homemade sailboat mast

15' Wooden Mast for a Sailboat

Introduction: 15' Wooden Mast for a Sailboat

In the event that you wake up one day and think, "Gosh, I could really use a fifteen-foot mast," I'm going to teach you exactly how to make one yourself, starting from scratch.

Actually, this tutorial is informative not only for aspiring boatbuilders, but for any application where you need to turn square stock into round stock.

The materials are easy to acquire, but you will need access to basic woodworking machinery.

• Hardwood stock - Sitka Spruce or Douglas Fir are traditional materials
• Wood glue - Titebond III is waterproof, affordable, and readily available
• Two Bic pens
• Two copper roofing nails
• Thickness planer
• Lots of clamps
• Drawknife or power planer
• Hand plane (#3 or #4 Stanley)

Step 1: Buy Lumber

Hit Up Home Depot

Assuming a fifteen foot mast, your finished dimensions will be 15' x 2.5" x 2.5". Depending on your geographic location, you should be able to find Sitka Spruce or Douglas Fir at your local box store or lumber yard.

If the lumber does not come in 15' lengths, buy enough lumber to splice two shorter sections together. If your lumber is less than 2.5" thick (likely) you will need to glue up two pieces for thickness.

Take the time to pick through the pile, looking for stock with tight grain.

Step 2: Mill and Dimension

Back at the shop, mill your stock square and parallel. If needed, glue up stock to get 2.5" thickness. Clamp and leave 24 hours.

Be sure to use waterproof glue. Titebond III is appropriate for outdoor applications, and readily available at hardware stores.

When clamping, remember that clamping pressure radiates at 45deg from the clamp heads. Use enough clamps to apply consistent pressure over the length of your stock.

If splicing, cut a 1:12 slope at the ends of your stock and glue up to get the required length.

Step 3: Square and Taper

Using a hand plane or cabinet scraper, remove any excess glue. Joint and square one set of adjacent faces, then square the stock with a thickness planer. Cut to length. Your stock should now be 2.5" x 2.5" x 15.'

If you are making a mast, you will want to taper the pole. Rather than apply a consistent taper, boatmakers like to use a gentle arc. Think of a blade of grass bending in a breeze. This provides strength when the sail is tugging on the mast.

Draw a center line in pencil on your stock. Your mast will taper from 2.5" at the bottom (0') to to 2" at a point near the top (13') and finally reaching 1.5" at the very top (15'). Mark these dimensions.

The profile of your taper will be drawn with the help of a batten - a flexible piece of wood which ensures a "fair" curve free of bumps. Any thin cutoff will do, so long as it is sufficiently flexible and of consistent thickness. Use clamps or lead weights to hold the batten in place, making sure it touches the three marks you just made. Trace the line.

Repeat on the other side.

With a drawknife or power planer, take the thickness down to your line, on both sides.

Repeat the process of marking the remaining two sides with the batten and shaping them with the drawknife or power planer.

Clean up the faces with a hand plane. You should now have a tapered rectangular pole.

Step 4: Octagonize

Making a Spar Gauge

This is my favorite step, a feat of ratios. It also involves a made-up word: octagonize.

The first step to rounding a four-sided spar is to make it an octagon. Once you have eight sides, it's easy to move to sixteen sides, and finally to the round.

Making your own spar gauge is surprisingly simple. Any scrap of hardwood will work, so long as the edges are square. Break two Bic pens and retrieve the inkwell reservoir. You can discard the rest of the pen. Insert two copper nails as fences at a distance slightly wider than your spar, and insert the inkwells between them spaced at a ratio of 1 : 1.4 : 1. You'll want to tap holes with a drill press or power drill first, and use the correct bit to ensure that your inkwells fit snugly.

A spar gauge will allow you to draw the edges of an octagon on any square stock as you drag it along, even as it tapers, thanks to the magic of ratios.

Use the spar gauge to mark a set of opposite faces, then work down to your line with a draw knife or power planer. Clean up the surface with a hand plane. Repeat for the remaining two faces.

Step 5: Sixteen to Round

From Eight to Sixteen

Every foot or so, draw a straight pencil line around the circumference of the mast. Using a hand plane, take passes along the length of the mast until the remaining line and the flats in between are of equal length.

From Sixteen to Round

At this point, you can almost taste sweet victory. Using a hand plane, take the corners off the sixteen sides. You will be close enough to round to sand your way to the finish line.

Sweep up your shavings. Find the nearest taco truck and reward yourself.

Step 6: Finishing

Two options for finishing spars for marine use are:

• Marine varnish, such as Le Tonkinois, which dries amber and glossy and needs retouching every season
• "Boat soup," a combination of boiled linseed oil, turpentine, and pine tar, a much lower maintenance "workboat" style finish

Be sure to use gloves and apply in a well-ventilated area.

Step 7: Go Sailing

Don't forget your life jackets!

Refastening a Wooden Hull   - Season 4, Episode 1 Now Available!

How to Build a Wooden Mast

A tapered, oval new york 32 spar from the original plans.

ISLA, New York 32 No.10 (of a total of 20), was thoroughly rebuilt last year by Buzzards Bay Yacht Services of Mattapoisett, Massachusetts. The job included a new mast, whose construction is detailed on the following pages.

W hen my company was hired to restore New York 32 No. 10, ISLA, in 2008, the boat had been out of service for over 25 years. The 20-boat New York 32 fleet was designed by Sparkman & Stephens in 1935 and built over the winter of 1935–36 by Henry B. Nevins of City Island, New York. When we found her, ISLA was a virtual time capsule, with an intact original interior and a complete set of original hardware. But the hull and deck were tired, to say the least, and the spars were beyond repair. So, included in the work list were a new mast and boom.

The New York 32 carries a hollow, oval mast measuring 63′ 5″. The owners were committed to maintaining ISLA’s originality, so we acquired the original spar drawings from the S&S plan collection at Mystic Seaport. These included ample detail: spreaders, tangs, boom, and masthead, along with the overall mast plan. The following steps describe how we turned those drawings into a new mast for ISLA.

Ordering and Preparing Lumber ISLA’s mast is built of Sitka spruce, which has long been prized by sparmakers for its long, clear lengths, light weight, and impressive strength for that weight. From the plans we developed a lumber list for the mast, boom, and spreaders. While it is still possible to acquire excellent-quality Sitka spruce, it takes some searching and a keen eye for defects. We required at least 12/4 stock to fashion the forward and after staves.

For spars, it’s imperative that the wood be dry (below 15 percent moisture content) and free of defects. The grain must be vertical. Our first attempt to procure lumber for this mast resulted in us receiving a batch of 12/4 Sitka spruce that was case-hardened. It was dry to both the touch and to the moisture meter, but once milled and its center exposed, its moisture content went off the scale. When we tried to rip it on the tablesaw, it pinched the saw’s blade and stopped the saw. We replaced that batch of wood with properly dried material, and learned a lesson in the process.

We ran the rough-sawn boards we had purchased through the thickness planer to take “fur” off of each one, allowing for a better inspection of the surface of the wood. When doing so, we kept in mind the minimum thickness of the staves, so we wouldn’t carelessly plane off too much. With this done, we examined each board, measuring its usable portion, marking visible defects, and labeling each piece for its intended location in the mast. A board with tight grain is slightly denser and thus heavier than one with wider ring spacing; we strived to locate these heavier pieces toward the bottom of the spar. If another board had slight grain runout, we’d consider using it in the mast’s heel where it is under less stress and is backed by solid blocking. It’s also important to keep in mind the locations of the scarfs when selecting the lengths of stock that will compose each stave, for the scarfs must be staggered.

Utilizing the Drawing

The drawing shown here is an illustration of the original Sparkman & Stephens mast plan for the New York 32, whose vertical scale was compressed in order to fit the mast’s dimensions onto a single sheet of paper. From the drawing we created a table of offsets for the mast. To do this we drew a series of stations, 5′ apart, perpendicular to the mast’s centerline. We did this for both the side and forward views of the mast.

The drawing shown here is an illustration of the original Sparkman & Stephens mast plan for the New York 32

For the forward and after staves, we recorded the overall thickness of the stave (that is, its thickness before hollowing) and its half width. For the side staves, we recorded the thickness and width at each station. We converted the mast plan drawing from 32nds of an inch to decimal units, which I find best when working to close tolerances using digital calipers. We then made up 10″ × 10″ lauan templates on which to draw the sectional shape of the mast at each station. Since the forward and after profiles are arcs of a circle, we transferred these shapes from the drawing to the lauan with the aid of a compass. After each shape was transferred we cut out these lauan templates with a bandsaw. On each template, we also recorded the sidewall thickness, forward and after wall thicknesses, and distance from the heel of the mast. Building this New York 32 mast as was done originally requires hollowing out the thick forward and after staves in order to lighten their weight. So, once again using the mast plan, we made templates for the mast’s inside shape at each section.

The Spar Bench

The first step in building the mast is to construct a spar bench. We wanted a sturdy bench that was straight and set at a good working height. Typically, a spar bench comprises a series of sturdy sawhorses spaced 5′ apart and fastened securely to the shop floor. Identical wooden sawhorses work well for this; once they were secured to the floor, a mason’s string was run to assure that the tops were all in the same plane; the tops were then shimmed as needed to achieve this. The 2 × 10 plank seen here being screwed to the sawhorses is to support the staves during the scarfing operation, and will later be removed.

Gluing Up Full-Length Staves

On our nice, solid bench, we laid out the wood for each of the mast’s four staves end-to-end and developed a final scarf plan. We planed the stock to the maximum designed thickness for the forward and after staves (2.875″) and for the side staves (1.25″). Then we scarfed the stock together to create the full-length staves. Careful layout and labeling were required for this step. We examined the stock and put the most visually pleasing sides facing out, and we spread out the scarf locations to avoid clustering them. Scarfs were cut to a slope of 12 to 1, with their lines drawn onto the edges of each piece. They were rough-cut on the bandsaw, and then finished with a jig and a router. With the scarfs cut, we assembled the pieces dry and ran a string down each of their centerlines to confirm that each of the four full-length staves, once glued, would be straight.

When we were certain that the staves would be straight and true, we screwed blocks to the spar bench to chock them in place. The individual pieces could then be removed from the bench, turned over for gluing, and placed back in their precise positions. The final step in preparing the scarf for epoxy glue was to rough up the surface of the glue joint. Eighty-grit sandpaper backed by a long block works well for this, as does the technique we used: a Japanese pull saw drawn across the grain so its teeth combed the surface. (This process is for epoxy gluing only; resorcinol and other glues rely on smooth mating surfaces.)

Once the surface was roughed up, we vacuumed both faces of the joint and then wiped them with a clean rag and denatured alcohol until the rags came up clean. We then wet out both gluing surfaces with straight epoxy and allowed that to stand for several minutes while it penetrated the wood. Dry spots were wetted a second time. We then applied epoxy thickened with colloidal silica to one face of the joint. Using large bar clamps and modest pressure, we clamped the joints, making sure we had a nice, even glue squeeze-out.

Tapering the Staves

Once the staves were glued full-length, we selected the aft stave, blocked it straight on the spar bench, and snapped a centerline. Then, using the information from the lauan templates and the offset table, the points representing the stave’s profile were laid out and connected with a long, limber batten. One of the side staves was marked similarly.

We rough-cut the profiles with a worm-drive circular saw being careful to leave the lines intact. We then cut closer with a power plane, and then shaved precisely to the lines with an appropriate hand plane, making sure that the edges stayed perfectly square. With one stave of each profile now complete, we used each as a template for its mirroring stave, making the final cuts with a router and bearing bit to complete the second pair of staves.

To minimize weight aloft, the wall thickness diminishes as we progress up the mast. Once again we turned to the lauan templates on which we’d recorded the wall thickness at each station. Using digital calipers, we recorded on both edges of each stave the wall thickness at each station and connected the dots with our long batten.

This line, yet to be cut, is shown in the drawing. The stock was removed from the outside faces of the staves, the bulk of it with a power plane. The final cleanup was completed with a bench plane.

Rabbeting the Forward and After Staves

Hollowing the Forward and After Stave

The final step before gluing the staves together was to hollow out the forward and after staves. On the lauan templates we referred to the inside profile shapes we had recorded from the mast drawing. Dividing the inside profile into 1⁄4″ sections, we measured and recorded the depth at each section. We did this at each station. The inside face of the stave was thus lined off in 1⁄4″ increments.

Then, using a circular saw set at the depth indicated by the lauan template, we cut kerfs in the inside face of the stave. With each pass of the saw, we reduced the depth of the cut as we moved toward the masthead and farther from the center of the stave. With the kerfs completed, we used a gouge to scoop out the waste. We arrived at the final shape by using a backing-out plane followed by 80-grit sandpaper on a round sanding block.

With the staves cut to their profiles and tapered in thickness, and the forward and after staves rabbeted and hollowed, we double checked that the spar bench was still straight. The next step was to lay the after stave on the bench, sail-track side down, and hold it straight with blocks screwed to the bench so the spar could not move. We then did a final dry-fit of the three remaining staves to make sure all joints were tight.

When satisfied with the bench and the joints, we began mixing glue. A large spar such as this takes about four people to glue up; any fewer, and panic would certainly ensue. The glue-up seems to work best as a two-step process. The first step was to glue the side staves to the after stave, using the forward stave as a dry-fitted guide to ensure that the side staves remained parallel. We clamped the spar in 1′ increments, checking that it remained square along its entire length. Using the two-step process allows ample time to fit and install the solid blocking at the head and heel of the mast. The drawing calls for blocking in the bottom 11′ of the spar and in the top 2′ 6″.

The blocking is solid until about the final foot, where it tapers to a feather edge on either side of the spar, forming a swallow-tail shape to avoid a hard spot. This heel blocking has a drain hole, in case of water intrusion. There is no blocking at the spreaders; instead, the spreaders have an external bracket and blocking system that transfers the load evenly to the spar.

We coated all interior surfaces with epoxy. At this stage, we also ran all of the wires inside the mast, securing them with large cable clamps. (Conduit fastened securely along the interior of the spar—and through the blocking—works well for this, too.) When everything was satisfactory inside the mast, the forward stave was glued to the side staves to cap the assembly. Several varieties of clamps can be used when gluing up a spar: spar clamps, bar clamps, C-clamps, or a banding tool. We used a combination of clamps and a banding tool supplemented with wedges to further tension the plastic band.

With the glue cured and the clamps off, it was time to begin the shaping process. The first step was to plane off the excess glue. With that done, we again turned to our handy lauan templates and began the process of eight-siding the spar. Using the exterior cross-section drawn on each template, we found where a 45-degree line would be tangent to the mast’s outside surface at each station. We transferred these points to the spar, and with the long batten connected them with fair lines.

We then set our circular saw to 45 degrees and made a cut, just leaving the line. Repeating this on all four sides of the mast, and then fairing up the saw cuts with a power plane followed by a hand plane, yielded an eight-sided spar. We then lined the spar off again to 16 sides, but this time we omitted the circular saw and removed the waste with only a power plane. When we had the spar 16-sided, we finished the rounding and fairing with hand planes and a custom-built concave fairing board. Once again our lauan templates came into play, as we used them to confirm the correct shape at each station. Two other details that had to be considered at this stage were the shape of the heel of the spar, and the masthead detail.

With the mast now shaped and sanded, we broke out the varnish and applied 10 coats before installing the track and hardware. We were fortunate to have all of the original tangs and other fittings for this spar, because fabricating them would have required quite a bit more work. With the spar varnished the hardware was installed, carefully bedded in soft compound. We were very careful in fastening into the Sitka spruce, as it is quite soft. We chose machine screws rather than wood screws for mounting the winches and the boom gooseneck track—after testing these fastenings on offcuts to find the best pilot-hole diameters.

This article was originally published in  WoodenBoat No. 214, May/June 2010.

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Wooden Mast and Spar Building

A mast or spar made from wood not only looks and feels good but it also takes advantage of the naturally ability that trees have developed over the centuries for creating a tall, strong, flexible pole.

Those tall straight pine and fir trees are able to grow to such heights and survive in wind storms because their natural elasticity absorbs the shock loads caused by gusting winds.

Structural Considerations

Solid/grown spars, rounding the square.

• Built Spars
• Your comments and suggestions

There are several reasons why soft woods are the chosen type of timber used in the making of masts and spars.

The first and most obvious is that so any soft wood trees grow exceedingly tall and straight.

And because they have grown so tall and straight they have developed the ‘elasticity’ to withstand all that the elements can throw at them.

Soft woods are also more likely to be lighter in weight.

Sitka Spruce (Silver, Tideland or Menzies Spruce) has long been the top choice for mast builders.

However many other spars have been built using whatever light, straight-grained wood was available, such as those shown below.

• Douglas fir (British Columbian, Oregon, Idaho, Red, pine also known as Red or Yellow fir)
• Scots pine (European redwood, Northern pine, Red pine, Redwood, Scots fir, Norway fir, Swedish fir, Finish fir)
• Port Orford cedar (Oregon cedar, White cedar, Ginger pine, Lawson’s cypress)

When choosing a timber look for one that is as light and straight grained as possible with, hopefully few knots.

However, a few small ones knots can be acceptable.

The timber should ideally be seasoned, especially if you are building a hollow spar.

I have heard of solid masts being made from green poles.

But green timber is more likely to develop shakes and will be less able to absorb any preservative, oil, varnish or whatever you use as a finish.

A mast/spar needs both strength and stiffness and be able to resist fatigue.

Sometimes these characteristics can be conflicting.

Strength or resistance to breaking in wood involves its elasticity which allows the wood to bend to absorb stresses.

Whereas stiffness is the resistance to bending.

All spars need to be able to absorb the shock of a gust which the wood absorbs by bending but too much bend will spoil the sail shape so a happy compromise is needed.

And stresses will differ depending on the types of rig and whether the mast keel stepped, deck stepped or in a tabernacle.

Another consideration is weight aloft.

Keeping weight within reasonable bounds is just one of the reasons for using soft woods.

It is also one reason for building a hollow mast.

However, most spars taper towards the top, as the diameter becomes smaller so the weight becomes less.

For the average cruising yacht the weight differences between a solid and a hollow spar are hardly significant.

The other advantage of the hollow, built spar is that it can be made from easily available timber sizes, and with a minimum of waste.

The simplest, easiest and least wasteful spars are produced from ‘grown’ timbers.

I theory it should be possible to acquire a trunk which has the length and taper needed for your spar.

In practice you will have to do some shaping, tapering and rounding.

While traditionally masts and spars were spherical, they don’t have to be.

However, in my opinion a spherical mast will produce the least turbulence to the air passing over the rig.

It is possible to make a spherical spar from one piece of square cross-section timber.

However, it will be much easier to source timers of smaller cross-section and then build the spar up from them.

And the advantage is that the grain can then be arranged in a radial fashion.

Building a spar from separate parts does require very careful attention to the gluing surfaces, they must be closely mating and the actual gluing must be precise.

If you are confident in your carpentry and gluing skills, short lengths can be scarffed  to produce the required length.

Scarf joints are best at least ten times the thickness of the piece and when the various pieces are assembled the joints should be staggered.

And remember to never ever cut a piece of wood to its exact length until you absolutely have to.

First determine the required diameter of your spar and then where you want your it to taper and by how much.

This will depend on the design of you rig.

You may want the spar to have no taper for some of its length/height, to just above the partners, then have a slight taper, perhaps as far as the spreaders,  then a bit more of a taper up to the truck.

Always best to start with the wood a little wider, thicker, and longer than the finished dimensions.

Plane one surface flat and level with your longest plane, preferably a jointer.

Then mark the center line on this planed face.

Use a string stretched between tacks in the middle of each end, use this to make several center marks on the timber.

Then join the marks using a long, straight batten.

Repeat on the opposite face.

Now use the centreline as the datum from which to mark the width of your mast at intervals along its length.

Then back to the batten to connect these marks.

You can now cut the outline of your mast to this drawn profile but cut it oversized as you still need to plane the timer square.

Now plane these two sawn, tapered faces flat and square to the original planed surface.

Repeat the steps for marking the center line and profile on these two new faces.

Cut this outline and plane these sides flat and square to their adjacent sides.

You now have a spar tapered to your requirement but it is still square in cross-section.

Now you need to start rounding the square.

So now you’ve got a nicely tapered, planed but square, four sided spar.

Next job is to plane off the four corners to give you an eight sided spar.

Then plane off those eight corners to give you a sixteen sided spar, which can then easily be rounded using sandpaper.

But before you start taking off the corners you need to mark the depth of the bevels.

The simple way is to draw a circle on the face of the timber with a compass.

The center of the circle will be on the centreline and the edge of the circle right on the edge of the face.

Then draw a line from the center of the circle, at 45 degree to the centreline and mark where it crosses the circle.

This mark is the edge of the bevel.

Do this for every transition point and as many points in between as possible, the more the merrier and do it foe both sides of the circle.

These marks can then be joined using your batten.

One you have planed the spar down to eight sides you can use the same method to mark it up for reducing it to sixteen sides.

But now the line from the center of the circle to the circumference needs to be 67 ½ degrees.

Now unless you are building a massive spar getting from 16 sides to 32 sides using the above measuring technique is going to become fiddly.

At this stage it is quicker to use your eye and your judgment to plane off the remaining corners.

Then the final rounding can be done by sanding.

Start with 60 or 80 grit paper for the initial shaping, then work the grits for finishing.

Use long strips of sandpaper wrapped around the spar and pull it backwards and forwards in a long, spiralling motion.

Occasionally sand along the length of the mast to help fair out any uneven spots.

Here is an easy way to mark out a tapered octagon using only one setting of your compass.

Building a spar is obviously much more difficult than simply shaping a solid pole.

However, if a pole of the required dimensions is not available building the spar might be the only option.

Built spars can be either solid or hollow.

But if you are building one it is relatively simple to make it hollow and thus save weight aloft and create a central channel for masthead wiring.

Building a simple cylindrical spar as those shown above from ‘square’ timbers does require wasting quite a lot of that expensive wood when 'rounding the square'.

One can build an almost waste free hollow spar which would suit a conventional bermudan rig.

However, a ‘square’ section with rounded corners such as this would be unsuitable for any rig which uses mast hoops or parrel beads or a lug rig where the spar turns against the mast.

The next problem when creating a hollow spar is that unlike the solid mast the taper cannot be created afterwards.

Any taper to the finished spar needs to be cut from the staves before they are assembled.

There have been several configurations used to increase the gluing areas across the width of built staves.

And several configurations which attempt to reduce wastage and at the same time produce large gluing surfaces.

Unfortunately while they will produce superb, strong spars they call for increasingly complex carpentry.

The ‘Birdsmouth’ technique developed by Nobles of Bristol UK is perhaps one of the most successful of these techniques.

However, it is a technique which really requires access to woodworking machinery, such as profiling and planing machines.

Setting up your standing rigging can be greatly simplified by using ‘Spectra’.

‘Spectra’ is virtually stretch free and can be tied off without much weakening.

It offers a real alternative to expensive swaged fittings, can be easily maintained and it is corrosion-free.

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I am perfectly aware that the majority of Wooden Boat aficionados are sensible folk. However, I need to point out that I am an amateur wooden boat enthusiast simply writing in order to try to help other amateur wooden boat enthusiasts. And while I take every care to ensure that the information in DIY Wood Boat.com is correct, anyone acting on the information on this website does so at their own risk.

50th Anniversary Collectors Issue - September/October Issue No. 300 Preview Now

A “New” Method for Hollow Wooden Mast Construction

By reuel parker.

I have developed a “new” mast construction method for use on light- to moderate-displacement sailboats having a Marconi rig, and for motorsailers. I put “new” in quotes because I am sure it has been thought of before now.

Mast Section from step to spreaders, 9 1/2″ x 7 1/2″ outside dimensions.

The four corners of the new construction sequence are all made identical in section, from Douglas fir or Sitka spruce 3″ x 3″ lumber. The corner pieces are rounded to a 2 1/2″ diameter radius, the inner corner is cut to a 45-degree bevel (to lighten the mast), and 1/2″ x 3/4″ rabbets are cut onto two corners to receive 1/2″ marine plywood front, back and sides. The corners are epoxy scarfed (8:1) full-height. They are identical in every location, greatly simplifying construction, as all corners are cut using a table saw set to the same settings. All mast taper is made on the plywood sides, back and front.

Construction uses epoxy glue and monel or stainless steel fasteners (staples, nails or screws) 6″ on center. With proper clamping, fasteners may be eliminated altogether.

The mast section is uniform from step to spreaders (as shown above). Above the spreaders, mast section tapers parabolically to 5 1/2″ x 7 1/2″. If so desired, for further weight-savings aloft, the inside corners may be cut deeper, removing more material. Doing so will weaken the mast only very slightly.

Mast Section at Head is 5 1/2″ x 7 1/2″—taper is parabolic above spreaders.

All fore & aft mast taper is on the front only—the back of the mast is perfectly straight for its entire height unless built-in “pre-curve” is desired. [The purpose of pre-curve is to automatically flatten the sail chord for windward work as the sail is sheeted in.] A 1/2″ plywood backup block is installed inside the mast back to receive fasteners for the #1808 Harken track shown.

Plywood panels from step to spreaders are ripped on the table saw to uniform dimensions. Panels above the spreaders are ripped for parabolic taper (back edge straight for the sides). Front and back panels above the spreaders are ripped along both edges for taper. Plywood panels are scarfed 8::1. If desired, for greater durability, the mast may be wrapped in 4 oz Xynole-polyester fabric saturated with epoxy, with the seam located under the mast track (this will add weight). The inside of the mast is epoxy sealed. Wires (including lightning ground) are pulled in PVC pipe attached to a side panel prior to lay-up.

Note that in my drawings, the edges of the plywood are affected by the radii of the mast corners. When finishing shaping, the outer laminate will be abraded along the edges. Masts finished in this fashion will definitely require fabric/epoxy covering. You can avoid this by making the radius 2″ instead of 2 ½″, at the expense of a more “square” looking spar section.

For the nut-cases (I have been one) who insist on having varnished spars—make the corners (use the 2″ radius) and plywood from the same species wood; epoxy seal and apply 12 coats of varnish that has a good UV filter—I recommend using Douglas fir for the species. I generally prefer using epoxy primers covered with linear polyurethane topcoats—very durable—and almost no maintenance.

The Harken #1808 track shown uses “Battcars” designed to receive the forward ends of solid fiberglass full-length battens. The only sail cars necessary are one for each batten, and reef points are located immediately below each of the lowest three battens. This simplifies sail construction and cost, and simplifies reefing, especially when used in concert with my Basket Boom, which contains the reefed portion of the sail. Said boom (my wishbone-style Basket Boom), also uses Battcars located at the base of the track (see Boom Detail drawing below).

Spreader details.

Spreaders are made from polished 1″ stainless steel thin-wall tubing (or 3/4″ aluminum pipe) welded to 1/8″ stainless steel side and back plates. The plates are attached to the mast with 1″ x #14 flat head self-tapping screws, and are bedded with polysulfide rubber. Spreader lift angle should bisect the angle the upper shrouds make at the wingtips.

Detail of a masthead—the SS top plate is configured fore & aft for application (shown is the foremast for a schooner with equal height masts).

The masthead is made by adding solid wood sections fore & aft with a 1/2″ plywood cap to support two stainless steel straps, drilled and bent at their ends to receive shackles for stays and shrouds. Delrin sheaves (3″ Schaefer) are used for internal halyards as shown above. Sheave pins are 7/16″ SS. Dimensions shown are for masts on a 45’ motorsailer using 5/16″ shrouds, triatic stay and twin backstays, and 3/8″ forestay and main stay.

The mast construction, as drawn, is much stronger than necessary for the specific application intended (Motorsailer 45), and the solid corners could be made from 2x4s (as described below), in lieu of the 3x3s shown. This would save materials costs, and to a lesser extent, labor. I would stress, however, that air-dried wood is much preferable to kiln-dried wood for durability and rot-resistance. If using kiln-dried wood, I would be very thorough in epoxy sealing the mast interior, and I would cover the finished mast with Xynole-polyester fabric and epoxy. As always, great care should be taken with bedding compounds (these days I mostly use Bostik #920, above and below the waterline).

Basket Boom details.

I developed a new type of boom several years ago to utilize the Harken track. The upper portion is a “wishbone” boom, which clears both sides of the sail. The lower portion eliminates the need for a vang. When the sail is dropped, it falls inside the “basket”, which may have lacing on each side (not shown) to contain the sail and battens. A sail cover may be placed inside the basket boom with a top covering panel secured by Velcro. The boom could alternately be fabricated from polished stainless steel, using 1-1/2″ thin-wall tubing.

The basket boom uses two Harken Battcars at each attachment point (upper & lower), and should incorporate a downhaul to increase luff tension. In adapting this boom to other vessels, note that the wishbone must be designed to contact the after shroud (when reaching or running) before it touches the mast to prevent damaging the track and fasteners.

The new mast construction is intended for the Motorsailer 45 shown above, but may be employed on any light- to moderate-displacement vessel in this size range using the Marconi rig and single (or double) spreaders.

The new masts may be tabernacled, deck-stepped (over compression posts), or keel stepped. The overall weight of these masts will be as light or lighter than that for aluminum masts of equivalent strength .

For lighter loads or for even lighter-weight masts, corners may be made from 2x4s (on the flat at 45 degrees); and sides, front and back may be made from 3/8″ 5-ply marine plywood (such as Shelman or Joubert). Smaller masts and spars can use the same construction, with scantlings down-sized appropriately. Fabric/epoxy covering will prolong mast life, but is not particularly necessary structurally. All fasteners penetrating the finished mast should be either sleeved (bolts for shroud attachment) or carefully bedded using flexible, UV-resistant compound.

I know carbon-fiber masts are all the rage now, but I still firmly believe that well-designed and –made wood/epoxy masts are the overall best in terms of light-weight, strength, durability and low cost. A mast made using the above method will cost a fraction of an equivalent mast in carbon fiber or aluminum, and it will be more durable. As I keep telling people, aluminum is good for beer cans!

4/2/2014 St. Lucie Village, FL

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