Black boat and the tropics, a good idea?

[mako]

That's a great chart that JerseyJoe provided, but take a reality check to those bars, because if you decide on a nice light tan or other color, similar in reflectance to yellow, then although it might look like it is 3X hotter, it is in reality only looking at a raise of a few degrees. Repainting (yourself) might be an option and so could adding some more insulation inside, even just in areas that you can reach.

Color is very personal and some people think white is incredibly boring and common.

[four winds]

Scuba, I notice you said you like the looks of the dark hulled boat. Well for me, there is some value in that observation.

Not every decision has to be based on purely empirical reasoning.

When I was researching for my boat I was hoping the eventual choice wouldn't end up being white. Because I think most any sailboat looks better with a dark topsides.

White would not have been a deal breaker, but I was pleased to find the right boat for me, for several reasons, ended up having dark blue topsides. Icing on the cake, if you will. I think it's a lovely boat and have never regretted the color.

Now six plus years later, living on board full time mostly at anchor along the US Gulf coast I'm still liking the dark hull.

It's dog days of summer now and the only time it's uncomfortable below is when the wind is not blowing. I have, I think, better than average air flow through the boat.

I think a white boat is also likely to be uncomfortable below when the wind is not blowing as well. And I suspect the difference to a dark boat would be all but imperceptible.

My preference for a dark hulled boat outweighs any concern that it might be measurably warmer below. Nor am I convinced it would be perceptibly warmer either, at least to me.

I'm sure it helps that I have lived without air conditioning for more than a decade now.

However, I've never owned a white boat so what the hell do I know.

[Jim Cate]

Well, I don't think this subject is a matter of opinion, for the simple physics are irrefutable: dark hulls absorb considerably more energy from sun irradiation.

But, how this affects the internal air temperature in the boat is subject to several factors.

The thermal conductivity of the skin layers of the hull (aluminium vs FRP vs steel vs timber, etc). High conductivity means that more of the absorbed heat can go directly to the sea... a good.

The amount of insulation between the skin and the interior of the vessel. Good insulation, as in cored hulls or ceilings with air space between hull and living space providing better isolation and lower temperatures than thin, solid FRP, etc.

The amount of ventilation available to remove heated air from the living space.

These factors do indeed have a big effect upon the internal temps. Now you need to factor in the intangibles: how do the occupants react to a given temperature? And here is where all the conjecture arises, for some folks have very different criteria for what is acceptable. One only needs to read the above post by a fellow who has lived without a/c for years, while other posters have in the past said that they simply could not survive in an un-airconditioned boat.

And thus we understand the kinda passionate but highly divergent opinions posted above: each respondent is reporting their reaction to their own boat with their own body (and possibly their own wife's opinion) as if it was the only truth.

But the physics don't lie...

Jim

[four winds]

I agree with your post Jim. I hope my previuos post doesn't seem to present itself as the only truth. Rather just my experience is what was intended.

There are indeed many factors at play, and hull color is only one.

My boat has a cored deck, and also an additional full inner fibreglass liner overhead, and on the cabinhouse sides, and a complete fiberglass inner hull with a cored cabin sole.

I don't have a bimini, dodger, or any external shading. And yet I do not feel any radiating heat near the inner surfaces of my boat.

I have been on boats with solid decks and no inner liner that had very noticeable heat radiating inside near the surfaces.

I don't think the hull color is the most influential factor in the build up of heat inside a boat. Just one of many.

The most influential factor is no doubt the human factor.

[tikirawker]

Put an offer in about a year ago on this black boat named 'imagine'.
The sale didn't go through as we got freaked out by the 7' draft and they got freaked out by our offer...
The boat had very smooth lines and was gorgeous.
I didn't even consider the extra heat from black paint.
Sometimes things work out for the best and you don't realize it until much later.

To the point of color. I don't even wear dark colored clothing in the daytime while on the boat. The extra heat makes life brutal and miserable.

[Scorpius]

Not a good idea. (I tried just saying "no" but the system won't accept answers less than five characters

[jkindredpdx]

I think Black below the waterline is OK ... Had a red hull and white deck before and could definitely feel the heat inside the hull on a summer day. Yesterday it was a 100 F in Portland and my white hull, white deck, with white dodger was about as comfortable as a person could get...

[DDabs]

I love my dark blue hull. Heat isn't an issue here in FL but I guess I have some pretty decent insulation.

[reed1v]

Lots of research on black fiberglass hulls in the tropics. Bottom line: not good. Has structural impacts.

[Eric Hansor]

I have a black hull which originally was quite warm. I have insulated and added ceiling boards in the cabinets and exposed living areas. Cooler then any boat around. Now insulating the undersides of the deck. Temps keep dropping.
More sunlight hours in the North during the Summer, boat and interior temps are fine.

[Eric Hansor]

My fiberglass hull has been black since 1959. No structural issues. Would like to look at research. Can you help with a link? Thanks.

[UNCIVILIZED]

Originally Posted by Eric Hansor

My fiberglass hull has been black since 1959. No structural issues. Would like to look at research. Can you help with a link? Thanks.

He may be referring to epoxy boats, & if so then the problems are obvious, especially with room temperature cure epoxies. The HDT is just to low to use dark colors. And even with a lot of post cured boats there can be problems, as a very large number of the common resins soften between 150-175 deg. F. At least the ones by West Systems, & System Three. And dark colors definitely reach those kinds of temps in direct sunlight in the upper regions of N. America. Such as at West System HQ, which in Bay City Michigan is 44 deg North. Go South & the temps produced by dark colors are a good bit higher.

[Bleemus]

Black boats in the tropics are fine if you can deal with small children and pets spontaneously combusting while down below.

[Gaia]

One issue that has not been addressed, unless I missed it, is safety. Black hulled boats are more difficult to see at night from speeding whatevers. When I look around at night in our anchorages here in the Indian Ocean it is the dark hulled boats that are hard to see particularly if they only have mast head anchor lights which the locals mistake for stars!

Personally, after 20 years in the tropics, I would either never own one or paint her.

Jim

[boatman61]

Steel.. Navy Blue hull with cream/white topsides.
No issues.. but then she does have a low freeboard despite 6'2" headroom in the boat.. usually nice and cool after the sun above deck. so no issues here.