A yacht deck is a stack of materials rather than one surface. Teak and other non-slip deck coverings, sealant joints between deck fittings, gelcoat on vertical surfaces, and stainless steel hardware all react differently to heat. A jet of high-temperature steam can loosen the organic film that builds up on non-slip grooves in minutes, while the same jet, held too close or passed over the same spot too often, can soften sealant, lift the edges of a covering, or dull a polished fitting. That is exactly why the temperature has to be established before the first pass, not judged by eye on the waterline.
On the buyer's side, the machine behind that decision is usually an industrial steam cleaner or a high-temperature steam grease removal unit rather than a domestic appliance. The distinction matters because the deck is cleaned with a wand at arm's length, in the open air, often on a swing mooring or alongside a pontoon, and those working conditions decide what the equipment has to look like.
Confirm the steam temperature of the machine as published
Ask for the steam temperature in writing, from the specification of the exact model being quoted, and keep that document with the purchase file. Two details usually get lost in an email exchange. First, whether the figure is the temperature of the steam inside the generator or the temperature arriving at the nozzle: by the time the steam has travelled through the hose and the wand, it is lower than the number in the table, and the gap grows with hose length. Second, whether the machine is set up for dry steam or wet steam. Dry steam carries the heat with little free water, which is what most deck work needs; wet steam carries a heavier water load, which cools the surface more slowly but leaves standing water in the cockpit and in the deck lockers.
PowerDe's published fixed machine, listed in the cleaning equipment series, prints its steam temperature, its vapour pressure and its heating power in the specification table on the product page. That is the format to expect from any supplier: a figure tied to a model, not a range offered in a sales call. If a supplier will not commit a temperature in writing, treat the trial as the only way to learn what reaches the deck.
Confirm the machine's movement and its power source
A deck has no floor outlet, and the distance from the shore supply to the working point is rarely short. The catalogue carries both fixed machines and driving-style or hand-pushed mobile machines, and that difference decides what the installation asks of the marina or the yard. For a fixed unit, confirm the supply voltage, the rating of the socket and the run of cable needed to reach the working area. For a mobile unit, confirm whether the variant quoted includes a battery or is supplied without one, because the without-battery variant depends on the cable from the start of the job, and cable length, cable protection and the route across the pontoon then become part of the working method rather than an afterthought.
Ask the supplier which variant each listing refers to. Model names are frequently printed at family level, and the with-battery and without-battery listings are separate products. A purchase file that names only the family invites the wrong variant to arrive.
Confirm the water supply and water quality on site
Steam machines are fed with tap water through a fitted inlet, and the water leaving the machine is what contacts the deck. The water hardness of the site supply sets the descaling interval of the boiler, and a boiler that has scaled up delivers less heat to the nozzle than the specification promises. For afloat working, confirm the inlet fitting size in writing, the pressure the inlet expects, and whether the machine can draw from a tank on the vessel or must stay connected to a shore tap. Where the supply is brackish or hard, ask the supplier which water treatment they specify and how often they expect the machine to be serviced.
Confirm what the trial has to prove before any purchase
A trial on one deck panel settles the temperature question that no data sheet can answer on its own. Fix the terms before it starts: which panel is offered as the test area, which deposits are on it, how long the operator may dwell on one spot, what distance the nozzle is held at, and who signs the result. Then inspect the panel for three specific failures rather than for general cleanliness: sealant that has gone soft or opened at the edge, non-slip covering that has lifted or changed colour, and hardware that has lost its finish. A trial that reports only that the panel looks better has proved nothing about temperature.
Ask for the result as a written working method, not as advice: the nozzle type, the pass speed, the dwell limit, the refill interval, and the point at which the operator stops and reports. Where deck work varies from one vessel to the next, that written method is also the basis for customized steam cleaning equipment discussion, because the supplier can only change what has been recorded.
Confirm run-off, drainage and the surrounding area
Steam condenses, and condensed steam leaves the deck as water. Ask what happens to that water where the vessel is working. Afloat, run-off into the berth is regulated in most marinas, and a wash plan that ignores it fails on the paperwork rather than on the finish. On a hard standing, confirm where the run-off collects, whether it carries oil and the organic film removed from the deck, and whether the yard requires interception. Ask the same question about the machine's own water use, since a low-water method only stays low-water if the refill and drainage arrangement on site matches what the supplier assumed.
Confirm the protection set in words, not in numbers
Protection features are listed item by item on the product pages: leakage, short-circuit, high-temperature, high-voltage and water-shortage protection, with some listings carrying an additional item. Do not accept a count of protections in a quotation, since the site itself is not consistent on that point. Ask instead which protections the quoted machine provides, how each one behaves during a job, and what the operator has to do to reset the machine after one of them trips. An operator who loses a machine in the middle of a mooring because a protection responded to a water interruption has a downtime problem, not a safety problem, and the two need different answers.
Confirm the after-sales terms for marine duty
Marine use accelerates the wear items: the wand, the nozzle, the hose, the seals and the boiler's scale. Ask which parts are stocked, how they are shipped, and what the response is when a vessel has to be cleaned on a fixed date. Ask which servicing interval the supplier applies when the machine runs on hard water, and who performs that service when the vessel spends the season away from the supplier. A machine without a service route is not suitable for scheduled marine work, whatever its temperature figure says.
Put the answers into one written comparison
Before any purchase, place the answers in one table: temperature at the generator and at the nozzle, steam mode, supply and battery variant, inlet fitting and water quality limits, run-off arrangement, protections as named items, spares and servicing route, and the trial terms for the test panel. A buyer who can produce that table has removed the three risks that make deck steam cleaning contentious: heat that is either too weak to clean or too strong for the deck, a machine whose power source does not match the berth, and a result nobody can reproduce the following season.
