Maintenance is what separates a 10-year tender from a 4-year tender
The difference between a tender that holds value and a tender that depreciates fast is rarely the build quality. It is whether someone follows a structured maintenance schedule from delivery onwards. A Pascoe or Wajer hull from a tier-one yard, well-maintained, holds 65-75% of new value after five years. The same boat run hard with reactive maintenance only is at 40-50% in the same period. Maintenance is the highest-leverage spend in tender ownership.
This page covers the standard maintenance regime, by interval, with the failures the schedule prevents.
Daily and pre-use checks
Before every use:
- Bilge dry, no fuel or oil sheen
- Engine oil and coolant levels
- Steering free, no binding
- Throttle and shift smooth
- Battery isolators on, voltage at rest above 12.6V (12V system)
- Navigation lights and horn working
- Fuel level adequate for the planned run plus reserve
- Lifting points and bridle visually intact (see launch and recovery)
- VHF, AIS, and chartplotter functional
- Safety gear stowed and accessible: lifejackets to passenger count, throw line, flares in date, fire extinguisher in date
A two-minute walk-round catches most pre-use failures. Skipping it is the leading cause of tender call-outs mid-season.
Weekly checks
Weekly during the operating season:
- Battery state of charge with the boat off shore power for 24 hours
- Coolant cap pressure and reservoir level
- Drive belt tension and condition
- Sterndrive bellows for cracks (sterndrive boats only)
- Waterjet impeller inspection through the inspection port
- Saltwater wash of all topsides, isinglass, electronics
- Fuel/water separator drain check
- Bilge pump test, automatic and manual
- Trim tab function and condition
- Dock lines and fenders inspection
Monthly maintenance
Monthly during the season:
- Engine oil and filter change at 100-hour intervals or per manufacturer guidance, whichever sooner; high-performance petrol engines often run 50-hour intervals
- Fuel filter change per OEM schedule (typically 100-200 hour)
- Hull and underwater unit inspection by diver or on the lift
- Anti-fouling touch-up where worn
- Sacrificial anode condition: replace at 50% wasted
- Steering hydraulic fluid level and lines
- Throttle and shift cable condition
- Stainless polish and corrosion check
- Upholstery and isinglass cleaning per manufacturer
Monthly inspection is also the slot for the systematic look at electrical connections, breakers, and the AC system if fitted. Salt finds every weak crimp eventually.
Annual maintenance and winter lay-up
Annual major service is the centrepiece of the maintenance year. Standard tasks:
- Full engine service: oil, filters, plugs (petrol), injectors checked (diesel), valve clearances per OEM schedule
- Full driveline service: sterndrive lower-unit oil change, waterjet bearing inspection and re-greasing, surface drive bearing and seal inspection
- Steering ram service and seal inspection
- Hydraulic system flush if applicable
- Fuel tank inspection for water and contamination
- Fuel polishing if fuel has sat for a season
- Battery load test; replace at 75% of original capacity or per OEM
- Electrical bonding and ground test
- Anode renewal complete
- Hull haul-out: bottom paint renewal (typically every 12-18 months in warm water), gelcoat repairs, prop and shaft inspection
- Hull moisture survey every 3-5 years
- Lifting point load-test and bridle inspection (see classification rules)
- Liferaft service per manufacturer (typically 12-month interval)
- Flare inspection and replacement
- Fire extinguisher service
Annual cost for a 10-12m sport tender, comprehensive service through the dealer network, runs typically EUR 8,000-18,000 depending on driveline, hours, and what comes up at survey. For a limousine tender with full air-conditioning, audio, and finer interior trim, the figure runs higher.
Engine hours and lifecycle planning
Tender engines have predictable lifecycles. Plan for:
- Diesel waterjet engines (Yanmar, Volvo Penta D-series): 3,000-5,000 hour expected life with full maintenance, before major overhaul
- Petrol sterndrive (Mercury Verado, Volvo Penta V8): 1,500-2,500 hour expected life, often replaced rather than rebuilt
- Surface drives (Arneson, France Helices): bearing replacement every 500-1,000 hours, full driveline overhaul every 2,000-3,000 hours
A typical superyacht tender does 200-400 hours per season. That implies a major engine event every 5-10 years on diesel, every 4-7 years on petrol, factored into total cost of ownership.
The cost of a superyacht tender covers the lifecycle economics in detail.
Hull and gelcoat
Composite hulls are durable but not maintenance-free. Standard cycle:
- Gelcoat polish and wax: quarterly during the season
- Compound and machine polish: annually before the season
- Gelcoat repair: as needed for chips, scratches, impact damage. Catch early; small chips become osmotic blisters within a season
- Hull moisture survey: every 3-5 years, more frequently for older boats
- Bottom paint: every 12-18 months in warm water, longer in temperate. Specialist anti-fouling for waterjets and sterndrives
- Topside paint refresh (Awlgrip, Alexseal, or equivalent): every 7-12 years depending on use and storage
For carbon-construction hulls, paint and structural inspection cycles are similar but the substrate is more sensitive to damage. Carbon repair is more expensive than glass repair and requires specialist labs.
Upholstery, soft-top, and trim
The cosmetic items that sell or sink a used tender:
- UV-resistant fabric and isinglass: replace at 5-7 year cycle in Mediterranean sun
- Cushion foam: replace at 7-10 years
- Bimini and convertible top covers: 5-7 years
- Teak deck (where fitted): seal annually, replace plugs and caulking as needed, full deck refurbishment every 10-15 years
- Stainless polish: continuous
Cosmetic neglect compounds. A tender with worn upholstery and tired isinglass photographs badly and trades 15-20% under a well-presented sister.
Storage and seasonal lay-up
Off-season storage doubles the life of every component if done correctly. Standard winter lay-up:
- Full annual service before storage
- Fuel system: full tank with stabiliser, or full drain depending on storage duration and OEM guidance
- Cooling system: drain or treat with antifreeze for freezing climates
- Battery: remove for indoor storage, on float charger
- Bilge dry, all drains open
- Cover or store under cover, ideally in heated facility
- Cradle the boat with weight off lifting points
- Disconnect and lubricate steering and shift linkages
For yachts that operate year-round, the equivalent is cycling tenders through scheduled service slots rather than full lay-up. See storage and transport for facility options.
Service partners and parts supply
Tender maintenance depends on access to OEM-trained service technicians and parts. The major drivetrain manufacturers (Yanmar, Volvo Penta, Mercury, Hamilton Jet, Castoldi) all maintain dealer networks across the major superyacht regions. The builder directory lists which yards have field service teams for the regions you cruise.
For programmes operating outside the standard Mediterranean-Caribbean axis (East Africa, Pacific, expedition cruising), parts logistics and on-call technician availability become the binding constraint. Plan service slots around accessible ports.
Insurance and maintenance interaction
Tender insurance policies require:
- Annual survey or service documentation
- Lifting equipment certification current
- Liferaft and safety gear in date
- Operator competency documented for crewed boats
Lapsed maintenance documentation is a leading cause of disputed claims. Keep service records, receipts, and certificates organised and on-yacht; the insurer will ask after any incident.
When to refit vs. replace
A well-maintained tender at year 7-10 is a refit candidate, not a write-off. Typical refit decisions:
- Engines at end of useful life: repower with current OEM units, often with a 10-15% efficiency gain
- Electronics: replace generation 1 or 2 systems with current chartplotter and AIS
- Upholstery and trim: full refresh for half the cost of a new boat
- Paint: full topside repaint to renew presentation
- Hull: repair, fair, and refinish
A comprehensive refit on a 10-year tender runs typically 30-50% of new build cost and extends useful life another 5-10 years. See tender refit guide for the full scope.
The replace decision usually wins when the hull design is outdated, when garage geometry has changed (yacht refit), or when the principal's use case has shifted enough that a different category of tender is needed.
Where we sit
We do not run service yards, but we brief and source tenders with maintenance access in mind. For programmes managing a fleet of multiple tenders across yachts, we coordinate service planning and parts logistics through the OEM dealer network. For specific maintenance challenges on an existing tender, send the details and we will route to the right specialist.