Air Conditioning at Anchor?

One of the biggest questions we received before we sailed away in 2016 was: But what do you do about ac at anchor?!?

I personally thought this was a weird primary concern. I mean, what about: Where are you going? Or: Do you even know how to sail!?! (The Bahamas, and no)

It turns out people apparently trusted us to both go somewhere fun and to stay alive – they were just worried about our creature comforts.

Both the monohull and the catamaran came with Cruisair brand air conditioners (pretty much industry standard) installed from the factory. But both boats are also small enough that they did not come with built in generators to actually run those ACs. This is perfectly normal – we don’t have a clue where you would install a built-in generator in a small catamaran or monohull…

If you’re living in a marina and “plugged in” you can run your air cons and various other 110v gadgets willy nilly. But air conditioning at anchor or at sea? Well, there we become reliant on our bank of lifepo batteries and solar (for charging those batteries.)

Current Situation (bah dum dum)

On Luna Sea², we currently have a 900ah battery bank and 1440 watts of solar. We also have dc chargers on the engines, so that when we are using the engines to move the boat (vs pure sailing) we are also charging the lithium bank.

As magical as our Battle Born batteries (affiliate link)and LG solar panels are, they simply cannot power the factory installed 110v ac’s for a significant amount of time.

Mark played around with the system and found that yes, we can actually start one of the 110v ac’s – but at max could run it for a few hours before needing to shut it down and conserve the rest of our power for silly things like refrigeration and making water… And that’s exactly how some cruisers use their ac at anchor: they run it in the evening for a few hours and cool down the boat for a good night’s sleep.

Game Changer: Mabru 12v Air Conditioner

Enter the Mabru 12v ac! << Here’s a link to the distributor we used. Everyone is out of stock at the time I’m writing this, but I’m sure more will eventually come in. We purchased the 12,000 btu unit to cool one side of our boat. It happens to make the entire boat cooler and dryer. (That’s not an affiliate link: we just really love their product. But STT Marine Services does now install these units, hint hint.)

I will be the first to admit that I was a bit peeved when Mark decided this past season to bite the bullet and drop a large chunk of change on this ac unit. I mean, seriously? We’ve been out and acclimated since 2016. When we go to the States (or anywhere that has ac) we are cold and dry and uncomfortable after more than an hour of the magically cold air.

But nope. I was wrong. 100% wrong-o. I LOVE the nights that we have plenty of power to run the ac at anchor. Particularly this September, as we were in the Grenadines (and briefly Grenada) where the temperatures are high and the winds are virtually non-existent.

All of that Caribbean sun meant we were nicely topped up during the day – and as often as possible, we cranked that bad boy up and enjoyed a solid night’s sleep -regardless of the lack of wind in the bays.

How Much is Enough?

So how much power is enough? That’s a good question. And until we started actually using the Mabru, we couldn’t really answer that one.

To sort out what we consider to be enough power in our house bank at the end of the day, we had to run the ac at anchor overnight – and see just how much juice it draws. We waited until we had a particularly full battery bank and then gave it a go!

It turns out that we can run the ac (as well as the two freezers, 2 fridges, fans in our cabin, etc) for about a 30% reduction of the battery bank. (approximately 270ah) So for example, if we go to bed with the battery bank at a 50% charge, we wake up with 20% remaining in the morning. And for the record, the draw is really high at first (30 amps DC), but it tapers off as the boat cools and the unit switches to maintaining the temp vs lowering it.

This is one of the instances having lithium on a boat comes in handy. We can run that bank down without the worries associated with damaging lead acid and AGM set ups. But just for the record, we typically don’t run the ac at anchor unless we have around an 80% charge before bed. That way we wake up in the 50% range, and can run the watermaker, electric kettle, etc without any thought to the house bank.

Was It Worth It?

YES! 100% yes. We love the Mabru 12v system for running the ac at anchor. It also works as a heater – but we haven’t really tested that setting out yet… I’ll be sure and update sometime in the future, if we ever go somewhere cold again 😆 (FYI, less than 75 means I need a hoodie.)

OFF GRID

Want more nerdy posts about living off grid? Check out my Off Grid page for all of my power posts in one place. Apparently I need to do a full run down of the systems on the cat… But I honestly was waiting until we got this bad boy dialed in. I’d say it’s about time to write that post!

Thanks as always for reading about ac at anchor and sharing my posts. Feel free to comment and ask questions. I love hearing from you guys!

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