JetSetGo's Vehicle Ferry Inventory Model — Capability Documentation
A vehicle ferry's deck is not a flat count of "spaces". It is a physical structure with measurable constraints — lane metres of usable length, weight ratings per deck, overhead clearance under cover, dangerous-goods rules governing where certain loads can travel, and charging-equipped bays some routes need to track separately. A platform that models the deck as a single capacity number works until a 12-metre tipper rolls up booked as "one truck", or a 3.5-metre van shows up at the under-cover queue with a 2.1-metre clearance, or a car-with-caravan arrives on a ticket that covers the car only.
This page documents how JetSetGo's vehicle ferry inventory model represents the deck — the structure the engine reasons over, the constraints it enforces, and how it composes with passenger inventory, pricing, and reporting.
What the engine models
The vehicle deck is modelled as a hierarchical capacity structure with several independent constraints checked simultaneously at booking time.
The vessel as a tree. A vessel breaks down into areas — a passenger lounge, a vehicle deck — and each area breaks down further into the spaces the operator allocates against. A vehicle deck might split into an under-cover area, an open area, an overflow lane, and a motorbike bay. The booking engine walks the tree to find the right place for each vehicle.
Capacity limits as independent units. Each bookable area carries one or more capacity limits — lane metres, tonnage, passenger seats, cabin berths, dedicated EV bays, bicycle slots, freight slots. When a booking lands, the engine decrements the matching capacity.
Per-deck checks that don't deplete capacity. Some constraints are checked but not consumed — overhead clearance, vehicle width, axle count caps, length-plus-trailer caps. A van taller than the under-cover clearance is rejected from that area regardless of how many lane metres remain. These checks describe a property of the space, not a quantity of it.
Explicit exclusions by vehicle category. A bookable area can refuse specific vehicle categories outright — motorbikes off the open truck deck, hazardous-class-1 loads off the under-cover deck, oversize off the upper deck. These exclusions are absolute and override anything else.
Fill order across the deck. Each area carries a priority. The engine walks the areas in priority order and the first area that can accept the vehicle (lane metres, height, tonnage, category, hazmat class all satisfied) wins. Priority is how operators steer demand.
The structure lives in a reusable template. Operators draw the deck once; each scheduled sailing copies the template into its own live capacity, independent of every other sailing. A maintenance day with reduced deck space gets a per-sailing override without touching the template.
How vehicle types consume the deck
Each vehicle category — car, motorhome, van, light truck, heavy truck, motorbike, B-double, articulated rigid, oversize, freight pallet — has its own consumption rule set per vessel. A car consumes lane metres. A truck consumes lane metres and tonnage. A motorbike consumes motorbike spaces, or lane metres if the operator models them that way. A car-with-driver-and-passengers consumes lane metres on the vehicle deck and passenger seats in the lounge — related but separate consumptions in one transaction.
The same category can consume differently on different vessels. A car on Vessel A might be 4.5 lane metres; on Vessel B, 4.8. The rule set lives with the vessel, not the category. Consumption is modifiable where the actual length matters — the customer enters their real length, or the catalogue looks it up by make / model / year. Where consumption is genuinely fixed (a passenger seat is one passenger seat; a bicycle slot is one bicycle slot), the rule is locked.
The configuration is operator-driven. A short-route community ferry that prices by vehicle class without measuring lane metres can model the deck as a count of spaces. A RoRo with weight-rated decks turns tonnage on. An under-cover deck gets a height limit; an open deck doesn't. Dimensions that don't apply aren't part of the configuration.
The constraints, one by one
Lane-metre allocation
Lane metres are the linear measurement of usable vehicle deck length — the most common unit of vehicle ferry capacity. A 4.5-metre car consumes 4.5 lane metres. A 12-metre semi-trailer consumes 12. A car-with-caravan consumes the car's lane metres plus the caravan's. The engine allocates in real time. A deck rated at 80 lane metres with 76.5 consumed has 3.5 left — it can accept a 3.5-metre vehicle but not a 4-metre one. No rounding to "vehicle spaces". Operators who prefer per-category counts can model the deck that way instead — the unit of capacity is whatever the deck actually constrains on.
Tonnage per weight-rated deck
On vessels where the deck has a weight rating — common on multi-deck RoRo where one deck is car-rated and another is HGV-rated, or on vessels where stability calculations require tonnage tracking — tonnage runs as a separate capacity limit. A truck consumes both lane metres and tonnage; a passenger car typically consumes lane metres only. When the deck approaches its tonnage rating, further heavy vehicles are blocked even if lane metres remain, and the engine looks for the next deck in priority that can carry the load. A passenger ferry with no weight-rated decks simply doesn't have tonnage in its configuration.
Height per under-cover deck area
Where a deck has overhead clearance — under-cover decks, decks below a mezzanine, decks under a passenger lounge — the height limit runs as a check that doesn't consume capacity. A 2.1-metre clearance refuses a 3.5-metre van regardless of how much lane-metre space remains.
The check runs at the booking stage, not at the wharf. A van booked online with a height the system knows from the catalogue is allocated to a compatible deck before the customer leaves home. A van that arrives taller than the booking declared — roof rack, surfboards strapped on top — is re-allocated to the open deck at the kiosk, and the lane-metre counts update across both decks. Width, length-with-trailer, axle count, ground clearance — any property that gates a vehicle from being there can be modelled the same way.
Hazmat class per deck
Dangerous-goods classification is a per-deck acceptance rule. A deck can allow specific hazmat classes (flammable liquids on the open deck only, no explosives at all, restricted-quantity exceptions for tradesman vehicles) or refuse classes outright. The booking flow asks the hazmat declaration question for vehicles where it applies — freight, tradesman vehicles, larger commercial loads, fuel trucks — and the deck allocation respects the answer structurally. A class-3 flammable load gets allocated only to a deck that accepts class 3. A booking with a class the vessel refuses cannot be confirmed; the customer sees the refusal before the transaction completes. A short tourist car ferry with no dangerous-goods carriage simply doesn't enable hazmat.
EV-spaces as independent inventory
Routes with charging-equipped berths, deck-side EV-charging insurance requirements, or policies around lithium-battery load distribution can model EV spaces as a separate capacity unit from regular car spaces. An electric car flagged as EV consumes one car space (in lane metres) AND one EV space (in EV bays). When the EV bays are full, further EV cars are refused even if car space remains. The catalogue carries an EV flag per model, so the booking flow knows which vehicles need an EV space without asking.
Vehicle category exclusions per deck
A deck area can refuse a vehicle category outright — motorbikes off the open-truck deck (rough-weather safety), heavy goods off the upper passenger-deck (weight rating), oversize off the under-cover deck (clearance), trailers off the bow-loading lane (manoeuvrability). These exclusions are absolute. The engine never places a refused category into a refused area, regardless of capacity remaining or priority order. The same category can be allowed on one vessel's open deck and refused on another's.
Vehicle catalogue and dimension lookup
For each vehicle category, the actual dimensions matter — and asking customers to measure their car is not a serious answer. The platform carries a catalogue of vehicle makes, models, years, and body types, each with length, width, height, weight, and an EV flag. When a customer selects their vehicle by make / model / year, the dimensions populate automatically and lane-metre allocation, tonnage check, and height check all run against them rather than customer guesses. For vehicles outside the catalogue — custom builds, older models, trucks, buses, fleet vehicles — operators maintain a per-vessel list.
Attachments extend the parent. Bullbars, roof racks, rear-mounted bike racks, kayaks, surfboards extending past the bonnet — anything that changes effective length, width, or height — get declared as attachments and the platform adds their dimensions to the parent for the allocation. A 4.5-metre car with a 0.8-metre rear overhang allocates as 5.3 metres.
Towed vehicles and trailers — linked but separate
A car towing a caravan is two related entities, not one. The platform models them that way: linked at the booking level, separate at the inventory level, separate at the reporting level.
The unity side. The car and the caravan book on one transaction. They sail together — the platform knows they're attached and treats them as a single unit on the deck. They share boarding state. They refund together if cancelled.
The separateness side. The platform knows what's really there: a car of a known type plus a caravan of a known type, each with its own dimensions, its own tonnage, its own hazmat declaration if either declares one. That separation matters in three places operators actually care about:
- Reporting. Operators can break out trailer movements from vehicle movements without inferring them from a combined "vehicle + tow" category. How many caravans crossed this season; how many bike trailers; how many boat trailers — answered cleanly because the platform tracked the towed unit separately rather than rolling it into one figure.
- Revenue accounting. Operators can price (and account) for the tow distinctly from the towing vehicle — a flat tow surcharge, a per-metre tow rate, a freight-trailer rate that differs from the towing-truck rate, included tow for certain customer segments. Revenue from the tow lands in whichever bucket the operator configures, not bundled into the main-vehicle line.
- Operational reality. A car-plus-caravan isn't the same as a long vehicle of the same total length. Manoeuvrability is different, and so are deck restrictions for the combination. A vessel with a tight bow-loading lane can refuse car-plus-trailer combinations from that lane — the combined unit can't make the turn even though the lane metres on the deck are sufficient. A vessel with stern-loading-only can refuse caravans on certain decks because reversing a caravan onto an upper deck isn't a manoeuvre the deck supervisor will sign off. These restrictions are specific to the combination, not to the length, so the platform needs to know it's a combination rather than a single long vehicle.
The platform also handles N-deep towing chains. A B-double truck pulling two trailers is three linked entities — the truck, plus each trailer, each with its own dimensions and its own hazmat class if it carries dangerous goods independently of the parent. A car-with-caravan booking that turns out to be a car-with-caravan-plus-bike-trailer at the wharf isn't an exception the operator hand-resolves — it's a modification that adds the bike trailer, re-allocates against the deck, and updates the deck-side allocation before the loading lane backs up.
Refusal at the inventory layer, not at the wharf
When the engine cannot place a vehicle on the deck, the booking does not confirm. Physical impossibility is rejected at the booking layer, not discovered at the wharf. A 4-metre van booked against an under-cover deck with a 2.1-metre clearance is refused — the height check runs and the booking is offered the open deck instead, or refused entirely if no compatible deck exists. A truck booked when its tonnage class is full is allocated to the next deck in priority that can carry the load, or refused if no deck can. A car booked when zero compatible deck space remains is refused — the website shows "sold out" rather than confirming a booking the deck physically cannot honour.
The alternative — confirming bookings that don't fit and resolving them at the wharf — is the failure mode deck supervisors live with on platforms that model the deck as a flat seat count. The vehicle that booked as "one car" but arrived as a 6.2-metre motorhome consumes 6.2 metres, not 4.5, and the deck sold to 30 cars at 4.5 metres each cannot fit the motorhome plus the remaining 29 cars. Refusing at the inventory layer is what makes the manifest honest. Every confirmed booking is a booking the deck can physically carry.
How vehicle inventory composes with passenger inventory
A vehicle on a vehicle ferry is rarely alone. There is a driver. There may be passengers. There may be a cabin on an overnight RoPax sailing. The booking is one transaction; the inventory is several related consumptions.
A car with a driver and three passengers on a day-sailing consumes lane metres on the vehicle deck; the driver and three passengers consume passenger seats in the lounge across the seating tier per the fare types selected. Five consumptions land on five separate inventory units; the booking ties them together for confirmation, modification, and refund. A car plus a 2-berth cabin plus two passengers on an overnight RoPax sailing is one booking with three consumptions — vehicle deck lane metres, cabin block berth count, lounge day-time passenger seats if the operator separates those.
Lane metres are a separate capacity from passenger seats from cabin berths. A sailing can run out of vehicle space while passenger seats remain. Booking-level rules (a car must have at least one passenger; a cabin must be booked with at least one named passenger; a freight booking doesn't require a driver) sit at the booking layer — the inventory model enforces what physically fits; the booking model enforces what makes sense as a sale.
Where a sailing offers value-tier or premium-tier products on the same physical deck, the variation's consumption rules add to the underlying consumption rather than replacing it. A "Value Fare Car" might consume the same lane metres as a standard car plus one slot on a parallel "Value Fare Slots" capacity capping how many value fares the operator releases per sailing.
Live availability and per-sailing overrides
The inventory model is per-sailing. Each scheduled departure has its own live capacity, independent of every other sailing. As bookings come in, capacity decrements in real time across every channel — website, kiosk POS, agent portal, OTA connectors. A walk-up vehicle sold at the wharf shows on the website's "two vehicle spaces remaining" indicator within the same second. A booking that changes from "car" to "car-with-trailer" at the gate updates the lane-metre count immediately.
Per-sailing overrides handle exceptions — a maintenance day with reduced deck space, a charter sailing with a partial deck reserved, a special-event sailing with a different layout. A vessel with a summer layout and a winter layout runs as two templates and the scheduler picks the right one at sailing-creation time.
Reporting and audit tie-in
The inventory model produces an audit trail at the line-item level. A council contract requiring reporting on under-cover usage versus open-deck usage gets the breakdown directly from the model. A funder that wants vehicle-category counts gets them from the consumption records. Operators reporting on hazmat carriage, EV adoption, towed-vehicle volumes, or oversize-load frequency get those breakdowns because the attributes are structured entities in the booking record rather than free-text notes.
Each allocation carries the timestamp it landed, the channel it came through, the operator who took the booking, the payment trail, and the chain of modifications applied to it. Council operators on probity-audit contracts use this as their primary reporting tool to the contract manager. Insurance claims and incident investigations draw on the same record — the manifest reflects what was actually on the deck.
How this composes with the rest of the platform
The vehicle ferry inventory model is one of several inventory dimensions on the platform; the surrounding capabilities operate on it.
Pricing. A car can be a flat rate, priced by the lane metres it consumes, or any combination — with peak / off-peak / shoulder tiers switching automatically by date, channel-specific tiers, and rules-engine surcharges for hazmat or oversize. The pricing engine reads inventory consumption and prices against it.
Channel management. Operators set rules on how vehicle deck inventory is exposed to different channels — cap OTA share, reserve under-cover deck for direct bookings, hold a freight allocation for trade-account customers.
Check-in and boarding. Every vehicle moves through a boarding sequence — Expected → Checked-in → Boarded — per-vehicle and visible to the deck supervisor, the wheelhouse, and the office at the same time. QR scanning at the gangway validates each ticket cryptographically.
Multi-modal packaging. A vehicle ferry leg can be one component of a packaged booking — ferry crossing plus accommodation plus a tour at the destination plus return ferry sold as one transaction. The vehicle deck consumption runs against the same inventory model as a standalone ferry booking; the package layer ties the components together for confirmation, modification, and refund.
What this capability is not
The vehicle deck inventory model is the engine's understanding of what fits on the deck. A few things it deliberately doesn't try to be:
- Not a load-planning tool. The engine knows what physically fits; the order vehicles are loaded — which lane, which slot, in what sequence — is a human decision made at the wharf with the manifest in hand.
- Not a ferry stability calculation. Tonnage tracking enforces caps the operator sets, sourced from the vessel's certificate of survey or equivalent. The calculation of the limit is a marine-engineering question that lives with the vessel's stability documentation.
- Not a hazmat compliance authority. The platform records declarations and enforces per-deck acceptance rules; the regulatory compliance — IMDG classification, documentation, segregation — sits with the operator's dangerous-goods process.
- Not a substitute for reality at the wharf. A van that arrives taller than the booking declared still needs to be re-classified at the kiosk. The catalogue carries standard dimensions; the wharf is where reality is reconciled.
Where to go next
For the marketing overview of how this fits into a vehicle ferry operation, read the vehicle ferry software pillar. For the broader ferry context, read the ferry booking system pillar. For how pricing layers on top of this inventory model and how check-in and boarding draws from it, see the pricing engine and check-in and boarding capability docs.
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