Blue or White Bimini

[rtbates]

Originally Posted by delmarrey

Maybe this will help.

UV-Visible Spectroscopy

Thanks Delmarrey.

Now I can say that I know The Importance of Conjugation.

[JayH]

I prefer the darker colors. Depth of shade was mentioned earlier, and I'd agree with that. I don't think heat buildup in the fabric has much relevance unless it is only inches above your head. I'd also think that a lighter colored fabric would contribute to glare, or reflected light from beneath.

There are fabrics that are different colors on each side. Herculite Regatta comes to mind. Light on top, dark underneath.

Marine Fabrics | Marine Vinyl Fabric - Herculite

I haven't used it myself.

[MarkJ]

White will show the dust from the Sahara, the polution of Asia and the bullet holes of Somalia.

Blue is better. But look at the range of blue you can get!!!!!!!!!!!

All blues are great... oh except for that quite revolting Ocean Blue by Sunbella. Thas quite chunderous and you wouldn't be seen dead in a marina with it. Disgusting.
The only reason why it will be Sea Lifes new colour is I'm getting a good deal on it. Not you, though - you'll pay top price... more maybe! Much more and its revolting.

[Bash]

I went from a navy blue to a medium gray, and found it to work better. It still gets hot, though.

[barnakiel]

If you use zippers, sew them UNDER, not on the edge - they normaly go very fast in direct sun. Perhaps the same rule holds for colors - avoid white zippers. These go real fast (and do not ask me how I know).

b.

[chuckr]

kinda depends on how you use the boat - we were ok with deep blue until we became full time cruisers -- the heat was tough in full sun - also as it got older we kept spraying moisture repellant on it to keep rain from coming thru -
me painted the top of the bimini with elastomatic paint that is for roofs and got it in the roofing section of home depot - really cut the heat and made it incredibly water proof and made it a bit stronger than before -- really pleased with it - blue on the bottom and white on top works for us

chuck patty and svsoulmates
on the wall cambridge md

[Mark Johnson]

Dark colors, like in our case Forrest Green, block about 99% of the UVs, VS White, which might block 50%. This is why you should always use a dark color on your sail covers. (or an opaque liner under white) The sails will last much longer if under total UV protection... For bimini / awnings & such, The dark color will block more light & provide better shade, so your cabin top & seats under this shade will be cooler. However the area just under the canvass (within 6"), will be hotter if a dark color, because it's higher heat absorption trumps it's Superior shade from UVs at this close range. We did experiments on a bright / hot Fl Keys day, by holding a thermometer under a mini tarp of Forrest Green, and then Off White Sunbrella. At close range the Green was a bit hotter, but given a good breeze, not so. Once we moved the thermometer 8" away, the Off White was consistently hotter, due to the sun shining through.

If it is a mostly closed up bimini / enclosure, a dark color might be hotter due to no way for the absorbed heat to escape, however if it is a stand alone bimini or tarp with at least 6" of space overhead, the absorbed heat will be blown away in the breeze, and the Superior UV protection will make your cockpit & cabin MUCH cooler. Especially when sitting down. (less squinting too).
Almost always... a dark color makes a better awning.

On our hard dodger's Sunbrella covers, we learned this the hard way. After 5 years under Off White covers, the lexan had serious UV degradation. After refurbishing, we made new covers. These were Forrest Green underneath for 99% UV blockage, & another layer of Off White sewn on the outside for it's Superior reflectivity. Best of both worlds! This worked great in this particular application, but it would be a beast to try to make a bimini this way. Plus it would probably be a moisture & mildew trap. It is too bad that they don't make a Sunbrella that is light on one side, but dark on the other, to make it opaque. There are Weblon fabrics & Sea Mark products that may come close, but they don't breath. Especially if you ever have enclosure curtains, you should have a bimini that breaths, like Sunbrella.

BTW... This same scenario applies to paint! If you want it as cool as possible down below, and plan to have your boat Awl Gripped, have it primed with enough GREY 545 primer that it is not then sanded micro thin anywhere, then go on with white top coat. White primer, which is standard, lets the sun shine right through, just like White top coat. Grey primer is 100% opaque which blocks the UVs, and the White topcoat gives the reflectivity. We painted a sample, about 2'X4', both ways... Half was White on White and the other White on Grey. Then with the sample facing the sun took measurements. The White on Grey was always a couple of degrees cooler.
Things that make ya go hmmm! Mark

[CaptPatAg]

My boat came with a Pacific Blue Bimini. I stitched up some side curtains out of natural color boat shrunk cotton canvas. I attach them to the sides of the top and tie the bottoms to the life lines. The cotton is a lot cooler than the blue top but it does show a few stains. I like the cotton because it is so easy to sew up, inexpensive and rugged. I also made a shade for the front of the boat and figure it drops the interior temp by at least 8 degrees.....FWIW

[landonshaw]

It would have saved a lot of time if I had just asked the first mate what color she wanted. Grey