Frederick 's BLOG


You ran aground. Now what?

Even the best navigators run aground. A vessel's driveline is made to help absorb vibration and eliminate noise. When these precise systems are impacted by colliding with an object, or the water ground, it’s a smart move to inspect beyond potential propeller damage.

After getting the vessel secured in a safe place, a captain or chief engineer should visually inspect the driveline, check for obvious damage, and document with photos and notes. A diver can perform this inspection underwater. If visible damage is minimal, at the very least, the propellers can be removed and repaired, and a vibration analysis should be performed to determine the operating condition of the running gear and machinery. 

Performing a vibration analysis is a crucial step in pinpointing additional areas that may have been affected. Here is our advice on how to repair additional components that were impacted: 

Propellers: Using a modern scanning device and balancing machines, propeller shops can make repairs to level class S or Class I at a minimum. 

Shafting: The most accurate method to inspect the shafts is to haul the vessel, draw back the shafts, and bench-check them on precision rollers. 

Struts: Check the internal hull area and strut mounting bolts for any sign of buckling or leaks. If strut or hull damage is present, haul the vessel, remove the struts and make necessary repairs. Struts can then be precision aligned and chocked when reinstalled. 

Cutless Bearings: Once the vessel is hauled, inspect the shaft bearings for running clearance, overheating, and delamination following a grounding.

Shaft Seals: Visually examine the lubrication system, hoses, clamps, and the raw water supply pump.

Shaft Couplings: After grounding, check the couplings for trueness and damage to the flexible elements.

Shaft Hubs: Send the shaft coupling hub together with the shaft when getting it checked for straightness. The shafting machine shop will then “fit and face,” which involves mounting the hub to the shaft and checking the fit of the shaft on the taper, checking the pilot is concentric to the shaft and verifying the runout of the face is true. 

Gearboxes: Vibration analysis is a powerful tool for picking up gear damage as a high-quality frequency analyzer. Oil analysis can also be used for determining gear conditions. If flexibly mounted and based on the force of the impact, it may be prudent to replace the mounts.

Engine Torsional Couplings: Torsional couplings should be inspected in the event of a grounding. This may require a video borescope to visually inspect the condition of the elastic element (Buna or Silicon Rubber). Inspect for tears, cracks, and distortion.

Engine Mounts: Mounts should be carefully and thoroughly inspected. Worst-case scenario, engine mounts should be replaced as internal inspection is not possible without disassembling the mount. 

Lastly, It’s crucial that a vessel’s machinery is aligned, especially following a run aground incident. 

The methods that we use here at AME include laser and/or optical alignment. We consider these the most precise methods for correcting shaft misalignment. 

Did you run aground and need a vibration analysis performed? Call Advanced Mechanical Enterprises/AME in Fort Lauderdale, Florida. We’re ready to help straighten things out. Contact us today.

Increase Your Machinery's Reliability