| Author | Message | ||
     Scott Corder New member Username: Pastcommodore Post Number: 40 Registered: 02-2001 Rating: N/A |
Brayden makes very good points below. Here's what little I can add as the subject was heavy on my mind during a very recent 11 hour crossing of Lake Michigan, 6 hours of which was spent watching lightning around us in all directions (across the vast open horizon created by Lake Michigan). It is truly incredible how clearly you can observe lightning in what seems to be at least a 50 mile radius when on open water. Our boat (hull#2) appears to be well grounded from the shrouds to the keel bolts via very heavy copper wire. This "circuit" also appears to be securely connected to the brass through hull fittings for the engine water intake as well as other through hull fittings. I haven't inspected the system thoroughly enough yet to know exactly what the design or intention (or effectiveness) is. Needless to say, our solution was simply to alter course along our trip to avoid squalls as they moved through our path (lengthening our trip but resulting in better peace of mind). When the heaviest rains passed through, we merely closed up the cabin, curled up warm and dry on our bunks (away from all things metal) with a good book and let our faithful Navico Auto-pilot follow the course being determined by our Loran (these electronics are by far my absolute favorite nautical investment - bar none). This mention of our electronics prompts a sidebar observation that may have some related value on this topic: namely redundancy in critical systems. Part of our confidence amidst this lightning storm was the fact that we have multiple layers of redundancy in our navigation electronics. In broadest terms: a 12v system backed up by a separate AA/C/9v battery system backed up by non-powered tools. Maybe we have false confidence in the survival of these non-12v items in the event of a lightning strike, but the methodology seems sound in our minds. Here's what we have on what system: 12v wired boat system: sailcomp fluxgate compass, KVH instruments with multiple displays, Apelco Loran and Navico TP 5000 autopilot with remote control kkeypad (that can be extended to reach anywhere on the boat and also plugged in to enable driving from inside the cabin)(the Navico also has a fluxgate compass)... all these items are NMEA interfaced to talk to each other. Also have a full size VHF on 12v. The boat drives itself as long as we have 12v power. Also, we always run on only one of our two batteries. Back-up system: AA battery powered Garmin GPS (not wired to anything) and Micro sized waterproof handheld VHF. Non powered system: two fluid compasses in the bulkhead and a handheld fluid compass. Here's the final trump card in the pile: a Mini EPIRB registered with the Coast Guard in my name to my vessel (and tested regularly). If we get in huge trouble or the boat goes down, they'll know WHERE we are, WHO we are and can typically be anywhwere to retrieve us on Lake Michigan in under 30 minutes. My wife LOVES this device whenever I do a solo delivery (which I often do). I know this info doesn't directly answer your question about electrical grounding but I think it offers several back-up scenarios in the rare case you might be struck. One final observation: On the last day of one design Class racing off-shore in Milwaukee this summer, the final race was abandoned due to a thunderstorm with lightning. As our Class, a few other classes and the entire J24 Nationals crowd all scrambled back to shore, we observed a Soling being towed that had its spinnaker pole clipped to the backstay and dragging in the water behind it. It was quickly explained that this was their effort to provide a direct ground should they receive a strike. It wasn't particularly "neat" but the logic made very good sense to all of us who had not seen this type of approach before. |
