Which surface on the deck is actually being cleaned?
Write the deck out as a list before any machine is discussed. A working deck usually contains a non-slip covering, a teak laying with seams, sealant at the joints, moulded gelcoat on the coachroof and coamings, stainless or aluminium fittings, and painted or varnished timber where the joinery meets the deck. Each of those behaves differently once heat and moisture reach it, so a single yes-or-no answer about the whole deck is not usable.
Ask which items on that list the deck plan shows as cleanable by heat, and which are already scheduled for another method. A covering that has been lifted or re-laid, sealant that has been renewed at the toe rail, or a coachroof that has been re-coated are all points where the cleaning method has to match the repair that was done, not the boat's age. If the yard holds those records, take copies; if nobody holds them, that gap is itself the first question to resolve.
How does heat and dwell affect the deck materials you listed?
The material question has two variables, not one. The first is how hot the surface gets, and the second is how long it stays there while the operator works a slow pass over a stained area. Sealant edges, the boundary between a covering and a moulding, and any edge lift are where heat and time combine, because the bond is already carrying movement and the heat softens what holds it down.
Ask the supplier for the working figure in writing for the exact unit quoted, and ask where it is measured. A figure at the generator is not what arrives at the nozzle, and the difference grows with hose length and with a wand that is held close for a long dwell. Where a page prints a temperature, a pressure and a heating power, keep the printout with the purchase file and treat those rows as belonging to that machine only. Figures for a fixed unit are not evidence for a mobile one, and the mobile units in the PowerDe catalogue publish a different set of rows.
Does the deck deposit respond to steam, or does it need a different action?
Sort the soiling into types before choosing a method. Loose grit and organic film on a covering respond to heat plus mechanical work with a brush. Grease from a winch drum, fuel marks near a filler and oil film around a hatch frame respond to heat plus dwell plus a physical wipe. Mineral deposits around a saltwater drain, and the dark streaking that follows a runoff path on a coachroof, are a different problem, and a machine that applies heat without addressing the deposit simply moves it.
Ask what the supplier expects to change for each type, in plain words: what lifts, what softens, what needs a brush, and what needs a second pass. A supplier who can describe the failure modes for a deck has usually worked on one. A supplier who answers only with the machine's capability has not.
Will the machine work where the boat is worked on?
Berths set physical limits that a workshop does not. Ask whether the unit is moved by hand over a pontoon, whether it can be taken down a pontoon ladder or a gangway, and what its footprint means on a wet grating. Ask whether power is taken from the shore connection at the berth and who authorises that connection, because many marinas restrict what may be plugged in and for how long. A machine intended for a garage bay or a hard standing is a different shape of problem on a floating pontoon.
Ask how the unit is fed with water and what happens when the feed runs out mid-job. A tank row on a page is not working time; it is the volume carried. Marina water quality, and the hardness of whatever supply serves the berth, set the maintenance interval for the heating element, so ask what descaling is expected and what the service route is when the unit is out of season.
Who signs off the water that leaves the deck?
Water applied to a deck does not stay on the deck. It runs to the scuppers, to the pontoon, and in most marinas straight into the water the boat floats in. Before any trial, ask the marina office in writing what cleaning is permitted at the berth, whether a collection mat or a bund is required, and whether detergents or additives are excluded. If the answer is that run-off must be collected, then collection becomes part of the method and part of the labour, not an accessory added later.
Ask who at the yard or the marina signs the working method that includes the run-off route. A method written by the buyer and never signed is the document that gets ignored on the day; a method signed by the party that controls the berth is the one that survives an inspection.
What would a trial on your own deck have to prove?
Settle the trial terms before a panel is offered, because a trial agreed afterwards proves nothing. Choose an area that can be discarded in judgement, not the middle of the best deck: a section near a joint, a piece of coachroof beside a hatch, and an area of the covering that has already been cleaned by another method so the comparison is real. Photograph each area before work starts and keep the photographs.
Write down what counts as a pass and what counts as a stop. A pass is a deposit removed on the first attempt with no lifting of a covering edge and no change at a sealant line. A stop is any edge that lifts, any joint that opens, any dulling of a coating, or any need to re-work the same area twice. Fix the stop condition before the first pass, and let someone other than the operator read the result.
What does the supplier have to put in writing?
Send the deck list to the supplier and ask them to mark, on that list, what they consider suitable, unsuitable, and untested. Ask for the working figures for the exact unit quoted rather than the range; ask which protective functions exist and what each one interrupts, without accepting a count of items, since the pages in the catalogue word this set differently; and ask what is supplied as standard against what is optional, including the fittings that connect the unit to a water supply at a berth.
Ask one further question directly: does the site list marine or vessel work as an application for the machine being quoted? The published cleaning pages in the catalogue describe vehicle, parking-facility and medical work, and the marine application is not written on those pages. A buyer who wants a marine duty needs it stated in writing for the unit being quoted, or treated as unproven and tested at their own cost.
How is the answer recorded so it can be compared?
| Question | Who answers | What a clear answer looks like |
|---|---|---|
| Which deck materials may receive heat | Owner, from yard records | A marked deck list, not a general assurance |
| Working heat at the nozzle for this unit | Supplier, for the quoted machine | A figure with the point of measurement named |
| What moves and how far it reaches on a pontoon | Supplier and owner together | A route walked at the berth, not a catalogue photo |
| What the marina permits, and where run-off goes | Marina office | Written permission with any collection condition |
| What a trial must prove, and where it stops | Owner, before work starts | Pass and stop conditions, with photographs held |
| Is marine work a stated application | Supplier, in writing | A statement, or an acknowledged gap |
Where the answers are incomplete, the gap is a scoping problem rather than a machine problem, and it is the kind of gap a supplier can close with an engineered configuration. That is the point at which customized steam cleaning equipment becomes a reasonable request, and it should be raised with the marked deck list and the marina's run-off condition attached, not as a general enquiry.
When should the answer be no?
Some decks should not be steamed on the strength of a brochure alone. A covering that has already lifted at the edges, sealant that is being renewed on a rolling programme, varnished or coated timber, and any laminate with a repair history nobody can document are all cases where the risk sits with the buyer. Through-deck fittings, instruments and any cabling that runs under the deck lining are excluded before work starts, and the exclusion is written down rather than remembered.
The practical test is whether every question above has a name against it: the yard that recorded the deck, the marina office that controls the run-off, the supplier who answered for the quoted unit, and the person who read the trial result without having held the wand. When those names are present, the decision is defensible and the deck is protected. When they are not, the cheaper answer is to clean the deck another way this season, gather the records, and ask again next year with the deck list already marked.
