When you think of driving a screw into wood, the tools that come to mind are probably a screw driver or a drill with a bit attached to it. These are certainly the modern choices to drive screws home, but there is a reason the old methods hang around.
Bronze screws are softer than galvanized steel and much softer than stainless steel screws. Steel screws can be driven in with an undersized bit with ease and at little risk to galling the head. For this reason, people tend to use whatever size screwdriver fits into the slot.
If you use a smaller than adequate screw driver on a bronze screw, you will quickly slip out of the slot and gall up the threads. If the screw driver is too big and doesn't sit into the bottom of the slot, the same will occur. Once the slot has been galled, the sides of the slot will be rounded and it will be even easier for the driver to slip out again, further galling up the head. To avoid any of these problems, you need to make sure that the screw driver reaches the bottom of the slot and there is no gap or void between the bit and the head. If the bit fills the slot perfectly, it will power the screw all the way home without issue. If there is any discrepancy in the fit, it will slip out and gall up the head.
Stainless steel is starting to sound better and better, isn't it? While stainless steel is a wonderful material, it has its time and place to be used. When stainless steel is in an oxygen deprived environment (such as deep inside a plank) the corrosion inhibiting properties of the stainless steel are compromised and crevice corrosion can wreck havoc on the metal. The screw can literally corrode in half and greatly reduce its holding power. Bronze on the other hand does not suffer this same fate, and is the superior fastener material for use on a boat.
Now that we have explained why we will put up with a softer metal that is more prone to galling while being driven in, it is time to look at how we can drive these screws into place.
Most drill bits that can be inserted into a power drill are much too small for a large bronze screw. The next issue comes from the amount of power that an electric drill can produce. It can spin the bit so fast that it will jump out of the slot and gall up the threads as you begin. If you can manage to run the drill at a slower speed and control the rate at which the screw goes into the wood, you may think you are in the clear! The increasing resistance on the sides of the screw's threads will compound and the screw will stop advancing as the drill continues to spin, slipping out of the slot and galling your head. After a lot of effort, the galled up screw will finally get driven home, but the head looks horrible and you may be rather embarrassed if the screw will remain visible.
The next option is the more labor intensive screw driver. The screw driver is a hand driven tool that provides a bit of leverage to allow you to drive the screw home. A screw driver is actually a lever in disguise! The handle of the screw driver has a larger radius than the head of the screw. The radius of the handle is your lever arm, so a thicker handled screw driver will provide more leverage than a skinny handled screw driver. As you can imagine, the leverage offered by this tool is rather low, but more sizes of the screw driver are readily available allowing you to find one that fits the screw you are working correctly.
A bit brace is a very old style of tool that offers you the fit of a screw driver in combination with incredible torque and control only available in a hand powered tool. The offset lever adds incredible amounts of leverage to spin the screw while you can maintain constant pressure on the pad to keep the bit driven deep into the screw head. A bit brace may not seem as glamorous as a fancy and colorful electric drill, but it does perform with utmost reliability.
The bit can be set to ratchet, allowing it to be used in close quarters; or it can be fixed, allowing you the ease of driving something in and back out without the need to change any settings. The speed of the bit brace is dictated by the speed you move it, and the force on the screw is very apparent to you. Very light finger pressure can drive a screw in, and any changes in force will be quickly registered by the operator. This can alert you to push harder on the pad to keep the bit from slipping out of the head before the slot becomes galled.
If you have little resistance, it can drive a screw home quickly as a fast turns are possible and easy to carry out with this tool. If the resistance on the screw begins to compound, you can start to put more force on the bit brace and force it in or just as easily retrieve the screw and drill a slightly larger pilot hole for it to follow.
The last and most important feature of a bit brace is its ability to function without electricity. Plug in drills are great as long as you have access to an outlet. Cordless drills offer the freedom of mobility without a tether to an outlet, but an invisible tether is still present. As the drill is used, the batteries will run down and need to be recharged. These batteries require access to an outlet, meaning that you can prolong your visits to an electrical distribution point, but you are in no way free from the restraints of electricity. Lastly, the marine environment is a harsh world for electronics, so an on board power drill will eventually succumb to the deteriorating effects of corrosion. A bit brace does not run on electricity, as it is powered by the users hands and arms. If there is no sign of electricity, the bit brace continues on without a worry! Being made of metal, the bit brace is not immune to the marine environment. It can still rust and corrode, but proper care can deflect these deleterious effects and keep a bit brace looking as good as any other tool that is older than your grandfather! There are few moving parts on a bit brace, and these parts can be maintained with proper oiling and cleaning. If the bit brace were to act up, simple disassembly and cleaning can usually resolve any issue. These tools have been around for a long time, and they have survived into the present due to their reliability and usefulness.
The finesse and reliability of the bit brace make it is an invaluable tool to have and use while building a boat or carrying out repairs while living aboard and cruising.