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  3. Cutter Ladders & Gantries
Offshore · Marine construction

Cutter Ladders & Gantries

The ladder of a cutter suction dredger and the gantry that hoists it, fabricated to your drawings: trussed side girders, trunnions, the suction pipe, the cutter shaft housing and the A-frame gantry.

Explore the 3D model Send us a drawing
Allmarc 3D model · to scale
Built to your size

Ladder length, pipe size and cutter power follow your dredger.

We have not delivered this product yet. We are equipped to build it: a 30 m bay with 11.5 m under the hook, plate rolling to 40 mm and welding to EN ISO 3834-3. The model shows a typical arrangement.

To your drawing
made
18 m
ladder shown
EN ISO 3834-3
welding
In our bay
trial assembly
Explore the model

How it is built.

Scroll: the camera moves to each part in turn and ends on the exploded view. Drag to turn it round yourself.

Loading model 0%

01 / 08

The working end of a cutter dredger

The ladder carries the cutter down to the seabed and the suction pipe back up. It takes hard wear and is rebuilt or replaced through the life of the vessel. We fabricate it; we do not dredge.

Scroll to see how it is built · drag to turn it round

02 / 08

Ladder frame

Two trussed side girders tied by cross frames. Tube ends are profile-cut so each joint fits before welding.

How is it possible at Allmarc?
CNC profile laser in the Allmarc works

Used here for: Ladder frame

  • Tube, beam and structural profile cutting
All our machinery
Manual MIG welding in the Allmarc works

Used here for: Ladder frame

  • Qualified welders, including 6G
All our machinery

03 / 08

Trunnions

The ladder swings on 2 trunnion pins in bearing housings. The housings are machined after welding so the pins line up.

How is it possible at Allmarc?
SKDX1030 CNC end-face milling in the Allmarc works

Used here for: Trunnions

  • Mills beam and column ends square for bolted splices
All our machinery

04 / 08

Suction pipe

The suction pipe hangs under the ladder in flanged lengths, rolled from plate, so a worn length can be changed on its own.

How is it possible at Allmarc?
Three-roll pinch cum pyramid plate rolls in the Allmarc works

Used here for: Suction pipe

  • Rolls plate up to 40 mm
All our machinery

Used here for: Suction pipe

  • Full-penetration welds on built-up sections
All our machinery

05 / 08

Cutter shaft housing

Bearing blocks and a gearbox seat on top of the ladder carry the cutter drive. The cutter head is supplied by others.

06 / 08

Gantry and sheaves

An A-frame with back stays stands at the bow. Sheave blocks on the gantry and the ladder carry the hoist wires.

How is it possible at Allmarc?
Kotec newRun10DX CNC beam drilling line in the Allmarc works

Used here for: Gantry and sheaves

Heavy profiles that need precise holes, where plasma cannot do the job: the lower structure and panel borders of a ground flare, and every bolted PEB and multi-storey frame.

  • H-beams up to 1,000 x 500 mm
  • Drills 3 faces in one pass
  • Channels, angles and box sections
All our machinery

07 / 08

Made to your drawing

Send the general arrangement or a sketch with sizes and loads. We detail it, fabricate it, trial-assemble it in our bay and pack it for sea. The model is a typical arrangement, not a delivered project.

08 / 08

Every part

Ladder, trunnions, pipe, shaft housing and gantry.

Why Allmarc

Experience you can trust.

We fabricate to your drawings and prove the fit in our own bay before anything ships. Open any line for the detail.

Talk to an engineer
Heavy rolled plate
  • Leg sections and yoke rings rolled from thick plate.
  • Seams welded on the submerged-arc line.
Round and true
  • Rings braced round while they are welded out.
  • Pin holes cut and checked to jig.
Fitted in the works
  • Yokes, guides and leg sections fitted together before dispatch.
  • A 30 m wide bay with 11.5 m under the hook.
To the designer’s drawings
  • Hydraulics, winches and cranes come from their makers.
  • We build the steel they work in.
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Start a project

Have a drawing? Let us build it.

We fabricate to your design, from plate to a packed container. An engineer will tell you honestly how we would build it.

Send us a drawing