A thermal cooker is one of the most useful things I’ve added to my galley in 17 years of living aboard. Start dinner at 9 AM. Plop it in the thermal cooker. Open it up at dinner time to a hot, ready meal. No babysitting a lit stove. No heat building up below. No worrying about it while you’re snorkeling, exploring ashore, or just enjoying happy hour.
If you’ve never heard of a thermal cooker, think of it as a non-electric crock pot. It’s a large, insulated container with one or two removable pans. You bring your food to a full boil on the stove, slide the pans into the thermal cooker, close the lid, and walk away for up to 8 hours. The retained heat does the rest.
[IMAGE: Thermal.jpg — Thermal cooker with two stainless inner pans on a boat galley counter | ALT: Thermal cooker with two stainless inner pans ready for boat galley cooking]
Why a Thermal Cooker Is Such a Big Deal on a Boat
Late afternoon is the worst time to cook on a boat. You’ve been busy all day. You want to enjoy a sundowner with your crew or friends on another boat. You don’t want to be stuck below at the stove while everyone else is on the dock.
Before I got my thermal cooker, I’d tell myself I’d start dinner earlier. And I would, for a few days. Then we’d get absorbed in a project, happy hour would creep up, and dinner wouldn’t happen until 8 PM. That wasn’t great for Dave’s acid reflux. And it just wasn’t how I wanted to end the day.
The thermal cooker solved it. I start dinner when it’s convenient for me, usually mid-morning or right after lunch. Then I forget about it. The food cooks itself while we do whatever we want with the afternoon.
Beyond that, the thermal cooker delivers some real practical advantages for life aboard:
- Saves propane. You heat the food once, then the thermal cooker takes over. No simmering for hours on the stove. See my full article on conserving propane on a boat for more ways to stretch your fuel.
- Keeps heat and humidity out of the boat. The lid seals tightly, so steam stays in the pot, not in the cabin.
- You can leave the boat while it cooks. Snorkel, hike, run errands, go to a potluck. Dinner is waiting when you get back.
- Great for underway passages. Start dinner before you leave the dock, put the cooker in the sink so it can’t slide, and open it up to a ready meal hours later. On longer passages, it means much less time with a pan on the stove in a moving boat. For more on planning food for passages, see planning the best passage meals.
- Perfect for potlucks. The outside of the cooker stays cool, and the locking handle makes it easy to carry. You can use it for foods you’ve cooked in the thermal cooker, or use the pans from it to bake something in the oven and then put the hot pan in the thermal cooker to take to the potluck. You can also use it in reverse: put ice in the bottom pan and cold food in the top pan to transport salads or cold dishes.
- Food doesn’t overcook. Unlike a crock pot, the thermal cooker slowly loses heat, so there’s no risk of mushy overcooked results even if dinner runs late.
How a Thermal Cooker Works
The principle is simple: food that is thoroughly hot, surrounded by hot liquid, continues to cook. No electricity needed.
The secrets to success:
- The food must be hot all the way through before it goes in. Frozen meat or vegetables will drop the temperature too fast and the cooking will stall.
- You need enough liquid in the pan. The liquid is what holds and transfers the heat.
- Move quickly from the stove to the cooker. Every second the lid is off, heat escapes.
- The fuller the cooker, the better it works. Less air space means less heat loss.
Step-by-Step: How I Use It
Here’s exactly what the process looks like. I’ll walk through the pulled beef and beans I made the first time I used mine.
I’m making pulled beef in the big pan and dried white beans for the next day in the small pan. Bring both to a full rolling boil. I like to boil for about 10 minutes so the food itself is hot through, not just the liquid.
There’s only one lid included with the set, but an 8-inch round silicone trivet fits the small pan perfectly (buy one here (Amazon)).
Now work quickly. Take the lids off both pans and nest the small pan inside the big one.
Put the stainless lid over both pans. Keep the burner on until this step is done.
Slip the pans into the insulated outer container.
Latch the lid and put the cooker somewhere it won’t be knocked over. I usually put it in the sink or wedge it on the floor. Now walk away for 4 to 8 hours.
The results speak for themselves:
That’s white chili made with the beans from the day before. I also had red beans going for Red Beans and Rice the following night.
Starting Dinner When It Suits You
One of the best things I’ve figured out: the longer you cook on the stove first, the less time the food needs in the thermal cooker. So if you start late, just boil it a bit longer, maybe 20 to 30 minutes on the stove, before sliding it in. The thermal cooker adapts to your schedule, not the other way around.
If things really get away from you, you can cook dinner completely on the stove in the late afternoon, then transfer it to the thermal cooker to stay hot while you have a sundowner. It’s not just a cooker. It’s a heated holding vessel.
The prep work is the same as cooking any dish. But the freedom of not having to babysit a lit stove, and cooking when it suits you rather than when dinner demands it, makes a real difference in how you feel at the end of the day.
What Cooks Well in a Thermal Cooker
Anything that cooks in liquid, or absorbs liquid while cooking, is a candidate. Here’s what I’ve had great results with:
Main dishes (in the large pan):
- Chili (regular and white)
- Pot roast
- Soups and stews
- Red Beans and Rice
- Jambalaya
- Gumbo
- Mexican-style taco meat (pulled beef, pork, or chicken)
- Spanish Rice
- Unstuffed Cabbage
- Spaghetti Sauce
- Swiss Steak
- Pork chops (cook in marinating liquid until tender, finish briefly in oven with BBQ sauce)
- Curries
- Corned Beef
- Ham and Beans
- Sloppy Joes
Sides and extras (in the small top pan):
- Rice
- Dried beans
- Boiled potatoes and sweet potatoes
- Hard-cooked eggs (bring water to a boil, add eggs when you transfer the pan)
- Spaghetti squash (cooked in boiling water)
I’ve only scratched the surface. Basically, if it would work in a slow cooker and has plenty of liquid, it will work in a thermal cooker.
More Thermal Cooking Techniques
For single ingredients like rice and dried beans, a regular Thermos bottle works beautifully and takes up much less space. I wrote a full guide to Thermos cooking if you want to start there.
For deeper reading on thermal cooker technique, I found a Kindle cookbook useful more for the techniques than the exact recipes: Let’s Make Sense of Thermal Cooking (Amazon). One note: the author approaches thermal cooking from a prepping perspective and discusses that background in the early chapters. The actual cooking techniques and methods start in Chapter 5 and are excellent.
Three Thermal Cookers Worth Knowing About
A lot of brands make thermal cookers. Here are the three I know from personal experience or trusted reader reviews.
Saratoga Jack’s
This is what I bought, and I use it 3 or 4 times a week. It’s foam insulated rather than vacuum insulated, which is not quite as efficient, but it works very well in warm climates if you fill it full. What I like most: it has two pans. The small pan nests into the top of the large one, so I can cook two things at once, or just fill the top with boiling water to maintain more heat mass when I’m only making a small batch.
Available in 5.5-liter (my size) and 7-liter versions. Both have a heavy bottom on the large pan, which is great for browning meat and helps retain heat. The 7-liter deluxe version also has a heavy bottom on the small pan.
You can buy it directly from the Saratoga Jack’s website.
Thermos
Vacuum insulated, which is a step up from foam in terms of heat retention. Thermos now has a two-container version in a 6-liter size. Read Cathy Draaper’s full review for a cruiser’s perspective. Shipping can be expensive, depending on where you are.
Thermos thermal cookers on Amazon (Amazon)
Wonderbag
The Wonderbag is an insulated bag rather than a rigid container. You use your own pots and tuck them inside. It works well and costs less than a dedicated thermal cooker. The tradeoff is size: it’s big, and even squished down it takes real storage space. I couldn’t find room for it aboard. Read the full Wonderbag review for more detail. For every Wonderbag sold in the US, one is donated to a family in Africa.
What to Look for in Any Thermal Cooker
If you’re considering a brand not listed above, here’s what matters:
- Size. Too large and you’ll have too much air space inside, which hurts cooking efficiency. Match the cooker to how much food you typically make.
- Insulation. Vacuum insulation is best. Foam is second. It still works in warm climates with a full pot.
- Number of pans. Two is better. It gives you the flexibility to cook a main dish and a side, or to fill the second pan with boiling water when you’re only making a small batch.
- Pan bottoms. Thicker is better. Check whether the inner pan works with an induction burner if that’s what you have.
- Overall dimensions. Think about where it will live on the boat, where it will sit when in use, and whether it fits in the sink when you’re underway.
Want to Go Further?
If you’re cooking on a boat, in an RV, or anywhere with limited space, power, or refrigeration, The Boat Galley Cookbook has 800+ boat-friendly recipes built for exactly these conditions. Techniques for cooking underway, baking without an oven, ingredient substitutions, and quick ideas for days when you’re totally uninspired.
Carolyn Shearlock has lived aboard full-time for 17 years, splitting her time between a Tayana 37 monohull and a Gemini 105 catamaran. She’s cruised over 14,000 miles, from Pacific Mexico and Central America to Florida and the Bahamas, gaining firsthand experience with the joys and challenges of life on the water.
Through The Boat Galley, Carolyn has helped thousands of people explore, prepare for, and enjoy life afloat. She shares her expertise as an instructor at Cruisers University, in leading boating publications, and through her bestselling book, The Boat Galley Cookbook. She is passionate about helping others embark on their liveaboard journey—making life on the water simpler, safer, and more enjoyable.
Jim Allen says
the cookbook is free for Kindles
The Boat Galley says
Yep, still free today. Don’t know how long it will be . . .
David says
Not free anymore: $20.65 on Amazon.com
Carolyn Shearlock says
The Kindle edition was free for two days — Sunday and Monday. I was working on this post when I saw it was free and posted on The Boat Galley’s Facebook page which also got Tweeted. I posted again on Monday that it was free — sorry you missed those announcements.
David Webster says
I’ve had a Mr Ds thermal cooker (aka Thermos Shuttle Chef) for years. It’s a vacuum type and has two inner pots, two lids and you can buy pudding, cake and bread tins to use in it as well. Worth it’s weight in gold.
The Boat Galley says
Those sound great! I haven’t seen that in the Shuttle Chefs currently offered in the US — apparently the Mr. D’s are sold only in the UK.
David Webster says
David imports them into the UK. He’s at a lot of the boat shows – and caravan shows for that matter. Here’s mine – less the accessories. Always in the kitchen ready. Although it’s in its carry bag at the moment…
Paula Turman says
May I ask what this cooker costs?
Thank you …
Sarah Garth says
I also have same Mr D’s Friends of Thermal Cooking cooker as David, it’s brilliant!
Pamela says
Curious about one thing–I found I didn’t use my crockpot on land as much as I thought I would because it made food mushy. I didn’t like the texture of chili in the crock pot as much as when I tended it on the stove.
Is this an issue with the thermal cooker? Or did you find the texture of beans and stews to be as good in the cooker as if you tended it on the stove?
Carolyn Shearlock says
I find the thermal cooker doesn’t tend to overcook things the way a crockpot can. I think that’s because a crockpot keeps adding heat over time, while the thermal cooker cools off very slowly. The beans and stews are great. About the only difference I notice is that with some recipes, I have to add more water than I would on the stove top (or less cooks away) and thus the “gravy” is a little thinner than if cooked on the stove. It doesn’t really bother me and with some thing (say chili, spaghetti sauce or Swiss steak) I use V-8 or tomato juice to add liquid instead of water.
Pam Dean says
I’ve been looking at these for months and you’ve convinced me to bite the bullet, especially with the free cookbook. Also, like the idea of reducing our footprint on the planet.
The Boat Galley says
Sounds like me . . . I looked for over a year before I bought.
pam says
Thank you for this wonderful article. I will read more about this but can you tell me how this would compare with using a pressure cooker and holding food under pressure to let it ‘slow’ cook? BTW the cookbook is also free to see in the Amazon Cloud reader.
Carolyn Shearlock says
I’ve never tried doing that in a pressure cooker myself, so I can’t make a good comparison. I think that the pressure cooker wouldn’t work as well as it cools down much faster — it depends on the food volume, of course, but usually the pressure cooker is pretty close to room temp after an hour. Pressure cooker starts out at a higher temp due to the pressure, but the pressure doesn’t do much to help it retain heat after it is removed from the stove.
Joan says
It is easy to make an insulated container for a crock pot. My crockpot is an older one and the ceramic pot comes out for cleaning. You could just take it out of the heating ‘container’ and put it into the insulated one. I use it to make yoghurt and at only 44 deg C going in it is still warm 12 hours later. You could do that with any pot of course but they are often different sizes and it really does need to fit well in there.
Sarah, s/v Mirador says
I just bought one of these! Haven’t tried it out yet, but love the idea. Thanks for the comment about putting boiling water in the top pot if you don’t have enough liquid, and for the link to the cookbook.
Pam Dean says
Hi again, I didn’t get the recipes in the free book although they are listed in the content page.
Carolyn Shearlock says
I think you may have downloaded the free sample or “first pages” — you have to “buy” the book for $0.00 to get the whole book.
Lyndy Atkinson says
Love mine too!
The Boat Galley says
They’re pretty similar. I just don’t have the space for the Wonderbag so it’s worth the extra expense of the other one. I wouldn’t think you’d want both unless there’s a large crew.
The Boat Galley says
For Pam Dean – make sure you didn’t download the “free sample” or first pages. You need to “buy” the book for $0.00 and then you’ll get the whole thing. If that’s what you did and you’re having problems, contact Amazon — I don’t have any connection to the book.
Ralph says
Cheapie 95% solution: At Walmart I bought a 2L Aladdin VACUUM bottle for _?_ . I don’t see it on Walmart right now, but they do show a 50oz Thermos for $41.
These are intended for coffee, but work fine for beans, smaller foods, Mine has a 2.5″ opening, which is pretty big. And they’re VACUUM, not foam, so better insulation.
LaMarr Harding says
Kuhn Rikon made an insulated pressure cooker some years back. Vacuum walls, two lids, and a sealed metal bottom. I don’t use it. Also have the Thermos 7 litre, from Japan, and the air-core with the insulated sides, two lids and thermometer.
If it doesn’t microwave, I don’t fix it.
Carolyn Shearlock says
Yes, we are a diverse group — I don’t have a microwave!
Deviant Dream says
Great article! My main reason for wanting a “crock pot” replacement for the boat is to make bone broth. Would this make bone broth?
Carolyn Shearlock says
I think you’re talking about boiling down bones from beef, chicken or turkey to make stock — right? If so, yes it works fine. You may want to heat it back up to a good rolling boil for 5 or 6 hours and then let it sit a second time, but I’ve done it that way with chicken bones and some veggies and it did wonderfully!
StarWish246 says
When my parents traveled in their RV, they would set up and start their slow cooker, and then go swimming at the lake or pool for hours. I was so worried that they could have a fire while they were away, and the slow cooker was unattended.
So, I bought them a Thermal Cooker. And, at least, I felt less worried about them.
P. S. The thermal cooker works great.
Margaret Morris says
Carolyn, I received a thermal cooker several years ago as a gift. I didn’t realize that it was actually a cooker and not just a thermal container for transporting hot food. This year we are planning an extended trip up the inside passage to Alaska. I got the thermal cooker out and I’m practicing. Today I used it as a dough proofer for my homemade French bread. I heated the outer container with hot water, oiled the inner pan and added my dough. Closed the container and let the dough rise. It kept the dough warm, secure and draft free. The thermal cooker has earned a place in my very small galley.
Carolyn Shearlock says
Great idea! You’re going to love it. And you’re going to love the Inside Passage. We did a three week trip (charter on a Morgan OutIsland 41 with a captain who became a great friend and convinced us we could cruise) in that area in the late 90’s and loved it! Breathtaking scenery and wildlife!
Margaret Morris says
Thanks Carolyn, In 2008 we took our CDory Tomcat 255 up the inside passage. It was an amazing voyage. We have been improving our boat, adding better heating, insulation and more batteries. We now have a 2000w inverter so we can power an electric pressure cooker or…our coffee maker or….our toaster oven. It is camping on the water but we love it. We always have incredible meals using a butane burner and the toaster oven. Thanks for all the great info!
Bill Coutts says
In Australia the equivalent Thermal cooker I use and have for years is the Dreampot.
It is fantastic. I even managed to make a cradle to hold it steady in one of our galley storage cupboards. It is great to prepare before you know you have 4 – 10 hours of fairly bouncy sailing to get to one of our islands in South Australia. On arrival its great to anchor and know that dinner awaits. There are other brands and they are not cheap but worth every penny.
Jeff Grant says
Susan Opladen
Susan Opladen says
I like it!
Deb Snella Temperly says
Thanks for the very clear introduction and explanation to this type of cooking.
Chris Hofmann says
Wonderbag
Deborah Woods says
Mr. D’s thermal cooker good piece of kit!
Michèle Boulay says
I have the Nissan brand & it is great. I’ve made the best pea soup, meatballs & sauce and even the Italian favourite for Sunday dinner, Braciole di Manzo (braised beef rolls).
Pamela Blanchard says
Carolyn, is your food storage book electronic only? Or can i get a hard copy from you?
The Boat Galley says
It is PDF only right now (can be read on just about any device) — you can, of course, print out a copy for yourself.
Matt Garand says
Skye this could be handy for the mooring!
Jonas Vignal-Olsen says
Det er vel egentlig bare en thermokasse, der bruger restvarmen. Ligesom når vi laver blødkogte æg
John Norman says
Had two for quite some time now, they are awsome
Darlene Luxton says
I have one too! Large to store but very convenient
Judith Nelson Cruzan says
That is a really nice set up. I’d seen some that looked like a quilt but didn’t feel like it could really hold the heat.
The Boat Galley says
Sounds like you’re talking about the Wonderbag. I looked at them but they are a lot bigger and I find this really easy to move around the boat, etc. Bottom line: I love it and wish I’d had it 15 years ago!!
Judith Nelson Cruzan says
The Boat Galley you know something is good when you feel that way about it.
Marta Crichlow says
Love mine. Now taking on a road trip!
Joy Harrison Canova says
Love mine. On a passage right now, and dinner is waiting.
Sharon Brown says
love mine. and it fits nicely in the small sink so never worry about it falling over etc. used it every day crossing the Atlantic
Ward Schmidt says
I have one at home and will soon purchase an offshore boat which I certainly will stock with another. We live in Japan and use it for cooking rice nearly every day as well as for beans. One thing I really appreciate is that one needs much less heat when cooking on hot summer days.
Katy Barth says
I have the Thermos cooker. I like it for all the reasons you mentioned in your article. But, I do have problems with volume. Has anybody got a suggestion for how to fill the cooker without adding more food or liquid? Sometimes I don’t want to add liquid because it messes with the recipe and sometimes I don’t want so much food (small fridge). I’ve been thinking of a bag of marbles or a jar of water with a lid. Has anyone done any experimenting?
Carolyn Shearlock says
That’s one reason that I like mine with two pans — I can fill one with just hot water (which I later use for dishes). I think your ideas would work but have not actually tried them.
Rebecca Nichols says
My husband and I are currently living on a sailboat. I bought the Thermos Nisson 4.5 liter a few years ago and found these same dilemmas – how do you get enough liquid in the pot to hold the heat without watering down the recipe? How do you fill it full enough to retain the heat without making enough food for an army?
If I had known about the Saratoga Jack version, I probably would have bought that, But then you lose the great vacuum insulation on the Nissan. Anyway, too late, I had already bought one and used it so couldn’t return it. SO – I found a site in Australia.
They are called Shuttle Chefs there, but the inner pans are the same as the Thermos Nissan. Don’t be too horrified by the price until you have the currency translated to your own. Then you can be horrified because it’s still expensive, but I found it to be worth it. I bought this “Bain Marie” pan two years ago. They do ship to the US, but it took a long time to get here, so be patient.
Now I have the great insulation (only need to boil for 5 minutes for most things before putting in the outer container), and the versatility of having two inner pans. I either use the top pot for rice, or I just put boiling water in there and then you can use less liquid in the bottom. Now I don’t get stuck with leftovers that won’t keep in a boat icebox.
I felt a bit ridiculous and embarrassed that I ended up spending so much $ on this, but now I’m so glad that I did. As my grandmother used to say, “Quality is remembered long after price is forgotten.”
Jack and Amy says
I loved reading this post…
Hi this is Jack from Saratoga Jacks!
Boat owners and also others who are energy conscience but love to live on the go too, like RV owners, tell us all the time why they love us, but you are one of the first blog posts we have ever seen online from someome who took the time to write about it. So thank you!
PS.
I just thought I would share why we use our propritary insulation versus a gas vaccuum sealed variety.
We actually tested several during development. Both kinds.
We saw that the vaccuum units failed more easily and frequently.
One good drop…micro movement
.and the seal failed and the entire unit became worthless.
Our cookers are subjected by our active users to camping, hiking, boating, kids soccer games, 4 wheeling, etc…and families just wear and tear on them. Frequently they get dented…and as long as they can still be shut…they continue to work. That was the difference.
Ours last 8 hours.
The vaccum seal units could have extened it to 10 hours.
Our customers after using both in trials…gave us feed back.
What we found in testing is rarely people went longer than 8 hours without meal, and that our customers wanted a guarenteed 8 hours… than a maybe 10 hours…but if dropped once could potentially never be used again.
The vaccuum models are less likely to be abused if only being used on a kitchen counter and never… being taken on road trips or subjected to being used in portable motion.
So although we had the option to provide a vaccuum unit… and seriously considered it…
We chose to go with a more rugged model…our customers are usually more adventurous people.
Hope that helps!
Lesa says
Jack, thanks for the input. I’ve been considering a thermal pot for a couple years. Your explanation is very helpful
Leland Parker says
Hello Jack and Amy. This is a revelation to me since I didn’t realize that anyone made an oversized thermos-type vessel for cooking. I’ve played with a thermal flask as sort of engineering experiment but the kitchen-sized version sounds like a must-have unit, especially where energy use and thermal leakage into a confined space are major factors.
I agree with your design decision to produce a more rugged unit and am reconsidering which model is best for me. To anyone who really wants that extra heat retention, you can always apply extra insulation to the thermal cooker by wrapping a dry towel or blanket around it. I melted the control knob a little on my crock pot this way when I wrapped a towel around it to get a higher temperature.
And thank you, Carolyn, for this fabulously informative web site and your books and courses. The value of good food on an adventure can’t be overstated. A happy crew is a good crew and a well-fed crew is a happy crew!
-Leland
Lulu Witt says
I loved the idea of your Thermal Cooker but your links no longer work and there do not seem to be any sold on Amazon at all anymore. Any ideas where you can still get them?
Carolyn Shearlock says
Hi Lulu!
I just checked and all the links to thermal cookers are working for Amazon in the US and units are in stock. They are also available on the manufacturer’s site: http://www.saratogajacks.com/
I’m not sure why you had problems with the links, but hope this helps!
Lulu says
Thanks for that. I’m guessing it just naturally directed me to the European site. Will try again. Cheers.
Carmie says
Hello
I just ordered the Saratoga Jacks 5.5 thermal cooker to use on our boat and was wondering if the pots can also be used for cooking when not using the thermal system – can I get rid of my two similar sized pots? I’m excited to start using the thermal cooker! Thanks for your great post about them!
Carolyn Shearlock says
Sure, no problem using them for other things.