Marine shims - Precision adjustments for engines and onboard assemblies

Why use a shim on a boat?

Often discreet, the shim plays a fundamental role in the proper functioning of a boat. Whether it's for a perfect engine alignment, a stable assembly of mechanical parts, or tolerance compensation, this simple part can make all the difference.

On a motorboat, each component is subjected to high stresses: vibrations, torsions, temperature variations... To ensure precise and reliable adjustment, shims allow you to work with thicknesses accurately. They contribute to the longevity of installations, the reduction of friction, and the preservation of critical alignments.

At DAM Marine, we offer a wide selection of marine-grade shims in various sizes, compatible with inboard, outboard engines, and many mechanical components. An essential solution for both professionals and demanding boat owners.

How can shims improve your boat's performance?

A shim is an adjustment part used to fine-tune mechanical clearances, compensate tolerances, or correct alignment between two surfaces. In the nautical world, this precise adjustment is essential to ensure the reliability and performance of your boat.

When positioned correctly, a shim helps to reduce unwanted vibrations (especially on engine mounts), limit premature wear of components, optimize sealing, and ensure the longevity of onboard systems. It also directly contributes to safety at sea, by preventing deformations or excessive play.

At DAM Marine, we select marine-grade shims made of stainless steel, aluminum, rubber, or reinforced composites. These materials are known for their corrosion resistance, durability against humidity, impacts, and mechanical loads. Conversely, building shims made of polystyrene or soft materials would not withstand the demands of a marine engine.

The many applications of shims in boating

Boat shims are not limited to simple adjustment roles. They are essential in many mechanical situations, whether for alignment, spacing, or stress reduction on onboard equipment.

For inboard or outboard engines, they allow adjustment of the engine's height and propeller shaft alignment, ensuring smooth operation of the drive line. On drives (Mercruiser, OMC, Volvo...), they are used for adjusting mechanical clearances and sealing.

Inside the engine, shims are also found in:
– Valve springs
– Crankshaft thrust washers
– Injection pumps
– and couplings.

For bow thruster installation, such as those from Sleipner or Side-Power, shims help correct a curved mounting surface (transom) or ensure galvanic isolation on metal hulls. Discover our selection of ready-to-install bow thrusters.

Finally, they are also used for structural adjustment on larger mechanical supports to reduce stress and optimize coatings or clamping areas.

Available in extremely varied thicknesses (from 0.003” to 30 mm), these spare parts must offer impeccable measurement precision. DAM Marine provides a wide range of marine-grade products, ready to adapt to all types of mechanical configurations.

How to choose the right shim for your engine or assembly?

The choice of a shim depends on several technical parameters. To ensure a perfect fit, it is essential to identify the specific application, the tolerance to be compensated, and the type of part to adjust.

Start by defining the location: is it an engine mount, a coupling, a gearbox, or a bow thruster? Each application involves different constraints (corrosion, vibrations, heat, mechanical load).

Then, select the right material: a stainless steel or aluminum shim for high mechanical stress, or composite and rubber for damping or galvanic isolation. Our marine-grade models are designed to withstand the marine environment.

Thickness precision is crucial: some tasks require adjustment to the hundredth of a millimeter, while others allow for a wider tolerance. At DAM Marine, we offer shims in various formats, with thicknesses from 0.003” to 30 mm.

You can also consult our specific categories:

• Marine engine mount
• Engine coupling
• Gearbox gasket
• Bow thruster

If in doubt, our technical team is at your service to help you select the shim suited to your assembly.

Maintenance, replacement, and regular checks

Although discreet, shims should undergo regular checks, especially during engine maintenance or transmission servicing.

Points to watch:

• Deformation or crushing of the shim after years of mechanical stress.
• Corrosion, especially on non-stainless or poorly protected steel shims.
• Irregular wear or excessive play appearing at the engine or coupling level.

Preventive replacement is recommended when the shim shows any defect or after disassembly. A worn or poorly positioned shim can alter the shaft alignment, increase vibrations, and reduce the lifespan of components.

When replacing, ensure you use a shim with the same dimensions and mechanical properties. Engine mounts, couplings, or bow thrusters must be reinstalled with precision to avoid misalignment.

Regular maintenance and the right material choice guarantee optimal performance and maximum safety at sea.

Need help choosing your shim? DAM Marine experts guide you

Choosing a marine shim should not be left to chance. It relies on several essential technical criteria to ensure perfect compatibility:

• Original reference (OEM): ensures compatibility with engines like Mercruiser, Johnson Evinrude, Yamaha, or Bombardier.
• Dimensions: knowing the length, width, and especially the exact thickness (in mm or inches) is essential.
• Material: opt for marine-grade materials such as stainless steel, aluminum, or technical composites, which can withstand humidity, loads, and vibrations.
• Engine or equipment model: each configuration (Yamaha, Volvo, OMC, Honda, Suzuki...) may require a specific shim.

At DAM Marine, you benefit from a catalog of over 70,000 references covering all major engine brands: Chris-Craft, Crusader, Mercury, Mariner, Honda, Volvo Penta, Yanmar, and many more.

Can't find your part? Our technical team is here to help you find the shim you need, even if it's not visible on the website.

Quality, stock, service: DAM Marine's triple commitment

Since 1975, DAM Marine has been supporting professionals and boat owners in maintaining their nautical equipment. Our commitment is based on three pillars:

• Quality: original or compatible parts, selected for their reliability, durability, and compliance with marine standards.
• Stock: over 30,000 parts in stock for fast shipping and 24-hour delivery for any order placed before 5 p.m.
• Service: secure payment, 15-day money-back guarantee, and a dedicated customer service team by phone and email for any technical request or personalized quote.

Are you in the Var region? Visit our showroom in Six-Fours-les-Plages, meet our team, and get personalized advice.

With DAM Marine, you are guaranteed a trusted partner for the maintenance and performance of your marine engines.

Conclusion

Essential for mechanical adjustment, shims ensure the performance, safety, and longevity of your nautical equipment.

At DAM Marine, take advantage of a wide selection of marine-grade parts, recognized expertise, and personalized support.

Browse our selection or contact our experts to find the perfect shim for your engine or assembly.