Proper Shim Use Marine Engines | PSL Palm Beach Alignment

Flexible mounts are critical components in marine propulsion systems, designed to absorb vibration and isolate engine movement from the hull. However, improper use of shims during installation or alignment is one of the most common causes of mechanical issues in marine engines.

Shims are used to adjust the height of the engine and achieve proper alignment between the engine and the shaft. While this may seem straightforward, incorrect practices such as uneven stacking, excessive shim thickness, or poor surface contact can lead to soft foot conditions, distortion of mounts, and long-term alignment problems.

At G&M Mechanical Engineering, we frequently encounter vessels where improper shim installation has caused increased vibration, premature wear of couplings, and even damage to bearings and seals.

Best Practices for Shim Use

• Use high-quality, corrosion-resistant shims
• Ensure full surface contact between shim and mount
• Avoid stacking too many thin shims unnecessarily
• Keep shim stacks clean, flat, and properly aligned
• Always verify alignment after tightening bolts

Flexible mounts are designed to operate under controlled compression. When shims are improperly installed, they can alter load distribution and reduce the effectiveness of vibration isolation.

Why It Matters

Incorrect shim usage can result in:

• Increased vibration levels
• Coupling stress and wear
• Shaft misalignment
• Reduced equipment lifespan
• Higher maintenance costs

Instructions

Always perform alignment using proper tools such as laser alignment systems. After installing or adjusting shims, recheck alignment under operating conditions to ensure long-term reliability.