Cobalt 343: specifications, checks and used prices

The Cobalt 343 is a petrol-powered performance day cruiser that puts speed, an open cockpit and occasional overnight capability ahead of long-range economy or cruising volume. This assessment is anchored to Cobalt’s own 2005 model-year brochure. A boat represented as a 2004 example should be matched to its HIN, builder’s plate and original paperwork before later specifications are applied to it.

Batoo’s editorial assessment is that the 343 suits an owner who wants fast day trips and short weekends, and who accepts the cost and inspection burden of twin big-block V8s, sterndrives and two-decade-old systems. It is a weak fit for buyers seeking low consumption, several private cabins or predictable annual expenditure.

Design, specifications and documented versions

Cobalt’s 2005 brochure identifies a stepped hull, an extended running surface, a full-length keel pad, reverse chines and a notched transom. Those features define a performance-oriented design, but they do not prove the condition or behaviour of an individual used boat. Promotional performance language should never replace a measured sea trial with a known load and weather conditions.

The official 2005 engine table lists five twin MerCruiser packages: 375 hp, two 425 hp Bravo 1 configurations, 500 hp and 550 hp per engine. The two Batoo observations instead state twin 496 MAG installations at either 425 or 431 hp each. Parts, propeller selection and insurance declarations should follow the engine and drive serial plates on the boat, not an approximate model-name match.

Cobalt’s 2007 manual repeats most dimensions but gives an estimated dry weight of 5,330 kg with twin big blocks, while the 2005 brochure says a 4,627 kg maximum dry weight. Batoo treats this as an unresolved model-year, equipment or definition difference and does not average it. Construction needs similar precision: the 2005 document says Kevlar-reinforced hull, fibreglass liner and stringers, and a composite transom. A listing field saying carbon fibre does not establish that the entire hull is carbon.

Strengths and limitations in context

The strongest argument for the 343 is a layout consistent with fast day use. A broad cockpit, extended swim platform and compact cabin with a separate head support swimming stops and an occasional night aboard without turning the boat into a heavy accommodation cruiser. The deep transom deadrise and twin installation suggest useful performance potential, although trim, propellers, load and maintenance determine the result on a particular hull.

The limitations are mechanical and financial. Two petrol big blocks duplicate many service items, while sterndrives add bellows, joints, seals, steering components and raw-water paths to the inspection list. Age also matters to wiring, tanks, hoses, actuators and accessories that may no longer be original. A 37.9-litre water capacity is modest for extended living aboard even though the fuel capacity is substantial.

The two observed listings state 550 and 951 engine hours. Hours alone are not a health score: light use combined with long lay-ups can be more harmful than regular, documented operation. Maintenance records, invoices, oil analysis, electronic diagnostics and compression or leak-down testing where appropriate provide more useful evidence.

Ideal use and who the Cobalt 343 suits

The 343 makes most sense for day excursions, rapid transfers and short weekends with a small crew. Its owner should budget for fuel, berth, winter storage and preventive maintenance before purchase. At 2.95 m beam and 11.34 m including the platform, casual road movement should not be assumed; specialist transport planning is necessary.

It is less convincing for families prioritising separate sleeping cabins, a complete galley and large domestic reserves. Nor should it be bought simply to pursue a claimed top speed. On a used performance boat, reliable cooling, balanced engine output, low-speed control and repeatable safe stopping matter more than an unverified maximum.

Broker Pro means only that a Batoo subscription is active. In this dossier, subscriptionactive, offerfresh, editorialeligible and identityverified remain four separate signals: the aggregate data says the offer set is fresh and editorially eligible, while neither offer is identity verified. A subscription is not identity or KYB verification and never guarantees editorial coverage, ranking or a favourable assessment.

Used-boat checks before committing

Identity comes first: verify the HIN, model year, CE status where applicable, both engine and drive serial numbers, title and documentary consistency. Only then can a surveyor choose the relevant specification sheet and parts records. Modifications to exhaust, steering, tanks or electrical systems should have traceable documentation.

The hull inspection should look for repairs, moisture readings interpreted in context, cracking near the step and transom, damage to running surfaces and movement around structural attachments. Kevlar reinforcement does not make an ageing boat immune to water ingress or poor repairs. Haul-out access is needed for the bottom, through-hulls, trim tabs, propellers, skegs and galvanic-corrosion evidence.

In the machinery space, begin with a genuinely cold start and compare pressure, temperature, smoke, vibration and rpm between sides. Bellows, universal joints, mounts, manifolds and risers, raw-water cooling, bilge ventilation and the fixed fire system all deserve direct checks. The sea trial should log rpm, GPS speed, temperatures and trim response under a declared load, without trying to reproduce an advertisement’s headline.

Domestic and deck systems can still create a large refit bill. Test chargers, batteries, pumps, toilet, freshwater circuit, refrigerator, lights, windlass and every 12 V or shore-power consumer. Upholstery, paint and deck coverings are visible costs; tanks, wiring and drives are often the consequential ones. A written post-survey work list lets the buyer compare safety repairs with cosmetic preferences.

Alternatives and a functional comparison

This is a usage-based shortlist, not a ranking or claim of technical equivalence. Compare examples in the same market and condition, then normalise immediate work, equipment, documents and ownership costs. If entertaining at anchor matters more than speed, a less extreme cruiser may be the stronger alternative even at a similar asking price.

Observed asking-price range and methodology

On 1 September 2026, the dossier contained two eligible active Batoo asking prices in euros: €69,000 and €83,000. The resulting observed range is €69,000–€83,000 from a sample of two. It is not a valuation, a completed-sale range or a forecast; tax, commission, location, year, condition, options and negotiation can change the effective amount.

Batoo analysis uses the range only as a snapshot of dossier asking prices. A buyer should add deferred maintenance, survey, haul-out, sea trial, transport and compliance work before comparing the all-in figure with live alternatives. Images come from current listings and may show different individual boats, model years and configurations; brokers and sellers have not reviewed, validated or approved this dossier.