Beat the heat in the Sea of Cortez


How do you stay cool in the Sea of Cortez? Summers place it among the hottest cruising grounds in the world. We’ve spent time during four different summers in the Sea of Cortez. From June through October, average daily temps are in the 90s F (33-36C), the water reaches this range as well, and the heat index we enjoyed the last few months was typically a daily 105-115F. Sure, it’s hot, but there are a range of ways to stay cool and enjoy the summer.

Embrace the siesta

A summer here ingrains the practicality of an afternoon siesta. A break in the afternoon to just… do… nothing, or do as little as possible, is practical in the steamy heat. Beyond trying to avoid going ashore during peak heat, there’s so much to do in cooler afternoon and evening hours.

Gathering with friends during cooler evenings.

Wildlife spotting ashore is best in the early morning; the beach is inviting at golden hour; a pueblo’s food carts fire up the grill for evening treats; card games nestled between sunset and cruiser’s midnight (that’s 9pm, by the way) in a friendly cockpit; dark Baja skies are illuminated by the milky way for stunning stargazing and navel gazing with friends.

Throw shade: on the beach

Our first summer in the Sea with Totem was 2009; the kids were 5, 7 and 10 years old. Getting off the boat was key to avoiding cabin fever! We used a popup, open-sided tent on the beach for instant shade that let the breeze through.

Siobhan playing in the shade; summer 2009. Spot the whale bone?

This summer one of our BBBs—bubble buddy boats—had a great setup for easy beach shade – love this open-air shade! Perfect for a kid’s birthday party on the beach with our ‘bubble’.

Beachtime fun with crews from Pulsar, Pablo, and Galatea.

Sometimes, you can’t get any shade. Easy DIY tactic: make your own mister. Spraying water on and around your body will help keep you cool. Add water from the fridge or an ice cube for a bonus hit!

The humble $.99 mister is a handy bonus for keeping cool.

Throw shade: on the boat

Keeping decks shaded makes a significant difference for lowering temperatures below deck. One of our BBBs, bubble buddy boats, is the lovey Island Packet Galatea; they added deck awnings with a sewing assist from fellow BBB Pablo. Initial reports: literally a 10°F temp drop in the cabin! What’s key is that the awnings can also be taken down quickly if the wind pipes up.

With most of the deck shaded, Galatea was significantly cooler.

Adding to our (work in progress) bimini has opened up the coolest “room in the house,” our cockpit! While a custom shade solution can be best, even a little bit of quickly assembled tarp makes a big difference – like this blue UV material over the Totem’s forward hatch.

An inelegant but fast, functional method to reduce temps below deck.

This is where a disadvantage of aesthetically pleasing teak decked boats comes to life: it’s great in Sweden, but hot in the tropics! The dark wood heats up and helps turn your boat into an oven during the day, then taking hours in the evening to cool. It’s also tough on the teak planks. The sealant between them is pliable, but if the planks dry out the sealant bond can fail.

Sluice the deck

Sluicing decks with salt water is good for teak, but helpful for cooling any deck; cool the deck, and you cool the boat. For teak, once the water evaporates, the salt left behind holds some moisture and may help keep teak from drying out.

When the heat of day begins to wane, Jamie often dips buckets of water to sluice Totem’s side decks. As I write this – 3pm on a sunny afternoon in mid-September in Santa Rosalia, Jamie recently measured our genoa track temperatures with an infrared laser thermometer at 141°F! That’s a great, inexpensive tool to have, by the way- for engine temp checks as well as satisfying curiosity about whether you could in fact cook an egg on deck.

Measured by Jamie as I composed this post…it’s HOT on deck!

Ventilation below deck

Good ventilation matters at least as much (maybe even more) than shade. If there’s no airflow, below deck can be truly stifling. This is partly a function of the number/size of deck hatches aboard, and partly how air flows through them and through your boat.

Here’s where being at anchor is a huge help; our boats naturally orient into the wind, and hatches on most open in a direction that helps funnel that breeze below. The exception is the forward hatch. Ours, like many, opens aft to enable opening underway in light conditions without inviting water below. A windscoop helps in any case, funneling air below.

Hull insulation

Winter in Sydney, Australia was brisk, so Jamie installed hull insulation to hold heat in better. He used thin closed cell foam with a foil skinned surface. Without air conditioning, the foam’s ability to block thermal conductivity has no benefit. But the foil does block the sun’s thermal radiation, just as shiny car window shades do.

Fans fans fans

Sometimes there’s just no breeze to funnel! But even when there is a breeze, fans below deck help with moving air and keeping life more comfortable. We have a fan hard wired over every berth on Totem, and additional fans at key locations in the galley, nav station, and main salon table. It’s a survival essential. The Caframo 747/757 cageless fans push a lot of air with little power use. Unfortunately, with full time use the motors burn out in 10 to 14 months…a very frustrating situation, as warranties are worthless when international shipping is involved.

Stay cool in the water

The farmer’s almanac says the “hottest ocean area is in the Persian Gulf, where water temperatures at the surface exceed 90 degrees Fahrenheit in the summer.” Cruisers in Mexico chuckle: that’s what we have here, too! But that’s still quite a few degrees lower than normal body temperature, and soaking in the comfortable saltwater has a wonderfully cooling effect.

Floatdowners with friends in Santa Rosalia’s marina pool, pre-pandemic… summer 2019.

Going for a swim helps, too, unless you’re really exerting yourself – a nice snorkel is good for cooling down. Just watch the sun protection during peak hours. If the water is too warm to feel refreshing, then bust out the freediving techniques, because it cools quickly the deeper you go.

Keeping cool in beautiful water! Isla Coronados, BCS.

We joke that this is when it’s good to have friends with a catamaran, so you can be in the shade AND in the water!

Happily, we love this region now as much now as we did in 2009. Learning how to stay cool in the Sea of Cortez was a big part of that! It can be an adjustment, but to those who persevere the rewards are precious.

Siobhan and Mairen, hanging out on the bow at dusk; 2020.

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