14-FEB-2018, Lake Union, Seattle – A mainsheet traveler adjusts where the mainsheet connects to the boat.
The mainsheet is the line (rope) that pulls the main sail towards the center of the boat. (It also places some downforce on the sail, specifically on the boom, but that is really a side effect.)
When CaroBabbo was originally sold the mainsheet connected to an eye in the center of the cockpit table. The problem with this is that when sailing very close to the wind, the boom should be very close to, or on the centerline of the boat. To make the boom come to the center line of the boat the attachment point of the mainsheet has to be past the centerline of the boat. The problem is that the attachment point must always be to windward.
The way this is conventionally done is to place the attachment point on a track so that it may move from side to side along the track. The track and the movable attachment point, called a car, are referred to as the traveler.
Depending on the size of the boat, and the budget, different techniques are used to reduce the friction of the car on the track and to stop the car at one place or another on the track.
Some travelers use nothing at all, other than, perhaps, some grease.
To position the car, it was once common to have individual stops at various places on the track. This is still common on foresail tracks. Most travelers, and some foresail tracks use lines attached to the car to move the car and hold it in position.
To reduce the friction on the car the current technology is recirculating ball bearings. The bearings work like traditional ball bearings but also circulate around a track inside the car so that not all of the ball bearings are in use at one time. I can think of ways that this might be more advantageous than the typical way we think of ball bearings, but I would just be guessing.
The traveler I’m replacing is noteworthy for a few things. Sometime in the not-too-distant past, though it may have been as long ago as 2016, ball bearings started appearing in the cockpit. I knew instantly what they were. And then, last summer, one of the steel wheels that the ball bearings were in broke in half.
That original car used four wheels, with ball bearings inside the wheels, rather than ball bearings directly against the track. How old was the traveler? My guess, based on who had ever seen one before, would be late 70s early 80s.
At each end of the track is a stop to keep the car from running off the end. Each stop has a sheave (pulley) to drag the car along the track. The entire force of the mainsail is generally pushing the car in the opposite direction.
As installed, there was no mechanical advantage (1:1): timing and muscle move the car from one side to the other. Timing, because during a tack, there is no opposing pressure on the car. In fact, the pressure of the sail makes the car move to the proper side for the next tack, so that properly timed the line only plays a positioning role. When the timing is off, or an additional adjustment needs to be made, muscle is the answer.
The old traveler was noteworthy in how the stops at the end of the tracks were attached. The stops were actually off a much smaller track, a dinghy track actually; the flanges on the track were ground down so that the smaller stops could be attached.
Tracks come in standard lengths. 48 inches was the length that was longer than, but closest in size to our current track.
Tracks are generally cut to size and then stops are attached to each end with a machine screw from the stop into the track. This requires drilling a hole in the track and then tapping the hole. Tapping is the process of putting screw threads into a hole.
To make sure everything matched I took the stop to StoneWay Hardware. The nice man at the counter and I walked from place to place in the store finding a metric flathead machine screw that would completely fill the screw hole in the stop. He then selected a proper size tap for me, a tap handle and the appropriate size drill bit. Along with some other screws I bought, the total came to about forty dollars.
There was a drill press in the workshop, which is great for drilling holes that are vertical in both axes. Without a drill press one can use tri-square, or just eyeball it. I chose the latter.
With some cutting oil borrowed from Harrison, and the 7 mm drill necessary for the 8mm machine screws, I drilled the hole for the screw. I tapped the hole quickly and easily but the screw would not screw in. I tend to be harder on myself than I am on other people. I hadn’t verified that the tap that the store worker gave me matched the machine screw that he gave me. (Idiot me!)
The machine screws were 1.25 mm pitch but the tap was 1.00 mm pitch.
Much of the day disappeared into looking for 1.00 pitch screws, before eventually speaking with Joel, the manager at Stone Way hardware. Joel was very good and very nice. He asked what would I like to solve the problem, then gave me a $40 helicoil set and a 1.25 mm “bottom” tap. A bottom tap is not tapered and is used to tap a threaded hole that does not go all the way through the piece of metal (the hole is “blind”).
There were no 1.25 pitch taps in a blister pack, only 1.00 pitch taps, which is why the counterman made the mistake he did. Joel looked at the 1.00 pitch taps and told me he would pull them off. “No one ever buys these, and look, this pack has been taped shut because it’s been returned.”
I felt very uncomfortable taking a forty dollar helicoil set, even though the track itself cost more than $200.
To drill a hole inboard of the hole I drilled would move the stop about 3/8 of an inch to the center, leaving about 3/8 of an inch of the track exposed. Rather than cut the track down, which would expose raw aluminum, I used the entire 48 inches. This made the track about 5 inches wider, but the properly-sized stops made the available distance from stop to stop only one and a half inches longer, or about three quarters of an inch on each side.
I drilled the new hole inboard, tapped it and attached the stop. I did the same on the other side and all was complete.
The track uses bolts through small plates inside the bottom of the track to make the positioning infinitely adjustable. The trick seems to be that the bolts need to be glued to the plates so that they won’t turn as the nut is tightened. After two hours figuring that out and getting it to happen, the track went on in a matter of moments, except that I mounted it backwards with the cleats on the stops facing forward rather than aft. I will remove the stops exchange them side to side and all will be fine.
I’ll use 3 to 1 leverage to move the track from side to side using a blue and white line, and will replace the very worn mainsheet with a bright orange line. I like the bright colored lines, though, no doubt, they will look gaudy and out of date in no time. The large functional advantage of colored lines is being able to tell someone who does not have a sailboat vocabulary to pull a line based upon its color.
It seems no job is ever completed, and to complete this job, besides correcting the stops, I need to put eye splices in both of the track lines and the new mainsheet. I’m not sure what needs to be done after that, but I’m sure there must be something.
Here is a picture of the plate and screw that slides into the bottom of the track extrusion.