Making the new sail

I left the boat in Greece back in November. I will be getting back to it in late April, hoping to finish it this spring and summer. While in the United States, I bought some chandlery (pieces of specialized hardware) and found some more left over from previous boat building efforts. I also designed and made the new sail. Like I said before, this time the rig will be a very simple, traditional and sturdy one, a sprit. One mast, one sail with a sprit (a sort of yard holding up the peak of the trapezoidal sail, attached to the mast with a piece of line improbably named a snotter). No halyard, no boom, no reefing. The mainsheet will be attached directly to the clew. The whole sail will be ready to be doused in an emergency with a simple contraption called a brailing line. Brailing pulls the leech and the sprit up against the mast, instantly killing the sail's power. Thanks to David Nichols' book The Working Guide to Traditional Small-Boat Sails for many of the ideas.

As usual, I bought my sailmaking supplies at sailmakerssupply.com. The sail is trapezoidal, approximately 100 square feet (9.2 m2). It's the largest single sail I've made, with a 9 ft luff, 12'8" leech and 10 ft foot. As with previous ones, it has three-layer reinforcing patches and grommets in each corner (first photo). It also has a series of grommets on the taped luff (second photo). These will be used to permanently lace the luff to the mast.

I used a dart (second photo) at the tack and broadseaming (a seam of variable width) down the middle to add camber (curvature) to the sail. There is an extra couple of grommets on the leech: one for the brailing line to go through and one to secure the peak if I choose to drastically reduce sail by another improbably named technique called scandalizing: this involves removing the sprit and folding the sail into a triangle. We'll see how that works and I will try to post photos of scandalizing in action when the time comes.

I will carry the folded sail and other supplies in my luggage. Hopefully the boat will be ready for them before the end of the summer. If not, we'll see how it goes in 2020. Getting the boat registered, plus buying and registering a trailer and a small outboard are such complex bureaucratic maneuvers that I have no idea when my boat will hit the water.

The new design

The design of the new, unnamed boat is very similar to Aerie’s: marine plywood, v-bottom, four strakes per side, 176 inches long. It has some important changes in the structure and sailing equipment, all born of experience:

1. It is built around a three piece backbone consisting of keel/skeg, keel/stem and centerboard trunk all joined together, with the keel made of two layers of 12mm (half inch) plywood. Instead of a keel batten, garboard cleats are glued and nailed to the keel and CB trunk. 
2. Another important modification is the design of the centerboard, whose pivot bolt is positioned on the keel under the hull, to prevent leaks through the pivot hole. The centerboard is wider and the CB trunk is almost completely enclosed, with a small corner opening for the line and blocks for raising and dropping the centerboard. This will prevent water from splashing into the boat. The centerboard will be weighted with lead, both so it can drop easily and for ballast below the waterline when lowered. The CB was designed in tandem with the sail for a balanced helm, using techniques learned from David Nichols' The Working Guide to Traditional Small-Boat Sails.
3. For simplicity, the boat will be a cat with a single sprit sail. This way there will be no halyards (the sail will be permanently laced to the mast), no boom and only three lines: a sheet clipped to the clew, a snotter for the sprit and a brailing line for dousing the sail in rough weather. Again, thanks to David Nichols for many ideas. This being a sea-going vessel (albeit in the Mediterranean and very close to land for beach hopping only), a small outboard and oars will be on hand for when the wind is too weak or too strong.
4. The fact that I am building a cat means that there is only one forward bulkhead, at 28 inches (711mm) aft of the stem of the boat. The mast partner will be secured to this bulkhead and the foredeck.
5. The new boat has a bit less freeboard. I found that Aerie had too much, especially for the purpose of fitting an outboard. An added bonus is that the long hull pieces (garboard & strakes) will fit on two pieces of plywood (scarfed together) per side.
6. There will be a bit less in the way of seating and no lockers (again for simplicity). Instead there will be four storage compartments with open access ports cut into the bench risers. In addition, there will be three buoyancy compartments (fore of the transom and under the foredeck and rowing thwart) filled with expanded polystyrene. I got tired of relying on watertight compartments for buoyancy: they never are fully watertight and are a pain to drain and dry after water gets into them. I will make sure that the compartments have drainage holes. 
7. There will be no floorboards, which proved to be an annoyance on Aerie. Instead I will reinforce the bottom with extra plywood strips and finish it with anti-slip grit.

Sail Plan

When I started this blog I said that my plan was for a cat ketch, with a balanced lug fore (main) sail, and a standing lug sail with a sprit boom at the mizzen (aft) mast.

Upon reflection, I decided that it would be simpler and better to have the same type of sail both fore and aft.  I like several things about sprit booms, and B&B Yacht Designs expresses them eloquently.  One of the best is that, when the boom goes about, at worst you get slapped by a bit of canvas, instead of a length of wood or metal which can knock you senseless and/or overboard.  

The second reason was a balanced helm.  The placement of the mizzen mast partner (at the rowing thwart, just forward of frame 5) and the centerboard (between frames 3 and 5) was largely dictated by the boat’s basic design (the placement of the boat’s frames), so I had to design the sail plan around them.  I did, but at first I neglected to take into account the effect of the skeg and rudder on the Center of Lateral Resistance (CLR).  Adding these to the calculations moves the CLR aft, which means that the original sail plan would have resulted in a serious lee helm.  A lee helm can be dangerous: the moment you let go of the tiller, the boat turns away from the wind and it’s off to the races.  It’s best to have a slight weather helm, where the boat will naturally turn into the wind in an emergency and stop dead in its tracks.  I therefore had to move the Center of Effort (COE) aft too.  

To accomplish this, first I moved the mainmast position aft to just forward of the foremost bulkhead, about 22 inches from the bow.  This led to a reduction in the mainsail size, which also moves the COE aft.  Then I changed the sail type to the standing lug/sprit boom combination, which added to the effect, since the tack of this sail is further aft than a balanced lug’s.  Finally, I opted for a smaller main mast/sail and a larger mizzen mast/sail.

Taking all that into account, the sail plan now looks as you see it below.  It took me a while to make good on my promise for a full hand-drawn sketch, but better to be late and accurate than early and wrong.  The centerboard did not fit on a regular sheet of paper at an inch-to-millimeter scale, so it's truncated.  COE marks the combined center of effort.

The mainsail has an 84-inch (2134 mm) foot and a 96-inch (2438 mm) yard.  The sail area is 58.5 square feet (5.44 m²).  The mast will be 142 inches (3607 mm) long and 2 ¼ inches (57 mm) in diameter at the partners (click on "spars" label on right to learn more).  That’s a short mast, which has many virtues: it fits easily inside the boat (with the fore locker sliding door open), it’s short enough to be unstayed (no standing rigging!), it has a lower COE and center of gravity (which makes the boat more stable), it’s cheap to make and simple to work with. The clew of the sail will have about 6 inches (152 mm) of clearance forward of the mizzen mast, and 36 inches (914 mm) of clearance from the seats, leaving plenty of room to avoid the swinging boom-end with no ducking for most people.

The mizzen sail’s dimensions are proportional to the mainsails, and about 93% the size.  Thus we have a foot of 78 inches, an 89-inch yard, and an area of 49.5 square feet (4.6 m²).  The boom-end at the clew will be a little aft of the transom.  Clearance from the seats is the same as with the mainsail.  Mast length is 139 inches (3531 mm), and diameter the same as the main’s.  Given the dimensions of the two masts, it is possible to make both with a total of nine 8-foot boards.  That assumes no errors: hope springs eternal. 

You may wonder why the two masts do not conform to the 93% ratio.  First of all, the mainmast step is a full 5 inches further above the baseline than the mizzen one, so the total length can be correspondingly less.  Secondly, what matters for the proportions is not total mast length, but the length between the tack and the yard, which is only 97 inches in the mainmast, and consequently 90 inches in the mizzen. 

Under the final sail plan, the COE is well aft of the middle of the lowered centerboard, which should make for a balanced helm (fingers crossed).  The total sail area will be 108 sf (10 m²), which should make the boat reasonably zippy.  

Balanced helm, zippiness and how close and how well the boat will sail upwind all remain to be seen, and I may need to make more adjustments after the boat’s launch.  I am hoping for 90-degree tacks but will settle for 100.  Heck, I won’t be racing against any tall-aluminum-masted affairs with complicated standing rigging, genoas, fancy boom-vangs, jibsheet capstans and the rest.  My whole boat design and building effort is based on a principled rebellion against high-tech complexity, uniformity and the racing rules that spawned them.  In any case, if other traditional sail aficionados are to be believed, my Aerie should be able to leave behind any comparable Bermuda-rigged boat on a beam or broad reach, where lug sails excel.

By now almost all of the hull work is done.  As you can see, though, there’s plenty more, so keep reading 176inches!

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Design Choices

What went into the design you say?  Well, it was meant to be an open boat, about 15 feet, with plenty of stability and freeboard, and pretty dry in a chop.  It needed to be a capable sailer (including single-handed sailing) and easy to row.  Preferably it would look old-timey, but not be impossibly hard to build.  I would have a short unstayed mast or two, but the rig would be flexible.  It would have adequate storage, plus extra buoyancy in case of swamping or capsizing.  The oars had to be stowable out of sight, and the floor had to be flat.

That's a pretty complicated combination.  What I settled on was a lapstrake design (nice and traditional looking) with a V-bottom (ditto, and less slappy on the waves), with four strakes per side (easier to build but still nicely rounded), built around a total of eight frames, including transom and two full-size bulkheads.  Unlike regular lapstrake forms, the frames will be permanent and will increase rigidity.  The boat will have side benches all the way from transom to main forward bulkhead, with storage and buoyancy built into them, and large storage lockers fore and aft.  It will have a foredeck and side decks for dryness, and a removable plank floor with room under it for oar stowage and lead shot ballast in a special compartment.

The hull will be built upside-down over two sturdy sawhorses, connected with wooden runners on wheels, so the whole thing can be moved in and out of my small, unheated garage.  Most of the work will have to be done in the warm season, because epoxy doesn't cure in the cold.  The vertical risers of the side benches will sit on top of the saw horses, and the frames and bulkheads will interlock with them like three-dimensional puzzle pieces. 

The other decision to be made was the rig.  At first I thought that it should be switchable from cat to sloop, the latter with a jib and a bowsprit.  But that would have meant a tall mast, which I dislike.  I then considered a yawl rig, which I rejected for various reasons.  The chosen rig was a cat ketch with a balanced lug main and a standing lug/ sprit boom mizzen.  For more on all these old-timers, you could read David Nichols's book.  Still, there will be four different possible mast steps that can accommodate all four possible rigs.  I like the cat ketch design, because it is stable, has two smaller and more manageable sails, and is very easy to tack and to sail single-handed.  It also means that a mast hole goes through the rowing thwart, and the centerboard case has to be slightly off center.

So there you have it.  Next time I'll talk about the mechanics of the design and planned building techniques.

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