Boat colour and heat absorption/reflection

[Neil2]

Does anyone think the colour of a narrowboat significantly affects how hot it gets inside?

 

A cabin repaint is probably still way down the to do list yet, but our boat does get awfully hot when the sun shines and I've always thought this is because she is very dark blue, almost black.

 

But I can count on one hand the number of white narrowboats I've seen.

 

So I'm wondering whether a change to a lighter colour would make much difference?

 

 

[MtB]

Does anyone think the colour of a narrowboat significantly affects how hot it gets inside?

 

<snip>

 

 

YES.

 

Painting my roof light blue (over dark blue) made a phenomenal difference. Far more than I was expecting.

 

(Even though I asked for 'Squirrel Grey', but I'll let that pass... eh Dave?)

Edited July 30, 2015 by Mike the Boilerman

[brassedoff]

White reflects heat, Black Absorbs heat.

 

any shades in between differ.

 

i dont think anyone notices it on a car, not sure on a boat.

Edited July 30, 2015 by brassedoff

[StephenA]

I suspect a white narrowboat would look very dirty very quickly. We have a grey roof and one section of it pops up and down depending on how hot it gets (and it makes quite a loud noise when doing it). So I suspect darker colours must lead to hotter steel and thus to a warmer inside temperature - however some of that will get blocked by the insulation.

 

Of course at night those darker colours lose heat back faster that light ones.

[Boatingbiker]

Hope this helps, taken from internet:-

 

 

When an object appears a certain color when illuminated by white light it means that it is reflecting light of that color and absorbing all other colors. For example, a red apple is reflecting red light and absorbing all other colors of light. The more light the object absorbs, the more heat absorbed since light is energy. If you consider it a color, black absorbs the most heat. A black object absorbs all wavelengths of light and reflects none. Objects that are white, on the other hand, reflect all wavelengths of light and therefore absorb the least heat.

Edited July 30, 2015 by Boatingbiker

[Ray T]

I would have thought there might be problems with light reflection (glare) on a sunny day on too light a roof?

 

I don't know as our roof is Oxford Blue.

Edited July 30, 2015 by Ray T

[MtB]

I would have thought there might be problems with light reflection (glare) on a sunny day on too light a roof?

 

 

 

Nope.

 

one of my roofs is sky bloo, the other Raddle Grey.

 

No probs with light reflection on either.

[tillergirl]

Our roof is Midnight Blue and when the sun shines (when) it's gets very hot. The plan is change it to Raddle Red.

[Boatingbiker]

Our roof was dark blue and was changed to sunflower blue (light blue) no reflection but less heat absorption

[ROBDEN]

 

 

YES.

 

Painting my roof light blue (over dark blue) made a phenomenal difference. Far more than I was expecting.

 

(Even though I asked for 'Squirrel Grey', but I'll let that pass... eh Dave?)

Better the other way round in the winter though.

 

Rob....

[Naughty Cal]

The majority of our Grp boat is white, however some of the cockpit, ie the dashboard and the headrests, are dark blue.

 

The difference in temperature between the two colours on a sunny day is really quite remarkable.

 

At this time of year when the sun is up early we are often woken up by the dashboard creaking and banging as it expands at a different rate to the white Grp around it!

[Nev]

I was pursuaded to go for a light roof on waterlily when she was painted, regretted it, I recall more times I cursed it for reflection and it was a real pain to keep clean, and the boat still got hot in summer. Might have got a bit hotter with a darker roof but as we prefer autumn winter and spring cruising when we want to attract heat we will go for a raffle red or grey roof this time .

[Neil2]

Interesting. I've no intention of painting the boat white but it does appear a lighter colour would help when the sun shines. I don't mind that much but the dogs do.

 

I think the proper colour for a narrowboat is red but seen a few light blue boats and that seem to work quite well.

 

Our first boat I repainted light grey and I thought it looked great but everyone kept asking me what colour it was going to be when it was finished.

[KJT]

We have a cream roof but the rest of the boat is dark blue. I think it does make a big difference in keeping the internal temperature down on a hot sunny day. We also have large windows and the curtains, which we keep closed on the sunny side, are lined with cream coloured material which helps also.

We get no reflection from the roof, possibly because it has a grit based non-slip surface.

 

We don't have any issues keeping it clean either, washing it every couple of months with 'Starbrite Foaming Non Slip Deck Wash'.

 

Our previous boat was dark green, including the roof, and we found it stifling on hot sunny days.

 

Ken

[Phil Ambrose]

Having lived on a all white GRP cruiser for 10 years I was surprised at how hot to touch our NB got so repainted it cream with blue hull and front and rear cockpit (semi trad) the roof remained raddle red, however decided that the roof was too hot, this year painted it very light grey. No problem with reflection as the paint had non-slip mixed in it.

By contrast my mate's grey boat is so hot you can't hold your hand on it.

Phil

[cuthound]

I think it depends upon the insulation.

 

The two share boats had spray foam insulation (generally accepted as the best). One was dark blue, the other dark green. On a hot day, both boats were cool inside but the roofs were too hot to touch.

 

DQ has Thinsulate insulation and a cream roof. On a hot day the inside is cool and the roof is much cooler to touch.

 

However on boats I have hired in the 70's, 80's & early 90's, which probably used polystyrene insulation, the inside got warm on a hot day, irrespective of the roof colour.

[Neil2]

I think it depends upon the insulation.

 

The two share boats had spray foam insulation (generally accepted as the best). One was dark blue, the other dark green. On a hot day, both boats were cool inside but the roofs were too hot to touch.

 

DQ has Thinsulate insulation and a cream roof. On a hot day the inside is cool and the roof is much cooler to touch.

 

However on boats I have hired in the 70's, 80's & early 90's, which probably used polystyrene insulation, the inside got warm on a hot day, irrespective of the roof colour.

 

That's an interesting point - our boat does have the old polystyrene type insulation.

[nb Innisfree]

Moored next to a white painted narrowboat in a heatwave once, our dark green nb was unbearable to touch, the white one felt remarkably cool compared to ours.

[boathunter]

I've had a matt black VW camper with a sheet of clear perspex replacing the pop-top at the workshop recently. Black vinyl covers on the seats and interior panels. If I'd put a chicken in it at the beginning of the day it would have been cooked by home time.

[blackrose]

I haven't noticed much temperature difference in summer on a black boat (with a cream roof) than friends boats which have lighter cabin sides. It was actually hotter on my friend's green Colecraft, but I think wider boats seem cooler because you are not always in such close proximity to the cabin sides.

Edited August 1, 2015 by blackrose

[DHutch]

Our cabin steelwork is a forest green type colour and on a sunny day get too hot walk on, we have quiet got roof insulation but it must make a difference. The wheel house roof however is white and when down in front of you does glare quite badly. So that's also and issue. With cars the difference/effect is reduced due to the amount of glass which is a common denominator of all colour cars.

 

 

Daniel

[Murflynn]

about 95% of cars in the Middle East are white.

'nuff said.

[DHutch]

Ditto India

[5thHorseman]

I have a red oxide coloured roof which gets too hot to touch and non opening portholes, the min/max thermometer in the boat has not shown above 30.5 this year and that was reached on the record breaking hottest July day ever. Our previous boat would get like an oven on a nice sunny day with a light grey roof and top opening large windows. the current one is spray PU insulation, the previous block PS.

The glare off the light grey made cruising unpleasant on a sunny day.

[Alan Saunders]

There are many shades, from ivory to brilliant, of 'white'. I once wandered around the car park at work on a sunny day feeling the roofs of cars. There was a detectable difference in temperature between white and off-white.

 

As above, my roof is also non-slip and does not produce any glare. I still enjoy some thermal gain on sunny spring/autumn days and suffer extreme temperatures when the boat has been closed up in my absence. It has a minimum of PS between the steel roof and the T&G deck head. There are hollow glass beads that you can incorporate into the paint but I do not know how effective they are. When the roof was shitty brown it was often unbearably hot for bare feet, the solution being to swab with canal water.

 

Certainly, an all white boat may not be aesthetically pleasing but neither, in my opinion, is any other plain colour. Some embellishment; coach lines, panels etc. is required. All grey with black details on a tug-style boat with portholes looks good but I have yet to see it on a 'standard' nb.

 

Alan