I am a relatively new sailor (A few years with Hobie Cats), and have stepped up to a Mirage 5.5, a small 'trailer sailer', and am refitting it, working on the electrical parts right now. It has an outboard that is pull-start, and the 12v electrical system is just one LiFePo4 battery charged by solar power (or an AC charger when at home/not in the water) to run the radio, instruments, and lights. All of my loads and the battery will be fused or breakered. I have read of 'grounding plates' which seem to involve putting a plate on the bottom of the boat with a wire through the hull so that one can ground one's electrical system to the ocean? But I'm reluctant to put any more holes in the hull than I absolutely must, and am wondering if it's essential equipment for a small, low load system, and if it is, if there's a way to do the electrical system properly grounded without having a hole through the hull?
Do I need a grounding plate?
- Thread starter JohnBisMe
- Start date
A grounding plate really isn’t a necessary part of the DC system. The entire DC system is a closed circuit - electrons flow over the wires between the battery, solar panels, and loads. There is no need for a connection to the earth for any of that circuit to work.
A ground plate can have basically two purposes. The first is to provide a ground for an SSB radio - likely not something you’ll have on your Mirage, so no issue there. The second purpose is as as part of a lightning protection/dissipation system. Depending on what you read that means keeping the boat at the same ground potential as earth so you’re less likely to be struck, or providing a place for lightning strike energy to be dissipated to earth without blowing through the hull. Any large underwater metal can serve that purpose as long as metal lightning targets like the mast are connected to it with sufficient cable. A keel is often used as the lightning ground on sailboats, or a grounding plate could be attached for that purpose. Since you’re only building the DC system and not building the boat from the ground up I’d be inclined to leave whatever lightning ground the designer originally deemed sufficient alone, as lightning protection and dissipation can be a rabbit hole of uncertain guidance. If there is a lightning ground bus of some sort already in place connecting things like the mast and shrouds to the keel it is generally accepted to attach the DC ground bus to that lightning ground system at one single point. That helps ensure any metal components attached to the DC system are all kept at the same potential as everything else.
A ground plate can have basically two purposes. The first is to provide a ground for an SSB radio - likely not something you’ll have on your Mirage, so no issue there. The second purpose is as as part of a lightning protection/dissipation system. Depending on what you read that means keeping the boat at the same ground potential as earth so you’re less likely to be struck, or providing a place for lightning strike energy to be dissipated to earth without blowing through the hull. Any large underwater metal can serve that purpose as long as metal lightning targets like the mast are connected to it with sufficient cable. A keel is often used as the lightning ground on sailboats, or a grounding plate could be attached for that purpose. Since you’re only building the DC system and not building the boat from the ground up I’d be inclined to leave whatever lightning ground the designer originally deemed sufficient alone, as lightning protection and dissipation can be a rabbit hole of uncertain guidance. If there is a lightning ground bus of some sort already in place connecting things like the mast and shrouds to the keel it is generally accepted to attach the DC ground bus to that lightning ground system at one single point. That helps ensure any metal components attached to the DC system are all kept at the same potential as everything else.
What a great explanation by @Davidasailor26 !
I'd have said don't even consider it as needed. I've had or sailed on many trailer sailors - none had a ground plate.
Even if you are putting in a SSB - there is a new method where the ground is a wire just lying in the bottom (it has a special name I don't recall). No need for holes with that either.
dj
I'd have said don't even consider it as needed. I've had or sailed on many trailer sailors - none had a ground plate.
Even if you are putting in a SSB - there is a new method where the ground is a wire just lying in the bottom (it has a special name I don't recall). No need for holes with that either.
dj
