Marian Hoskins SAMS-AMS® | Principal Marine Surveyor | (312) 315-7362 |


Surveyors are a relatively small group in the U.S. and we are guilty of spewing words we use every day but the average customer has no idea what we’re talking about. Below are definitions to some the most commonly used terms.

Anode: The positively charged metal surface and the corroding part of an electrochemical corrosion cell at which the oxidation or loss of electrons occurs. Sacrificial anode or impressed current anode. Also, Sacrificial Anode.

Athwartships: From one side to the other of a vessel at right angles to the keel

Beam: The widest part of the boat athwartships

Bilges: The round areas of the hull between the topsides and the keel.

Bow: The front of the boat

Cavitation: The formation of bubbles on an aerofoil section in areas of reduced pressure. Can occur on heavily loaded ship propellers.

Cavitation Damage: Degradation of metal surfaces, characterized by pitting, in which the pit profile is irregular, occurring when very turbulent fluids are in contact with the metal surface, and associated with the formation and collapse of cavities in the liquid at the solid – liquid interface.

Chine: A boat that has an essentially flat bottom that joins the sides of the boat at a distinct angle is called a chine boat, and the line that the angle forms as viewed from the side is called the chine.

Documentation Number: The USCG documentation number is the official number (ON) of a documented vessel. It stays with the boat for its lifetime. In some states, they allow state registration and federal documentation. Other states, however, do not let vessels to be identified as both a state registered and federally documented.

Floors: Floors don’t have anything to do with the cabin sole. They are the athwartship structural members that connect pairs of frames to each other and to the keel and ballast y means of keel bolts. Floors are perforated with limber hole to let the bilge drain into the sump.

FRP: Fiberglass Reinforced Plastic. The material used to build the majority of boats existing today.

Hull Identification Number (HIN): The Hull Identification Number (Hull ID or HIN) is a serial number assigned by the manufacturer that uniquely identifies a boat, similar to the VIN on an automobile. Hull ID numbers distinguish one vessel from another and help prevent theft. Vessels build on or after November 1, 1972 should have a unique 12-character HIN and should meet one of the approved US Coast Guard formats. Vessels built before November 1, 1972 may have a non-standardized Hull ID format.

Knee: A short, triangular block of wood used to connect and reinforce two other members of the hull.

Longitudinal Members: The pieces that run fore and aft except the parts that make up the backbone and the planking.

Latitudinal Members: The pieces that run athwartships

Moisture meter: Used to measure the amount of water within a material sample. This measurement allows the user to discover if the moisture levels are appropriate, or if repairs need to be made.

Phenolic hammer: A plastic hammer used to discover delamination on a hull or deck.

Powers Up: The electrical component showed electrical connection when power was applied. This does not refer to the operation of any system or component unless specifically indicated.

Rubrail: The trim that is mounted on the hull just under the toerail is called the rubrail. Rubrails can also be any longitudinal protective strip of wood mounted on the planking anywhere above the waterline.

Serviceable: Fit for its intended use

Sheer: The upward curvature or angle of a vessel’s deck at the bow or stern.

Stern: The back of the boat

Stringers: Fastened to the inside of the frames and used to stiffen the hull and to carry or distribute the weight of other parts of the hull. They are usually identified by where they’re used or by what they do (bilge stringers, engine stringers, etc.)

Soundings (un)remarkable: When using a phenolic hammer, it produces soundings which are remarkable or unremarkable. “Soundings Remarkable” means the sound produced with the hammer indicates signs of delamination. “Soundings Unremarkable” means the sound produced does not indication delamination.

Subrogation: the right your insurance company holds under your policy — after they’ve paid a covered claim — to request reimbursement from the at-fault party. This reimbursement often comes from the at-fault party’s insurance company.