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Monday, March 09, 2009

Prefit of the T-Track

Before hull and deck bonding can happen, the T-track, which is thru-bolted to the caprail, must be pre-fitted. For the non-sailors: the T-Track is a long piece of aluminum track in a standard "T" profile to which a number of attachments can be fitted. It is primarily used for attaching blocks and fair leads to manage sheets for the head sails. But there are a number of optional attachments (cleats, eyes, etc.) that can be added to make the job of "sailing" a bit easier. Its very versatile. Ideally, the T-track should be thru-bolted for strength. And, it is ideal to mount it such that it can easily be removed in the future. This translates into threaded backing plates for the bolts instead of washers and nuts (future removal requires one person, one wrench). The backing plates are pre-threaded and glued to the underside of the caprail. Since the track mounts on top of the caprail, the thru-bolts for the track also act as thru-bolts for hull-deck joint (I neglected to figure this in when I ordered fasteners for the joint, so I will have lots of bolts left over, oh well). So, on a rather chaotic weather weekend (we had just about every type of weather last weekend, except for fog), I installed the two 8 foot tracks, port and starboard, along the sides of the cockpit, standard for the Westsail 42. The "one person" installation method went something like this...
  1. Cut a bunch of 1 1/2" x 1 1/2" x 1/4" aluminum squares cut from flat bar (this project required about 50 squares).
  2. In each square, drill and tap a hole for a 5/16-18 bolt
  3. With the caprail clamped in position for final bonding, spot the track in the desired position.
  4. Start with one end, using the track as a guide, drill a hole through the caprail for the first hole AND the plastic end stop.
  5. Cut, drill and tap an aluminum square to match the two holes just drilled.
  6. Thread 2 1/2" full-thread bolts through the square, all the way to the hex head.
  7. Apply glue around the perimeter of the square and, from the underside, using the bolt as a guide, insert through the hole in the caprail. Push firmly, the tackiness of the glue will keep it from falling.
  8. Go topside. Gently place a washer and nut on the bolt now poking above the T-track and tighten. This now clamps the backing plate in perfect alignment with the track.
  9. Repeat steps 6,7,8 for the next bolts. If the track must be bent to match a curve along the way, do no more than two bolts at a time.
Tips:
  1. Thoroughly wipe down the underside of the caprail with acetone.
  2. If the track is to be curved, start on the end that has the "most curve". This gives more length of track to leverage to match the curve.
  3. After drilling a hole, burr off any glass fibers sticking out over the hole on the underside. Something like a dremel tool with a round grind stone works. This reduces the chance of those fibers getting cross-threaded when the final bolts are installed.
  4. On gluing, keep the bead to the outer edge of the square to reduce risk of glue getting in the threads, potentially making things a bit more difficult for removal. 3M 5200 would be fine for this application. If you don't want to wait two weeks for final cure, something like Plexus works (as I did in this case, less messy too).
  5. On the plates for the first/last hole plus the end stop, CHECK ALIGNMENT OF THE HOLES AT THE ENDS OF THE TRACK BEFORE INSTALLING! The distance between the two holes may be different depending on which end you are looking at. At least this is the case for the tracks made by Schaefer. Don't ask how I learned this!
  6. If just aligning/setting the backing plates, no need to use stainless fasteners. Zinc steel is just fine as they will be removed in a couple weeks. Save the expensive stuff for the final install.
So, that is it for pre-fitting of the eight foot T-tracks. We will also be installing two six foot tracks, one each forward of the eight foot sections. The more track, more versatile setups, and now is the time to do it. This based on Dave's recommendation (if I take anymore tips from that guy I will have to give him design/build credit! lol).
From Building A Westsail 42: Bonding the Hull and Deck
From Building A Westsail 42: Bonding the Hull and Deck
From Building A Westsail 42: Bonding the Hull and Deck
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