On a yacht exterior, most of what decides whether a steam job ends as a clean hull or as a repair invoice happens before the machine is switched on. The lance only does what the surface, the setting and the moment allow, and all three are chosen in the hour before work begins. This article covers the exterior surfaces a crew can reach from the dock, or from the yard after haul-out: topsides, hull sides, the waterline strip and the transom. Deck work has its own preparation and is not the subject here.
Choosing yacht exterior cleaning equipment is the visible part of this preparation; the parts that decide the outcome are reading the hull, protecting its fittings, and closing the questions the product pages leave open. A crew that arrives with the preparation written down works a different job from a crew that improvises at the gangway. What follows walks through that preparation in the order it should be done, from reading the hull to the check signed before any trigger is pulled.
Read the hull and its coatings before choosing any setting
A yacht exterior is not one surface. Above the waterline there is usually gelcoat, often with a wax or polish layer on top, and around it varnished trim, canvas, decals and caulking lines of different ages. At and below the waterline there is antifouling coating, whose condition tells you what that band will tolerate. Each of these materials answers heat and dwell differently, so the crew should read the hull before choosing a setting, not after.
Ask for the owner's records before the job: when the hull was last coated, when the topsides were last polished or waxed, whether there are repair areas or blisters, and whether the antifouling is still sound or has gone chalky. Steam lifts wax and polish layers as it cleans, the same way it strips protection when an engine compartment is degreased, so a job on freshly waxed topsides is really two jobs. Fresh slime and biofilm respond to heat and loosen with a short dwell; calcified growth such as barnacles and tubeworm cases does not come off with heat and must be removed mechanically first, with steam cleaning what the scraping exposes. Knowing which of these two jobs is actually booked changes the crew list, the tools and the time.
Before anything is heated, walk the hull with a camera. Photograph blisters, edge chips, lifting decal corners, dull patches and open caulking. A defect recorded before the job is a fact; the same defect found after the job becomes an argument.
Mask and protect the fittings that must not receive heat
The fittings along the topsides and the waterline are where yacht steam jobs go wrong. Seacocks and through-hulls, skin fittings, anodes, transducers and log pickups, antennas, vents and water intakes, and the housings of deck electronics mounted near the topsides all depend on clean, dry interfaces or on adhesives and sealants that soften with heat. Old caulking can open where a jet finds it, varnish and vinyl decals are the classic lifting candidates, and bare or coated zinc anodes should stay out of the direct stream.
- Mask what cannot be removed: tape and sheeting over transducer faces, anodes, vent openings, decal edges and any housing whose sealing rating nobody can state in writing. A rating nobody can name is a rating about which to assume nothing.
- Aim the lance at brackets and structure, not at connectors and sensor faces. A jet aimed at a bracket pushes water away; a jet aimed at a connector pushes water through a seal that was only ever meant to keep rain out.
- Write down what was masked, and remove coverings only after the surface beside them has been inspected. A mask left on hides both the job and the damage.
Agree where the runoff goes before work starts
Steam uses little water, and that is exactly why the little it uses matters at a dock. Runoff from a hull carries dead marine growth, antifouling residue and whatever the surface was holding. Many marinas regulate where wash water may enter the water and what must be collected and disposed of on land, and the rule is set by the marina and the local authority, not by the equipment supplier. Ask the dockmaster before the job: what is allowed, from which side of the vessel, whether collection is required, and whether the answer changes afloat versus on the hard.
On the hard the answer is easier: runoff can be contained and directed. Afloat, the water beside the hull is the collection point, and the crew's working method decides what reaches it. This conversation belongs to the planning stage because it can change the sequence, the working position and the equipment, and a crew that asks after the opening pass has already answered the question with their presence.
Check what the berth actually offers
Machines of this class are built around two hookups, and a berth rarely offers both in the form the paperwork assumes.
- Power: the product page for the mobile unit used as the example in this article lists a 48 V mobile battery supplied by the customer. Where the battery is charged, what the charger needs, and how long a charge lasts under real work are not published, so confirm them in writing before planning a day away from a power source. Shore power at a pontoon pedestal serves the vessel; whether it suits the machine's charger is a separate question for the harbour electrician.
- Water: the same listing shows a 60 L fresh water tank and a tap-water inlet with a 1/2-inch female thread, listed on the page as a 4-point internal thread. At a berth the nearest tap may be far away, on another pontoon, or on a thread nobody brought an adapter for. Measure the refill walk, and carry the matching connector.
A tank is a buffer between the machine and a water point. Where there is no water point, the tank is the working radius. The listing does not publish a water use rate or a runtime per tank, so any schedule built on the tank before you have a written answer or your own measurement is a guess. Plan refills as scheduled lines in the job, because a low-water stop with a plan is a refill, and without a plan it is an hour nobody booked.
Measure the route and the reach before the machine arrives
The published footprint of the example machine - 1275 mm long, 570 mm wide and 1185 mm high - is a box that has to cross gates, stiles and gangways to reach the working side of the vessel. Measure the narrowest point of the actual route with a tape, check clear heights and the behaviour of grates and ramps when wet, and decide where the machine stands while it is not moving. A machine that cannot reach the working side does no work, and a word like compact on a page is not comparable to a measured gate.
Reach above hull level is a separate question. From the dock, a crew can work the topsides and the waterline band at arm height; the mast, rigging and the upper topsides need a platform, a swing, or a lance length the listing does not publish. Request the hose and lance lengths in writing and compare them with the vessel you actually have. On the hard, plan positions around the cradle and the keel, keep feet off bonded surfaces, and treat a wet dock as the slipperiest floor in the marina. Near the waterline a second person is worth the cost: one works the lance, the other watches the surface, the runoff and the people walking past.
Read the machine's published numbers as preparation inputs
The listing for the PowerDe HMW2 steam cleaner publishes a set of numbers a crew can actually use, and it is worth being precise about what each one is for.
- The 4.5 kW PTC heater and the 60 L fresh water tank describe a working cycle: how fast the machine recovers, and how far it can run from a water point. Neither number says how long that cycle lasts, which is why the runtime question belongs in writing.
- The 1/2-inch female tap inlet decides how close the machine can stand to water and which adapter belongs in the kit.
- The battery line, 48 V and supplied by the customer, says who owns the first part of the machine to fail. Whoever supplies the battery also owns its charge time, its warranty and its storage, so the charging arrangement belongs in the job plan.
- The three modes - hot water, dry steam and wet steam - are water decisions before they are cleaning decisions. Dry steam leaves little free water and belongs near electronics and anywhere the dock must stay walkable; wet steam carries more heat and more water to the surface. The high-pressure water gun named on the page is a second function whose pressure is not published, and it is the wrong tool anywhere drying time is the constraint.
- The protections named on the page - earth leakage, short circuit, high temperature, high pressure, low water and high pressure burst - protect the machine. They do not rate your circuit, notice a wet gangway, or decide what a gelcoat surface tolerates.
One gap deserves naming. Some listings in this category publish boiler-side steam temperature and pressure - the fixed model in the same category lists 160 degrees Celsius and 0.8 MPa - while the mobile listing used here does not. Even where those numbers are given, they describe what the machine produces, not what arrives at the surface through a long hose and a cold lance, and the page carrying them describes vehicle cleaning. Ask for nozzle-side values for the configuration you will actually be handed, and treat borrowed numbers from a neighbouring model as questions, not answers.
Put the missing numbers and the marine question in one written request
For the machine used as the example here, the numbers a dockside job needs and the page does not carry are the same list every careful buyer ends up writing: nozzle-side steam temperature and pressure, warm-up time from cold, runtime per tank and per charge, hose and lance lengths, and machine weight for planning onto pontoons and lifting gear. Name each item in one written request and ask for the answer per quoted configuration.
The same letter should carry the applicability question, because it is the one that decides whether the rest of the list matters. The listing places this machine in indoor garages and narrow outdoor parking spaces for vehicle work. Salt spray, dockside humidity, gelcoat, antifouling coatings and marine fittings are not discussed on the page. Ask the manufacturer in writing which surfaces and conditions they consider in scope for marine use, and keep the answer with the job record.
Sequence the work and protect the finish afterwards
Work from the top down. Upper topsides and hardtop edges first, hull sides next, the waterline band and antifouling area last, so runoff from the surfaces above never lands on a finished band below. Sensitive fittings get their pass with the machine already warm and the crew already practiced, not as the opening minutes of the job.
Drying is part of the job, not what happens after it. Steam wets less than a pressure wash, but it wets: water hides in chain lockers, under fittings, in deck drains and behind the corners a hull shape makes invisible. Do not polish, wax or cover a damp hull, because water sealed under a cover produces exactly the marks the crew was trying to remove. Write the drying window into the schedule beside the weather, because wind and sun change it more than any setting on the machine. After saltwater work, wipe the machine's metal parts, store it out of the salt air, and ask the manufacturer in writing how they recommend storing this equipment near the sea.
Wear the right kit and mind the dock
Steam burns come from condensed water and from touching hot surfaces, not only from the jet. Gloves to the wrist, eye protection against lifted residue and condensate, and closed non-slip shoes are the minimum on a wet dock. Route cables and hoses off the walking line of the gangway, keep bystanders and dogs out of the spray zone, and know where the fuelling and pump-out points are before steam meets a dock that has fuel on the water.
A one-page check before the first trigger pull
- Surface and coating inventory read, with the owner's records on last coating and last waxing.
- Existing defects photographed and filed.
- Fittings masked, and the mask list written down.
- Runoff route agreed with the dockmaster, afloat and on the hard.
- Power source and charge plan confirmed; water point located and the matching adapter in the kit.
- Written answers received for the unpublished numbers and for marine applicability.
- Route measured against the published footprint; platform or confirmed reach for anything above arm height.
- Sequence and drying window written into the job; weather checked.
- Protective kit worn, bystanders briefed, trip routes clear.
- A named person signs the check, and the same name appears when the job is handed over.
The check takes an hour and costs nothing. It is the difference between a crew that cleans a vessel and a crew that explains a bill.
Frequently asked questions
Does steam remove barnacles and hard growth?
No. Heat kills fresh slime and loosens biofilm, but calcified shells need mechanical removal first. Steam then cleans what the scraping exposes. If the hull has been in the water for a season, book the scraping as its own line and let steam finish the surface.
Will steam strip the wax on my topsides?
It will remove wax and polish layers as it cleans, the same way it strips protection when degreasing an engine compartment. Plan the job before the next waxing, or plan to wax again afterwards.
Can a machine listed for garages be used at the dock?
The published pages describe vehicle work in garages and parking areas; the dock adds salt, humidity and surfaces the pages do not discuss. That is a written question for the manufacturer, not an inference from the numbers on the table.
What if the berth has no power or water?
The battery configuration and the tank define how far the crew can work, but the runtime figures are not published. Get them in writing, then measure once on your own vessel before anyone promises a full day at the dock.
Preparation is the cheap part of a yacht exterior steam job. Read the hull, mask the fittings, agree the runoff, measure the route, close the missing numbers in writing and sign the check before the machine is switched on. If you need the written answers this article asks for - nozzle-side values, runtimes, reach and marine applicability - send your vessel type and berth conditions to the PowerDe team through the contact PowerDe page and ask for them per quoted configuration.
