AC Into Boat - Ground Safety Question

Status
Not open for further replies.
Jun 21, 2007
2,117
Hunter Cherubini 36_80-82 Sausalito / San Francisco Bay
I have my doubts that the following is a good idea, so I'll put it out for opinions from those that are a lot more knowledgeable about marine electrical topics than I am. I really do not need AC into my boat except for instances of running power tools. Batteries are maintained by the engine alternator when motoring in/out and a by a 15W solar panel. In order to extend zinc life, and for peace-of-mind when away from the boat (the AC wiring and grounding has been around for a while -- a thorough inspection and upgrade as necessary is on the to-do list), I'm not connected to shore power when its not needed. Recently I washed down all the accommodation area, refinished all the interior the wood trim/paneling/floor, washed my interior upholstery, and soaked the foam cushions in bleach. To slow down the formation of new mold and mildew, I'm thinking that I will want to have a small marine space heater in the boat next winter. So here is the question: Can I by-pass the boat's AC system and power the space heater directly from the shore AC? An adapter would be necessary of course and I would install a GFI receptacle in-line. I think that the weak link in the idea is that if someone was to make contact with the live current, then a proper ground to the boat might be important. The ground from the shore receptacle might not do any good? Look forward to comments/opinions. regards,
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
It seems like you are planning to go to a lot of

effort to find a way around good ventilation. 2 air intakes and 2 exhaust fans powered by a solar panel have kept our 30 foot boat dry and fresh for 10 years, summer and winter, both in the water and on the hard.
 

Manny

.
Oct 5, 2006
983
Hunter 82? 37 Cutter Wherever the wind takes me
Solar fans and vents

Ross is right, ventilation is the key. I have a day/night solar fan and two passive vents. I couldn't believe the difference after installing the fan! Boat stays drier and smells better too. As for you original grounding question, hopefully someone here with electrical experience can answer that for you. I think the real question is if it safe to leave an electric space heater unattended???? Manny
 
Mar 28, 2007
637
Oday 23 Anna Maria Isl.
Ross and Manny- Are your fans wired direct to a solar

panel or do they have a small dedicated battery inbetween? Are fans on intake or exhaust?
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Mine only run when the sun shines.

On clear days they start within a few minutes of sunrise and run until sunset. The panel is a little 5 watt unit about a foot square.
 
Feb 26, 2004
23,047
Catalina 34 224 Maple Bay, BC, Canada
If you really want to have a heater during the winter

and understand all the risks that it entails, AND you want to bypass the AC power that is installed on your boat, you do NOT need a receptacle for the heater. Just run a long extension cord from the shorepower on the dock and plug the heater into the other end of that cord. It avoids potential for corrosion since you're not using your boat AC. The ventilation ideas sound way better and safer. BTW, good work on all that cleaning, but I'd bet that by the time next winter comes around everything will be pretty dry. :)
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
my experience has been that with the fans running only during dry sunny

days and shutting down at night that I have filled the boat with warm dry air and when the relative humidity rises after dark that air is left outside. my boat stays dry enough that if there is a little water in the bilge within a week it has dried up. My bilge is almost always dry. The only reason I would keep a heater on board would be if I didn't winterize and planned to use it on warm day during the winter months.
 

Manny

.
Oct 5, 2006
983
Hunter 82? 37 Cutter Wherever the wind takes me
Mine is a Nicro solar day/night vent

It runs off it's little solar panel during the day ( which also charges its battery) and it runs off its rechargeable battery at night. It's the closest thing to perpetual motion I've ever seen. Manny Edited to add: I have mine set to exhaust, but it came with two blades so you could set it to intake
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
AC extension cords

You don't get too excited when you run an extension cord out the window to power the hedge trimmer do you? I don't recommend taking that analogy to working under water with power tools but just running an appliance will be fine as long as the dock side has proper grounding. Leaving electrical appliances running unattended is probably not a real hot idea and lots of marinas don't allow it. Ventilation is the proper way to solve your problem as others have noted.
 
Jun 21, 2007
2,117
Hunter Cherubini 36_80-82 Sausalito / San Francisco Bay
Thanks All - I'l Give More Attention to the Ventilation Option

Great responses and I will give more attention to the solar ventillation option. I see from various internet sites that non solar 12V vents are much more reasonably priced than the solar ones. Given that I already have a 15 watt panel to keep the house/starter batteries charged, maybe that's the way to go? Mr. Roosa, your comment that its not the best idea to leave appliances on unattended has good merit. When we leave home on vacation, I make sure that virtually everything is turned off. But at my marina, I've noticed the electric meter discs rotating at "sprint speed" every time a pass by for many sailboats ... boats whose owners rarely (if ever) visit. Batteries don't normally need constant full blast charging. What do you think is gulping down so much electricity? The meters for these boats are rotating faster than at my house.
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
Rardi, I use 12 volt computer fans

salvaged from junk towers.
 
May 24, 2004
7,173
CC 30 South Florida
The same as my home I rely on breakers to do their

job in case of a short in a running appliance. I run the refrigerator and battery charger. I switch off the 12V side as it is not necessary when boat is unattended and the bilge pumps are hardwired and fused. Been doing it for decades and do not consider it a bad idea. It is nice to get to the boat and have fresh batteries plus avoiding having to pre-cool the refrigerator and having to carry supplies back and forth. I avoid the use of space heaters on land as well as water. I mantain proper insurance coverage and sleep quite well.
 
Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
They have heaters going

and they are putting your boat in danger when they do it!!! If a storm comes up and knocks over their heater and it sets their boat on fire it could set the whole dock on fire. A heater in an unoccupied house has a much greater probability of going undisturbed than the same space heater on a boat. If you are going to go that route then get something that has a tip switch and no open heating elements......
 

Ross

.
Jun 15, 2004
14,693
Islander/Wayfairer 30 sail number 25 Perryville,Md.
An unattended heater on a boat should also have

a cage around it to keep combustables from falling onto it.
 
Dec 27, 2005
500
Hunter 36 Chicago
Just to add a comment on the GFI

There's some misconception on how GFI breakers work. I attended an electrical safety seminar at work that did a good job of explaning how a GFI actually works. A GFI measures the differential current between the 'hot' wire and neutral return. Any slight difference in the current between the two current carrying conductors will cause the breaker to trip. So even if you have a boat that isn't well grounded, you will still cause the GFI to trip if it senses that there is a 'leakage' of current somewhere - say you touch a piece of metal that has somehow gotten shorted to the shore power AC hot wire on your boat, the GFI will still sense the diffence in current since some of the AC current will flow through your body to ground, even if it is a bad or high resistance ground. Same goes if somehow you break the neutral return on your boat and grab both ends of the wire.. part of the current will go to ground through you and trip the GFI. (Reason I bring this up is because I saw a somewhat experienced electrician grab both ends of a disconnected neutral return because he thought the neutral was 'grounded' and he wouldn't get shocked. He was lucky he was wearing insulted boots and standing on dry ground).
 
Status
Not open for further replies.