A multihull can look remarkably reassuring at first sight: wide decks, generous accommodation, level sailing, and a layout that makes family cruising feel achievable. Yet the same features that make a catamaran or trimaran attractive also create a more complex asset to inspect. Two hulls, bridge-deck structure, multiple engines, duplicated systems, and large rig loads mean that condition cannot be judged from a tidy interior or a recent coat of antifouling. This multihull buying guide focuses on the questions that should be answered before enthusiasm becomes a signed contract.

Start with the right multihull for the intended use

The first decision is not brand, age, or cabin count. It is whether the vessel suits the way it will actually be used. A privately owned cruising catamaran based in Bodrum and used for seasonal Mediterranean passages has different priorities from a charter-oriented boat, a performance sailing catamaran, or a power catamaran intended for long-distance operation.

A broad-beam multihull offers space, stability at rest, and shallow-water access. It also requires suitable berthing, greater maneuvering awareness in tight marinas, and an honest allowance for haul-out, lifting, winter storage, and maintenance costs. In popular Mediterranean marinas, a catamaran berth can be limited and materially more expensive than a comparable monohull berth. Buyers should verify availability and pricing before assuming the vessel will fit their preferred cruising base.

Consider the crew as carefully as the vessel. A large sailing catamaran may be easy to handle in open water but still demand confidence with twin engines, windage, docking geometry, and a substantial sail plan. A power catamaran may simplify sail handling, but it does not simplify machinery management. It adds propulsion systems, fuel capacity, cooling circuits, exhausts, and electronic controls that all need independent assessment.

Multihull buying guide: inspect structure before cosmetics

The central structural question is how loads travel through the boat. On a multihull, the hulls are connected by a bridge deck, bulkheads, crossbeams, and deck structure that must work together. These areas deserve careful inspection because defects can be difficult to see and expensive to correct properly.

A professional pre-purchase survey should examine accessible internal structure, hull-to-deck joins, bulkhead tabbing, crossbeam connections, forward locker areas, steering compartments, and the underside of the bridge deck. Particular attention should be paid to evidence of movement, such as cracking around bulkheads, separated tabbing, distorted joinery, leaking deck fittings, or uneven gaps around doors and hatches. None of these observations automatically means a vessel is unsound, but each may indicate that further investigation is needed.

Moisture readings and percussion testing can help identify suspect areas in composite construction, especially around deck hardware, stanchion bases, chainplates, windows, hatches, and transom fittings. They are diagnostic tools, not verdicts on their own. Elevated readings may result from recent weather, surface coatings, or localized water ingress; their significance depends on construction method, location, corroborating evidence, and the vessel’s history.

The bridge deck requires a practical eye. Repeated slamming in rough conditions can stress the underside, internal laminates, furniture supports, and forward structure. A buyer should not rely on a seller’s statement that the boat has only been lightly used. The vessel’s condition, repair history, cruising record, and evidence of hard use must be assessed together.

Repairs need documentation, not reassurance

Composite repairs are common and often entirely acceptable when completed to an appropriate standard. The concern is not the existence of a repair but uncertainty about its cause, extent, and quality. Ask for invoices, photographs, insurer correspondence where applicable, and details of the repairer. A professionally documented repair may be a manageable part of the vessel’s history. An unexplained fairing area, inconsistent laminate finish, or fresh paint around a high-load zone warrants closer scrutiny.

The same principle applies to osmotic blistering, previous grounding damage, and rudder or keel repairs. Multihulls can sustain localized impacts without obvious symptoms during a casual viewing. Haul-out inspection remains essential.

Assess machinery as separate systems

Twin engines can provide welcome redundancy, but they also double the routine service burden. Each engine should be evaluated on its own maintenance record, running behavior, cooling performance, oil condition, mounts, exhaust system, controls, and charging arrangements. Similar engine hours do not guarantee similar condition. One engine may have been used extensively for maneuvering while the other has carried more charging load or received poorer maintenance.

During sea trial, machinery should be brought to operating temperature and run through an appropriate RPM range while observing temperatures, smoke, vibration, gearbox engagement, steering response, and charging output. A brief run at the dock is not a substitute. The inspection should also consider access. An engine room that is clean but difficult to service can create costly maintenance compromises later.

Electrical and hotel systems deserve equal attention. Large multihulls often carry significant domestic loads: refrigeration, watermakers, air conditioning, inverters, battery banks, solar arrays, generators, and extensive navigation equipment. The issue is not simply whether each item turns on. It is whether the installation is safe, logically arranged, adequately protected, and supported by current documentation.

Look for unlabelled cables, unsupported wiring, corrosion at terminals, improvised battery connections, non-marine components, overloaded distribution panels, and equipment added without regard for ventilation or access. These findings may be correctable, but they affect both purchase value and the first refit budget.

Treat the rig and deck hardware as load-bearing equipment

On a sailing multihull, the rig is not an accessory. Standing rigging, chainplates, mast base structure, spreaders, running rigging, winches, and sail-handling systems manage large and repeated loads. The rig’s age, service history, and inspection records should be established early in the process.

Chainplates and their attachments require particular attention because water ingress around deck penetrations can affect concealed structure. Winches should be operated under load where possible, and furlers, clutches, tracks, blocks, and traveler systems should be inspected for wear, corrosion, and correct alignment. A sail inventory also needs more than a visual glance from the dock. UV damage, stretched cloth, worn stitching, tired furling systems, and aged canvas can materially alter the immediate ownership cost.

For power catamarans, substitute a similarly disciplined assessment of deck lifting points, davits, tender arrangements, rails, anchoring equipment, and mooring hardware. A large tender or heavy davit installation can impose meaningful loads on the stern structure. The anchor system should be tested in operation, not assumed functional because the chain and windlass appear clean.

Read the maintenance record critically

A detailed folder is encouraging, but paperwork should be tested against the vessel. Service invoices should align with engine hours, equipment serial numbers, replacement dates, and the physical condition observed on board. Gaps are not always disqualifying, particularly on older private vessels, but they should change the level of caution and contingency allowed in the negotiation.

Ask specific questions. When were the standing rigging and seacocks last replaced? Has the saildrive diaphragm or shaft seal been serviced according to the manufacturer’s requirements? When were through-hulls, batteries, fire extinguishers, life raft, gas system, and safety equipment last inspected? Has the vessel had water ingress, grounding, lightning exposure, or insurance claims?

A seller who does not know every answer is not necessarily concealing a problem. However, unanswered questions should remain open items in the purchase process rather than becoming assumptions made by the buyer.

Make the survey and sea trial part of the decision

The purchase agreement should allow time for an independent pre-purchase survey, haul-out, and sea trial, with clear provisions for material findings. These stages are not procedural formalities. They establish the technical facts needed to decide whether to proceed, renegotiate, require repairs, or walk away.

An independent surveyor’s role is to report condition objectively, not to sell the boat or create unnecessary alarm. The most useful report distinguishes between safety concerns, structural or machinery risks, maintenance deficiencies, and items that are normal for the vessel’s age and type. It should also identify where specialist inspection is justified, such as engine diagnostics, rig inspection, thermal imaging, or detailed laminate evaluation.

For buyers operating in Turkey and the Mediterranean, The Blue Matter approaches pre-purchase work with that practical distinction in mind: factual findings, clear priorities, and advice that supports a sound commercial decision.

A well-chosen multihull can deliver exceptional cruising comfort and capability. The right purchase is rarely the boat with the newest cushions or the most persuasive listing. It is the one whose structure, systems, history, and future costs are understood well enough for you to proceed with confidence.