If you’re in the tropics or near-tropics for the summer, you know that sunlight streaming through every window — hatch, port, or whatever you call it — just adds to the heat inside the boat.
Catamarans, trawlers and some newer monohulls are the worst, with large non-opening windows. They offer gorgeous views from inside the boat, but can raise inside temperatures considerably.
And so, the first thing most boat owners do is to make (or have made) snap-on exterior shade panels with a fabric such as Phifertex or Phifertex Plus. Both of these block a fair amount of the light (70-90%) but still let you see out a bit. Our boat came with one for the saloon windshield, and I made another for the large window in our cabin.
They snap on, which is helpful for the one that the helm looks through (we take it off before getting underway — it’s part of our “Before Moving Boat” checklist), and they do a great job nine months of the year.
But, we’ve learned, they are woefully inadequate during the summer. Enough sunlight comes through that the window gets uncomfortably hot to touch!
We looked at all sorts of possible solutions and ended up going for the 5-minute, less than $20 solution. We bought a roll of Reflectix (bubble wrap with foil on both faces) and cut it to the size of the windows and slid it under the snap-on shades. I simply cut out little places where the snaps are so that the Reflectix can be the full size of the window.
My technique was simple — I cut the pieces roughly to size, put them in place (on our boat, it was easiest to set them against the bottom snaps), made the cutouts for the snaps on that side (on ours, the bottom), slid the Reflectix into its “final” spot, trimmed up the other sides and cut the holes for the rest of the snaps, then snapped the fabric covers back into place. Two done in about 5 minutes.
It has made a big difference in the temperature inside the boat. Temps inside the boat used to be about 10 degrees (Fahrenheit) hotter than outside “in the shade” temperatures; now they are about the same. 90° in the boat is a lot more tolerable than 100º!
We got the idea from another boat that was going on the hard for hurricane season, but it works just as well if you’re living on the boat.
NOTE: Putting the Reflectix on the inside of the boat is a bad idea we’ve learned — the heat will build up between the window and the Reflectix and can damage the window. Putting it on the outside, on the other hand, helps to protect the window.
When we get ready to get underway, we always remove the snap-on shade over the windshield anyway and put it back in place once we’re anchored or at a dock. With the Reflectix in place, we simply roll the Reflectix up with the shade to get underway and put them on together at the end of the trip. It takes no more time.
We had seen various ways to make pockets in the shade cloths for the Reflectix or to otherwise attach the Reflectix either to the boat or the shade. We have found it totally unnecessary.
Yes, with the Reflectix in place we lose the view and so don’t use it during the cooler months. The pieces are easy to store under a mattress during the winter and we’ve found that even in tropical sun and rain, they last two to three years. They didn’t disintegrate; the foil just slowly wore away so that light started coming through. Exact longevity will depend on how much of the year you use them and how intense the sun and rain are.
A couple weeks ago I had to replace one and walked over to the Home Depot in Marathon, Florida (it’s a couple blocks from Boot Key Harbor, making it very convenient for cruisers). I figured with all the part-year residents leaving homes and boats here, Reflectix would be a popular item. Discovered that they don’t carry it or anything similar in stock at this store (only their larger stores do). Turns out that no local store carries it. Okay, off to Amazon (seems to me that there’s a business opportunity here for a local entrepreneur):
Reflectix comes in a bunch of different sizes, so you’ll have to do some rough measuring to figure out what width and length roll will work best for you. It also comes in “tabbed” for stapling in home construction; this generally isn’t needed for making sun shades but can easily be cut off if that’s all you can get.
P.S. If you have large “glass” hatches, look at Outland Hatch Covers to insulate (and also protect) them. Read my post here.
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Carolyn Shearlock has lived aboard full-time for 17 years, splitting her time between a Tayana 37 monohull and a Gemini 105 catamaran. She’s cruised over 14,000 miles, from Pacific Mexico and Central America to Florida and the Bahamas, gaining firsthand experience with the joys and challenges of life on the water.
Through The Boat Galley, Carolyn has helped thousands of people explore, prepare for, and enjoy life afloat. She shares her expertise as an instructor at Cruisers University, in leading boating publications, and through her bestselling book, The Boat Galley Cookbook. She is passionate about helping others embark on their liveaboard journey—making life on the water simpler, safer, and more enjoyable.
Claire Ford says
Great article. Since we’ll be moving the boat to Texas from Kentucky in a few months, I’ll be looking into doing this. In Texas, anything that keeps it cooler is welcomed.
Jim Taylor says
I have a 3′ x 4′ plexiglass roof on our pilot house and have used this material with a layer inside and outside. Know of an coating or film I could use on the outside to reflect sun, rays, heat but still see through?
Carolyn Shearlock says
Use automotive/limo window tint film — the darker the better. You can get it at almost any auto parts store and also on Amazon: http://amzn.to/2thV0K9
Eve says
Be very careful about which window film you buy. Most labeled UV are not tested or lose their UV abilities in a very short time. The Skin Cancer Foundation recommends only 2 brands (3M & Llumar). I have had both on my vehicles, as I tend to get benign skin cancers easily. 3M Crystalline and 3M Color Safe are the most durable in my opinion (I had a bad experience with scratching on Llumar Air 80).
The 3M tints even come in clear and block 99.9% of UV-A and UV-B rays, PLUS…. it rejects up to 62% of solar energy and up to 97% of heat-producing infrared rays. It makes a HUGE difference in my car (I live in a hot part of California). I have the lightest tint on my windshield and medium on my side windows. Even on 100 degree days, you can get in the car and it’s not very warm at all.
Eve says
Forgot to note… many window films interfere with electronics, such as GPS and cell signals. The 3M Crystalline and 3M Color-Stable do not interfere with electronics.
http://www.3m.com/3M/en_US/automotive-window-solutions-us
Bob Menches says
If you can’t find reflectix and have an autoparts or Walmart near, get a windshield shade made the same material. That’s what we did before we knew reflectix existed.
Thomas Conover s/v Double Life says
I believe I had Home Depot in Marathon ship a roll into their store free shipping and then just picked it up at the store in a few days. Seems like they would stock it but ordering was simple.
Carolyn Shearlock says
At the time we needed it, they said 10 days for delivery. Amazon was two. And it was HOT.
Carolyn Shearlock says
At the time we needed it, they said it would be 10 days for delivery. Amazon was two. And it was HOT. Guess who won?
Cheryl Geeting says
Sounds great, but does the Reflectix damage the plastic ports with its heat? I thought I read somewhere on your site about That? We definitely need something here in Louisiana!
Carolyn Shearlock says
If you put it on the OUTSIDE it does not. It protects the plastic from the heat.
Carey Mitchell says
I covered every inch of the interior of our refrigerator and freezer (like wallpaper) with Reflectix and boy did it make a difference. I used the accompanying foil tape to hold it in place. Not only does our top-loading fridge lid not sweat on the outside in high humidity, but we also save a lot of compressor use and thus battery power. We keep our boat on a mooring in Maryland in the summer and never have to turn off the fridge while we are away.
Amanda Roberts says
Hi
From the Norfolk Broads uk ,my husband lined our windows .with foil car sunshades on the outside under our screens ,,bought from Lidl’s this works great we are warm in the winter and cool in the summer ,he has also put the foil bubble wrap behind all interior panels and beneath the headlining ,,an easy job so I’m told ,you can definitely tell the difference in the winter ,we are lovely warm and snug ,compared to our other friends ,
Anonymous says
Merran Sierakowski?
Kris says
Hi Carolyn
Two questions on the window covering post.
1. Would you recommend laying tape over the cut edges of the foil material to keep water (rain) out?
2. We’d like to use this to block sunlight on small lewmar ports, say 15×4, but worried about the reflective heat as mentioned in your article. Ports are mostly vertical.
Thanks
Kris
Carolyn Shearlock says
You could, but getting the tape residue off is a pain (we used tape in the sun one year for something else). The best way to get it off is with WD-40 and a green scrubby. Not sure how bad the reflective heat problem would be on those side ports — my guess it would be okay, particularly if they were not facing directly east or west.
Allyson says
For those of us that says l in the winter months, could you use the reflex to help keep the warmth in the galley? For flexible vinyl windows on the Dodger areas can you use the reflex on the outside to protect the windows?
Carolyn Shearlock says
I would think Reflectix could help a bit in the winter if used on the inside. I’d be afraid of using it against Stratoglas or similar things as they scratch so easily. The usual recommendation is to use very soft fabric against them. So you could cover the side of the Reflectix that will rest against the “glass” in something like t-shirt material.
Lynn Van Den Broeck says
Hi there, I am interested to know how you made the snap on exterior shade panels voor the for the large window in your cabin. How are they attached to the boat?
Thank you!
Carolyn Shearlock says
On the boat side, we used the SNAD fasteners available from Sailrite (you can get them in both white and black). https://www.sailrite.com/search?keywords=YKK%20Snad They attach with Very High Bond adhesive rather than having to drill a hole.
Lynn Van Den Broeck says
Thank you, Is the black fabric also from sailrite?
Carolyn Shearlock says
Yes, it’s Phifertex Plus.