Catamarans combine relatively modest displacement with very large windage and beam. The berth therefore needs strong lateral restraint, appropriate pile design, a wide mooring envelope and cleat positions that permit long spring lines.
Do not size piles from vessel tonnes alone. Provide the engineer with full geometry and topside area where possible.
What changes for a catamaran berth
Beam is the controlling dimension. A catamaran that is unremarkable by length can be impossible to berth in a marina laid out for monohulls, and the problem is rarely solvable after the fact — the fingers and fairways are already built.
Catamarans also load differently. Two hulls a long way apart place their loads at the outside of the berth rather than along one side, and the vessel's large deck area adds windage well above the waterline.
Questions to settle before you specify
- What is the maximum beam to be accommodated, including any future vessel?
- Will the vessel berth alongside, between fingers, or on a hammerhead or end berth?
- Can the fairway accommodate the turning and manoeuvring of a wide, twin-screw vessel?
- Where do lines lead from each hull, and are there cleats in those positions?
- Does the boarding point on the vessel match the pontoon freeboard, given a catamaran's typically higher deck?
What to put in the RFQ
- Beam, length, displacement and windage of the design vessel.
- Berth configuration, clear width between structures and fairway width.
- Cleat positions referenced to the vessel's line leads, not to a standard spacing.
- Fender arrangement suited to a hull that presents a narrow contact area.
- Confirmation that the restraint design accounts for the wider load footprint.
Where catamaran berths go wrong
- A berth specified by length, so a wide vessel is allocated a space it cannot use.
- Hammerhead berths offered as the fix without checking exposure at that position.
- Cleats spaced for monohull line leads.
- Access and freeboard mismatched to a high-decked vessel.
Questions buyers ask
Why are catamaran berths harder to find?
Marina layouts are set by berth width and fairway geometry, both fixed at construction. A wide vessel needs a wide berth, and retrofitting width usually means rebuilding structure, not moving a finger.
Does a catamaran need a different pontoon type?
Not necessarily a different type, but the geometry, cleat layout and restraint design have to reflect the beam and the load positions.