Wooden sailboats are wonderful things; nothing beats the style and grace of boats from the golden age of sail. The first bad part is as follows; wood rots if you don’t take care of it. Wooden boats need wooden masts for the most part, even some fiberglass and metal boats use them. Now here comes the second part; boats are expensive, wooden boats need a lot of upkeep, you need to keep them dry and well ventilated, and when something breaks you need to replace it. Since I’m a poor student I tend to build most of the parts that I need.

Wooden masts are usually hollow and made up of a bunch of smaller pieces glued together. Unless the mast is intended for a very small boat; under 16 feet with 2 masts, you’ll need to glue up a mast. Boats up until about 20 feet can use solid masts. Solid masts are easy to build, that’s good; they’re also heavy and that’s bad because that means you’ll have all that extra wood really high up in the air. Hollow masts are obviously lighter, but they are also harder to build, hollow masts need very fine joinery and clear lumber.

I’m going to tell you how to build a hollow box mast; this is a simple square mast with simple joints and a minimal amount of cuts. I’m not going to get into the bevels and tapers that you’d need to build a hollow, tapered octagonal section mast for, lets say a 50 foot topgallent schooner or a 3 masted tops’l fishing boat. If you can maintain one of those, you wouldn’t need to follow my lesson.

To build a mast you’ll need some basic tools and a free weekend to build this thing. You don’t need anything fancy, just something that does the job accurately. You’ll need:

  • Table saw
  • Handsaw to cut the splices
  • Clamps, lots of clamps; at least 2 clamps for every foot the mast is long
  • Sawhorses to rest the mast on, about 1 for every 3 feet
  • Sandpaper for finishing the mast
  • Box Scraper for finishing the mast
  • Rags

You also are going to need a spot to build this mast. I like to have a space that is as long as the mast plus about 6 feet and maybe about 6 or 8 feet wide. Place the sawhorses about 3 feet apart along the space the mast will built in, line them up and place the end sawhorses about 6 inches back from the ends of the mast. Now that you have all of these tools, time and space. You need the most important thing, wood. I like spruce for my masts, spruce is springy and light for it’s weight but it’s a little bit pricey, You might be able to get away with a cheaper wood but I wouldn’t count on it, I won’t say “I told ya so”, don’t come crying to me when you break your mast because you skimped on the materials. If you already have a mast, make a copy of it; if not you need to go to a marine engineer and have him design you a mast, or you can find somebody who has a boat like yours and is willing to let you measure and copy their mast. I’m going explain how to build a simple mast like the one that I built a few weeks ago. The mast was 19 feet long and 3.5 x 4 inches wide. I built the mast out of 1 inch thick Sitka spruce and used West system epoxy to glue it together. I started by going to the lumberyard picking out 9 pieces of 12 foot long 1x 6 Sitka spruce. The pieces I picked out didn’t have any big knots or defects. It took about 30 minutes for me to find 9 pieces of straight clear lumber. The steps below tell explain the next major step in the process.

  1. Pick out good straight and clear lumber
  2. Measure and mark the wood that you’ve choosen
  3. Measure everything again
  4. Cut the wood to size on the table saw

You need to be really careful when you cut the wood, the saw needs to make square straight cuts. This is important, very important. When I cut the pieces for my mast I recruited 2 others to help me keep the wood against the tablesaw fence. Once I had 8 of my pieces cut I laid the out on the floor 2 pieces to a row. Once the pieces were laid out on the ground you need to move the joints around so the don’t line up, the joints need to be staggered up and own the mast.

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Yes                          NO

The joints are very important. If they all fall in a line the mast will have a weak point and will break right on that line. When the joints are staggered the load is transmitted evenly through the mast and along all of the sides.

Once you have the joints laid out lay out 8 inches of overlap for the scarf joints that are used to join the planks together. I used simple slash scarf joints on this mast as they are strong and this mast didn’t need to be highly finished. The slash scarfs should use a 6:1 ratio, 6 inches long for every inch of thickness. Once you’ve made the scarf joints, the pieces of wood that make up the sides of the mast need to be glued together to form 4 long planks that will be glued to make the final box. Lay the pieces for the side on the ground and dry fit them. Once you are certain the joint fits tightly, attach a piece of scrap wood on either side of the joint. Spread the glue on the faces of the joint and lay them together. You need to line up the pieces of wood so they form one straight piece. Once you have the wood straight you need to put the clamps on you’ll need 6 clamps for this. Put 2 clamps perpendicular to the wood right on top of the joint; don’t tighten these too tight yet. Now place 2 clamps on either side of middle of the planks, place the clamps so that they pull on the blocks that you put on the mast earlier. Once you have all of the clamps on, tighten down the clamps so the joint is pressed tight and isn’t pulled apart by the incline. Check to make sure the planks line up and are straight and then let the glue dry, don’t move the planks for at least 12 hours. Do this to all 4 sets of sides and let all of this cure overnight.

Now that we have 4 planks that are long enough to actually build the box that will become the mast that you all want so badly. After the glue has cured take the clamps off and remove the blocks that you added. If you have any glue that’s squeezed out of the joints, you’ll need to remove it before you up the sides. Check the sides to make sure they line up straight and lightly sand the thin side of actual sides of the mast. Now it’s time to actually glue this whole thing together. Make sure you have this thing laid out right before you start, this is really important. Lay one of the wide sides face down on the sawhorse place one of the skinny sides on either side of the wide one. Mix your glue and brush it on one side of a skinny plank. Now get your helper to help you lift the skinny plank on to the wide one, glue side down; do this to the other matching plank. You have 2 options at this point, the first one is to stop here and clamp the sides down and wait for the glue to dry before attaching the final side. The other one requires you 2 glue the remaining 2 edges and clamp the top piece down right now and letting the whole box dry together. Either way you will need to clamp it every 2 feet or so. Make sure you clamp each edge tight Choose one, glue the mast together and after it dries you can finish the mast.

Once the mast is dry, you can remove the clamps and clean up any excess glue. You’ll need to round the edges of the mast so they don’t chafe through any lines that touch it. I used a half inch round-over bit on a small router to do the job; you could sand it too. After the edges have been rounded over, cut one end of the mast, square and measure, mark and cut the other end to the finished size of the mast. Now that you have your mast at its final length attach the mast cap if it’s a wood one. Finishing the mast is pretty easy, sand the mast so it’s smooth and apply 2 coats of spar varnish if you want the wood to show, or primer it and apply 2 coats of paint. Once the paint is dry you can attach your hardware, lines, etc. There you go one simple wooden mast for your sailboat, go step it and go sailing… Oh and don’t forget to place a coin under it for good luck.


The mast I described in this article is very simple, most of the masts I have built are tapered and of the double box type. I intended this write up as a foundation only. Feel free to msg me with any questions, I’m always willing answer any questions and lend a hand if possible.

cbustapeck says: The lazy way to the same end is to check the newsletter for your particular boat - there are quite often orignial masts, free, in good condition, within a reasonable driving distance!

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