No. The threading process for bolts that are hot-dip galvanized is no different from the process for bolts with no coating.
There is a common misconception that threads for galvanized bolts and rods must be cut undersized to accommodate the added thickness that hot-dip galvanizing adds. The added thickness from the galvanizing is actually addressed in the galvanized nut, or other female thread, which is tapped oversize to properly fit on a galvanized bolt.
Additionally, threads should not be “chased” after galvanizing. Chasing threads is a term used to describe re-cutting threads on a galvanized bolt after galvanzing to remove the excess zinc from the threads. This procedure will not only remove the excess zinc, but also nearly all of the zinc, and subsequently the corrosion protection from the threads.
In almost all cases, bolts used in marine environments are either hot-dip-galvanized or stainless steel. Zinc plated fasteners offer very little in the way of corrosion protection.
Hot-dip galvanizing is a process of applying a protective zinc coating by dipping product in bath of molten zinc, and the zinc bonds with the steel. Zinc plating (or electroplating) is a process where zinc is applied by using a current of electricity. This coating is much thinner than hot dip galvanizing and in general is not specified in outdoor environments, especially marine environments.
It should also be noted that galvanized nuts are tapped oversize to accommodate for the added thickness from the galvanizing process on the bolts. A zinc plated nut would not fit properly on a galvanized bolt.
Shear plates are round, malleable iron discs that are embedded in timber to increase the load capacity of wood-to-wood or wood-to-steel connections.
The primary marine application of shear plates is in the construction of wooden fendering systems, which are a type of floating dock used by marinas.
More information about shear plates can be found at www.shearplates.com, including available sizes, technical specifications, and a detailed installation video with instructions.