Aluminum Mounting Plate 300×95 mm for Outboard Engines

This aluminum mounting plate measuring 300×95 mm is useful for all kinds of installation tasks related to outboard motors and marine hardware. It’s made of high-strength aluminum and has an anodized finish, which protects it from corrosion and provides a smooth surface. The plate is large enough to span the distance between typical outboard motor bolt holes, and it significantly increases the strength of the area around the bolts. When used as an interior transom backing plate, it prevents localized stresses – instead of the wood or fiberglass transom taking all the pressure from the nuts, the aluminum plate distributes it evenly over a larger area. This keeps the transom from cracking, crushing, or the bolts from loosening over time.
Besides engines, this plate can be used for mounting other transom accessories: e.g. when attaching automatic trim tabs, fishfinder transducers, boarding ladders, or other fittings where you want to reinforce the mounting area. The plate’s thickness is chosen to provide the needed rigidity without being overly heavy or difficult to work with. Drilling holes in it is easy with a standard drill – you can mark and drill precisely where your engine or accessory holes need to be. Once installed, the plate remains hidden on the inside of the transom (if used as a backing plate), but its effect is evident in a more solid and reliable installation.

• Typical use cases: As an interior backing plate when through-bolting medium to large outboard engines – to prevent washers from sinking into a wooden transom; in transom repairs – to cover a damaged or weakened area and restore strength; as a general mounting plate for brackets, transducer mounts, rails, etc., where an aluminum foundation is desired.
• Recommended boats: All types of boats (fishing boats, cruisers, RIBs), especially those with wooden or composite transoms. Also useful on aluminum boats – using an aluminum plate ensures similar material to the hull, reducing the risk of galvanic corrosion compared to steel fittings in direct contact.
• Installation tips: When using as a backing plate, position the aluminum plate on the inside of the transom aligned with the holes, then insert your bolts – this way it acts as a large washer. If your engine’s bolt pattern doesn’t perfectly match the plate’s dimensions, drill new holes in the plate according to the engine’s template. All edges of the plate are smooth, but you can slightly round the corners with a file if needed for a better fit. Use marine sealant between the plate and transom (especially on metal transoms) to eliminate any vibration noise and seal against water ingress. Check your bolt lengths – adding this plate might require bolts ~5–7 mm longer to fully engage the nuts.