Definitely one of the cooler toys we've used to build this boat... it consists of a huge 600 pound battery pack with ac charger that allows you to deliver extremely high amperage for a very short duration, a timer box, and a gun that position and "fires" the threaded stud into the surface that you are working on. With the battery pack, we can reload and shoot a stud about every 45 seconds so there is a huge time savings over hand welding the studs or drilling and using bolts. The result is a very strong, permanent attachment point for anything that you need bolted down. When we folded over our test studs with a 10 pound sledge, the stud broke but the weld stayed intact, so no worries about strength. We are using this machine to install studs for all the fuel tank inspection hatches and zinc anode attachment on the bottom of the boat. We are also shooting studs for the floor supports, interior framing, and ceiling nailers for attaching our wood interior. With this machine, we have been able to shoot studs at the rate of about 100 per hour... which is good since we will end up with well over a thousand threaded studs throughout the boat.
Also got all our zincs together and drilled. The zincs serve as sacrificial anodes to protect the hull and fittings below the waterline from galvanic corrosion, which can erode metal at an alarming rate if you are not properly protected. This is especially of concern in harbors and marinas where there is often quite a bit of stray current from other boats and electrical hookups. The idea is that the zinc is more reactive than the other materials that the boat is built from, and will sacrifice themselves before your underwater metals are affected. Since much of the bottom and keel of the boat is fuel tankage, weld-on zinc anodes are not really an option. So all our zincs will be bolt on with 1/2" studs welded to the hull. This also makes it easy to change the zincs out in the water if needed. Our planned anode arrangement will give us about 200 lbs of zinc below the waterline which should keep us well protected for 2+ years even in relatively "hot" harbors.