ReferenceGlossary

The boat owner's glossary

Every term defined the same way: what it is, how it is recorded aboard, and the Apex Marine Labs document that keeps it. No term here carries a normal value, a threshold or an interval: your boat is measured against itself.

By Apex Marine Labs · Last reviewed 9 October 2026 · US, Canadian, Australian and New Zealand usage

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A

AIS: AIS, the automatic identification system, transmits and receives vessel identity, position, course and speed by radio. Contacts seen on watch are recorded in the night log, and the boat's own AIS identity is recorded with its MMSI.

Recorded in Watchkeeping Roster & Night Passage LogRead the guideSee also Closest point of approach, MMSI

Passage planning

Amp-hours: Amp-hours are the unit of charge a battery delivers or receives, a current multiplied by the hours it flows. Daily consumption is recorded in amp-hours for each load and each way of using the boat, from measured current and observed running time.

Recorded in 12V Load & Energy Budget WorksheetSee also Battery monitor, Duty cycle, Energy regime

Electrical & power

Antifouling: Antifouling is the coating applied below the waterline to slow marine growth. Where fouling was heaviest is recorded in the slings before washing, and each application is recorded with the date and the product used.

Recorded in Haul-Out & Winterisation RecordRead the guideSee also Haul-out, Sacrificial anode

Ownership & admin

Apparent wind: Apparent wind is the wind felt aboard a moving boat, the combination of the true wind and the boat's own motion, and the wind the masthead unit measures. True wind is worked out from it and from boat speed, so both depend on calibrated instruments.

Recorded in Rig Tune & Target Speed LogSee also True wind, Log calibration

Rig & sails

B

Battery management system: A battery management system is the electronics that monitors a lithium bank's cells and disconnects charge or loads to protect them. Its make, model, firmware and what it controls are recorded at installation, and every disconnection or alarm is logged with what was running at the time.

Recorded in Lithium & DC System RecordSee also LiFePO4, Cell spread, Cell balancing

Electrical & power

Battery monitor: A battery monitor measures the current flowing in and out of a bank through a shunt, a calibrated resistor in the negative line. It is the instrument each load is measured with, one at a time, and its daily counters are what the energy budget is checked against.

Recorded in 12V Load & Energy Budget WorksheetSee also Amp-hours, Parasitic draw, Plate-to-shunt gap

Electrical & power

Bilge: The bilge is the lowest part of the hull interior, where water collects. What is found in it is recorded at viewings, over the winter and at relaunch, because water where there should be none is one of the first signs worth a dated line.

Recorded in Haul-Out & Winterisation RecordRead the guideSee also Through-hull, Keel bolts

Ownership & admin

Bill of sale: A bill of sale is the document that records the transfer of a boat from seller to buyer. Each one in the boat's history is recorded with its reference, date and where the original is held, as a link in the chain of ownership.

Recorded in Title, Registration, Insurance & Handover RegisterSee also Chain of ownership, Hull identification number

Ownership & admin

C

Carriage requirement: A carriage requirement is an obligation to carry a given item of safety equipment, set by a flag state, an insurer, a race organiser or a charter company. Each one is recorded with the document that imposes it and where you read it, because there is no universal schedule.

Recorded in Safety Equipment & Expiry RegisterSee also Flag state, Liferaft service

Safety & inventories

Cell balancing: Cell balancing is the process by which a battery management system brings individual cells to the same state of charge, usually near the top of a charge. The first balance at commissioning is recorded with how long it took and the cell readings at the end.

Recorded in Lithium & DC System RecordSee also Cell spread, Battery management system

Electrical & power

Cell spread: Cell spread is the difference between the highest and lowest cell voltage in a lithium bank, read at the top of a charge, rested, with charge sources off. Recorded at commissioning and at each full charge, it shows whether the bank is drifting from its own starting point.

Recorded in Lithium & DC System RecordSee also Cell balancing, LiFePO4, Commissioning baseline

Electrical & power

Chain of ownership: The chain of ownership is the sequence of documented transfers from one owner to the next. Each transfer is recorded with its document, reference, date and where the original is held, and any gap is marked as a gap.

Recorded in Title, Registration, Insurance & Handover RegisterSee also Bill of sale, Hull identification number

Ownership & admin

Chainplate: A chainplate is the fitting that anchors a shroud or stay to the hull. Each one is recorded with its position, and what is seen of it and of its deck seal at each inspection is photographed and dated, for a rigger to judge.

Recorded in Standing Rigging Inspection & Tension RecordSee also Standing rigging, Turnbuckle

Rig & sails

Closest point of approach: The closest point of approach is the nearest two vessels will come to each other if both hold course and speed. It can be worked out from two bearings and two ranges recorded in the night log, as a check on what the instruments show, never as a substitute for a proper lookout.

Recorded in Watchkeeping Roster & Night Passage LogRead the guideSee also AIS, Handover line

Passage planning

Cold start: A cold start is the first start of an engine that has not been run beforehand that day. On a sea trial it is observed and recorded before anything else: the hour meter, how readily it fires, the exhaust and the raw water flow, because it cannot be repeated once the engine is warm.

Recorded in Sailboat Sea Trial LogRead the guideSee also Sea trial, Engine hours, Raw water cooling

Buying a boat

Cold-morning check: The cold-morning check is the calculation of the highest voltage a solar array can present to its controller, on the coldest bright morning you expect. It uses your own panels' datasheet figures and your controller's input limit, and is recorded once and redone whenever the array changes.

Recorded in Solar & Hydro Yield RecordSee also Open-circuit voltage, MPPT controller

Electrical & power

Commissioning baselineApex method: A commissioning baseline is a set of readings taken once, when nothing is wrong, under conditions you can reproduce. It is recorded with the date, the conditions and who took it, and every later reading of the same kind is measured against it.

Recorded in every Apex Marine Labs documentSee also Reference page, Deviation log, Drift rate

The Apex method

Competence coverApex method: Competence cover is a record of which skills are awake at each hour of a watch rota: who can reef, navigate, handle the engine or recover someone from the water. It is built by laying each person's competences over the rota, so the hours with a gap are visible before departure.

Recorded in Watchkeeping Roster & Night Passage LogRead the guideSee also Watch system, Handover line

The Apex method

Cost per hour: Cost per hour is a boat's total running cost for the year divided by the engine hours run, with cost per mile worked out the same way from miles logged. It is built from every invoice entered as it arrives, in categories that stay the same each year.

Recorded in Annual Running Cost ModelSee also Planned and unplanned spend

Ownership & admin

Course to steer: Course to steer is the heading that makes good the intended track once the stream and leeway are allowed for. It is worked out for each leg from figures taken from your own charts and tide tables, and recorded with those sources.

Recorded in Coastal Passage & Float PlanSee also Tidal gate, Float plan

Passage planning

Cruise RPM: Cruise RPM is the engine speed you normally run at under way, chosen as the fixed load for comparable readings. Temperatures and pressures are recorded at that same speed each time, so the readings can be laid beside each other and beside the baseline.

Recorded in Marine Diesel Baseline & Trend LogSee also Engine hours, Commissioning baseline, Drift rate

Engine & drivetrain

Cutless bearing: A cutless bearing is the water-lubricated rubber bearing that supports the propeller shaft where it leaves the hull. Any play is measured or felt with the boat ashore and recorded vertically and horizontally with the engine hours, so its wear can be followed over sessions.

Recorded in Drivetrain Alignment & Shaft RecordSee also Engine alignment, Stuffing box, Haul-out

Engine & drivetrain

D

Days of autonomy: Days of autonomy is how long a bank can carry the boat's measured consumption without a charge source, worked out for each energy regime. It is an estimate built from your own measurements and your manufacturer's usable capacity, not an assurance.

Recorded in 12V Load & Energy Budget WorksheetSee also Energy regime, Depth of discharge, Amp-hours

Electrical & power

Defect matrix: A defect matrix is the table that sets every finding against its severity, its cost and the source of that cost. It is filled after the inspection and the survey, and it is what turns a list of findings into an offer that can be defended line by line.

Recorded in Due Diligence KitRead the guideSee also Severity class, Walk-away price, Subject to survey

Buying a boat

Delamination: Delamination is the separation of layers in a laminate or of the skins from the core of a deck or hull. It is usually noticed as a soft or hollow-sounding area; the location and extent are recorded and photographed, and the judgement is left to a surveyor.

Recorded in Due Diligence KitRead the guideSee also Osmosis, Moisture meter

Buying a boat

Depth of discharge: Depth of discharge is the share of a battery's capacity that has been drawn out. The usable figure for your chemistry and your cells comes from the battery manufacturer's documentation and is transcribed on the reference page; the energy budget then works from it.

Recorded in 12V Load & Energy Budget WorksheetSee also Amp-hours, LiFePO4, Days of autonomy

Electrical & power

Deviation logApex method: A deviation log is the running record of readings taken the same way over time, each set beside your own baseline. It is kept with enough rows to show a trend, so a slow change becomes visible as a number while the absolute values still look fine.

Recorded in every Apex Marine Labs documentSee also Commissioning baseline, Drift rate

The Apex method

Draft position: Draft position is where the deepest point of a sail's curve sits between luff and leech. It is followed with the same photograph taken from the foot of the mast each season, in steady conditions and with the same settings, so its movement shows before the eye notices.

Recorded in Sail Inventory & Condition RegisterSee also Sail hours, Sail wardrobe, Polar diagram

Rig & sails

Drift rate: A drift rate is how fast a reading moves away from its baseline over engine hours or time. It is worked out from the deviation log, so a slow change is seen as a rate while each single reading still sits within what your manual allows.

Recorded in Marine Diesel Baseline & Trend LogSee also Commissioning baseline, Deviation log, Engine hours

Engine & drivetrain

Drill record: A drill record notes when the crew last handled each piece of safety equipment: found the flares in the dark, rigged the liferaft painter, clipped on to a jackline. It records when it last happened, not a certification.

Recorded in Safety Equipment & Expiry RegisterSee also Jackline, Flares, Liferaft service

Safety & inventories

Drogue: A drogue is a device streamed astern to slow a boat and hold her stern to the seas, while a sea anchor is streamed from the bow to hold her head to the seas. The gear carried, how it is rigged and who has practised deploying it are recorded before departure.

Recorded in Offshore Passage Planning WorkbookRead the guideSee also Heave to

Passage planning

Duty cycle: Duty cycle is the share of time a cycling load, such as a fridge compressor, actually runs. It is observed by watching or logging the load in the conditions you will actually be in, and recorded with those conditions, because it cannot be reliably guessed.

Recorded in 12V Load & Energy Budget WorksheetSee also Amp-hours, Energy regime, Parasitic draw

Electrical & power

E

Energy regime: An energy regime is one distinct way of using the boat, such as at anchor, on passage or alongside, each with its own pattern of consumption. Loads and hours are recorded separately for each regime, because a single blended daily figure hides the regime that will let you down.

Recorded in 12V Load & Energy Budget WorksheetSee also Amp-hours, Duty cycle, Days of autonomy

Electrical & power

Engine alignment: Engine alignment is how closely the engine and gearbox output line up with the propeller shaft. It is recorded as the face gap and offset at four positions around the coupling, with whether the boat was afloat, tank levels and who measured, because the geometry changes with each of these.

Recorded in Drivetrain Alignment & Shaft RecordSee also Shaft coupling, TIR, Engine mounts

Engine & drivetrain

Engine hours: Engine hours are the running time shown on an engine's hour meter, the clock most services and wear are measured against. They are recorded with every entry, beside the readings taken at the same time, so each reading sits on the engine's own clock and two entries give a rate.

Recorded in Marine Diesel Baseline & Trend LogSee also Cruise RPM, Deviation log, Drift rate

Engine & drivetrain

Engine mounts: Engine mounts are the flexible feet that carry the engine and absorb its vibration. Their condition and replacement dates are recorded with the alignment sessions, because mounts that settle or age move the engine relative to the shaft.

Recorded in Drivetrain Alignment & Shaft RecordSee also Engine alignment, Shaft coupling

Engine & drivetrain

EPIRB: An EPIRB is a distress beacon registered to a vessel that transmits its position to search and rescue services when activated. Its registration, battery date and service history are recorded, and the registration reference is kept with the boat's paperwork.

Recorded in Safety Equipment & Expiry RegisterSee also PLB, MMSI, Hydrostatic release

Safety & inventories

F

Failure history: A failure history is the record of what has broken aboard: what failed, when, what it took to fix, whether the part was aboard and how long the boat was out of action. It is the best guide to which spares to carry on your installation.

Recorded in Spares & Tools Inventory RegisterSee also Reorder point

Safety & inventories

Flag state: A flag state is the country under whose flag a vessel is registered, whose rules apply to her. It is recorded on the reference page of the safety and paperwork records, beside each requirement that comes from it.

Recorded in Safety Equipment & Expiry RegisterSee also Carriage requirement, Vessel registration

Safety & inventories

Flares: Flares are pyrotechnic distress signals that carry a printed expiry date. Each one is recorded with its type, where it is stowed and the date photographed from the tube, then sorted by date with the rest of the safety equipment.

Recorded in Safety Equipment & Expiry RegisterSee also Carriage requirement, Drill record

Safety & inventories

Float plan: A float plan is the written description of a passage left with someone ashore: the boat, who is aboard, the route, when to expect contact and when to raise the alarm. It is written for a non-sailor, filled before each passage and cancelled on arrival.

Recorded in Coastal Passage & Float PlanSee also Shore copy, Tidal gate, Port of refuge

Passage planning

H

Handover file: A handover file is the set of documents and records that passes to the next owner when a boat is sold: ownership papers, service records, survey reports and logs. It is assembled as you go, and what changed hands is recorded with who signed for it.

Recorded in Title, Registration, Insurance & Handover RegisterSee also Chain of ownership, Bill of sale

Ownership & admin

Handover line: A handover line is the short entry at the end of a watch that tells the next person what the last watch learned. It is written in the night log after position, course, speed, wind, sea, sails and traffic.

Recorded in Watchkeeping Roster & Night Passage LogRead the guideSee also Watch system, Competence cover

Passage planning

Haul-out: A haul-out is the lifting of a boat out of the water, for storage or work below the waterline. What the hull shows in the slings, before it is pressure washed, is photographed and recorded: fouling, anodes, propeller, cutless bearing, rudder and keel joint.

Recorded in Haul-Out & Winterisation RecordRead the guideSee also Sacrificial anode, Antifouling, On the hard

Ownership & admin

Heat exchanger: A heat exchanger is the unit in which raw water takes heat from the engine's closed coolant loop without the two mixing. Each service is recorded with the date, engine hours, what was found and who did it, because fouling builds gradually and only the history shows the rate.

Recorded in Cooling & Exhaust Service RecordSee also Raw water cooling, Impeller

Engine & drivetrain

Heave to: To heave to is to set the sails and helm so the boat lies quietly with little forward way. Whether and how a crew intends to use it is a decision made ashore and recorded with where it came from and who aboard has practised it.

Recorded in Offshore Passage Planning WorkbookRead the guideSee also Drogue, Port of refuge

Passage planning

Hull identification number: A hull identification number is the unique code marked on a boat's hull, usually near the transom. It is read off the hull and transcribed separately from the number printed on the title or registration, and the two are compared character by character.

Recorded in Title, Registration, Insurance & Handover RegisterSee also Vessel registration, Chain of ownership, Bill of sale

Ownership & admin

Hydrogenerator: A hydrogenerator is a charging device driven by water flow past the hull while the boat is sailing. Its output is recorded with the boat speed at each reading, so a change in output at the same speed stands out.

Recorded in Solar & Hydro Yield RecordSee also Specific yield, Energy regime

Electrical & power

Hydrostatic release: A hydrostatic release is the device that frees a liferaft or beacon automatically when a vessel sinks. The date on it is photographed and recorded on its own line of the locker inventory, using an Other line until the next revision.

Recorded in Safety Equipment & Expiry RegisterSee also Liferaft service, EPIRB

Safety & inventories

I

Impeller: An impeller is the flexible rotor inside the raw water pump that drives seawater through the cooling circuit. Each change is recorded with the date, engine hours, part number and the state of the old one, including any missing vanes, which usually end up in the heat exchanger.

Recorded in Cooling & Exhaust Service RecordSee also Raw water cooling, Raw water strainer, Heat exchanger

Engine & drivetrain

J

Jackline: A jackline is a line or webbing run along the deck for crew to clip a harness tether to. When the crew last clipped on and moved along it in a drill is recorded with the other safety drills.

Recorded in Safety Equipment & Expiry RegisterRead the guideSee also Drill record

Passage planning

K

Keel bolts: Keel bolts are the fastenings that hold an external keel to the hull, usually reached from inside the bilge. At an inspection, what can be seen of each bolt, nut and backing plate is recorded with its position and a photograph, and referred to a surveyor.

Recorded in Due Diligence KitRead the guideSee also Bilge, Pre-purchase inspection

Buying a boat

Kit GuideApex method: A Kit Guide is the document included with every Command Kit and Super-Pack that sets the order of work across the records in the kit. It gathers every dated check from all of them on one page, sorted for you in Adobe Acrobat Reader.

Recorded in every Command Kit and Super-PackSee also Reference page

The Apex method

Kit specification: A kit specification is the record of who decided the contents of a medical kit, their profession, the date and the source. It is the first page of the medical record, ahead of the inventory, because the contents are a medical decision with an author.

Recorded in Medical Kit Inventory & Expiry LogSee also Telemedical service

Safety & inventories

L

LiFePO4: LiFePO4, lithium iron phosphate, is the lithium battery chemistry most often fitted as a house bank on boats. A LiFePO4 bank is recorded as installed, with its cells, management system and protection, and followed through the spread between its cells at full charge.

Recorded in Lithium & DC System RecordSee also Battery management system, Cell spread, Cell balancing

Electrical & power

Liferaft service: A liferaft service is the inspection and repacking of a liferaft by a service station. Each one is recorded with the date, the station, the next date set by the source that applies to you and the lead time needed to book it.

Recorded in Safety Equipment & Expiry RegisterSee also Hydrostatic release, Carriage requirement

Safety & inventories

Log calibration: Log calibration is the check of the speed log against speed over ground on reciprocal runs, and the correction factor that comes from it. The date, method and result are recorded, and the check is repeated after any replacement or lift-out.

Recorded in Rig Tune & Target Speed LogSee also Speed over ground, Reciprocal headings, True wind

Rig & sails

M

Marine survey: A marine survey is a professional assessment of a boat's condition by a qualified surveyor, delivered as a written report and often required by insurers and lenders. The buyer records what was asked of the surveyor and what the report found, to price findings afterwards.

Recorded in Due Diligence KitRead the guideSee also Pre-purchase inspection, Survey brief, Subject to survey

Buying a boat

Mixing elbow: A mixing elbow is the fitting where raw water is injected into the exhaust to cool it before it leaves the boat. Each inspection or replacement is recorded with the date, engine hours and what the inside looked like, because it narrows gradually long before it fails.

Recorded in Cooling & Exhaust Service RecordSee also Raw water cooling, Heat exchanger

Engine & drivetrain

MMSI: An MMSI, Maritime Mobile Service Identity, is the nine-digit number that identifies a vessel's radio, DSC and AIS equipment. It is recorded with its licence and every place it is programmed aboard, because the copies do not always agree.

Recorded in Title, Registration, Insurance & Handover RegisterSee also AIS, EPIRB, Vessel registration

Ownership & admin

Moisture meter: A moisture meter is a hand-held instrument that gives a comparative reading of moisture in a laminate. Readings are recorded by location and compared across the same boat; what counts as normal for a given laminate is a question for a surveyor.

Recorded in Due Diligence KitRead the guideSee also Osmosis, Delamination

Buying a boat

MPPT controller: An MPPT controller is a solar charge controller that tracks the operating point at which a panel delivers most power. Its make, model, input limit and the strings it serves are recorded as installed, and its daily harvest counter is read for the yield log.

Recorded in Solar & Hydro Yield RecordSee also Specific yield, Open-circuit voltage, Cold-morning check

Electrical & power

N

Noon position: A noon position is the position recorded at the same time each day on an offshore passage, with the run since the previous noon. Distance to run, average speed and days left follow from it, and so does the drift against the plan.

Recorded in Offshore Passage Planning WorkbookRead the guideSee also Point of no return, Port of refuge

Passage planning

O

On the hard: On the hard describes a boat stored ashore, out of the water, usually in a cradle or on stands. Days ashore, work done and the cost of the period are recorded, and each visit over the winter gets a short dated line.

Recorded in Haul-Out & Winterisation RecordRead the guideSee also Haul-out, Winterization

Ownership & admin

Open-circuit voltage: Open-circuit voltage is the voltage a solar panel produces with nothing connected, the figure that rises as the panel gets colder. Each panel's figure and temperature coefficient are transcribed from its datasheet onto the reference page for the cold-morning check.

Recorded in Solar & Hydro Yield RecordSee also Cold-morning check, MPPT controller

Electrical & power

Osmosis: Osmosis is the process by which water passes into a fibreglass laminate and can raise blisters in the hull below the waterline. At a viewing or a haul-out, a buyer or owner records where blisters are seen, photographs them and refers them to a surveyor, who judges them.

Recorded in Due Diligence KitRead the guideSee also Moisture meter, Delamination, Marine survey

Buying a boat

P

Paired registerApex method: A paired register is a lay-up record in which every job done in autumn sits on the same line as the job that reverses it in spring. Each reversal is ticked, with who did it and when, so nothing closed for the winter stays closed at launch.

Recorded in Haul-Out & Winterisation RecordRead the guideSee also Reversal column, Winterization, Recommissioning

The Apex method

Parasitic draw: Parasitic draw is the current still flowing when everything you can switch off is off: standby losses, monitors, alarms, bilge floats. It is measured first in an energy session and recorded per day and per month, because it runs constantly and is the load most often forgotten.

Recorded in 12V Load & Energy Budget WorksheetSee also Battery monitor, Amp-hours, Plate-to-shunt gap

Electrical & power

Planned and unplanned spend: Planned and unplanned spend splits each invoice into work that was scheduled and work that was a reaction to a failure. The share of unplanned spend, tracked across seasons, says more about a boat's condition than any single figure.

Recorded in Annual Running Cost ModelSee also Cost per hour

Ownership & admin

Plate-to-shunt gapApex method: The plate-to-shunt gap is the difference between the current printed on an appliance's data plate and the current measured for it at the battery monitor's shunt. It is recorded load by load, and the measured figure is the one the energy budget uses.

Recorded in 12V Load & Energy Budget WorksheetSee also Battery monitor, Parasitic draw, Duty cycle

The Apex method

PLB: A PLB is a personal distress beacon registered to a person rather than a vessel. Each one is recorded with who carries it, its registration reference and its battery date.

Recorded in Safety Equipment & Expiry RegisterSee also EPIRB

Safety & inventories

Point of no return: The point of no return is the position on a passage after which continuing is no longer worse than turning back. It is identified and written down before departure, with how the decision will be made when the boat reaches it.

Recorded in Offshore Passage Planning WorkbookRead the guideSee also Port of refuge, Noon position

Passage planning

Polar diagram: A polar diagram is a chart or table of the boat speed reached at each true wind angle and true wind speed. Your own polar is built from steady runs recorded on both tacks with calibrated instruments, one cell at a time, and leaves the cells you never sailed empty.

Recorded in Rig Tune & Target Speed LogSee also VMG, True wind, Log calibration

Rig & sails

Port of refuge: A port of refuge is a harbour or anchorage identified before departure as somewhere to divert to if conditions or the boat require it. Each one is recorded with the leg it serves, so the alternatives were chosen ashore rather than when tired.

Recorded in Offshore Passage Planning WorkbookRead the guideSee also Point of no return, Float plan

Passage planning

Pre-purchase inspection: A pre-purchase inspection is the structured look a buyer takes at a boat during a viewing, to decide whether she is worth a professional survey. Each finding is written down with where it is, what was seen, a photograph reference and the severity the buyer assigns.

Recorded in Due Diligence KitRead the guideSee also Marine survey, Survey brief, Severity class

Buying a boat

Propeller slip: Propeller slip is the difference between the distance a propeller would advance in one turn and the distance the boat actually travels. It is worked out from the revs and the speed recorded on the RPM ladder, and compared between steps and between trials.

Recorded in Sailboat Sea Trial LogRead the guideSee also RPM ladder, Speed over ground

Buying a boat

R

Rake and prebend: Rake is how far the mast leans fore and aft, and prebend is the bend set into it at rest. Both are recorded the same way every season, because what matters for the record is whether they moved, not their absolute value.

Recorded in Standing Rigging Inspection & Tension RecordSee also Rig tension, Polar diagram

Rig & sails

Raw water cooling: Raw water cooling is the part of a marine engine's cooling system that draws seawater through a seacock and strainer, pumps it through the heat exchanger and injects it into the exhaust. Its condition is followed by recording the temperature at a fixed engine speed with the sea temperature beside it.

Recorded in Cooling & Exhaust Service RecordSee also Heat exchanger, Impeller, Raw water strainer

Engine & drivetrain

Raw water strainer: A raw water strainer is the filter between the seacock and the raw water pump that stops debris entering the cooling circuit. Each clean is recorded with the date and what was in it, which tells you what the circuit has been facing.

Recorded in Cooling & Exhaust Service RecordSee also Seacock, Impeller, Raw water cooling

Engine & drivetrain

Reciprocal headings: Reciprocal headings are two runs in opposite directions over the same water. Recording a speed on both and taking the mean removes the effect of current, so the figure describes the boat rather than the tide she was in.

Recorded in Sailboat Sea Trial LogRead the guideSee also RPM ladder, Speed over ground, Log calibration

Buying a boat

Recommissioning: Recommissioning is the work of returning a boat to service after lay-up. Each job closed in autumn is reversed and ticked with who did it and when, each system is confirmed ashore and again afloat, and the first engine start is recorded.

Recorded in Haul-Out & Winterisation RecordRead the guideSee also Winterization, Reversal column, Paired register

Ownership & admin

Reference pageApex method: A reference page is the first page of every Apex document, where you transcribe the figures that apply to your own boat from your own manuals, with the document and page beside each line. Every later reading is compared against it rather than against a published figure.

Recorded in every Apex Marine Labs documentSee also Commissioning baseline, Deviation log

The Apex method

Reorder point: A reorder point is the stock level at which a spare or consumable is replaced, worked out from your own consumption and the lead time to get it. It comes from the draw-down log, in which every item taken off the shelf is recorded.

Recorded in Spares & Tools Inventory RegisterSee also Failure history

Safety & inventories

Reversal column: The reversal column is the second column of a paired lay-up register, where each autumn job is ticked when it has been undone, with who did it and when. An open line is visible before the boat goes back in the water.

Recorded in Haul-Out & Winterisation RecordRead the guideSee also Paired register, Recommissioning

Ownership & admin

Rig tension: Rig tension is the load carried by each shroud and stay, measured with a gauge. It is recorded at the same points on both sides at every session, against the figures from your spar maker or rigger, so asymmetry and movement show in the series.

Recorded in Standing Rigging Inspection & Tension RecordSee also Turnbuckle, Rake and prebend, Standing rigging

Rig & sails

RPM ladder: An RPM ladder is a series of engine speed steps, each held until settled and recorded the same way. At every step the revs, speed, temperatures and pressures are written down, on both reciprocal headings, so the boat's behaviour can be compared from step to step.

Recorded in Sailboat Sea Trial LogRead the guideSee also Reciprocal headings, Speed over ground, Propeller slip

Buying a boat

S

Sacrificial anode: A sacrificial anode is a block of more reactive metal that corrodes in place of the underwater metals it protects. Each anode is recorded at every haul-out with its position and how much has wasted, compared year on year.

Recorded in Haul-Out & Winterisation RecordRead the guideSee also Haul-out, Antifouling

Ownership & admin

Sail hours: Sail hours are the time each sail has been in use, the most useful number in a sail record. They are tallied per outing, with the hours used near the top of the sail's range noted separately, and give each sail's cost per hour.

Recorded in Sail Inventory & Condition RegisterSee also Sail wardrobe, Draft position

Rig & sails

Sail wardrobe: A sail wardrobe is every sail belonging to the boat, aboard and ashore. Each sail is recorded with its type, maker, cloth, date made and where it lives, so the replacement question can be answered sail by sail.

Recorded in Sail Inventory & Condition RegisterSee also Sail hours, Draft position

Rig & sails

Sea trial: A sea trial is the part of a boat purchase where the boat is taken out and run under power and sail before the deal is final. Each step is recorded in a fixed order, with the conditions beside it, so the day can be compared with the survey and with other boats.

Recorded in Sailboat Sea Trial LogRead the guideSee also Cold start, RPM ladder, Reciprocal headings

Buying a boat

Seacock: A seacock is the valve that opens or closes a through-hull fitting below or near the waterline. Each one is recorded with its location, its condition and when it was last operated, and every one closed at lay-up has a line to tick when it is reopened.

Recorded in Cooling & Exhaust Service RecordRead the guideSee also Through-hull, Raw water strainer, Paired register

Engine & drivetrain

Severity class: A severity class is the grade a buyer gives each finding at the moment of seeing it, as their own reading and not a verdict. It is recorded beside the finding and later decides which items lead the offer and which belong to a professional.

Recorded in Due Diligence KitRead the guideSee also Pre-purchase inspection, Defect matrix

Buying a boat

Shaft coupling: A shaft coupling is the joint that connects the gearbox output flange to the propeller shaft. Alignment is measured across it at four positions, with the conditions of each session recorded, so successive sessions can be compared.

Recorded in Drivetrain Alignment & Shaft RecordSee also Engine alignment, TIR, Cutless bearing

Engine & drivetrain

Shore copy: The shore copy is the page of a float plan held by one named person ashore, with the time at which to stop waiting and call, and who to call, in order. It is filled in words a non-sailor can read aloud to a rescue authority.

Recorded in Coastal Passage & Float PlanSee also Float plan

Passage planning

Specific yield: Specific yield is the energy an array produces divided by its rated power, which makes months and installations comparable. It is worked out from the daily harvest recorded at the same time each day, with the conditions beside each entry.

Recorded in Solar & Hydro Yield RecordSee also MPPT controller, Hydrogenerator

Electrical & power

Speed over ground: Speed over ground is the boat's speed relative to the seabed, read from satellite positioning, while speed through the water is her speed relative to the water around her, read from the log. Both are recorded together, because the difference between them is the current.

Recorded in Sailboat Sea Trial LogRead the guideSee also Reciprocal headings, Log calibration, RPM ladder

Buying a boat

Standing rigging: Standing rigging is the fixed wire or rod that holds the mast up: the shrouds at the sides and the stays fore and aft. Each element is recorded individually with what it is, when it went up and what every inspection found, under a name used the same way everywhere.

Recorded in Standing Rigging Inspection & Tension RecordSee also Chainplate, Swage terminal, Rig tension

Rig & sails

Stuffing box: A stuffing box is the seal where the propeller shaft passes through the hull, either packed or a dripless type. Its condition and any adjustment are recorded at each session with the engine hours, beside the alignment and cutless bearing readings.

Recorded in Drivetrain Alignment & Shaft RecordSee also Cutless bearing, Engine alignment

Engine & drivetrain

Subject to survey: Subject to survey describes an offer on a boat that is accepted on the condition that a survey follows before the sale completes. The findings of that survey are what the final price is negotiated from, so each one is recorded with a cost and a source.

Recorded in Boat Purchase Budget WorksheetRead the guideSee also Marine survey, Walk-away price, Defect matrix

Buying a boat

Survey briefApex method: A survey brief is the list a buyer hands to a marine surveyor before the survey: the points they referred to a professional and the points they could not reach at the viewing. It is written from the inspection record, so the surveyor starts where the questions are.

Recorded in Due Diligence KitRead the guideSee also Pre-purchase inspection, Marine survey, Severity class

The Apex method

Swage terminal: A swage terminal is a fitting pressed onto the end of a rigging wire to connect it to the mast or a turnbuckle. Each terminal is recorded with the element it belongs to, and what is seen at it, such as staining or cracks, is photographed and referred to a rigger.

Recorded in Standing Rigging Inspection & Tension RecordSee also Standing rigging, Turnbuckle

Rig & sails

T

Telemedical service: A telemedical service gives medical advice to vessels at sea by radio or satellite link. The record kept aboard of what has been used from the kit, when and for whom is what the person on the call will ask for.

Recorded in Medical Kit Inventory & Expiry LogSee also Kit specification

Safety & inventories

Through-hull: A through-hull is a fitting that passes through the hull to let water in or out, usually closed by a seacock. Each one is listed with its location and purpose, and its condition is recorded at every haul-out, so none is missed at relaunch.

Recorded in Haul-Out & Winterisation RecordRead the guideSee also Seacock, Haul-out, Bilge

Engine & drivetrain

Tidal gate: A tidal gate is a point on a route that can only be passed within a window set by the tide or the stream. Each gate is recorded with its window, the source of the times and the latest departure that reaches it in time.

Recorded in Coastal Passage & Float PlanSee also Float plan, Course to steer

Passage planning

TIR: TIR, total indicated runout, is the full movement shown by a dial indicator as a shaft or flange is turned through one revolution. It is recorded at the same points each session with the instrument used, and compared with the figure from your own documentation.

Recorded in Drivetrain Alignment & Shaft RecordSee also Engine alignment, Shaft coupling

Engine & drivetrain

True wind: True wind is the wind as it blows over the water, with the boat's own motion removed. Its angle and speed are recorded on every observation run, from instruments whose calibration has been checked and written down first.

Recorded in Rig Tune & Target Speed LogSee also Apparent wind, Polar diagram, VMG

Rig & sails

Turnbuckle: A turnbuckle is the threaded fitting used to adjust the tension of a shroud or stay. Each one is recorded with its element, and the tension set through it is logged at the same points on both sides at every tuning session.

Recorded in Standing Rigging Inspection & Tension RecordSee also Rig tension, Chainplate, Swage terminal

Rig & sails

V

Vessel registration: Vessel registration is the record of a boat with an authority, which identifies her and, depending on the system, her owner. Each registration is recorded with its reference, the issuing body, the renewal date and where the document is kept; what applies to you comes from the authority itself.

Recorded in Title, Registration, Insurance & Handover RegisterSee also Hull identification number, Flag state, MMSI

Ownership & admin

VMG: VMG, velocity made good, is the component of the boat's speed directly towards or away from the wind or a mark. It is worked out from the boat speed and true wind angle recorded on each run, and the best value at each angle is kept on the polar.

Recorded in Rig Tune & Target Speed LogSee also Polar diagram, True wind

Rig & sails

W

Walk-away price: A walk-away price is the figure above which a buyer will not buy, decided and written down with the date before the negotiation starts. It is kept beside the costed findings so the limit set calmly at the desk is the one used in the room.

Recorded in Boat Purchase Budget WorksheetRead the guideSee also Defect matrix, Subject to survey

Buying a boat

Watch system: A watch system is the pattern that divides the day and night into watches between the crew. The rota chosen is recorded and laid over each person's competences, so the hours when nobody awake can do a needed task are found before departure.

Recorded in Watchkeeping Roster & Night Passage LogRead the guideSee also Competence cover, Handover line

Passage planning

Weather helm: Weather helm is the boat's tendency to turn towards the wind when the helm is released. It is noted on a sea trial and under sail on each point of sail, as one sign of rig tune and sail condition.

Recorded in Rig Tune & Target Speed LogRead the guideSee also Rake and prebend, Draft position, Polar diagram

Rig & sails

Winterization: Winterization is the work of laying a boat up for the off season, ashore or afloat. Every job is recorded at the moment it is done, on the same line as the job that will reverse it in spring.

Recorded in Haul-Out & Winterisation RecordRead the guideSee also Paired register, Recommissioning, Haul-out

Ownership & admin

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