Masts as if they Grew on Trees

Dried out for Mastwork… Lumberyard in Background.

Most of the boats who’ve ever sailed have had solid, grown masts.

Extruded aluminum, fiberglass, modern adhesives and even spiral welded metals have recently brought hollow masts to the fore. They’ve taken over to such an extent that it’s sometimes overlooked that alternatives are possible!

And for some good reasons. Well made hollow masts are lighter, stiffer, in some cases stronger… and hollow. Haulyards and wiring to masthead electronics can be lead up the hollow, which can provide floatation in a beam-ends knockdown. That haulyards can jam and electronics fail causing mast high hassle somewhat detracts from the advantages, but still. Net plus, so far.

But solid, grown masts are generally free. They only take felling, cutting to length, barking and maybe a little shaping at the head and foot. A morning’s work at an easy pace with bowsaw and draw-knife, leaving the afternoon for transferring hardware, erecting and rigging. Vamanos!

All this takes place in the woods or on the beach, requiring no shop, tablesaws, level sawhorses, clamps, scarphing, rounding, end-plugs or butterfly internal supports.

We live in a good area for spar stock. Sitka Spruce has been considered prime material since the age of sail. It’s light weight and long fibers are bio-engineered for the high winds of the Pacific Northwest. Many other trees – fir, larch, pines and members of the cypress family, to name a few – work fine, and grow straight and true in almost any area that sports trees at all.

We find good candidates on alluvial fans and in dense, middle aged stands, where young spruce got a good start, but shaded out. Close to the water is always a plus!

One advantage of lug rigs is that, since the sails aren’t fixed along the mast, they needn’t be straight. There’s a kind of funky beauty to masts with a wow… but I must admit I’m not yet taoist enough to take advantage. If you can, it’s best to orient the wow fore and aft (in a plane with the centerline of the boat).

I’ve read that more than 9 annular rings per inch gives no strength advantage, but figure the more the merrier. We generally avoid less, and regretted it the one time we made an exception. If flaws or rot pockets are found, then we’ve got a weeks worth of firewood.

Sizing is by formula – we use that from The Chinese Sailing Rig by Van Loan and Haggerty for our free-standing Junk Rig. This specifies mast diameter at the partners (hinge pin at the tabernacle, in our case). The mast may taper to half that at the masthead. CSR gives a method for trimming to an even taper, but life’s too short! The tree’s already perfectly engineered. We look for about the right proportions and go with that.

We like deck oils (UV resistant) to coat, and smear the upper endgrain thickly with anhydrous lanolin. Paints open when it inevitably checks. The lanolin seems to ride with ’em, and keeps water out. I doubt this is a real problem, though, if the head is shaped to shed water.

A Heron adorns the MastHead Fitting.

Something is required to anchor rigging up high. A simple wooden cross pin or two work perfectly well, siezed above and below with nylon marline to resist splitting. Spliced eyes in the upper rigging are slipped over the masthead and bear up on these.

To support a welder friend, we went with a metal weld-up from aluminum pipe with flanges at 0, 90 and 270deg off forward.  A fourth flange 45deg off aft on the side the sail hangs, and a bit longer carries the haulyard. The forward one anchors the lazy-jacks (which pass around the mast, down and aft). The other two are standby for if we ever want running backstays or somesuch.

If setting in a tabernacle (which I warmly recommend), the other piece of hardware is a hinge, affixed to the front or back of the mast at a level that lets the foot hang an inch or so proud of the deck. We use a heavy galvanized strap hinge used for fences. Lag screw it onto the mast and seize it with wire just under the hinge loop (to back up the lag screws).

Once the mast is in position and we’ve inserted the hinge pin (stainless rod). We tie a lanyard to the bolt, and start taking wraps… away from the bolt, round the mast, round the bolt on the other side and back, repeating until we’re out of room, and then make fast. This further backs up the hinge mountings. Might be overkill, but we rest easy!

Aft Tabernacle with cushion
Fore tabernacle showing lanyard wrap (doubles as cushion for this mast).

One problem we’ve had is that the tabernacles tend to be a bit loose fit. We build them oversized, to take non-exact trees, but the slop lets the mast move, slightly, from tack to tack. Cedar wedges work for a bit, but compress and fall out. Our solution was to wrap narrow firehose (wide webbing would work, too) with just enough turns to make a tight cushion between tabernacle sides. It’s a little more work getting it to set on raising, but stays nice and firm in all weathers.

Last bit is pinning the foot. Usually, this hardware goes with the tabernacle. We use a cross pin of the same stock as the mast hinge pin, passing so as to block the swing of the mast foot. We flatten the foot, parallel to this pin, and add a wedge from top. Typically, we’ll set a screw through the wedge and into the mast, to ensure it stays in place. To prevent side to side motion at the foot, we stand planks to either side (they can’t fall out, like the upper preventers did.

Forward tabernacle, pinned foot.


When we were finishing up with SLACKTIDE, we put the masts up and bent the sails – time for a party to bid farewell to our Sitka friends. One of them immediately dubbed it our erection party.

A good time was had by all!

Originally posted 2016-05-03 18:56:06.

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