An air orbital sander uses about 350 L/min, for guidance only, and runs without a break while a hull is sanded. For one sander, aim for at least 450 to 550 L/min at working pressure; for two sanders, about 1,000 L/min. An M 75 mobile unit (1.0 m³/min at 10 bar) runs one sander with a reserve. Two or three sanders call for a K 110 or an M 220.
For the other stations in a yard, see our page on the compressor for boatyards. Here we only size antifouling sanding.
Why sanding counts as continuous use
An impact wrench runs for a few seconds, then stops. A sander runs for hours. Our configurator therefore counts it at 100% of its consumption, with no reduction.
That rules out piston compressors for sanding a whole hull: they are built for intermittent use. A screw compressor handles continuous work. See piston vs screw compressors.
The calculation, step by step
- The sander's consumption, from its manual. For guidance: 350 L/min for an orbital, 400 L/min for a rotary.
- The number of sanders working at the same time.
- The blow gun for dusting off: 150 L/min, used in short bursts, counted at 50%.
- A 25% margin for tool wear, leaking couplings and pressure loss.
Example: two people sanding one hull.
- Sanders: 2 × 350 = 700 L/min.
- Blow gun: 150 × 50% = 75 L/min.
- Total: 775 L/min.
- With the margin: 775 × 1.25 = about 970 L/min, or 1.0 m³/min.
One sander: 350 + 75 = 425 L/min, about 530 L/min with the margin.
Which compressor for one, two or three sanders?
| Case | Need (margin included) | Suggested model |
|---|---|---|
| One sander, boat on the hard | About 530 L/min | M 75, 1.0 m³/min at 10 bar |
| One sander, covered workshop | About 530 L/min | K 75, 1.1 m³/min at 8 bar |
| Two sanders | About 970 L/min | K 110, 1.7 m³/min at 8 bar |
| Two or three sanders, on the hard | 970 to 1,400 L/min | M 220, 2.0 m³/min at 12.5 bar |
With two sanders, the M 75 would be at its limit with no reserve at all: go up a size.
Pressure at the tool and the hose
A sander works at around 6 bar at the tool. The compressor produces more, but the hose loses part of it. Around a hull, the person sanding often drags a long hose, and the sander slows down.
- Bring the compressor or the air outlet closer to the boat.
- Use a hose diameter suited to the flow and limit the number of quick couplings, which narrow the passage.
- Set the pressure with a regulator at the station, following the sander's manual.
Dry air for the sander
Water getting into a sander's motor makes it rust and lose power. In sea air, there is a lot of water. K Series compressors have the refrigerated dryer and filtration built in. An M Series compressor needs a dryer at the outlet. Lubricate the tool as its manufacturer specifies.
Antifouling dust
Antifouling dust contains the active substances of the paint. For collecting it and for protective equipment, follow the product's safety data sheet and the rules of the yard.
On the compressor side:
- Place it well away from the sanding area, with a clean air intake.
- Check the intake filter and the cooler often during the season.
- Keep to the service intervals: 500 hours, then every 1,500 hours. Our service kits group the parts.
Enter your sanders in the configurator or send their manual with a quote request: we will confirm the model with you.
For your trade: Compressor for boatyards and marinas.