I've seen that this has been discussed multiple times before but the discussions seem to trail off about a year ago, so I figured I'd start fresh for 2013. I'm evaluating options for replacing mainsheet blocks and I've developed some confusion. There doesn't seem to be much debate that the upper/boom block should be the 40mm Harken H2640
. For the lower/cam block, there seems to be a bit of disagreement. My understanding is:
- * The original shipping part was the H194 which is discontinued, but was a 57mm sheave diameter - old stock may or may not be around to be had.
- * Harken recommends the H2629 which is a 57 mm Triple Ratchamatic® Block — Swivel, Cam Cleat
- * And then various threads here seem to agree on the H2612, which is a 40 mm Triple Ratchet Block — Swivel, Cam Cleat
The H2612 seems like an attractive choice, being 40mm instead of 57mm (lower profile), not to mention almost $90 cheaper. BUT! Harken's specs on the H2612
state a maximum line diameter of 0.25in/6mm, and the max working load (750lbs) is half that of the H2629 and H2640. That said, it appears that the working load of the H2612 is more than the H194 was (500lbs) in its time.
The undisputed upper/boom block (H2640) specifies a max line diameter of 10mm, and the physical dimensions of the 40mm upper and lower blocks appear the same, so I feel confident that a 0.375in/9mm mainsheet would physically fit through the sheaves, but I'm vaguely concerned about the delta in working load, and I'm left wondering if the lower line diameter specification is being driven by the lower working load, or if it's because of the cam cleat, or if the reeving is such that a larger rope would be likely to bind up, or what...
EDIT: Further googling indicates that one complaint about the H2612 is its always-on rachet, whereas the 57mm H2629 automatically switches based on load between ratchet and free-running operation. If that's the principal deciding factor, I think I'd go with the smaller always-ratcheting block. I've never bothered to turn the ratcheting action off on the switchable blocks I have now... not sure I see that behavior changing.
What is the current (2013) wisdom on this?