreviations tell you what the hull is made of — a fundamental factor affecting longevity, maintenance requirements, and repairability. See also the hull types explained guide.

GRP: Glass Reinforced Plastic. The standard term in British and European usage for fibreglass composite construction — polyester, vinylester, or epoxy resin reinforced with fibreglass cloth. The vast majority of production boats built since the 1960s are GRP. GRP hulls are durable, low-maintenance, and repairable, but can suffer osmotic blistering if the gelcoat is compromised.
FRP: Fibre Reinforced Plastic / Polymer. The equivalent North American term for what Europeans call GRP. Functionally identical. In listings, GRP (UK/EU) and FRP (US) refer to the same material.
GRE: Glass Reinforced Epoxy. A higher-specification variant of GRP using epoxy resin instead of polyester or vinylester. GRE is lighter and stronger than standard GRP and is far more resistant to osmotic blistering, making it the preferred construction method for performance and offshore cruising vessels. A listing specifying GRE construction commands a premium.
HIN: Hull Identification Number. A 12-character alphanumeric code permanently affixed to the transom of any recreational vessel built for the US market after 1972. The HIN encodes the manufacturer, hull serial number, and production date. It is the primary identifier for verifying a vessel's identity, checking for stolen status, and confirming the date of manufacture. Always verify the HIN on a US-documented vessel matches the title and registration.
CIN: Craft Identification Number. The European equivalent of the HIN, required on recreational craft sold in the EU/EEA under the Recreational Craft Directive. The CIN is typically etched or moulded into the transom or starboard quarter. It encodes the country of build, manufacturer, production serial number, and year. Verify the CIN matches the boat's documentation when purchasing a European vessel.

Legal & Commercial

Buying a boat involves legal and financial terminology that differs from buying property or a car. These abbreviations appear in sales contracts, survey reports, and purchase documentation. For an overview of the process, see the what happens after accepting an offer guide.

USCG: United States Coast Guard. The US federal agency responsible for maritime law enforcement, safety regulation, and documentation of US vessels. "USCG documented" means the vessel holds a USCG Certificate of Documentation — a federal title that facilitates international travel and financing. Preferred over state registration for vessels over 26 feet used offshore.
MCA: Maritime and Coastguard Agency. The UK government agency responsible for maritime safety and the UK Ship Register. MCA compliance appears in listings for commercially coded vessels (e.g., charter boats) and in the context of the UK Part I Ship Register for recreational vessels.
RYA: Royal Yachting Association. The UK national authority for recreational boating. RYA qualifications (Dayskipper, Coastal Skipper, Yachtmaster) are widely recognised internationally. In a listing context, RYA may appear in references to the Small Ships Register (SSR) or RYA-coded training vessels.
IIMS: International Institute of Marine Surveying. A professional body for marine surveyors. A survey conducted by an IIMS member gives buyers confidence that the surveyor holds recognised professional qualifications. When arranging a pre-purchase survey, look for surveyors accredited by IIMS, YBDSA, or ABYA.
YBAA: Yacht Brokers, Dealers and Surveyors Association (sometimes styled YBDSA in the UK; YBAA in North America refers to Yacht Brokers Association of America). Membership indicates the broker or surveyor has agreed to a professional code of practice. Working with a member broker provides a degree of consumer protection in the sales process.
ABYA: Association of Brokers and Yacht Agents. A UK professional body for yacht brokers. ABYA membership requires adherence to a code of conduct covering client money handling, listing accuracy, and professional conduct. Listings placed by ABYA members typically include the ABYA logo.
VAT: Value Added Tax. A consumption tax applied in the EU, UK, and many other jurisdictions. In a boat listing, "VAT paid" or "VAT status paid" means the tax has already been settled and the buyer does not face a VAT liability on import into a VAT jurisdiction. "VAT not paid" or "VAT status unknown" is a significant financial consideration — the unpaid VAT may become the buyer's liability. Always clarify VAT status before making an offer.
BoS: Bill of Sale. The legal document that transfers ownership of the vessel from seller to buyer. The BoS records the agreed price, the HIN or CIN, and the signatures of both parties. It is a mandatory document for re-registration and for obtaining financing against the vessel.
MOA: Memorandum of Agreement. The formal purchase contract for a vessel, more detailed than a simple Bill of Sale. An MOA sets out the agreed price, deposit terms, survey and sea trial rights, the condition at delivery, and the completion deadline. The MYBA (Mediterranean Yacht Brokers Association) MOA is the most widely used standard form in international yacht sales.
PSA: Purchase and Sale Agreement. An alternative term for a vessel purchase contract, used particularly in North American brokerage transactions. Functionally equivalent to an MOA. Both documents should include provisions for a satisfactory survey and sea trial as conditions of completion.
LOI: Letter of Intent. A non-binding (or sometimes binding) document in which a buyer signals their intention to purchase a vessel, often used to reserve the boat while financing or survey arrangements are made. An LOI typically includes the offered price and proposed timeline but does not commit the buyer to completion in the same way that a signed MOA does.
COD: Cash on Delivery / Completion on Delivery. A payment structure in which the balance of the purchase price is transferred at the moment the vessel is physically delivered to the buyer or the buyer's representative, typically after a satisfactory sea trial and survey. COD terms are common in international deliveries where the boat must be sailed to a new location before completion.
P&I: Protection & Indemnity. A form of marine liability insurance covering third-party claims (personal injury, property damage, pollution) arising from the operation of the vessel. P&I cover is separate from hull and machinery (H&M) insurance. It is standard for commercial vessels and recommended for larger recreational yachts, particularly those used for chartering.
H&M: Hull & Machinery. The form of marine insurance that covers physical damage to the vessel's hull, machinery, and equipment. H&M is the standard recreational boat insurance policy type. When a listing notes "insured H&M value" it refers to the agreed or market value used as the basis for the insurance policy.

Next Steps

Now that you can decode the abbreviations, you are ready to assess listings more confidently. Browse all boats currently for sale or filter to sailboats only. When you find a vessel of interest, the following guides will take you through the next stages: