SQ8ZA4T Marine Crane on a Work Barge in Bahrain

A wrapped load on a wooden pallet swinging up from a work vessel to the deck of an offshore rig: four photos from our customer in Bahrain show a BOB-LIFT SQ8ZA4T knuckle boom marine crane mounted on a steel work barge.

At a glance: SQ8ZA4T 8 t knuckle boom marine crane · Bahrain · steel work barge · pedestal mounting · 4 customer photos.

What the photos show

• The crane. A red knuckle boom crane, folded, stands on a round slewing base at the edge of the deck. The boom is marked BOB-LIFT and SQ8Z, with a NO STANDING UNDER THE BOOM warning. A control stand is fixed beside the column.
• The barge. The steel deck carries a yellow winch, coils of rope and hoses. Mooring ropes run from bollards to the quay, and a white work boat lies alongside.
• Near the shore. One photo looks along the boom towards shallow water, where workers stand among old steel piles and concrete blocks while an excavator works beside them.
• Lifting to a rig. Two photos show the crane at work beside the legs of an offshore rig. The boom is raised and extended, and a wrapped load on a wooden pallet hangs from the hook below the rig's deck, where workers in hard hats wait at the rail.
• Tag line. A worker on the barge deck, in a life jacket and helmet, holds a rope tied to the load.

These are the customer's own photos. No load weights, dates or comments came with them.

SQ8ZA4T specifications

The SQ8ZA4T is an 8 t knuckle boom marine crane with a maximum lifting moment of 16.7 t·m. All figures are read from the technical department's dimension and load chart drawings.

Lifting moment is the load times its distance from the slewing centre. That is why the rated load drops as the boom reaches out. For example, the SQ8ZA4T lifts 8,000 kg at 2 m but only 1,420 kg at 10.5 m. Working radius is the level distance from the slewing centre to the hook. On a vessel, the pedestal takes the place of outriggers. It must be strong enough for the crane's weight and its full lifting moment. For general crane safety rules, see the OSHA cranes and derricks standard.

At 6.45 m from the slewing centre the crane is rated for 2,470 kg; at 8.47 m it is 1,820 kg. Lifts up to a rig deck often happen in this middle part of the chart.

The SQ8ZA4T product page has the full drawings, and other 8 t models are on the 8 t knuckle boom marine crane page. A telescopic marine crane goes onto a vessel in our delivery record from New Zealand, and a 12 t truck crane works in our record from Bahrain.

Lifting from a vessel to an offshore deck

A lift from a barge to a rig is harder than one on land. The barge moves with the sea, while the rig stands still, and the landing point is high above the crane. Four points to plan for:

1. Measure the real radius. Measure from the slewing centre to where the load will land on the rig, not to the rig's edge. Read the rating there: 2,470 kg at 6.45 m, 1,820 kg at 8.47 m.
2. Use a tag line. As in the photos, a rope on the load lets the deck crew stop it from turning or swinging into the rig's legs.
3. Agree signals with the rig crew. The operator often cannot see the landing point. Use a radio or a signal person on the rig deck, and land the load slowly.
4. Watch the weather and the swell. When the barge rises and falls, the hook does too. Stop lifting when the motion makes it hard to land a load under control.

Sea water is hard on steel, so the marine cranes get an epoxy zinc primer with a polyurethane acrylic top coat. Other capacities are in the knuckle boom marine crane range, and the marine crane buying guide covers deck mounting in more detail.

What to send us for a marine crane

To check a crane like the SQ8ZA4T for your vessel, we need a few details. Short answers are fine.

• The vessel. Its type, such as a barge or a work boat, its length, and where on the deck the crane will stand.
• The lifts. The heaviest load, and how far from the crane it is picked up and set down.
• The power. The hydraulic power pack you have now, or whether you need a new one. The SQ8ZA4T needs 40 L/min at 28 MPa, about 25 kW.

Send these through the contact page, and our team will check reach and load against the chart.

Record compiled by Achord Chan, Product Operations Director at BOB-LIFT, from the customer's photos and the technical department's drawings.