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How to make a DIY Cathedral Arch Boat Shed


Strangely this was the most intimidating task we had to do in our boat restoration project so far. The sheer size of the shed left us feeling in doubt the entire time. Will this be large enough? Will this stand? Will this get blown away from the wind?

We did lots of research to conclude that the Cathedral Arch structure would be the easiest and most practical for us to build. Since we are renting land and do not own it, we didn't want to create any permanent structures or throw cement. So the cathedral arch boat shed checked off all the right boxes.

We were limited by the supplies we had here in Brazil and their availability. We had the option of eucalyptus or pine planks and went with pine since they were cheaper, However they were shorter so we had to connect more together to get our overall length. We found a maximum of 3 meter (3 yard) planks of 6 x 1 inch pine so we had to attach 3 together. If you find longer planks, you are better off.


  • Wood planks (see paragraph above)

  • Wood separators (These are the block in between each plank. We used 2 x 2 inch (5 cm) blocks by 6 inches (15cm) the width of our wood planks. But we recommend rectangle ones (which were not available to us at the time) that could be better since they wont twist under pressure.

  • Bolts and nuts (to connect planks together for the over all height. We used 4 bolts per intersection)

  • Nail (so many it's unfathomable)

  • Glue (we started out gluing but it was so much that we abandon this step...)


  • Power drill (with extra batteries!)

  • Drill bit (For bolts)

  • Nut driver drill attachment (for bolts)

  • Hammer (or if you are smart, a nail gun would be way better)

  • Anchors (We used rebar stakes, but you can use cement blocks or anything heavy)

  • Cover of your choice (We went with a thick tarp)

  • Friends (Help makes this job go faster!)


To find the size we needed, we measured the size of our boat in the cradle as if it was in a large box. We then measured on the ground how much space we wanted on each side of the boat to move around. Calculating a reasonable height from the top of the boat, we measured from the center point above the boat to the ground points. The arch was determined by how much we had to clear the side of the boat.

NOTE: We messed up when we didn't calculate the stanchions so when we take the boat out of the shed, we will have to manually move the arches out of the way to avoid from hitting the structure. Make sure you keep this in mind and give enough space because eventually this thing has to leave the shed!


To create the template for all of the arches, we found a large enough space on the ground that we could create half arches which we would connect later on. On the ground we measured from the middle point of the boat to the outer ground point and also the height (creating a large L). At these points we placed something that would be able to secure the wood while we would arch it and nail it. We found that strong metal stakes in the ground served well for this purpose. We also tried wood blocks drilled into concrete but these failed us more often since we were constantly bumping and rubbing them as we moved the wood, placing it in and removing it from the template.

Then we placed a stake where the wood would be curved to create the arch. This was a little tricky because this is also limited by the amount of curve the wood could withstand. We found that our planks being only 3 yards (3 meters) and with several connections, didn't seem to want to arch as much as we hoped. Also, they had lots of knots on them so several broke before we found an arch that was suitable. We've seen others able to arch much more than ours so perhaps we were rather conservative on this part.


Since we had to make 3 planks to make up our overall height, we had to go though the process of connecting all the planks together with bolts. Ideally you have found longer planks so you can reduce this step or eliminate it.

All the wood was cut at different lengths, so we found it was easiest to create your first perfect height in the template, then remove it and lay everyone next to that instead of measuring. It seemed like madness to try to use a ruler and eyeballing it next to the completed one went much faster.

The inside piece of wood will be shorter than the outside, so keep this in mind. It's the same process to create this guy, just note the difference in height and create it accordingly. For the inside piece, we also already nailed on the separating blocks of wood while it was flat on the ground. This was important because we could line up all the blocks more or less. Again, without needing to measure all the time.


If you have to connect planks together to get the height, make sure when you assemble your piece the inside piece and the outside piece to mimic each other NOT mirror each other. Example; you wouldn't want your mend on the outside to be on the outside of the arch, and the mend on the inside to be on the inner side of the arch. You would want them both be mended the same way; both inside, or both outside. We made this mistake the first time and it effected not only the curve but out blocks didn't fit on the inside since the wood placed incorrectly created different spacing.


Place your two pieces together loosely and then place them on their side in your template. Line up the foot of the planks on the inside of the stake in your template that will be at ground level. Make sure the wood is lying on the outside of the stake that will be holding the template curve. Then carefully take the upper most piece of your wood planks and gently walk them back until you can get it to curve around the center stake. At this point you will need to ever so slightly lift the planks in your hand over your top stake and place them down on the inner side of that stake, thus securing your wood and establishing the curve. At this moment we discovered that our center stake needed to be moved as the curve was too aggressive for our wood. Make adjustments correctly and try again till you get it right. Once your planks are correctly curved in your template, start nailing it all together. Repeat this till you have created all of your half arches.


Take the half arches and measure the distance of the feet to match calculations. Then join the arch points at the top. We did this by adding the same square blocks on the point and nailing them together. Next you need to reenforce that top triangle part. We've seen this as large boards cut to triangle which reenforce the points and look very sturdy. However the boards cost more so we personally went with planks and they did the trick. We took one 6 x 1 inch plank and made a triangle in the top and nailed it to the side. Then we measured down about 2 feet (60 cm) and placed another plank passing from the side of one side to the other, cutting off the excess. If you want to reenforce it even more, you can do this to both sides. Choose whats best for your project.


We put the feet near the boat and then lifted the arch by its point then stood them up one arch at a time and walked it into place. This was tricky because ours is around 20 feet tall (6 meters) so we had to have help for this. We had to lay 2 down on the boat to get going. They were then righted next to each other as we put in some horizontal reinforcements. Try to get the highest point first and lowest point to get some stability then add more horizontal points. We had to add the highest point last since it was impossible to reach till the end, but it made all the difference.

RECOMMENDED: Create diagonal supports going from the foot of the structure to midway in the arch to prevent the structure from buckling


Cover it! Once you have completed the structure, you can choose how you want to cover it. We went with a large tarp that left enough area for wind to pass below the structure.

Ground it! If you haven't already, you'll need to put in your ground supports. This can be cement weights or rebar stakes.

Enjoy it! Congratulation! You finally finished this structure. Hopefully it went much smoother and took less time than it took us to make!

How many arches do you need?

We don't know the mathematical answer to this. We created one every 3 feet (1 meter) so we ended up with 11 arches (so we had to create 22 halves in our template). But we've seen people put them closer together, and reenforce them more than we did. This probably depends on a couple factors, how much. money you want to spend and also how long you want the structure to last. Our's is very temporary so we went for the minimum, but if you wanted to create something more permanent with a solid roof, we'd suggest reenforcing it. It will stand and be very strong if you do!!


We are amateur DIYers, this blog is how we personally made our structure. Please do check out our references below and always make sure you do your own research before trying to make anything! Good luck and be safe!


Don't take our word for it alone, check out these great videos we based our build on:


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