Tuesday, September 8, 2020
End of Project
Saturday, February 29, 2020
Custom Hardware
Three years ago I bravely published a post titled “The Final Sheeting Arrangement.” I was filled with optimism at the time. After much experimentation I had discovered a simple way to keep Quidnon’s Junk sails sheeted perfectly flat. I had tested it out on a 1:12 scale model and verified that it worked very well indeed. But soon after I published it my friend and very experienced Junk rig operator Dave Zeiger blew my boat straight out of the water by pointing out a major problem with my design: it would not keep the sails anywhere near flat once they have been reefed. I accepted his critique with equanimity and, since I had no solution to offer, kept quiet about it for three years, during which, luckily, not a single person endeavored to build a single Quidnon, and so this unsolved problem hasn’t hurt anyone.
But now I believe I have finally found a solution. With this problem solved, the Quidnon project can finally move past the head-scratching phase and on to the next phase, which will involve grinding out a large number of mechanical drawings, assembly diagrams and other documentation without which no boat can ever get built. Here, then, is my plan, which I will call “The Final-Final Sheeting Arrangement.”
The previous, “final” sheeting arrangement involved attaching the sheet to a padeye on the deck arch near the centerline of the boat, sending it through a block on the boom, down through a block some distance out on the deck arch, up to the first batten, down to another block a bit further out, up to the second batten, and so on. The blocks on the deck arch are mounted on a T-track, allowing their positions to be fine-tuned. Likewise, the blocks hanging from the boom and the battens can be repositioned closer or further away from the leach of the sail for optimum performance on all points of sail. Here is what that looked liked on the scale model, in quite a stiff breeze.
The reason this arrangement works so well is that each block on the sail receives exactly 1/5 of the overall tension on the sheet.
However, this only works on the full sail, all 50 sq.ft (4.6 m2) of it. But if it’s reefed (lowered part way, that is) to compensate for stiffer breezes, more force is concentrated at the bottom, warping the sail and ruining its efficiency. This effect is only slight for the first reef, and gets progressively worse, so that by the time the sail is on its third reef it wouldn’t work as a sail at all because all of the wind would simply be spilled out of it.
As I mentioned, I have now found a way to solve this problem, using a custom piece of hardware.
But before I explain my solution, I’d like to mention another custom piece of hardware, which was already part of the plan: the take-up spool. It solves a number of problems. First, it eliminates cockpit clutter: all loose line magically disappears. Second, it makes a simple winch into a self-tailing one: just take a few turns on the capstan and crank; the take-up reel maintains the tension for you. Third, by automatically taking up slack, it reduces the chance that a loose sheet will get caught on the roach of the sail, requiring a trip out of the cockpit to free it.
Quidnon’s cockpit layout provides an ideal place to hide all of this loose line: directly under the cockpit floor, at the top of the anchor chain locker, where there is plenty of room. The details of the take-up reel are not particularly interesting. It is a sealed metal box bolted to a bulkhead that has a shaft sticking out of it. Inside it is the sort of mechanism found in every wind-up toy or mechanical watch: a constant-force spring and a gear reduction mechanism. The shaft goes through a shaft seal to keep water out and grease in, and the entire mechanism is designed to never require any maintenance. A spool is splined to the shaft and a fairlead some distance away from the spool makes the turns wrap onto the spool tidily.
There will be a total of 12 take-up spools hiding under the cockpit floor, 6 for each sail:
• Halyard (to raise the sail)
• Reefing line (to pull the battens down when reefed)
• Port and starboard sheets – tension end
• Port and starboard sheets – slack end
Why do the sheets have a slack end, and why does it need a take-up reel? That’s what I will explain next. The key element in my cunning plan is a custom piece of hardware that is probably something I invented, because in all of my years of perusing sailing gear catalogs I have never come across such a thing. It is a remote-operated locking sheet block.
In its unlocked state it is just like any sheet block: the sheet goes in one side, around a pulley and out the other side. The pulley is on a bearing and spins freely to minimize friction. In its locked state, the sheet is firmly clamped between the pulley and a shoe. The shoe has a dog that matches a recess in a pulley, preventing it from turning. The shoe has a channel with diagonal serrations similar those on a jam cleat which grab the sheet tighter when it tries to slip in one particular direction. That is, the locking action is unidirectional.
The block is switched between its free state and its locked state by means of a control line which goes through it. On the control line is mounted a very specifically shaped plug. It is prevented from slipping along the line by a ferrule which is crimped onto the line. The ends of the plug are tapered to reduce the amount of tension on the control line needed to move the plug into position by compressing a very strong spring whose job is to clamp the sheet in place. There is also a much weaker tension spring whose job is to keep the shoe away from the sheet when the block is in its free state.
The locking sheet blocks are mounted on the T-track on top of each side of each deck arch, observing correct orientation, so that the locking action is when the sheet is pulled to outboard. There are four signal lines which are sent through four cascades of five locking blocks each. A fairlead at each end of each cascade prevents the plug from escaping. Each of the four control lines is led to the cockpit, forming a loop.
When the sail is fully raised, the inboard-most block is locked. When the sail is at first reef, the next block to outboard is locked; and so on. As each reef is taken in, the sheet purchase is reduced from x10 to x8, x6 and so on down to x2, at which point only the topmost panel is showing (to use the mainsail as a riding sail when at anchor, or to use on the foresail for scudding off with a drogue in extremely heavy weather). Note that there are two control line adjustments to be made: one for the port sheet and one for the starboard sheet.
The steps to take in or to let out a reef (or two or three or four) are as follows:
• Open the sheet clutch to depower the sail
• Open the reefing line clutch
• Open the halyard clutch, pay out/haul in the required amount of halyard, close the halyard clutch
• Haul in the reefing line, close the reefing line clutch
• Move the starboard control line the required number of clicks; repeat for the port line
• Haul in the sheet to power up the sail, close the sheet clutch
Importantly, all sail evolutions can now be done without leaving the cockpit. This has been a requirement all along. Quidnon is designed for easy single-handed operation.
There are a couple more changes to the design which are small but important. Previously, the two pilot berths, which are on both sides of the salon and on top of the water/ballast tanks, were accessed by climbing up on the settees and going through a door in the two bulkheads that make up the keelboard trunk.
This plan raised several objections. First, this method of ingress seemed rather undignified, required rather excellent range of movement in the hips and wasn’t at all convenient if attempted in the course of a dinner party, during which the settees in the salon would be occupied. Second, cutting a door through the keelboard trunk resulted in some significant structural complications, Third, it wasn’t clear how to provide good sound insulation, which would be important if pilot berth occupants wished to sleep while a dinner party was in progress.
For all of these reasons, the pilot berths will now open to the stateroom, which is in the bow, with a small two-step ladder leading into each and with the opening fitted with a sliding door. This makes the layout of the pilot berths much more convenient, with some free space at the entrance, then the berth, and some cabinetry at the head.
Finally, the decision to eliminate one of the keelboards has been reversed. The reason is that a single keelboard positioned off-center would give Quidnon a different turning radius depending on which direction it was turning. If the keelboard were mounted to starboard, the boat would turn tighter to port; and vice versa. This seems like a very bad feature. With such a wide hull, it is important to be able to reliably execute the tightest possible turns when maneuvering in and out of marinas. Another advantage of having two keelboards is that they can be made smaller, easier to manage and less likely to damage the hull if they hit something underwater.
As I already mentioned, this completes the head-scratching phase of the project. The next phase will involve producing detailed construction plans and cost estimates.
But now I believe I have finally found a solution. With this problem solved, the Quidnon project can finally move past the head-scratching phase and on to the next phase, which will involve grinding out a large number of mechanical drawings, assembly diagrams and other documentation without which no boat can ever get built. Here, then, is my plan, which I will call “The Final-Final Sheeting Arrangement.”
The previous, “final” sheeting arrangement involved attaching the sheet to a padeye on the deck arch near the centerline of the boat, sending it through a block on the boom, down through a block some distance out on the deck arch, up to the first batten, down to another block a bit further out, up to the second batten, and so on. The blocks on the deck arch are mounted on a T-track, allowing their positions to be fine-tuned. Likewise, the blocks hanging from the boom and the battens can be repositioned closer or further away from the leach of the sail for optimum performance on all points of sail. Here is what that looked liked on the scale model, in quite a stiff breeze.
The reason this arrangement works so well is that each block on the sail receives exactly 1/5 of the overall tension on the sheet.
However, this only works on the full sail, all 50 sq.ft (4.6 m2) of it. But if it’s reefed (lowered part way, that is) to compensate for stiffer breezes, more force is concentrated at the bottom, warping the sail and ruining its efficiency. This effect is only slight for the first reef, and gets progressively worse, so that by the time the sail is on its third reef it wouldn’t work as a sail at all because all of the wind would simply be spilled out of it.
But before I explain my solution, I’d like to mention another custom piece of hardware, which was already part of the plan: the take-up spool. It solves a number of problems. First, it eliminates cockpit clutter: all loose line magically disappears. Second, it makes a simple winch into a self-tailing one: just take a few turns on the capstan and crank; the take-up reel maintains the tension for you. Third, by automatically taking up slack, it reduces the chance that a loose sheet will get caught on the roach of the sail, requiring a trip out of the cockpit to free it.
Quidnon’s cockpit layout provides an ideal place to hide all of this loose line: directly under the cockpit floor, at the top of the anchor chain locker, where there is plenty of room. The details of the take-up reel are not particularly interesting. It is a sealed metal box bolted to a bulkhead that has a shaft sticking out of it. Inside it is the sort of mechanism found in every wind-up toy or mechanical watch: a constant-force spring and a gear reduction mechanism. The shaft goes through a shaft seal to keep water out and grease in, and the entire mechanism is designed to never require any maintenance. A spool is splined to the shaft and a fairlead some distance away from the spool makes the turns wrap onto the spool tidily.
There will be a total of 12 take-up spools hiding under the cockpit floor, 6 for each sail:
• Halyard (to raise the sail)
• Reefing line (to pull the battens down when reefed)
• Port and starboard sheets – tension end
• Port and starboard sheets – slack end
Why do the sheets have a slack end, and why does it need a take-up reel? That’s what I will explain next. The key element in my cunning plan is a custom piece of hardware that is probably something I invented, because in all of my years of perusing sailing gear catalogs I have never come across such a thing. It is a remote-operated locking sheet block.
In its unlocked state it is just like any sheet block: the sheet goes in one side, around a pulley and out the other side. The pulley is on a bearing and spins freely to minimize friction. In its locked state, the sheet is firmly clamped between the pulley and a shoe. The shoe has a dog that matches a recess in a pulley, preventing it from turning. The shoe has a channel with diagonal serrations similar those on a jam cleat which grab the sheet tighter when it tries to slip in one particular direction. That is, the locking action is unidirectional.
The block is switched between its free state and its locked state by means of a control line which goes through it. On the control line is mounted a very specifically shaped plug. It is prevented from slipping along the line by a ferrule which is crimped onto the line. The ends of the plug are tapered to reduce the amount of tension on the control line needed to move the plug into position by compressing a very strong spring whose job is to clamp the sheet in place. There is also a much weaker tension spring whose job is to keep the shoe away from the sheet when the block is in its free state.
The locking sheet blocks are mounted on the T-track on top of each side of each deck arch, observing correct orientation, so that the locking action is when the sheet is pulled to outboard. There are four signal lines which are sent through four cascades of five locking blocks each. A fairlead at each end of each cascade prevents the plug from escaping. Each of the four control lines is led to the cockpit, forming a loop.
The steps to take in or to let out a reef (or two or three or four) are as follows:
• Open the sheet clutch to depower the sail
• Open the reefing line clutch
• Open the halyard clutch, pay out/haul in the required amount of halyard, close the halyard clutch
• Haul in the reefing line, close the reefing line clutch
• Move the starboard control line the required number of clicks; repeat for the port line
• Haul in the sheet to power up the sail, close the sheet clutch
Importantly, all sail evolutions can now be done without leaving the cockpit. This has been a requirement all along. Quidnon is designed for easy single-handed operation.
There are a couple more changes to the design which are small but important. Previously, the two pilot berths, which are on both sides of the salon and on top of the water/ballast tanks, were accessed by climbing up on the settees and going through a door in the two bulkheads that make up the keelboard trunk.
This plan raised several objections. First, this method of ingress seemed rather undignified, required rather excellent range of movement in the hips and wasn’t at all convenient if attempted in the course of a dinner party, during which the settees in the salon would be occupied. Second, cutting a door through the keelboard trunk resulted in some significant structural complications, Third, it wasn’t clear how to provide good sound insulation, which would be important if pilot berth occupants wished to sleep while a dinner party was in progress.
For all of these reasons, the pilot berths will now open to the stateroom, which is in the bow, with a small two-step ladder leading into each and with the opening fitted with a sliding door. This makes the layout of the pilot berths much more convenient, with some free space at the entrance, then the berth, and some cabinetry at the head.
Finally, the decision to eliminate one of the keelboards has been reversed. The reason is that a single keelboard positioned off-center would give Quidnon a different turning radius depending on which direction it was turning. If the keelboard were mounted to starboard, the boat would turn tighter to port; and vice versa. This seems like a very bad feature. With such a wide hull, it is important to be able to reliably execute the tightest possible turns when maneuvering in and out of marinas. Another advantage of having two keelboards is that they can be made smaller, easier to manage and less likely to damage the hull if they hit something underwater.
As I already mentioned, this completes the head-scratching phase of the project. The next phase will involve producing detailed construction plans and cost estimates.