Transom Plates

P&M Plastics fabricates custom transom plates for outboard motor mounting on aluminium tinnies, fibreglass boats, and commercial vessels. A transom plate distributes the concentrated load and vibration of an outboard engine across the transom, preventing cracking, deformation, and stress fractures over time. We offer transom plates in both plastic and aluminium. Our plastic plates are CNC-cut from HDPE, nylon, and UHMWPE — marine-grade materials that won't corrode, absorb water, or react with stainless steel fasteners. For applications requiring greater rigidity or higher engine ratings, we also fabricate aluminium transom plates from marine-grade 5083 and 6061 alloy, precision-cut and drilled to your specifications. Every plate is cut to your measurements at our Gold Coast fabrication workshop, with bolt hole patterns, radiused corners, and countersunk fastener holes machined in-house. We supply single replacement plates for weekend boaters through to batch runs for boat builders and marine workshops.

Plastic vs Aluminium Transom Plates

Plastic transom plates (HDPE, nylon, UHMWPE) are the standard choice for most outboard setups. They're lighter than aluminium, absorb engine vibration effectively, won't corrode in salt water, and create no galvanic reaction with stainless steel bolts. They're ideal for tinnies and fibreglass boats running outboards up to around 150 HP. Aluminium transom plates suit higher-horsepower applications where maximum rigidity is required. Marine-grade aluminium resists corrosion well in salt water (especially when anodised) and provides a stiffer mounting platform for heavier outboards. We can anodise or powder-coat aluminium plates for added protection.

Why Transom Plates Matter

Without a transom plate, the outboard mounting bolts concentrate all engine load, thrust, and vibration into a small area of the transom. Over time this causes the fibreglass or timber core to crush, crack, or delaminate. A properly sized transom plate spreads that load across the full mounting area, extending the life of the transom and reducing hull vibration. It also makes remounting or upgrading engines far simpler — just re-drill the plate rather than patching the transom.