Grounding System
This is tricky ground to traverse. (pun intended) A well-grounded mast could provide a better zone of protection from a direct lightning strike. The trick is getting it "well-grounded" because halfway measures could worsen the effects. The idea of a "ground" in this sense is to dissipate the current directly into the water surrounding the boat. Generally, you want as much ground surface area in the water as possible to do this, as it lowers the overall current density. Metallic keels are fine as long as they are exposed to the seawater. Getting (and maintaining) a total top-to-bottom resistance of less than 0.1 ohm on your boat will be a real challenge. Whether the mast is deck- or keel-stepped, you'll need to establish a very robust grounding connection to the keel. That generally involves dissimilar metal connections at both ends, which introduces corrosion/maintenance issues. To establish a well-grounded system, you need to think of the entire boat as a complex network electrical circuit ("Complex" in the sense that this is not a static DC problem (resistance loading) to solve, although that can be a starter). A lightning strike is generally "direct" (one way) current, but it is characterized by a pulsed waveform with a steep rise and slower decay over time, and has extreme currents (10,000+ amps possible). That pulsed waveform brings into play inductive and capacitive loading. As such, all of the stays, wiring, rails, etc. come into play as conductors. Ohm's Law: Voltage = Resistance x Current Example: If you have 10,000 amps of current passing through a resistance of 0.1 ohms, there will be 1000 volts across that resistance. So, your mast top can have 1000 volts relative to the water. If your chainplates & fore & aft stays aren't well-grounded, they too will be at 1000 volts to water. At that voltage, they can arc-over to something (either through your hull, or along the hull, or both). Either way, they can cause damage to the hull integrity. Of course, any radio, radar, instruments, or electrical devices (lights, etc) connected to stuff on the mast is instantly toasted. I would suggest doing some deep research on this topic before changing your boat. There are many books available, plus advice from your boat's manufacturer (Catalina), the USCG, and various boating safety/standards organizations. --RonD
