Silicon Bronze fasteners and nails
Silicon Bronze is probably the best metal for marine nails, screws and bolts. It is an alloy of copper and small amounts of silicon. It is to all intents immune to self-corrosion either in the atmosphere or immersed in seawater. It is hard and nearly as strong as the so-called marine grades of stainless steel.
Stainless Steels require constant exposure to oxygen to maintain a Chromium Oxide film on the surface. This protects the steel and makes it corrosion resistant. Inserting 316 Stainless Steel fittings through a deck or other tight cavity that does not allow exposure to air and water makes contact you will get crevice corrosion. That is why the Australian Yachting Federation banned plastic coated wire for life lines on yachts. Through deck fittings are classics to suffer from crevice corrosion.
WHY Square Drive
Square Drive allows better torque and less slip for easier driving.
Square drive gives better control. The driver does not jump out under heavy load.
Longer driver life, the bits don't wear rapidly due to the more positive drive.
High quality heat treated steel for strength.
Sharp thread angle grip and less splitting.
Deep threads grip the timber without crumbling.
Minimum body diameter allows for better clamping without stepped drilling.
Sharp point for easier starting and driving.