How much deck can one operator descale in a day?
The machine is rated by the hour. The operator is limited by the day. Here is the arithmetic for the SF11 deck hammer, the TFP200 deck scaler, the PPT and the Trident Neptune.
Plan on about 180 m² per operator-day on an SF11 deck hammer and 65 to 125 m² on a corded TFP200 deck scaler, not the 200 m² or more that eight hours at the machine rate suggests. Hand-arm vibration caps trigger time, coating over 3 mm needs two passes, and a real shift holds four to five hours of cutting. Plan deck programmes on operator-hours, not machine hours.
Three things between the machine rate and a day's work
Divide a 3,000 m² deck by "up to 30 m² per hour" and you get 100 hours, which sounds like two people for a week. It is not.
- The body
Vibration caps trigger time
Directive 2002/44/EC sets a daily action value of 2.5 m/s² A(8) and a limit value of 5.0 m/s² that must not be exceeded. A tool that vibrates twice as hard uses the allowance four times as fast.
- The coating
3 mm per pass is the maximum
The TFP200 cuts at most 3 mm per pass. Built-up coating on a weather deck is often thicker, and two passes halve the rate.
- The shift
Trigger time is not shift time
Moving hoses, emptying the extractor, changing cutters and working round deck fittings are shift time, not cutting. Four to five hours of trigger time in an eight-hour shift is realistic.
A(8) = a × √(T / 8)a = declared vibration, T = trigger hours. Solved for time: T = 8 × (limit ÷ a)²Trigger time before one operator has to stop
Calculated from Trelawny's declared vibration figures. The corded TFP200 and the PPT with C-flaps never reach the limit value in a shift. The petrol TFP200 does identical work and reaches it at 4 h 12 min: the difference between one operator and two.
| Machine | Declared vibration | Trigger time to action value (2.5) | Trigger time to limit value (5.0) |
|---|---|---|---|
| PPT 4" air, C-flaps | 3.1 m/s² | 5 h 12 min | |
| TFP200, corded, air or battery | 4.4 m/s² | 2 h 35 min | |
| SF11 deck hammer | 5.76 m/s² | 1 h 30 min | |
| TFP200, petrol | 6.9 m/s² | 1 h 03 min | |
| PPT 230 V, star cutters | 7.8 m/s² | 49 min | |
| SF11 at its +40% upper bound | 8.06 m/s² | 46 min | |
| Trident Neptune | 8.7 m/s² | 40 min |
The uncertainty factor nobody quotes. Trelawny declares the SF11 at 5.76 m/s² with K = +40% / -0%, measured to BS EN ISO 20643. At the honest upper bound, 8.06 m/s², the limit value arrives after about 3 hours: 90 m² a day, not 180. Every declared figure carries an uncertainty. Plan with a range, and measure on site when the programme is big enough.
Why the walk-behind machines vibrate less than the handhelds, though they hit harder. The operator steers them rather than holding the impact mechanism: the machine rides on wheels and the SF11's sub-frame sits on rubber mounts. A handheld 3BPG needle scaler reaches the limit value in under 7 minutes at the front hand. Indispensable at welds and corners, hopeless for stripping a deck. Every Trelawny tool, one table →
Plan a deck: operator-days, not machine hours
Pick the machine and the deck area. The planner uses the same rates and vibration figures as this page.
- Per operator-day
- 125 m²
- Trigger time counted
- 5 h
- To action / limit value
- 2 h 35 min / 8 h
- Rate used
- 25 m²/h
- Air
- -
SepcoTech arithmetic on Trelawny's declared figures, for planning. It is not a risk assessment.
Edges and fittings are not included: every deck scaler leaves a border for a hand tool, see edges, dust and finish.
Four machines, four different jobs
They are not competing models. They solve different geometry: open deck, small areas, and anything a machine on wheels cannot follow.
SF11 deck hammer
- Format
- Walk-behind, 11 heads
- Impacts
- 33,000 / min
- Rate
- Up to 30 m²/h
- Vibration
- 5.76 m/s²
- Air
- 100 cfm free air
Fractures thick scale off plate. Rides irregularities up to 5 mm. Deck hammers →
TFP200 deck scaler
- Format
- Walk-behind planer
- Cutting width
- 200 mm
- Rate
- 25 m²/h at 3 mm
- Vibration
- 4.4 (petrol 6.9)
- Power
- Petrol, 110/230/400 V, air, battery
Open deck, hatch covers, tank tops. 58 to 71 kg. Deck scalers →
PPT handheld
- Format
- Handheld peening
- Cutting width
- 50 or 100 mm
- Rate
- 4-5 m²/h
- Vibration
- 3.1 to 7.8 m/s²
- Noise
- 76-78 dB(A)
With C-flaps, Trelawny states near-white metal and up to 100 µm profile. PPT →
Trident Neptune
- Format
- Flexible drive, skid
- Working width
- 30 mm
- Rate
- 5 m²/h
- Vibration
- 8.7 m/s²
- Air
- 68 cfm (air model)
An access tool, not an area tool: 40 min to the action value. Trident →
Is the battery TFP200-VM a real option? Not yet for full-shift work. It runs 35 minutes per battery and a battery takes 50 minutes to charge, so with the two batteries in the kit the sustained duty cycle is 70%, about 42 minutes of cutting an hour. A third battery closes the gap. Vibration is 4.4 m/s², the same as the corded machines. For short, scattered jobs where dragging a cable is the real cost, it already makes sense.
Size the compressor from the manual, not the datasheet
The SF11 datasheet gives 33 l/s (70 cfm) of air consumption. The operation manual, in its troubleshooting table, asks for at least 100 cfm of free air at 90 psi per machine. One is consumption, the other is what a real supply needs to deliver it. Two machines on one compressor want around 200 cfm, not 140.
Get it wrong and nothing stops. The machine drags, output falls, and the crew concludes the heads are worn. On a tight dock window an undersized compressor causes more overruns than the steel does.
- SF11, per machine
- 100 cfmFree air at 90 psi (6.2 bar)
- TFP200, air model
- 165 cfm78 l/s: beyond most ship service air
- Trident Neptune, air
- 68 cfm32.1 l/s
- PPT, air models
- 30 cfm840 l/min, about 14 l/s
- Hose: at least 19 mm (3/4") bore for the SF11, and keep the run under 30 m.
- Losses: every extra 15 m of hose costs about 0.21 bar (3 psi).
- Pressure: hold 6.2 bar (90 psi). Below 5.5 bar the SF11 drags; above 6.9 bar it bounces.
The edges, the dust and the finish
Three things routinely surprise first-time buyers. Budget for them with the machine.
A deck scaler cannot finish its own job
The TFP200 stops 55 mm from a wall, leaving a border against every bulkhead and coaming and round padeyes, bollards and fittings. The SF11 gets closer but does not reach a corner either. That work goes to a needle or chisel scaler.
No dust collector is included
The TVS® shroud is a connection, 50 mm on the TFP200 and 40 mm on the PPT, not an extractor. On coatings that may contain lead or chromate the collector must be HEPA-filtered, H class for lead. Lead paint dust guide.
Clean steel, not blast profile
Impact tools reach ISO 8501-1 St 2 or St 3. They do not create the Rz anchor profile a blast grade such as Sa 2½ requires. Used first, they make the blast far cheaper. Carbide heads have no business on aluminium, GRP or thin plate.
- Specification accepts St 3Live vessel, no containmentPower-tool cleaning stands on its own. The deck hammer is the fastest way to that grade over a large area.
- Specification says Sa 2½With a stated profileSequence it: break the heavy scale off mechanically, then blast clean steel rather than blast scale. Blasting or scaling →
3,000 m² over a weekend, and what it really took
Anglia Waterblast stripped a 3,000 m² ship's deck carrying corrosion up to 6 mm thick over a single weekend in dock, with two SF11 deck hammers. 80% of the whole task was completed with the two machines, cutting the duration, the cost and the blasting time.
Case reported by TrelawnyEighty per cent of 3,000 m² is 2,400 m². At 180 m² per operator-day that is about 13 operator-days of trigger time inside four machine-days. Two people working straight through would manage about 700 m². The job only closes with operators rotating through the machines. The machines made a weekend possible; the rota made the machines usable.
- Mechanical share
- 2,400 m²80% of the deck
- Operator-days needed
- ~13at 180 m² each
- Machine-days available
- 42 machines, 2 days
- Two people, straight through
- ~700 m²why the rota decides it
Deck descaling output: common questions
How many square metres per hour does a deck scaler or deck hammer do?
Trelawny's TFP200 datasheet gives an average of 25 m² per hour at 3 mm per pass. The "up to 30 m² per hour" quoted elsewhere is a maximum, not a planning rate. Trelawny rate the SF11 deck hammer at up to 30 m² per hour. Coating thicker than 3 mm needs two passes, which roughly halves the rate.
How much deck can one operator clear in a day?
About 180 m² on an SF11 deck hammer, where one operator reaches the EU limit value after about 6 hours of trigger time. On a corded TFP200, 65 to 125 m²: the low end keeps the operator below the action value, the high end assumes four to five hours of real trigger time. The petrol TFP200 reaches the limit value after 4 hours 12 minutes.
What is the hand-arm vibration limit for deck work?
The EU Physical Agents (Vibration) Directive 2002/44/EC sets a daily exposure action value of 2.5 m/s² A(8) and a daily exposure limit value of 5.0 m/s² A(8). Exposure must not exceed the limit value. Because A(8) scales with the square root of time, halving a tool's vibration roughly quadruples the time an operator can use it.
Why does a walk-behind deck hammer vibrate less than a handheld needle scaler?
Because the operator steers it rather than holding the impact mechanism against the work. The machine carries its own weight on wheels and isolates the scaling head from the handlebars on rubber mounts. Trelawny declare 5.76 m/s² for the SF11 against 42.57 m/s² (K = 14.26) at the front hand of their 3BPG handheld needle scaler.
What size compressor does a deck hammer or pneumatic deck scaler need?
For the Trelawny SF11, at least 100 cfm of free air at 90 psi per machine, from the manual rather than the 70 cfm consumption on the datasheet, with 19 mm bore hose under 30 m. The pneumatic TFP200 needs 78 l/s (165 cfm), the Trident Neptune Air 32.1 l/s (68 cfm) and the air PPT 30 cfm (840 l/min, about 14 l/s). Confirm your compressor's free air delivery before specifying pneumatic.
Can a deck hammer or deck scaler replace grit blasting?
Only where the coating specification accepts a power-tool grade, St 2 or St 3 under ISO 8501-1. Impact tools do not create the anchor profile that blast grades such as Sa 2½ require. Used ahead of blasting, they remove the heavy scale that would otherwise be paid for in abrasive and blast hours.
Can a deck scaler get into corners?
No. The Trelawny TFP200 stops 55 mm from a wall. Edges, corners and the area around deck fittings have to be finished with a needle or chisel scaler. The SF11 deck hammer gets closer but does not reach a corner either, and it rides surface irregularities only up to 5 mm.
What can I use in a tank or a gas zone?
An ATEX-certified variant with spark-resistant heads. For the SF11 that is the SF11EX with beryllium copper heads, which Trelawny state is certified for Gas Zone 1. Certified equipment lets the work proceed without waiting on a hot work permit, subject to the site's own risk assessment.
Keep planning
SF11 and SF11EX deck hammers
Part numbers, heads, service kits and the ATEX variant.
View the range → ProductsTFP200, PPT and Trident Neptune
Every power option, the cutter drums and the full specifications.
View the range → VibrationHAVS and the Vibro-Lo range
Why trigger time is the budget, with a workforce calculator.
Read the guide →Tell us the deck, and we will size the whole job
We come back with the machine, the compressor capacity it really needs, the consumables for the programme and a realistic operator rota, quoted in EUR. Tools you add as you browse appear below.
- Deck area
- Coating and thickness
- Plate condition
- Power or air on site
- Zone classification
- Dock window
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