Originally Posted by jbinbi
1. Thanks for the other link, i will read that.
2. Sorry to say, but basic physics lab would tell you that if you hung a 40lb wt from the ceiling with a spring scale it would show 40lbs with 1 wire, 20lbs each with 2 wires, 10lbs each with 4 wires.
3. There is less force on the masthead sheeve with a 2:1, but for my boat, I don't believe this should be an issue. For the first 8 years of 380 production, it didn't have a 2:1.
My mainsail is not even close to the size of say a Beneteau/Hunter/Catalina/Juneau 50' mainsail and none of them have 2:1 purchase.
The mainsail on a 450 is much larger than those, so I can understand the need for it.
If you put a spring scale on the ceiling and then a pulley at the bottom of it, then hoist up 5 pounds, what do you think the spring scale will read while you hold the line at ground level.?
Try it and see.
You will have noted that Lagoon
and mast styles from year to year for many models. The latest trend it seems is to build a lighter (probably more economical mast). A lighter mast may compress more easily, also they could cut down on the size of the sheaves and pins and so on with aim to cut costs with a lighter rig. I have no idea if they have done this with the 380 over time, but you would have to ask the mast builder
, and from my experience with Z Spars for example, they are not great communicators on mast rigging
(ie. - no response at all). In my view a lot of the systems have come from someone's professional drawing board, and there has been some thought behind it. We can all guess at Lagoons motives for the types of rigs they put together or have designed for them,, but until you get a technical response from someone at Lagoon
, for myself I would not be game
to try it. Any boat that has a single halyard should have had the halyard loads (and all the other loads) specified for those loads. If we as amateurs in the design game
think we know better, or run off anecdotal evidence that because it works for someone else's boat it must be OK- well that is chancing your arm with some costs associated with repair if it fails.
We all might assume Lagoon put a 2:1 to make it easier to lift
the sail only and that the rig and components were actually designed to handle 1:1. But then again they may have changed to 2:1 because they had too many complaints about clutch
slip, sheave failure etc. I don't know. There are too many unknowns to make a call, unless Lagoon themselves make a comment.
Anyway, I was not attempting to create a storm in a tea cup, and say dire things will happen if you use 1:1, probably won't make much difference, the main purpose was to get to the bottom of the 2:1 v 1:1 compression effects and I myself have learned something as a result of your original post, because I was considering going to 1:1 on the 450 to get the sail up quicker, but now I have studied this all in more detail that is not going to happen. I am even now considering changing my Gennaker
Halyard to 2:1 like the newer 450's have.
Sorry for the long winded reply.