Double-ended Main Sheet
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This project seems to get good reviews from everyone who's done it. If you're considering doing this, read
Stingy Sailor's description and Joe Becker's in the C-22 Association's Technical Manual. On lazy light-wind days, we often sail with the bimini up; the forward sheet end isn't as useful then, but when we have the bimini down, it really rocks!
I actually spent just a bit more than
the $222 kit from Catalina Direct, but got better parts and a new Salsa mainsheet in the process. Stingy used a double block on the aft end of the boom; I elected to use 2 separate blocks - one of them a ratchet block, the same as the CD kit. So the forward sheet end is held by ratchet pressure when it's not cleated, which is nice.
This system reuses the existing lower fiddle block w/cam. I might eventually replace with a new fiddle block with a ratchet on that end as well. If a day of weakness coincides with a good sale or eBay deal...
Mounting the aft blocks was pretty simple - just tie the soft-attach lines as described in the block's instruction sheet (using the existing eye strap for the aft block and adding another one for the forward block). Note that the aft block takes the full load of the sheet, but the forward block is at the end of the tackle arrangement and only sees ~1/3 of the load. So I was fine with just a simple eye strap for that one.
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Pivot Block: At the forward end (on the boom), Stingy used a Viadana 28mm pivot block. But it maxes out at 5/16" line, which seems really small for a mainsheet. CD uses what appears to be a Harken 140 (40mm sheave). Even that seemed small to me, and I went for a Harken 2135 instead (57mm sheave).
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The force on the pivot block will be sideways as well as downward; when I took a look at the block, I had 2 concerns:
1) The radius of the block's mounting plate is (unsurprisingly) considerably larger than our skinny C-22 boom. So the plate might tend to rock back and forth. I cut and sanded a little piece of black Starboard to match the 2 radii (you can see it in the picture above if you look closely).
2) I was a little paranoid about using only 2 small fasteners into the thin aluminum of the boom. Tapping threads into the boom or riveting - either one seemed like it might eventually work loose or pull out of the aluminum (again, because of the sideways forces that might tend to work the fastener free over time).
So I added a thin insert of G10 inside the boom and tapped threads into it. Threads in G10 should match SS bolt strength at ~1 bolt diameter of thickness - I.e., good threads in 1/4" G10 will match the strength of a 1/4" bolt. So tapping into ~3/8" G10 should easily exceed the strength of #10 screws.
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From memory, I believe I:
1) Laminated together 2 layers of 1/4" G10, approximately 5" x 1"
2) Sanded it down to match the interior curvature of the boom
3) Drilled and tapped a hole for one of the two mounting bolts
4) Drilled the first mounting hole in the boom
5) Wrapped duct tape around a long rod, sticky-side-out
6) Stuck the insert to that tape and used the rod to position it inside the boom (aligning the holes I'd already drilled in the insert and the boom); screwed the insert to the boom (anchoring it solidly for the next steps)
7) Drilled the second mounting hole in the boom and insert, tapping the latter
8) Mounted the pivot block
Sheet: 10mm Salsa single-braid.
@Jackdaw swears by Maffoili Swiftcord, but I couldn't quite swing the $3.67/ft. When I found a 50' hank of NER Salsa for $1/ft, I went with that. It feels at least as nice as the thicker 1/2" Dacron it replaced, and the single-braid coils neatly. Recommended.
Time: 2.75 hours
Cost: $226
* Harken 2157 Pivot Block: $63
* Harken 2159 T2 Ratchet Block: $39 @eBay (all eBay blocks were new old stock items)
* Harken 2149 T2 Block: $29 @eBay
* Harken 2135 57mm ratchet block: $44 @eBay
* 50' 10mm Salsa line: $51 @Hamiltonmarine