What thickness of teak decking is suitable for a boat?
I'm considering replacing the teak on my yacht and have been offered several thicknesses. How thick should the new decking be, and how do I tell whether the existing teak has enough left to repair?
Answer
For new teak bonded onto a sound fibreglass deck, 6 to 9 mm is a practical starting range, with thicker boards allowing more wear and future repairs. Older screwed decks often started at 12 to 14 mm, so choose thickness to suit the fixing method, available clearance and condition of the supporting deck.
Check deck construction and fixings
Establish whether the teak covers a structural deck or forms part of the structure itself. These thicknesses apply to teak laid over a supporting deck; structural timber decking needs a specification suited to its beams, spans and fastenings.
On a fibreglass yacht, check for leaks, soft patches, loose planks and moisture around fittings before ordering timber. Thicker teak cannot cure a wet core or a detached upper laminate. Those repairs can determine the scope of the whole job.
Check whether the old planks are screwed and plugged, fully bonded, or both. Screws need enough timber above their recessed heads for plugs. A properly specified bonded installation avoids these recesses and can use thinner teak.
Before drilling or routing, establish the deck construction and locate concealed wiring and pipes.
Choose the right thickness
Use these ranges when discussing a replacement with a deck specialist:
- About 4 to 6 mm: suitable for some fully bonded panels and cockpit coverings, provided the system is designed for that thickness. There is little allowance for sanding or deep seam repairs.
- About 6 to 9 mm: a useful range for a fully bonded replacement deck on a cruising boat, balancing timber weight and finished height against wear allowance.
- About 10 to 12 mm: provides more timber for wear and maintenance, but increases weight and cost, as well as finished height. Check that the extra thickness serves a purpose.
- About 12 to 14 mm: found on some older screwed yacht decks. This is a useful reference when matching original construction, rather than a requirement for every replacement.
An owner reported an original thickness of 12 mm on a 1989 Hallberg-Rassy 42E; decks from that period were also reported at 12 to 14 mm. For a 1990 HR382, around 12 mm is therefore a reasonable starting assumption. Confirm it at an unworn edge or against the builder's specification.