Interislander with a campervan or trailer: measure what is actually coming

The campervan’s model name is useful when collecting the keys. For a ferry booking, the more useful detail is how much space the vehicle occupies with everything attached.

A bike rack, a caravan drawbar or an outboard motor can extend beyond the length you first think of as “the vehicle”. Interislander’s measurement rules treat some of those arrangements differently, so the answer is not simply to add one impressive total to whichever box appears first.

Measure a campervan or motorhome including extensions, but measure a towed caravan or boat separately from its towing vehicle, starting at the towball. Cars, SUVs and utes have a separate bike-rack question. The examples below apply Interislander’s published instructions checked on 21 October 2026; they are illustrations, not measurements of your hire vehicle. Interislander vehicle measurements.

For vans, motorhomes, trucks and horse trucks, Interislander asks for an accurate length entered to the nearest 0.5 metres. Anything extending the vehicle, such as a rear bike rack, needs to be included in the overall measurement.

Consider a hypothetical motorhome whose body is 6.2 metres long and whose loaded rack extends a further 0.8 metres behind it:

Front of vehicle                         Rear of loaded rack
|----------- motorhome: 6.2 m -----------|---- 0.8 m ----|
|---------------- overall: 7.0 m -----------------------|

The relevant length is 7.0 metres, not the 6.2 metres from the body specification. The rack does not become invisible because it is optional equipment, and the bicycles have not agreed to swim across.

Use the overall physical measurement rather than adding an accessory’s advertised depth automatically. Some attachments overlap the vehicle body; what matters is the actual distance between the front and rear extremes of the travelling setup. Record the measured length first, then enter the nearest 0.5 metres as Interislander instructs; do not shorten the physical measurement by excluding the rack. Motorhome measurement guidance.

A caravan’s living space is only part of the length that matters. Interislander says to measure the towed vehicle separately from the car, SUV or ute, beginning at the towball so the drawbar is included. A bike rack on the caravan belongs in that measurement too.

For a hypothetical setup, suppose the distance from the towball to the rear of the caravan is 6.5 metres, with a rack extending another 0.5 metres:

Towing car        Towball                       Rear of rack
[ car ]              |---- caravan setup: 6.5 m ----|--0.5 m--|
                     |------ towed length: 7.0 m -----------|

That produces a 7.0-metre towed-vehicle measurement. It does not turn the towing car into a seven-metre vehicle, and it is not a reason to count the drawbar twice. Keep the car’s booking details and the towed measurement separate, following the relevant fields or the booking team’s instructions. Caravans and towed vehicles.

If the seller quotes an internal or body length, ask for the towball-to-rear measurement with the ordered rack attached. That is the figure to compare with this example.

For a boat trailer, Interislander also starts the measurement at the towball and specifically tells passengers to include the outboard motor’s overhang.

In this illustrative setup, the distance from the towball to the back of the boat is 6.6 metres. The motor extends a further 0.4 metres in the configuration being transported:

Towball                      Back of boat     Motor's rear edge
|--------- 6.6 m ----------------|---- 0.4 m ----|
|--------------- total: 7.0 m ------------------|

The booking measurement is therefore 7.0 metres. Measuring only the boat hull would miss the space between the towball and the boat, while stopping at the boat’s rear would miss the motor.

These are measurement examples, not instructions for how to configure or secure a boat. Use the actual approved transport setup and confirm anything unclear with the relevant operator. Boat measurement instructions.

Interislander’s measurement page says its car, SUV and ute booking category allows 5.5 metres without requiring a vehicle-length measurement. For a bike rack at the rear, it tells passengers to answer yes to the bike-rack question; it says extra space will be allowed without a charge for that declared rack.

Car / SUV / ute                 Rear bike rack
[ selected vehicle category ]---[ declare rack: YES ]
                    Do not omit the attachment

That is different from entering the overall motorhome length. Do not borrow the car’s no-charge rack wording to price a motorhome, and do not assume that answering the rack question covers every other load.

For a canoe, paddleboard or surfboard on the roof, the same page says to include its full length if it extends beyond the car. If the actual booking flow does not provide an obvious way to describe your combination, ask the booking team rather than squeezing it into a smaller category. The operator’s separate bicycle guidance also emphasises allowing for rack space; the measurement page supplies the category-specific method.

If the vehicle has not been collected yet, ask the hire company for its ferry-booking category and actual external dimensions with the equipment you have ordered. Be specific about the bike rack or other attachment, because the base vehicle specification may not include it.

It is also worth settling two separate questions: whether your hire contract permits the crossing, and who is making or amending the ferry booking. Correct dimensions do not establish rental permission. If the hire company substitutes a different vehicle, compare it with the ferry confirmation before travelling to the terminal and arrange any necessary amendment through the appropriate booking channel.

Keep the written measurements beside the ferry confirmation and check them when collecting the hire vehicle.

Interislander says vehicles are measured at check-in. If yours is longer than booked, an additional charge can apply; if the extra space is unavailable, you may need to move to another sailing at your cost. A willingness to pay the difference does not create more deck space. Vehicle check-in measurement policy.

Resolve the dimensions while there is still time to adjust the booking. Then save the confirmation, departure-terminal details and hire-company contact information offline.

For hire-company and ferry messages during the wider drive, our New Zealand SIM and eSIM guide compares app data, ordinary calling and Australian roaming. Even a very well-connected phone cannot make a seven-metre motorhome fit the space booked for a shorter one.