Tuesday 6 March 2012

11 - Some Initial Rigging

Well, it's that time of year again - time to head to Florida, so there will be another hiatus (forced as opposed to idleness on my part!).

However, before I go, here is a bit more rigging, Similar to the last post but this time dealing with some specific aspects of the fore and main sails.

I briefly covered the details of the gaffs in a previous post so this is a bit of a review. Both main and fore gaffs are similar, in that they have "jaws" or "forks" that hold the gaff in position on the respective masts. However, the forks on the main gaff are bent or curved in order to maintain a purchase on the mast when the gaff is raised and angled fairly steeply upward. They also have a pivoting wood block ("clapper") - positioned in the throat between the jaws - that provides a larger bearing surface against the mast.

Here are a couple of shots of the main gaff, showing the bend in the forks, as well as the clapper positioned against the mast. Also in the pictures is the lifting cradle, to which the throat halyard is attached.

Main gaff components.

Main gaff in raised position.

Note the simulated metal reinforcing applied to both fore and main mast to protect them from wear when the booms are in the raised position.

With the main and fore sails fitted to their respective booms and gaffs, it was time to install the main and fore sail peak halyards.

Main sail peak halyard

Fore sail peak halyard

The only difference between the main and fore peak halyards is the number of bridles - three in the case of the main sail (shown above, top) and two in the case of the fore sail. Note that the bridles are considered standing rigging and hence are black. This stems from the fact that standing rigging was usually tarred for weather protection.

In conjunction with the peak halyards, the throat halyards were also installed. The fore sail throat halyards are relatively straight forward, comprised of single three-sheave and two-sheave blocks, yielding a 4X mechanical advantage. 

Fore sail throat halyard.

Given the weight of the main sail and gaff, the block arrangement for the main throat halyard requires more mechanical advantage. For this reason, three double-sheave blocks plus a single-sheave block are employed, to yield a 6X mechanical advantage.

Main sail throat halyard.

(When determining the mechanical advantage of a pulley system, merely count the number of lines that are supporting the load. In the case of the fore sail, there are four. The other two lines do not directly support the load and hence don't contribute anything other than to change the direction of the pull. Of course, there is no "free lunch"! While it will only take 1/6th the effort to raise the main sail - plus a bit more to overcome friction - you will need to haul in six times more line. In the case of the main sail, that amounts to about 360 feet of line!) 

With both peak and throat halyards fitted, the rigging is starting to take shape. Note that the spreaders had previously been fitted as well. (See also that I forgot to wax my lines. Close-up shots show some fuzz - need to get that sorted when I get back!)


That will have to suffice for now. 

If I get the opportunity, will post a few pictures while in Florida.

TFL