Black boat and the tropics, a good idea?

[MarkJ]

Originally Posted by UNCIVILIZED

Firstly, if you're asking for proof, then were are the studies showing the validity of your (absurd) stance?

Anyway, here's a chart showing examples. http://www.colourcoil.com/enewsvol5i...emperature.gif



PS: Also, there are easier, healthier ways to get attention than via wasting the time of good people.

Geez. You don't need to be so Middle Ages about it!
All I asked was evidence to support peoples claims.

Obviously from the site you have supplied the increase is higher than I thought.

Wonder why we have so many red tiled roofs in Australia?

[LakeSuperior]

Originally Posted by 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

Jim - you are missing 1/2 the simple physics here. Radiative exchange with your surroundings is a significant factor in comfort and most non-heat transfer lay people miss this part.

So if the air temperature inside is 70 F (due to ventilation) and the inside hull temperature is 80 or 89 F you will be significantly more uncomfortable than if the inside hull temperature is 70 or 75 F.


Also, because the skin layers are relatively thin compared with the hull area only a very small fraction of the heat will be conducted to the seawater. Conduction depends on the cross-sectional area, distance heat must travel, and temperature difference.

[Eric Hansor]

Thanks. Mine was laid up with polyester resin.

[Redpcx]

I have a dark Blue schooner.
Only the hull is blue. The deck and cabin are white. The boat is well ventilated.
In the Chesapeake, it is tolerable.
If the boat is already in the tropics, the price certainly reflects a discount to cover the paint job.
On my boat, much of the hull is not exposed to the interior of the cabin, Seats, cabinets, and other furnishings are effectively insulating the cabin. In the Masters Cabin, otherwise known as the v-berth, we have a couple of foam camping pads on the SIDE of the cabin for insulation.
Does the dark color Matter? Oh Yeah. This boat is tolerable because of the dorades and 10 ports which can stay open in the rain. Yes we close the 2'by2' hatch when it rains. If your boat is a modern design, you probably dont have enough ventilation to tolerate a dark boat.

And another thing... I was reading about Awl-Grip... Some "experts" have told me the texture you can see on my boat is a sign of bad something or other. Paint manufacturer says the print through of the woven roving is normal in dark colors. The glass and the resin expand at different rates, during the daily expansion and contraction dues to temp change.

Black? Not for me. I get hot wearing black clothes.

[Sailmonkey]

Originally Posted by MarkJ

Wonder why we have so many red tiled roofs in Australia?

There's a pollock type joke in here somewhere........

[crazyoldboatguy]

Originally Posted by Reefmagnet

And I totally agree! Had a red boat with light grey non skid once. That did me. These days I only buy white cars, too.

Reefmagnet WINS!!!

[Tetepare]

My boat has a "pink" (tan-ish) deck, and gets warm in the sun.

My friend's boat, which is identical, has a grey deck which is far more attractive than my pink deck. However, it gets so hot one cannot stand on it.

I can say that on very hot days those with the luscious blue hulled boats are either off the boat or have tarps all over the place.


FYI, a good way to cool off hot decks (so obvious I didn't think of it) is to flush them with water. When the water stops instantly evaporating you've cooled the deck. This WILL have results below deck.

[four winds]

Tetepare, you can say it but you might be wrong.

It's 93 degrees outside and I'm lounging on the settee, surfing the web as usual and listening to Science Friday on the radio. A nice breeze blowing through the boat and I'm not sweating or uncomfortable.

I don't even use a fan unless the wind isn't blowing.

I don't go ashore to escape the boat. Nor do I have any shading of any type on the boat.

Go figure.

[sainted]

My Stevens 47 is painted flag blue and she (and I) live in South Carolina, which is hot as hell during the summer. With a.c., the temperature below is fine. Mind you, every boat in South Carolina needs/has a.c. no matter what color it's painted. The Stevens is pretty well insulated though, because there is cabinetry between the hull and the living spaces almost everywhere. Literally, the backs of the cupboards are plywood and a few inches from the hull. I think that helps a lot.

Scott

[reed1v]

The problem with a black fiberglass hull has less to do with comfort and more with structural integrity of the hull. Called structural deformation. Might look it up. For a modern hull, it is an issue.

[Dr. Sea]

Originally Posted by ScubaNinjaB

I am well aware of the differences that darker temps absorb. I've lived in Phoenix AZ for many years, hence my hesitation. I'm actually very resilient with heat having worked in it for most of my adult life, I would however like to be cooler in my next life.
Thank you for all of the info, and am still interested in more responses from those that own darker color boats.

Find out the cost of repainting the hull. If that cost added to purchase price ( including the cost of everything you know you will have to do to the boat x 4 or 5) is in your budget, then buy this beautiful boat and try it out. If it proves to be too hot, you've already got the cost of the repaint.

[UNCIVILIZED]

Originally Posted by Bleemus

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

Priceless!!!


To those who would discount the idea of low angle Sun heating boats up. Why then do so many boat awnings have side curtains? Or dodgers & biminis have mesh side curtains, made of fabrics purpose designed to cut down on solar radiation making it into the cockpit. And which are often left up 24/7.

As, when last I checked, most people are lighter in color than the hues in question in this thread. Me included. So then I'd figure that dark colored boat hulls do quite a good job of absorbing direct, & indirect, low angle Solar radiation (heat).

PS: You still wear sunglasses at noon, right? Why is that, as few folks look up at the sky.
Oh, must be that pesky low angle, direct & indirect light wave thing. Especially on beaches, around snow, or on the water...

[DDabs]

So basically if I take my dark hull boat to the tropics I'm going to either die down in the cabin from a heat stroke or my boat is going to fall apart structurally. Hm!

[capt jgw]

The statement that the tropical sun only shines on the deck has some validity. I'm up here in Michigan, close to 45N, and the sun rises and sets at about a 45 deg angle to the horizon. At the equator it goes straight up and down. I noticed that my first trip down there, it got dark a lot faster than I was used to. The charter company was very adamant that we had the boat moored by 1800 knowing that we weren't used to that.
The tropical sun does shine on the sides of the hull, but for a much shorter length of time.

[four winds]

Originally Posted by DDabs

So basically if I take my dark hull boat to the tropics I'm going to either die down in the cabin from a heat stroke or my boat is going to fall apart structurally. Hm!

Yea man, get with the program. That dead Hershoff dude says your an idiot.

Oh man, I think I'm dying and sinking as we speak.