In our years of cruising, I don’t think I have ever blogged about cooking gas (propane or butane) on our boat. Propane/butane is a popular topic on many other cruising blogs, mostly when they neglect to fill the bottles and go in search of a refill. Its a problem that happens so often that there is a often discussions about completely removing propane from the boat and going straight electric (induction cooktop). Its an idea that I think is silly, but I might be biased because of the situation on our boat and the locations we cruise.
On Party of Five we carry 2 standard 20lb north American style propane bottles. With our family of five, one of those bottles will last us about 40 days or normal use. We don’t baby our propane and cook just like we would if we lived on land. This includes baking things (chicken, casserole, pizza, ect) in our oven about 15 of those days. Down here in the eastern Caribbean propane is easily available on every big island except the 2 French islands (Guadeloupe and Martinique). France has a law against refilling propane bottles and instead uses an exchange system with butane. So with 80 days worth of propane aboard we an easily cover our usage with a little planning. Even then, we carry a small French bottle of butane and have the ability to switch our system if we are in a French island and run out of propane. All of our appliances are compatible with both propane and butane (pretty much all post 1980s equipment is). I say its a French bottle, but its actually CampingGaz brand and available in many countries around the world.
Now I can hear you saying “That is great in the Caribbean, but what if you go somewhere else?”. That is a great question! If we planned to do some more remote cruising, like the south Pacific then we would make some changes. Our propane locker is big enough to accommodate 2 standard 30lb bottles plus the small CampingGaz bottle (lasts about 12 days on our boat). So if we switched to 30lb propane tanks with the emergency CampingGaz we could go over 130 days without refilling. I don’t think there is any cruising ground that Party of Five would stay for over 4 months without heading to a major center that would have the capability to refill our bottles.
Finally, there is the point about safety. Having a flammable heavier than air gas aboard definitely has the potential for safety problems. That is a valid argument that must not be ignored. A properly built and maintained system is required to ensure that propane/butane can be used aboard safely. The system needs to comply with the ABYC rules (sealed locker, overboard drain, remote solenoid valve, ect). If such a system is in place then the safety risk is pretty much nonexistent. Again, this is where our boat may skew my opinion. The Island Spirits were built with an excellent propane system from the factory and I have never been concerned about using propane safely on our boat.
Based on all the above, I don’t think I could ever get behind ditching cooking gas on our boat and going completely electric. I really only see NOT having to refill tanks as the only benefit, with many downsides to electric cooking. Propane is just easy for us. Especially since we have been here long enough to know exactly where to get our propane refilled on each island. Hell, here in Grenada there is a guy that picks up at the dinghy dock and returns your filled bottle the same day. Now for those that have been bored by reading this post, you can stop here. If you aren’t bored yet and want to read more of my ramblings about electric cooking on a boat, then read on.
So I realize that all the above is touting the benefits of cooking gas on a boat. Maybe you are thinking that I haven’t given enough thought to switching to electric. While I will be the first one to admit that I can be a little hard headed, I have definitely tried to look at this objectively. Actually, we are not completely adverse to having some electric cooking. We have recently fallen in love with our immersion cooker that we run off our inverter. We have also talked about buying a single portable induction burner if we get back to Martinique to help stretch our propane use on sunny days. However the logistics of completely electric is just too much. Follow me down the rabbit hole.
First there is the actual power draw of the items. A 7 inch 3 burner induction hob requires about 1400 watts per burner on full heat. Its not uncommon on our boat to have 2 burners running at full for a short while during cooking (cooking pasta and sauce). That would require the ability to provide around 3000 watts to the hob (with a little overhead). While there are certainly inverters that can supply that kind of wattage, they are at the the limit of a 12V battery system. 3000 watts @ 13.5V is 222 amps (really 235 amps after adding the %6 loss of the inverter). While possible, there would be some constraints (inverter would need to be very close to battery bank, cable size would be huge, wear on the battery bank unless lithium). Of course that is only on the battery side. If we look at the high voltage side, things are also difficult. A standard 12 gauge wire is only capable of carrying 20A @ 120V. That is only 2400 watts and not enough for our above scenario. With a 120V system you would be required to run multiple breakers and wires to carry enough power, complicating things. Now remember, this is just to give you the ability to run 2 of the 3, 7 inch burners at full power. The 3rd burner would need to be turned off.
Now lets talk about the oven. Depending on the make and model of oven they can draw from 2000W – 5000W. If we fall somewhere in the middle and say the oven will take 3500 (a very common wattage for an oven). While there may be a company that makes a 12V inverter with that capacity, my quick Google search showed 3000W is max for a 12V inverter. So we either have to find an oven that draws less power on warm up (taking longer to warm up), or switch the boat to 24V. Not to mention that while the oven is working, you could not have ANY burners on the induction hob on as the inverter would be maxed out. If you had a 24V boat, then you can get a 5000W inverter that would allow the extra room to use both.
Ok, so we have shown that although its not easy, its definitely possible to run the appliances (much easier on a 24V boat). We haven’t talked about the actual energy it would take to achieve it though. I’m going to do all my math in watt/hours (Wh) so that its the same no matter if the boat was 12 or 24V. Of course every meal would be different, but I’m going to try and ballpark it. Its very rare we make a meal that doesn’t require 2 burners (or 1 burner and the oven). However, depending on the dish depends on how much heat we actually require. Based on some Googling and thinking, I think a pretty good AVERAGE number is 1500 Watts of power for about 20 minutes to cook a meal for a family (shooting for the low side). At points in the meal you will draw more, and at points less, but 1500 watts is a good average guess. So 1500 * 0.333 (20min) = 499.95 watt-hours(Wh). Now we cook 3 meals a day on our boat, but some probably use less power (lunch is sometimes ramen which just requires boiling enough water for 5 bowls). So I’m going say that 1 meal uses 400Wh, one meal uses 450Wh and 1 meal uses the full 500Wh to be fair. That is 1350Wh for just cooking each day (1.35 kW⋅h).
I don’t know about you…. but I think its crazy to trade refilling my propane tanks every 40 days with the stress of if I have enough power to make my family dinner EVERY SINGLE DAY. Sure, I could just turn on the generator when we don’t have enough power, but isn’t that missing the point. Now, I’m just trading the burning of a clean fuel for another more dirty fuel that requires a high maintenance device to actually burn it, not to mention the efficiency losses. I know there are boats that have gone completely electric, however I’m guessing they may be not telling the whole truth when talking about it. Of course, maybe I’m being a hard headed realist but, we will stick with propane, proper planning and some supplemental electric cooking on our boat!