The words below turn up in quotes, drawings, approvals and sales conversations, and several of them are used loosely enough to cause real disputes. Each definition links to the page that explains how the term affects a purchase.
- Anode (sacrificial)
- A block of a less noble metal fitted so that it corrodes instead of the structure it is bonded to. Anodes are consumables: they have an inspection interval and a replacement point, and both belong in the maintenance schedule. Read more →
- As-built drawings
- Drawings that record what was actually installed, as distinct from what was tendered. They are the document you need when the structure is modified, inspected or sold. Read more →
- Berthing energy
- The energy a vessel brings to the structure when it comes alongside. It drives fender selection, and it is a function of vessel mass and approach speed rather than of vessel length. Read more →
- Bollard
- A heavy mooring fitting used where line loads exceed what a cleat is intended to carry. Like a cleat, its useful capacity is set by the load path behind it, not by its own size. Read more →
- Chamber (tube)
- A sealed compartment within a float or pontoon tube. Dividing a tube into chambers limits how much buoyancy is lost if one compartment is breached. Read more →
- Cleat
- The fitting a mooring line is made fast to. What matters to a buyer is the complete load path: line, cleat, fasteners, backing plate and the structural member behind it. Read more →
- Crevice corrosion
- Localised corrosion in a tight gap where water is held and cannot dry or exchange freely, such as under a clamped joint or washer. It is a detailing problem before it is a maintenance problem. Read more →
- Crown land
- Land held by the state rather than in private title, which in many places includes the bed of waterways and the foreshore. Whether your structure sits on Crown land determines what tenure or licence you need. Read more →
- Datum
- The reference level that water depths and heights are measured from. Two figures quoted against different datums cannot be compared, which is why the datum should always be stated. Read more →
- Defects liability period
- The contractual window after completion during which the builder must rectify defects. It is distinct from a warranty, has its own term, and is usually where retention earns its keep. Read more →
- Displacement
- The mass of water a vessel or float displaces, which equals the mass it supports. It is the figure that matters for load, not overall length. Read more →
- Draft (draught)
- The depth of the structure or vessel below the waterline. For a pontoon it determines grounding behaviour; for a berthed vessel it determines whether the berth is usable at low water. Read more →
- Fairway
- The navigable channel between berths or structures in a marina. Fairway width is fixed at construction and constrains what vessels can manoeuvre in the facility. Read more →
- Fender
- The consumable interface between vessel and structure that absorbs berthing energy and rubbing. It wears by design, so replaceability is part of the specification. Read more →
- Fetch
- The distance of open water over which wind can act to build waves. A short fetch limits wave height regardless of wind strength, which is why exposure is site-specific. Read more →
- Finger
- A narrow pontoon projecting from a main walkway to form a berth. Finger length and the spacing between fingers define what vessel fits. Read more →
- Freeboard
- The height of the deck above the waterline. It is set by the use — boarding a rowing shell, a cruiser or a ferry each demand different figures — and it falls as load is added. Read more →
- Galvanic corrosion
- Accelerated corrosion that occurs when two dissimilar metals are electrically connected in an electrolyte such as seawater. The less noble metal corrodes to protect the more noble one. Read more →
- Gangway
- The hinged access ramp between shore and a floating structure. Its gradient changes with water level, so it must be assessed at the extremes of the range rather than at the average. Read more →
- Grounding
- The structure resting on the bed at low water. Some pontoons are designed to take that load; others are not, and grounding an undesigned structure damages it. Read more →
- Guide pile
- A vertical pile that a pontoon is restrained against, usually through a pile guide or roller assembly. The pontoon rises and falls with the water while its position is held. Read more →
- HDPE
- High-density polyethylene, used for floats, modular cubes and complete rotationally moulded pontoon elements. Corrosion-immune, but UV grade, thermal movement and connection wear all need verification. Read more →
- Hinge (shore)
- The articulated connection at the landward end of a gangway that allows the structure to move with the water while remaining connected to the shore. Read more →
- Point load
- A concentrated load applied over a small area, such as an equipment foot. Deck capacity stated as a distributed load says nothing about whether a point load is acceptable. Read more →
- Reserve buoyancy
- The float volume still above water when the structure is fully loaded. It is the margin between normal operation and a deck that starts taking water. Read more →
- Restraint system
- Whatever holds a floating structure in position: guide piles, struts and hinges, chains, cables or deadweights. Each behaves differently and suits different beds, depths and water-level ranges. Read more →
- Retention
- An amount held back from payment until defects are rectified or the defects liability period ends. It is the practical leverage a buyer has after handover. Read more →
- RFQ
- Request for quotation. A document that states scope, loads, deliverables and commercial terms so that every builder prices the same thing and the responses can be compared. Read more →
- Slip resistance
- How much grip a surface offers, which for a pontoon must be assessed wet rather than dry, and for the users who are actually on it — including bare feet. Read more →
- Storm surge
- The rise in water level driven by a storm's wind and low pressure, over and above the predicted tide. It extends the water-level range the structure must handle. Read more →
- Stray current
- Current leaking through the water from an external source, such as a nearby installation, which can drive rapid corrosion in a structure that is otherwise correctly detailed. Read more →
- Strut
- A rigid arm connecting a floating structure to a fixed shore structure. Simple and economical, but it constrains the water-level range the pontoon can follow. Read more →
- Tidal range
- The vertical difference between high and low water at a site. It drives pile length, gangway length, restraint travel and whether a berth is usable at all states of tide. Read more →
- Tidal works
- A regulatory term used in Queensland for works carried out in or over tidal water. The classification determines the assessment pathway, so it should be confirmed for the specific project. Read more →
- Tritoon
- A pontoon boat with three tubes rather than two, giving more buoyancy and supporting higher power and heavier fit-outs, at more weight and cost. Read more →
- Waterplane area
- The area of the structure at the waterline. A larger waterplane area means the structure sinks less for a given added load and generally feels more stable underfoot. Read more →
- Wave attenuator
- A floating or fixed structure that reduces wave energy reaching berths behind it. Frequently the first item value-engineered out of a marina, and frequently rebuilt afterwards. Read more →
- Windage
- The area a vessel or structure presents to the wind, and therefore the wind load it transfers into moorings and restraint. A tall, light vessel can load a berth harder than a heavier low one. Read more →