Skylight insulation hats, our cheap DIY solution

As the winter arrives and the temperature drops we quickly found out that we needed something to prevent the heat from escaping through the skylight hatches. The skylights are only made from a single layer of acrylic glass and does not provide much insulation. Our solution was to sew our own skylight “hats”. It’s a cheap solution, that did not take long to make. We can also leave the hats on even if we want to open one of the skylights or go out sailing. We figured we wanted to share how we made them so that you could make your own! Did we forget to tell that we love them 🙂

Good luck! 

Our 4 quick tips

1. Use a thick sleeping mat as primary insulation.

2. Buy residue fabric that would else go to waste.

 3. Use a strong sewing machine, the fabric will get very thick in some places.  

4.  Make the hats in one single piece.  

What you’ll need to buy

– Canvas

– Sleeping mats

– Elastic Cord

– Double sided tape

Selecting Materials

As primary insulation we used a thick (14 mm) sleeping mat. On the outside we used a blue canvas that we bought from a local boat canvas maker. To make the fabric more stiff and even more insulating we added a felt fabric. Both the canvas  and the felt were bought as scrap pieces. The canvas is resistent to sun and rain and protects the felt and the sleeping mat from the weather. We selected the blue color that matches our other canvas, like the sailpack and sprayhood.  

Cutting the Sleeping Mat

Measure the top part of the skylight and make a template of its shape. To make it easier to handle we only made a template for one of the rounded corners. So we cut the sleeping mat in the correct width and length, then we applied the template to the corners to get the correct shape.  To make a more tight fit inside the fabric bevel the top edges (those that will end up agains the fabric).

Cutting the Canvas

When cutting the canvas, use the sleeping mat as a template for size and shape. Start by making a solid line tight against the sleeping mat on the hind side of the canvas. Then use a measuring tape to mark an outer dashed line. For our skylights 5 cm was a good measure. For us that corresponds to the height of the skylights. Make sure you measure your own hatches and adjust this measure accordingly! It is at roughly this dashed line position the elastic cord will end up later. When cutting the canvas, make sure you have enough canvas outside the dashed line to later make the hem. 

Adjusting the Corners

Now it’s time to adjust the corners of the fabric. Since we wanted these to be rounded we made two “cones” down towards the solid line. The cones shall be made on the inside of the hat with the sharp end towards the solid line. Sew a straight seam to the edge of the canvas and cut the residue fabric off. Do this with all four corners. 

Sewing the Hem

Now it is time to fold the hem that will fit the elastic cord. You are going to fold the canvas around the outer dashed line and then sew it in place. After a trial and error we found out that the easiest way was to add the elastic cord at this step. 

We started by filling in the dashed line, making it solid, in order to see it better. Then we added the elastic cord while sewing the hem. This way you don’t have to try to thread the elastic cord with a safety pin afterwards. 

We used double sided tape to keep the hem in place while sewing. Taking small sections at a time and tape it down, will make it easier to keep the elastic cord in place. Leave a 5 cm wide gap in the seam where you start and finish as the entry and exit point for the elastic cord. 

Don’t tighten the elastic cord at this point. You’ll want an as flat “hat” as possible when going forward to the next step. If you tighten the cord the fabric will become bag-shaped and it will be harder to sew in the felt fabric. 

Adding the Felt Fabric

When the hem and elastic cord is sewn in place, it’s time to add the felt fabric. Use the sleeping mat to once again measure the size of the fabric. Use the measuring tape to mark 3 cm outside of the sleeping mat. Cut the fabric at the marking you just made. 

Place the felt fabric on top of the canvas (on the inside). It is supposed to just precisely cover the seam of the hem and you might need to adjust it a bit in the corners to get a good fit. 

Sew the felt fabric in place. 

Tighten the Elastic Cord

This step is a bit tricky, especially the last part, so it might be a good idea with an extra set of hands and gloves. Once tightened, tie the ends together. When the elastic cord is tightened it’s time to mount the hats to the skylights. Don’t cut the ends of the elastic cord until you have tried the hats on the skylights to see if each hat is tight enough. Since we want to be able to open the skylights, and go sailing with them in place, we decided to add a thin security line that we tied around the elastic cord and pulled through the skylights. That way, in case the hats would ever come off the skylights by mistake, they will stay on the boat and not blow away. 

Put the sleeping mat on top of the skylight and pull the hat on top of both the skylight and the sleeping mat. Make sure the elastic cord is well secured between the skylight and the deck, around the entire edge of the skylight. Open and close the skylight to make sure it stays in place and adjust it if needed. 


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