Unlike a lot of other small racing sloops, the Wayfarer class does not tension the rig by tightening the forestay. Instead, the jib hoist is used to apply as much as 300-400 pounds of tension (sue me, I was raised in the US) to the rig.
The issue is, my dad's new-to-him boat, #2413, has spent her life thus far as a cruiser. As a result, she only had a bare halyard and the grunt of the crew (me) to put as much tension on it as she could (not much).
This is hampered further by the routing of the free end of the halyard out of the bottom of the mast, through a turning block, and thus pulled upwards to tension relying then on the crew's (me) muscles (very minimal especially after a year of HRT).
Most racing Wayfarers either use a 40:1 block and tackle set to tension the halyard after the sail was hoist, or a worm-driven friction winch contraption affectionately dubbed a "magic box". Since dad was uncertain whether he would keep #2413, he was reluctant to put the kind of money into her just yet that either of those venerable solutions would run him. In addition, as a not-very-svelte, not-very-graceful crewmember, I disliked the solutions because they are bulky and liable to give me even more things to run into during fast racing maneuvers. Enter my replacement (finally!).
I figured that a winning design needed to meet the following:
- Be cheap, preferably under $100 to replicate
- Be reasonably easy to make with common machine shop tools (though to be honest a CNC mill would have been helpful)
- Be compact, preferably protruding less than an inch into the cockpit from under the deck
- Mount along the side of the tabernacle, to catch the halyard as is dropped out of the bottom of the mast
- Be operable underway without power tools
As such, I ended up basing the design around an ACME leadscrew. Compact, inexpensive, and powerful, and driven easily by a socket and ratchet onboard (though a power drill on shore makes much quicker work of it). The system is self-contained, putting minimal force onto the old wood of the tabernacle, and protrudes barely enough for a socket to clear the drive nut. A basic metal lathe and manual mill are the only machines needed to make the custom parts, though of course CNC variants of either would turn out more consistent parts more quickly.
There were a handful of custom parts that had to be produced, either from raw stock or as modifications to purchased components:
- Bushing Blocks
- Cut from 6061, these hold the brass bushings and support the leadscrew ends
- Cut from 6061, this encompasses the bronze ACME nut and rides along the leadscrew, carrying the V cleat and thus the free end of the halyard
- Turned from the leadscrew stock, one end is threaded for the 1/4-20 acorn nut, then cross-drilled for a roll pin to retain it. Both ends are turned to be a turning fit in the bushings.
- Cut from the S/S angle, this piece serves as the backbone of the system, to put as little force into the tabernacle as possible
- center drill or punch
- deburring tool or file
- drill for 6-32 tap
- 6-32 bottoming tap
- drill for 12-24 tap
- 12-24 tap (1" long cut, so maybe bottoming too?)
- 1/4-20 die
- 1/8" carbide roundover router bit (edge break)
- 1/4" 82° countersink
- 3/8" diameter 3/4" cut length end mill, minimal radius
- 1/2" diameter end mill or counterbore
- 1/8" drill (roll pin rough)
- 1/8" reamer (roll pin fine)
- 5/32" drill (clearance for 6-32)
- 25/64" diameter 4" length drill (leadscrew/bushing rough)
- 3/8" reamer (leadscrew/bushing fine)
- fly cutter or shell mill
- 1/8" radius lathe tool, HSS or carbide
Approximately 20 hours of my time went into the machining and assembly of the system, though I am a slow machinist so take that as it is.
I turned the bushing seats first, then further reduced a section on one end to the threading diameter for a 1/4-20 die. Then I hand-threaded it with a die; I hate cutting small threads on the Acer.
One exciting and unexpected incident was that the length of leadscrew was slightly longer than the Acer can turn in a stable fashion, and so suddenly the section in the spindle bore threw itself to one side and violently shook until I could stop the lathe. As a result, my leadscrew is slightly bowed. I fixed this by wadding it up with shop towels until it was a snug fit, and that kept things true for the rest of the cutting work.
I squared up the piece of 6061 that would become both blocks and the car, then indicated it in clamping in a square fixture and the vice with the long axis vertical. Then I drilled and reamed for the leadscrew clearance hole all the way through the piece -- pair drilling in the finest form!
After this, I parted off the rough thicknesses for the blocks on the bandsaw, then took them to final dimensions with a shell mill. I picked up the bore with an indicator, and counterbored one face on each block for the flange of the bushing.
I drilled and tapped the two 6-32 holes on the bottom of each block, then stamped a "T" and a "B" into each, to aid in reassembly (top and bottom block, stamps face the same way). Then I shaped the top curve on the belt sander, smoothed the cutter marks on a Scotchbrite wheel, then polished with a medium grit polish and buffer.
A light press on the Arbor press set the bushings in place at depth, and the leadscrew ran smoothly in each block. I did end up coming in and reaming the bushings back to 0.2510", because installed on the frame, the leadscrew's gentle curve jammed the system at certain points.
Once parted from the bushing blocks above, much the same treatment was done: cut to final dimensions on the shell mill, drilled and tapped the 12-24 holes for the V cleat. However, I also carefully slotted the side to encompass the bronze nut firmly and centered on the reamed bore.
To dress and break the edges, I used a carbide 1/8" round over router bit on the highest speed the old Bridgeport spindle can reach (about 2500rpm). Cut like a dream with a little Tap Magic. Once softened, the same Scotchbrite and polish steps were performed.
The frame was simple: On each of the two faces in turn, zero the DRO on the corner as a datum, then center drill and drill each hole per the face's hole chart, countersinking as needed. Two tapped holes did get the better of me, but I was using cheap carbon steel taps from Lowe's so this was more or less expected.
Once all components have been manufactured, begin assembly. NOTE: Since there are a variety of metals present in this project and this is destined for wet environments, make use of anti-seize at final assembly on joints between disparate metals, especially with the stainless screws into aluminum. In addition, a touch of heavy silicone grease, like SuperLube, is useful on the leadscrew to reduce sliding forces.
- Install the bottom bushing block on the end of the frame with the holes for the fairlead. Ensure the flange points towards the other end of the frame. Use 2x 6-32 0.625" screws to retain this.
- Insert the shorter shaft end of the leadscrew into the bushing.
- Slide the top bushing block onto the other end of the leadscrew, with the flange facing in towards the leadscrew. Retain this with another 2x 6-32 0.625" screws.
- Test the screw; it is free-running, or do you need to ream the bushings or otherwise adjust fit?
- Gently press the leadscrew nut into the car, making sure the threaded section is concentric with the reamed hole.
- If the screw ran well, remove the top bushing block and slide the car onto the leadscrew until it encounters the nut, then turn the leadscrew to engage the nut until the threads are visible on the other side of the car.
- Place the flat face, without edge breaks, against the frame, then reinstall the top bushing block.
- Does the car move smoothly end to end on the leadscrew? If not, adjust as needed.
- If all went well, tighten an acorn nut onto the threaded end of the leadscrew.
- Drill and ream a 1/8" diameter hole through the acorn nut and leadscrew, preferably from one flat face on the nut to the opposite.
- Press a 1/8" spring pin into the hole, ensuring that the pin is below flush on both sides.
- Install the fairlead with the chain link captive within it.
- Install the V-cleat, ensuring that the larger end is away from the fairlead.
Mark the top hole, ensuring that the upper end of the frame is secure against the bottom of the deck, there is clearance for the 7/16" socket to drive the acorn nut, and the lower end is flush with the aft side of the tabernacle. Drill a hole through the tabernacle large enough for the shaft of the tee nut. Install the tee nut and clamp down to set it using a strong clamp. Install a 6-32 1.25" screw and mark the remainder of the five mounting holes. Remove the screw and drill those, then reinstall all five screws into their respective tee nuts.
Our connecting link had an opening too small to fit over our lacing eye, so we just leave the RF280 captive by a stop knot on the halyard. To rig, once the mast is up, simply drop the block's loop into the connecting link and secure, then hoist the jib normally. Once taut, set the halyard into the V cleat and tension using the screw.
Deviations from Design
- Had to replace the 6-32 fasteners for the block attachment fitting with 1/4-20 points because I broke off the 6-32 tap in those holes.
- Had to ream the bushings because the leadscrew is slightly bent due to the incident above.
The system works well, though 12tpi means lots and lots of turning. A power drill or screwdriver is recommended for shore work. The system stays nicely out of the way during even heavy air sailing (I have many bruises, but none of them from the tensioning system).