The Taming of the Shrew  
By Bob Booth - Warwick, Rhode Island - USA

The Cape Dory 10’ is the boat that started the venerable Cape Dory line back in 1963. Designed by Andrew C. Vavolotis, it was the first of the many designs produced during the company’s lifetime. Now only fifty-eight 10’s remain listed in the current Cape Dory Sailboat Owners Association registry. Why.

Perhaps one answer--off the wind, the boat is a shrew becoming unsafe and unwieldy in even a moderate breeze. Again, why?

The boat is first and foremost a rowing craft. According to the company’s 1970’s sales literature, “a thoroughbred pulling boat” with lines similar to many successful skiffs the CD10 is 10’6” LOA with 49” beam, narrow bows, hourglass stern and 150-pound displacement. She is only secondarily, a sailing vessel, featuring cat style mast placement and “modified” Gunter rig of 68 square feet.

It is from this rig, or more correctly, because of this rig, that the boat’s shrewish nature is derived—despite Cape Dory’s claim that the boats have “proven themselves very able and lively performers” and despite the active class racing organization mentioned in company brochures of the time (now defunct), it is difficult to take as serious any rig with no provision for reefing and which places the mast step in an elevated position in the bows only a matter of inches from the stem. Perhaps it is this distinction of design which lead to Cape Dory’s claim that, “the expert sailor as well as the novice will find them challenging…” In fact, I suggest that it is this characteristic alone which has lead, apparently quite often, to the parking of these boats in a field and there being left to rot (refer to the Cape Dory Sailboat Owners Association registry for some interesting narratives on the “finding” of CD 10’s).

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CD 10 “Sea Minor”. Note the hollow bows—mast step is located in the extreme forward end approximately 12” down from the rub rails.

On a run, should the boom go forward of what would generally be considered a broad reach position; immediate broaching will ensue, with bows buried, stern up and most likely the rudder out of the water. Secondly, barring a broaching occurrence, another trick of this rig is a tendency to self-tack when running. Here, the very forward mast placement enables movement of the center of effort forward and ACROSS the boat’s centerline as the boom lifts and the sail billows. If you are running say, on the starboard tack and sitting warm and dry in the stern sheets on the high side, the immediate impact of this action will be a wet behind as you instantly find yourself tacked and now on the low side.

All this wetting of body and loss of control may not be an issue for bikini clad teen-somethings bouncing around with the buoys but away from a closed-loop, patrolled race path, loaded with camping gear, and often in mixed company, control issues, pitch-poling or settling by the stern are not the things of fond memories. As I mentioned, this tender condition is exhibited down wind. One might well be romping along with a bone in the teeth to weather and fully enjoying the sail without one hint of the rig being overpowered only to find, upon falling off for the sleigh ride home, an immediate issue and some very hair-raising moments if in traffic.

Why then bother? Firstly, as claimed by Cape Dory, the boat is, “a thoroughbred pulling boat” and I happen to be as enamored of rowing boats as I am of sailing ones. Secondly, the GRP hulls are generally sound even if all those years in a field have wrecked havoc upon the mahogany thwarts, gunwales and fittings. Thirdly, I enjoy cruising on Narragansett Bay and the boat was free. The question became, therefore, and given that all wood required replacement, could the more or less sound 30-year-old glass hull of a finicky thoroughbred one-design be overhauled to become a sane and safe workhorse cruiser?

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Original mast step placement (shown during overhaul with original mast partner removed and new gunwale rails in progress)

Mast placement and rig: Even the most modest of studies of hull forms similar to the CD 10 will invariably indicate mast placement at the point where the bows flare into the hull—in other words where there is buoyancy to support the sailing loads. In the Cape Dory 10, this means somewhere near the center of the forward thwart. Of course, moving the rig aft means having to look into boat balance and CE vs. CLR. If we are to have a sane workhorse, what is required, in the words of John Glasspool (Open Boat Cruising, Nautical Publishing Company, Ltd. 1973), is a workboat mentality.

Conversion of the Forward Thwart

The forward thwart is comprised of a floatation chamber containing rigid foam floatation topped by a mahogany seat board. The floatation chamber is made of laid glass bonded to the hull with ½” thick pads of Bondo type material. The chamber is supported amidships by a pedestal, also of laid glass, bedded in a ¾”-1” thick pad of the same Bondo material.

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Forward thwart—note pedestal

Modification of the thwart consisted of converting the pedestal to a mast step and the thwart cover board to a mast partner.

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Interior view of forward thwart/pedestal

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Establishing mast rake and alignment

Taking angles off lines drawings of several different dinghies and testing them against the “line of beauty” by eye developed the initial mast rake angle. The hull was squared and leveled and the final angle was achieved by use of spacers. Mast was positioned using plumb bob. All was clamped tight when angles were fixed and the angles were recorded for transfer to the doublers and the thwart chamber marked with indexing marks for final assembly.

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6/4” mahogany filler block and 6/4” lower doubler—note bury. Doublers were drilled on drill press with 2” Forstner bit to the initial rake angle.
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Fitting the upper and lower doublers to index marks

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Lower doubler and filler block bedded with thickened epoxy. Thwart doubler glued and screwed—thwart doubler was used as a drill guide for cutting the thwart hole at the correct angle.
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Dry fitting the cover board

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3” bronze cover plate let into covering board.

Final fastening and alignment of cover board was done with mast in place. Cover board was clamped down and the mast was checked for binding. The mast holes in the doublers were dressed using a drum sander on the electric drill. Seat was adjusted prior to drilling and running down screws so mast was properly aligned to index marks and could be shipped or unshipped with no binding.

From a structural point of view, the method employed by Cape Dory to tie the thwarts and centerboard trunk together was to use one #12 screw through the side wall of the forward and amidships float chambers and into the end grain of the centerboard trunk cover. When fitting the new trunk cover, allowance was made for the addition of a heavy trim board screwed and bedded to the forward chamber’s sidewall. 90-degree cast brass knees were then used to tie the thwart and trunk together.

click to enlargeCompleted forward thwart—note the breast hook. The original design was retained and boat is fully convertible to the original rig. Also, foam floatation was “custom” fit with use of a band saw. Despite the loss of volume due to modifications, more foam was fit during the overhaul than had been originally installed.

Sea Trials Report

Failure of Initial Mast Step Design

A little story here concerning the bottom of the float chamber: close examination of the interior photographs will show an uneven and slopping structure around the opening for the pedestal. My first attempt at securing the mast step employed thickened epoxy. When fully set this appeared sound—permitting the boat to be shaken and moved about using this piece as a “handle”. Initial sea trials on flat water and moderate breeze found no problems. However, this design did not hold up when the boat was put on Narragansett Bay. Given wave and wake, about an hour and half into sailing north off the Jamestown shore, at the passing (and the wake) of a large motor cruiser, a loud crack was heard and the lower end of the mast gained considerable movement. The postmortem found that the epoxy bond with the thwart bottom had failed. Despite a generous portion of thickened epoxy, actual bonding contact was found to have occurred in only three places. Clearly a rethinking was in order.

All unevenness around the pedestal was taken out using micro-light filler mixed with epoxy. This was sanded and wiped clean with acetone. Three layers of cloth were laid across the bottom, covered with a sheet of plastic and the doubler laid in place and weighted. When the glass had kicked, the plastic & doubler were lifted to reveal a flat mating surface. This foundation was lightly sanded and cleaned and a coat of 5200 was spread on both mating surfaces. The doubler was realigned to its index marks and weighted until the 5200 cured. Four #8 bronze machine screws were then run down, one in each corner, red Lock-Tite was applied and all were drawn up tight with oversized backing washers & nuts.

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Faired and reinforced thwart bottom, 5200 bonding.

The modified rig has undergone four sea trails, two preceding (includes the mast step failure) and two subsequent to the step redesign. The order of trials in both cases was a flat-water trial on Lake Tiogue and a trial on Narragansett Bay. The only variable in the later two was the addition of my 12-year-old grandson as crew. Time duration of each trial was approximately 2.5 hours and included all points of sail.

Downwind performance is significantly improved, not only is the boat stable she is very fast and well balanced. This carries directly over to broad reaching: here the boat is again stable and fast. Hard on the wind the boat carries a bit more weather helm than I would like. This is not a significant issue in light airs but can be a little tiring in a good breeze (11-12 knots) if a lot of working to weather is required.

Jibes are smooth and safe enough given placement of crew in the bottom and not on the stern sheets. The boom tends to lift when running and thus does not pose an issue with heads—the boom is merely allowed to come in using a controlled turn, is caught in hand, and swung across as the boat to complete the turn.

Tacking requires the boat be carrying moderate way. Rather than pinching up, I have found falling off slightly to build speed, then putting the helm over does very well. With two onboard tacking can be improved by having the crew stand by the centerboard on “ready about”. As soon as the bow crosses the wind, raise the board and sheet home. Boat speed will come up very nicely and the board may again be dropped.

Boom height. The only time the lower step/boom causes an issue is when sheeted in hard. The boom at this point is only slightly higher than the gunwale. This does not impact the mechanics of tacking as the boat is deep enough to allow even someone like me, in my upper 50’s with arthritic stiffness to duck, but does impact the ability to see well and forces the helmsman to shift sides with each tack in order to clearly see the luff.

Rig Remedies—Some Thoughts

Boom Height

Rig-Rite of Warwick Rhode Island carries all components for the Spartan S-1 Spar System and offers a replacement mast kit comprising both end fittings and a 12’ tube section. This is sufficient mast material (total loss of step height being approximately 9”) to offset the lower step and would, weather helm not withstanding, allow maintaining the CD 10 one-design sail.

A second alternative could be to lower the attachment point of the halyard on the gaff. This would have the effect of increasing the hoist of the gaff thus raising sail and boom height while retaining all class spars and sail. My only concern with this approach is the increased length of unsupported gaff and; therefore, the increased lever arm acting upon the upper mast fittings and gear.

Weather helm: In close-hauled conditions, weather helm can be improved to some degree with the centerboard and outboard weight. Pivoting the board up moves the center of lateral resistance aft while carrying weight outboard at the rail lessens heel and therefore the tendency to turn into the wind. This will not however elevate the imbalanced induced by the aft movement of the rig.

My thoughts at this juncture lean towards a complete new rig, perhaps a lugger that would address not only the boom but also the increased weather helm. In this scenario mast height would be increased about 10”, the main sail would be reduced slightly in size and perhaps a small jib would be added. Keeping in mind the tenderness of the boat when weight is placed forward, sheet and halyards leads would need to be run aft to allow single-handed sailing while maintaining weight aft. This option, while the more costly, has the advantage of offering sail reduction choices (given reef points are placed in the new sail) and better tacking. It should also improve windward performance by allowing the boat to point higher. Even though US Sailing no longer carries the CD 10 as an active class, class compliance is retained with the old rig should a class event pop up while, in the mean time, cruising performance enhancements are offered with the new.

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Completed thwart, halyard, Cunningham leads

Alternative Use of the Original Step

A close look at the original layout of the CD 10 will reveal a lack ground tackle accommodations. Here, the advantage of retaining the original mast option becomes manifest, there is now a 2” diameter hole in the breast hook begging for attention. This hole, with accompanying mast step, is ideally suited for mounting a Samson post.

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Samson post in place