Trelawny deck hammers
SF11 - head assembly, ball valve and T-handle
Eleven independently floating carbide heads, 3,000 blows a minute each, 252 mm of deck per pass. The SF11 breaks heavy scale and thick coatings off steel at up to 30 m² an hour and cuts to within 15 mm of a bulkhead - and because you walk behind it rather than hold it, it puts 5.76 m/s² into the operator instead of the 13 to 20 m/s² a handheld scaler doing the same work would.
Two models: the standard SF11 with tungsten-carbide heads, and the SF11EX with beryllium copper heads, ATEX certified so the work can go ahead without a hot work permit.
Eleven heads on a walk-behind frame
Every figure on this page lives somewhere on the machine. Hover or tap a number to trace it to the hardware.
- 01Handle5.76 m/s²Declared vibration. You walk behind the machine and steer it; the sub-frame sits on duplex rubber mounts.
- 02Ball valve3/4"With the claw coupling on the handle. If the machine bounces above 6.9 bar, the manual says to close it slightly.
- 03Cutting width252 mmCuts to within 15 mm of a bulkhead and between structures less than 300 mm apart.
- 04Air inlet33 l/s (70 cfm)Consumption at 6.2 bar (90 psi). Size the compressor for at least 100 cfm free air, on 19 mm (3/4") bore hose.
- 05Pistons11 × 3,000 bpmEach carries its own cruciform cutter head and floats independently: 33,000 impacts a minute. Head life is about 100 hours.
SF11 Deck Hammers
Every tool, cutter head, piston, service kit and accessory carries its genuine Trelawny part number (with IMPA where available) and can be added straight to your quote. ShipServ TN 317548.
SF11 or SF11EX?
SF11
Carbide heads. The default for open deck, tank tops, hatch covers and bridge decks where there is no explosive atmosphere.
SF11EX
Beryllium copper heads, ATEX certified - Trelawny state Gas Zone 1. Specify it for tanks, holds, fuel and gas areas, rigs and petrochemical work. The value is not only the certification: it is that the job proceeds without a hot work permit, and permits are usually what the schedule is actually waiting on.
Beryllium copper heads are a consumable and cost substantially more than carbide, so the running cost of the Ex is higher over a long programme. If your work is split between certified and uncertified areas, price both rather than buying one machine and hoping.
Why operators pick it
It follows the deck, it doesn't skate over it
The eleven heads float independently, so on plate that has corroded unevenly the machine keeps every head in contact instead of riding the high spots. This is the practical difference between an impact machine and a rigid rotary drum on a deck that is no longer flat.
It reaches where the big machines stop
15 mm from a bulkhead, between structures less than 300 mm apart, and under pipework - Trelawny's SF11 brochure gives 150 mm of working head clearance. A rotary deck scaler stops 55 mm out and leaves you a hand-tool job around every edge.
It takes the vibration out of the job, not out of the numbers
The sub-frame sits on a duplex rubber mounting system. Trelawny declare 5.76 m/s². Their own handheld triple-head scaling hammer declares 13.4 m/s² and a 3BPG needle scaler 42.57 m/s² at the front hand. On a large deck that difference decides how many operators you need on the rota, not how comfortable the day is.
It makes the blast cheaper
Breaking 6 mm of scale off with abrasive is the most expensive way to remove it. Anglia Waterblast used two SF11s to strip a 3,000 m² deck over a weekend in dock; Trelawny report that 80% of the task was completed with the two machines, cutting the blasting time, the abrasive bill and the duration.
It collects its own debris
40 mm vacuum port, designed around Trelawny's TVS shroud and the K-series and KAV30 vacuums. Nothing washed overboard, nothing to sweep up before the coating crew arrives.
Eleven pistons, each tracking the steel on its own
Eleven pistons, each carrying a taper-fit cruciform cutter head, cycle at 3,000 blows per minute - 33,000 impacts a minute across the head assembly. Each piston recoils on its own spring, so heads track the surface independently rather than as a rigid plane.
The machine runs on compressed air at 6.2 bar (90 psi), rides on two wheels, and is driven back and forth over the work. It is not held against the surface; the operator steers it.
One head, eleven times over
Cutter heads are taper-fitted and swapped with a drift pin and a soft-faced hammer when production drops off, which Trelawny put at roughly 100 hours of head life. A hard-faced hammer destroys the carbide inserts - the manual is explicit about it.
Carbide head 426.5351 for the SF11, beryllium copper 606.5303 for the SF11EX. Eleven per set, and falling production is the usual first sign they are worn rather than the machine being at fault.
What you get
Machine complete with 11 carbide cruciform heads fitted, pistons, cylinders, brush seals, 3/4" ball valve and claw coupling, wheels, and the folding handle with locking pin. The TVS vacuum shroud (437.0100) is listed as part of the machine assembly in Trelawny's current parts list - confirm with us which configuration your quote covers, because the part numbering has changed.
Ordered separately: 15 m of 3/4" air hose with couplings (843.0752), inline lubricator (859.1580), whip hose and oiler assembly (458.1580), whip check (815.5550), the vacuum unit itself, and the service kit (446.1540, or 446.1540X for the Ex).
Dust, and the reason to specify the shroud
The SF11 fractures coating and scale into debris at deck level. With the TVS shroud and a K-series or KAV30 vacuum on the 40 mm port, that debris is captured at source. Without it, you have created an airborne hazard on a working deck and a clean-up job before anyone can coat.
For yards working to old coatings of unknown composition, capture at source is usually the difference between a straightforward job and a controlled one.
Where a deck hammer stops
Worth saying plainly, because it decides whether this tool belongs in your specification at all.
- 1SF11 deck hammerSt 2 / St 3
Removes scale, rust and thick coating. ISO 8501-1 grades this as power-tool cleaning.
- 2Abrasive blastingSa 2½ + stated Rz
A separate scale (Sa 1 to Sa 3). The anchor profile a coating needs comes from abrasive, not impact.
- 3Coatingto the specification
The SF11 is the step that makes blasting fast and cheap, not the step that replaces it.
The largest surface irregularity the machine rides, per the manual. Beyond that you risk cutter-head damage, so weld seams, doubler plates and heavy pitting need planning around, not driving over.
Not for aluminium structures, GRP or thin plate where deformation is a real risk.
Frequently asked questions
How much deck can one SF11 cover in a day?
The machine is rated at up to 30 m²/hr, but the operator is the binding constraint, not the tool. At the declared 5.76 m/s², one operator reaches the EU exposure limit value of 5.0 m/s² A(8) after roughly six hours of trigger time - about 180 m². To stay under the 2.5 m/s² action value, roughly 45 m² before rotating. Plan the rota, not just the rate. The full arithmetic, tool by tool →
What size compressor do I need for an SF11?
At least 100 cfm free air at 90 psi per machine, per Trelawny's own manual - not the 70 cfm consumption figure on the datasheet. Two machines want around 200 cfm. Use 19 mm bore hose and keep the run under 30 m.
Can I use a deck hammer instead of blasting?
Only where the coating specification allows a power-tool cleanliness grade (St 2 or St 3). Where Sa 2½ and an anchor profile are specified, the deck hammer is a pre-blast step. Used that way it pays for itself: Trelawny report 80% of a 3,000 m² deck strip completed with two SF11s before the blast crew started.
Is the SF11 safe to use in a tank or gas zone?
Use the SF11EX (159.5930). It carries beryllium copper spark-resistant heads and ATEX certification - Trelawny state Gas Zone 1 - which is what lets the work proceed without a hot work permit. The standard carbide-headed SF11 is not certified for those areas.
How long do the cutter heads last?
Trelawny put cutter head life at approximately 100 hours. There are 11 heads per set, and falling production is the usual first sign they are worn rather than the machine being at fault. Keep a service kit (446.1540) on board.
Why is the deck hammer's vibration lower than a handheld needle scaler's?
Because you are not holding the impact mechanism. The SF11 is walk-behind, with the sub-frame isolated on duplex rubber mounts, so Trelawny declare 5.76 m/s² against 13.4 m/s² for their handheld SF3 triple-head and 42.57 m/s² at the front hand of a 3BPG needle scaler. On a large deck that is the difference between rotating operators every twenty minutes and every few hours.
Does it work on aluminium decks?
No. Carbide impact heads are for steel. Talk to us about the right method for aluminium structures.
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The machine, the warranty and the documentation are Trelawny's. The stock, the EUR quote and the person who answers in your time zone are ours. Warranty is 12 months, conditional on registering the product within 30 days of purchase.