Case Study: A 7,352 kg MSB-FWD Control Console

The equipment was an MSB-FWD control console installed on a container ship.

Why We Did Not Divide the Weight by All 16 Mounts

Only the ten bottom mounts carried the main static load.

Dividing 7,352 kg by ten gives an average of approximately 735 kg per load-bearing mount, which is below the isolator’s rated static load of 1,250 kg.

That number is useful, but it is not the final design load.

Switchboards are rarely balanced perfectly. Busbars, switchgear, structural frames, and other internal components can shift the center of gravity toward one section of the cabinet. The load on one mount may therefore be much higher than the calculated average.

After installation, static deflection should be checked at every load-bearing position. If one mount is heavily compressed while the next shows little movement, the likely causes are:

• an uneven mounting surface;
• different installation heights;
• local frame deformation;
• an offset center of gravity.

Adding more mounts is not always the answer. When the load per mount becomes too low, the wire rope may not deflect as intended, making the system stiffer and reducing isolation performance.

Why Rear Isolation Was Critical

The cabinet length influenced the mounting arrangement as much as its weight.

A 7.3-ton switchboard can be supported from below, but a structure more than 10 meters long may still rock or move laterally under shock. Bottom mounts alone do not always provide enough directional control.

A rigid rear brace would restrict movement, but it could also create a vibration bypass. Shock and structural excitation could travel directly from the ship into the cabinet, reducing the benefit of the bottom isolators.

The six rear wire rope isolators provided elastic restraint instead. They limited excessive movement without locking the console rigidly to the vessel structure.

This is the key design balance:

Restrain the equipment enough to keep it stable, but not so much that the restraint bypasses the isolation system.

Cable trays, grounding straps, pipework, and external brackets must be checked for the same reason. A correctly selected isolator cannot perform properly when a rigid connection crosses the isolation interface.

Why Wire Rope Isolators Were Used

Wire rope isolators dissipate energy through cable bending and friction between individual wire strands. They can respond to vibration and shock in several directions without relying on rubber elements.

This all-metal construction is suitable for marine installations exposed to humidity, salt spray, temperature variation, and long service periods. It also avoids common elastomer failure modes such as compression set, hardening, cracking, and bond separation.

The JGX-2228D-1250A was selected for this project because its static-load rating matched the required support range while its wire rope structure provided multidirectional shock control. HOAN’s product range includes wire rope isolators for different load levels, mounting directions, and equipment sizes.

The applicable vibration or shock standard should always follow the project specification. Passing one pendulum shock test confirms performance under that defined test condition; it should not be treated as universal approval for every shipboard installation.

Marine Isolation FAQ

Why were the rear mounts not included in the static-load calculation?

Their main function was lateral stabilization, not vertical weight support. The ten bottom mounts carried the primary static load.

Can rigid rear supports be used instead?

They can limit movement, but they may also create a direct vibration path between the vessel and the equipment. Elastic restraint is usually preferred when isolation must be maintained.

How can vibration bypass be identified?

Check every connection crossing the isolation interface, especially cable trays, grounding straps, pipework, brackets, and adjacent panels.

Does passing a pendulum test prove that the design will work on every vessel?