Refrigerator question

Check out this link for some cooler reviews:  https://huntingwaterfalls.com/best-coolers-ice-retention/

We have a Lifetime cooler that we purchased on our last trip out west when our refrigerator's electronics died and we had no refrigeration. I agree with the review on the site that the Lifetime cooler, while not the best in ice retention, is the best value.

The EcoFlow power banks don't require solar at all.  They can easily be charged by AC when it's available and discharged over time.  One or two power banks might not be enough for a multi-day ferry ride, I don't know; you'd have to do the math.  I don't recommend this, or not, I'm just saying it's an option.  Maybe not so great if its only purpose would be to keep food cold for a while.

Of course it's inefficient, but I don't think one cares about that under the circumstances.  There is no efficient way to generate or store power when essentially boondocking.  It's all relative and almost all that matters is what works for you.  As noted, a power bank works in other situations besides ferry rides too.

Just an idea, but it might be worth checking with the ferry operators to see if shore power might be available for an extra fee.  I've never heard of a ferry offering it, but the bigger boats do have it on board.  It would probably involve loading early to get you near an outlet.  I can think of various reasons they wouldn't offer it if they could, not the least of which would be the liability of a hot power line running across a metal deck.  Just the trip hazard would probably be a deal breaker.

I have one of the EcoFlow power banks because our home is subject frequent power outages.  My wife can plug in her oxygen concentrator and press 2 buttons and be good for 20 hours.  Plenty of time for me to get home from work and crank up the generator outside. No solar.  Very inefficient.  Easy and it works very well.

I'm also thinking about getting a telescope that requires power.  These power banks are small, very portable, and silent, so I'd likely use it for that too.  Efficiency isn't even part of the equation.

TT

The OP has a propane/AC only fridge.  I doubt he'd be able to use a generator on a ferry.  If this is indeed a one-off or rare situation a cooler and ice or dry ice is probably best.  I really like dry ice.

The other thing that might be better than all of this is to have the fridge empty for the start of the ride and stock up on perishables when you disembark.  Maybe not a perfect idea either, but being able to go with a smaller Yeti could save hundreds of dollars.

TT

You can also use regular ice.  The best is to use paper milk cartons with the little lid on top.  Fill them with water and freeze them, then put them in the fridge to keep it cold.  If you have a good quality ice chest, you can freeze the cartons at home and put them in the chest.  We have a Lifetime chest and had ice last over a week, with not that much melting.  Just try to keep it closed as much as you can and before you reach the point at which you can't run the refrigerator, cycle the cartons through the freezer to refreeze them to have as many frozen solid as possible.  Avoid opening the refrigerator during the time you can't run it, except to cycle the cartons through from the ice chest.  This method can give you two or 3 days of adequate cold, unless the weather or the place where the trailer is parked in the ferry is hot.  I've never taken a ferry from Seattle to Alaska, but I have sailed off the San Francisco coast and can say with some confidence that it's not likely you'll have hot weather along the north east Pacific coast.  Best of luck in your travels.