The summer sun finally killed my polytarp boat cover after 2 seasons. I quickly wrapped the boat in a fresh tarp and set off to make a new boat cover.
A good quality polytarp will last 2 seasons if you are lucky. I wanted better lasting power and bought Sunbrella, here is a source: Sunbrella Marine Grade - 6001-0000 Pacific Blue Fabric
I bought twice the length of my boat of 60 inch wide fabric. I knew this was too much but I also could use the offcuts for a patio umbrella. The price was the same for 60 inches slightly odd colour than for 42 inches of a more popular shade. I added a few extra yards to make my sail cover and the extra cost was recouped by getting free shipping for the larger order.
I already had heavy duty polyester thread which I had bought for a sailmaking project as well as good quality sewing machine needles in large size.
Sunbrella is a marine grade polyester fabric with UV inhibitors. Previously I had used awning material which claimed to be UV resistant but did not have much joy when I used it for my sail cover. I only got 3 seasons out of it. Sunbrella claims that their fabric will last 5+ seasons so I'm hoping it will last.
Also in my treasure trunk were grommets and grommet setting tools.
From my sewing bucket I found some tailor's chalk. It's easy to mark cloth and can be rubbed off.
This is my fourth boat cover. The others had been mostly flat sheets with pointy ends folded and sewn in the front, and reinforcements for the grommets. By tightening the ties well the cover would work quite well but never fit perfectly.
One cover was of oiled canvas 60 inches wide. I found that although it worked I could not get much of a peak to keep water off since the fabric after hemming was not quite wide enough. I like to build a little tent and have the cover shed water even if the fabric stretches.
By keeping the fabric tight it worked but as soon as the fabric sagged at all water would pool and come in the boat eventually. The Skerry's ends are slightly higher than the middle and any loose cover will sag.
The other 2 polytarps were also flat covers with pointy ends and lots of grommets, and I made them wider than the 60 inches. I shaped the front a bit so that I could hook on the cover to the front and go to the back and pull tight. This worked very well particularly since polytarp stretches and will make quite a nice boat covering tent. It does not last well though. I use supports in the mast partners to make a tent pole.
I have 2 posts, one is in the mast partner and the other is free-standing with a small base and it gets placed behind the middle seat. Both have foam and duck tape covers so they don't tear the covers.
Some boats use their mast and boom to make a cover tent. This works well if the mast is kept stepped but in the Skerry the mast is taken down after sailing.
I used a string to measure the distance between the front of the boat to the back and added enough to fold and finish the front. About 10 inches is what I left front and back.
I measured how high the post was from a string stretched front to back. It helps to get an assistant for this.
The overall length is the length of the boat plus 20 inches. The top of the point is where the front post will be. The height of the peak is the distance between the stretched line from front to back, and the top of the post, not from the boat to the top of the post.
Now is when I fitted the cover onto the boat. It's like haute couture for boats.
I temporarily stitched the peaked top line using strong thread. This allowed me to fit the cover. I think it would have been easier to use old sheets or a cheap polytarp to make a pattern THEN cut the good fabric. The fabric was harder to handle than I expected.
I draped it over the boat and realized that I needed to take a dart to adjust the fit. I gradually did this and the top part of the cover fit quite well.
The darts are shown in red. I just folded the fabric and sewed it temporarily. I did not want to cut any extra fabric off until I was sure I had a good fit.
Once the top fitted well I measured to the edge of the top board plus enough for a seam to be folded under and marked the distance. I then put the cover on the ground and measured the trim width all around. I took a deep breath and trimmed to my marked line. This made the cover much easier to handle.
Using my long suffering sewing machine, I stitched the seams and top pleats. I could not make a proper french seam which is a very tidy seam. Instead I sewed the seams, zig-zagged the edges and put a top seam over the zig zag and the fabric essentially sewing the seam to the side. It is strong but not as nice as when all the edges are covered. My sewing machined could do 3 layers competently but would not do 4.
After putting the cover back on the boat, I was able to fold up the front so that it fit the bow nicely. This I sewed by hand. The extra thicknesses I folded in help to pad the bow and reinforce the cover. This was fiddly but not hard. The outside had to look nice, the inside be tidy and the cover be strong.
Next step was to hand finish the stern. I wanted the back of the boat cover to hook up over the stern but then I would lace the back to tighten the fit. I stitched the back by hand. I had to trim some to be able to lace the cover.
To avoid the cover sort of bulging between the grommets like the first canvas cover I made (see above) I took a couple of darts in the bottom part. They are not very deep. I've shown them in green in my diagram.
Finishing was simple. I just folded the fabric under and sewed a edge all around. Where I planned to have grommets, I zig zagged a reinforcing patch in place under the edge.
I applied the grommets and attached lines to one side and put the cover on the boat. I will add some padding where the tent posts hold the cover up.
The cover fits quite well and keeps water out. I could have put in another dart on the underside and maybe another smaller one in the top towards the front.
This cover could have been made by laying the fabric at 90 degrees width to width and adding shaping in the seams. This would be more economical of fabric. I have a use for the offcuts so it's not an issue.
Draping a lighter fabric even a plastic drop sheet, would have been easier. The pattern could then be used to cut the actual fabric. I found that handling the heavy Marine Grade Sunbrella to be harder than I expected.
It took me 2 days work to make this cover. I had the time to do it and used the best possible material. It might be cheaper to get a professional to make one if you count the time. I checked commercial ready made covers and the fabric was very flimsy. They don't fit my boat anyway. A neighbour paid 1000 for a similar sized custom boat cover. My boat cover was less than 200.
Time will tell if the cover lives up to the UV of the Sun.
Note: A after one season the boat cover is as good as new. It has not stretched out or faded. I think getting the good material will be worth the extra cost. Here is a link to a Sunbrella supplier: Sunbrella Marine Grade - 6001-0000 Pacific Blue Fabric
This is a project I made. I don't claim it is the only way or even the best way. It is just the way I made my boat cover.