These bolts are often referred to as Carriage Bolts or Cup Square Bolts. Silicon bronze is a strong material which is very resistant to corrosion making it one of the best fastening material to be used for boat building. Please note not all sizes come fully threaded we cannot guarantee a fully threaded bolt . Use these silicon bronze machine screws to fasten all gunmetal, bronze or brass fittings. Do NOT use for fastening galvanised iron, Bronze is definitely one of the noblest metals on a boat, excelling in strength and corrosion resistance. It also has the advantages of being generally non-magnetic so it won't deviate your compass. Those working near inflammable gas will also appreciate that bronze tools are non-sparking. It has been known since 3000 BC, making it the first alloy to be used by humans. Hasn't it done well! Not all bronzes are the same. Commonly it is a blend of mainly copper with about 12% tin but other metals such as aluminium, zinc, nickel and manganese are often used, as are non-metals such as silicon, arsenic and phosphorus. Each alloy has its own characteristics. Silicon Bronze is a red coloured bronze with great corrosion resistance and high strength which is often used for screws and bolt fastenings. If you have bronze fittings, fixings or equipment on your boat then you can rest assured that it will be strong and resilient. Please don't muddle it with brass which is next to useless at sea! .
