Captain’s log
Dateline: 14.03.2023
Titanium for Lewmar ocean mainsail track car
Originally stainless, four button head screws:
- 2 × M8-1.25mm, about 23mm long, fully-threaded
- 2 × M6-1.00mm, about 23mm long, fully-threaded
One of the M8’s is already a victim to galvanic corrosion — the head broke off when I tried to turn it. Yours truly will have to drill it out (very carefully).
And of course, I’m going with titanium, grade 5. The length is a bit weird, unless I’m really bad at measuring things. To be safe, I’ll go with 25mm length, not 20mm. If I have to cut them, I will — can always make them shorter, never longer.
Replacements:
Shopping spree
While we’re at it, I’d like to also get new screws to replace brand-new stainless steel ones that just came with the official end cap kit for that track car.
Originally stainless, they are four flat head screws:
- 2 × M6-1.00mm, fully-threaded 20mm shaft
What I don’t like is the fact that they don’t use any washers with that — neither locking, nor flat. The danger here is if two of those screws got loose on either side of the car, the Torlon balls would just fall out, and then my boom could easily get either stuck, or the whole car would simply fly off the track, releasing my boom free, letting it hit one of my backstays, essentially taking down the standing rigging, dismasting Curious Cat. That’s the worst case scenario.
The tricky part here seems to be that the original screws “stick out” — they’re what touches the rubber buffers at both ends of the track. That means I can add extra height to the bolts, they just have to be flat.
The replacement will be:
- M6-1 Pitch × 40mm Socket Head Cap Screw, Grade 5 (already have them, will need to cut and shorten, but seem to be perfect for this)
A 1.85mm outer diameter washer barely fits in there, and nothing can be over 10mm in diameter, Decided not to go with washers for now, can’t go above 10mm anyway, and don’t want to drill M5 washers to fit M6 bolts, that’d be silly. A bit weird that Lewmar went with a flat head slotted drive screw here, it has sharp edges on both sides, could chafe the line. I’ll drill the heads later to pull a safety wire through all four bolts, this way I won’t lose my precious Torlon balls if they become loose.
Been told that titanium sparks are white, can’t wait to see them.