Inside your boat....hotter or cooler than outdoor temps?

[softdown]

Just got my boat in the springtime. Will be working on the bottom for awhile, still drying out some osmotic blisters.

I see plenty of talk about air conditioning etc. Which leaves me wondering about typical cabin temperatures in more tropical regions. Lets say that we are using a white fiberglass boat. For this debate, lets say we are in the Caribbean.

It is interesting that ~80F indoors feels about as "comfortable/uncomfortable" as ~90F outdoors.

[S/V Illusion]

Not sure what your question is...

It's no different than a house in this respect - if you live someplace, on a boat or a house, and it's hot, ....

Some people think living aboard should be like camping and rely on wind to ventilate and keep cool. Personally, if I'm living aboard for an extended time, I prefer the comforts of home.

[Seabeau]

I don't have AC. But I do have a boat built in Florida. Four large Wiley opening ports on either side, one 24"X24" foredeck hatch, two 20"X20" main cabin hatches and of course the companionway hatch. Plus two solar powered exhaust fans in the most appropriate locations in head and galley.

[LakeSuperior]

Originally Posted by softdown

Just got my boat in the springtime. Will be working on the bottom for awhile, still drying out some osmotic blisters.

I see plenty of talk about air conditioning etc. Which leaves me wondering about typical cabin temperatures in more tropical regions. Lets say that we are using a white fiberglass boat. For this debate, lets say we are in the Caribbean.

It is interesting that ~80F indoors feels about as "comfortable/uncomfortable" as ~90F outdoors.

Outdoors you have two things going for you. One is increased convection (air flow) around your head and body. Second is on a cloudless day you are seeing less longwave IR radiation from the sky. Both work to make you feel cooler. This assumes you are not standing in the direct sun.

[Cheechako]

Yes , boats get very hot inside in warm climes when not anchored. Unbearably so at times. We dry stored a boat in Florida in June once. We thought we'd use a couple days before our flight to do some things inside the boat. No way. By 10 am it was unbearable.
In Trinidad we had a bunch of work done on the hard while living aboard. An A/C unit was absolutely necessary. At anchor we didn't need it at all.

[dwedeking2]

I live on a boat in Florida without AC. When down below airflow is very important. I have no problem when there's a nice air stream through the cabin is no problem. When the wind is hitting from the wrong direction (I'm at a dock so don't shift with the wind) it can be rough.

[sailm8]

In addition to what has been said, you need to consider that your boat could be sitting in 90
+ degree water.

[bailsout]

Awnings.

[roverhi]

An awning keeps the sun off you and the boat, an absolute must for comfort in warm weather. In the marina opening ports help but keeping the boat from heating up in the first place makes it livable.

[Dave22q]

Originally Posted by softdown

Just got my boat in the springtime. Will be working on the bottom for awhile, still drying out some osmotic blisters.

I see plenty of talk about air conditioning etc. Which leaves me wondering about typical cabin temperatures in more tropical regions. Lets say that we are using a white fiberglass boat. For this debate, lets say we are in the Caribbean.

It is interesting that ~80F indoors feels about as "comfortable/uncomfortable" as ~90F outdoors.

It's highly variable. With good ventilation you can be very comfortable at anchor but sweating at a dock. Bimini and dodger helps a lot as does fans and a wind scoop. Bottom line is that the wind matters a lot. I like my AC and generator although I really don't need it on most days. In port when the no-see-ems are out, AC is necessary.

[belizesailor]

Originally Posted by roverhi

An awning keeps the sun off you and the boat, an absolute must for comfort in warm weather. In the marina opening ports help but keeping the boat from heating up in the first place makes it livable.

Especially on boats w large deck houses like cats...big difference. Weve got two that deploy from the boom and cover the deck house sides to the deck...really cools the boat down a lot.

[belizesailor]

A theory Ive never tested with a themometer: My perception is that fiberglass boats get a little warmer just after sunset. My hypothesis is that all day that mass of FRP acts as a big solar heat sink. Then, when the sun gets low, and quits pumping heat into the FRP, it begins to release heat.

One of these days Im gonna remember to test that...

[S/V Illusion]

It's 91 degrees right now where we live in Florida. The breeze is also 91 degrees. I can turn on the fan and it's still 91 degrees. No amount of ventilation is going to change anything.

[lesterbutch]

Originally Posted by S/V Illusion

It's 91 degrees right now where we live in Florida. The breeze is also 91 degrees. I can turn on the fan and it's still 91 degrees. No amount of ventilation is going to change anything.

I have to agree with this, I just left my boat a couple of hours ago and it was fairly warm below decks, but with all the ports and hatches open not even near unlivable!

[SaltyMetals]

I had a set of white screens made which then clip onto the same studs as my standard blue canvas winter screen. The white screen material is see-through but still stops the sun. A lot of power boats use it. My saloon is 2-4 deg C (4-7°F) lower than the outside temp. This is at anchor or on a buoy which I think is an important part of getting airflow through the boat. I have an air scoop but so far have not had to use it. Have a bimini over the cockpit but so far have not found the need for an awning over the boom. This is in temps of 32°C (90°F). I don't think a sailor should be resorting to AC.