Page 322 - Brion Toss - The Complete Rigger’s Apprentice

and-aft support for the lower section of the mizzen. Nabob II
This is an effective configuration for a racer like So much for simplicity. Nabob II’s mizzen is infested
Cirrus, but it’s a no-no for a cruising vessel, pre- with rigging, radar, baggywrinkle, antennae—it
cisely because it ties the two masts firmly together. looks like the winner of a design competition for
In the event of a rigging failure, it’s “as the main Most Occupied Mast. But once you look at the gear
goes, so goes the mizzen.” piece by piece, in the context of the vessel it fits,
As a final note, there are running backstays you’ll see that it’s thoughtfully configured.
here, because, unlike the Jenny Ives’s aft-swept Nabob II is a beefy, 55-foot (on deck) Spauld-
upper shroud spreaders, the diamond stays support- ing Dunbar ketch. Her entire purpose in life is to
ing Cirrus’s masthead provide lateral staying only. take people to far-off lands in utmost comfort and
security. Europe, Africa, the South Pacific, the Far
Concordia Yawl Portunus East—Nabob’s been there.
If Cirrus has an innovative change-of-era rig, the So let’s start with the upper shrouds (Figure
Concordia yawl (Figure 8-4) represents an early 8-5). They’re easiest to find. There are two sets, one
mature version of Bermudian mizzen design. The going over wide, well-padded spreaders for upper-
soft eyes are gone, replaced by tangs all around. panel lateral support, and another leading aft as
The main backstay angles off to one side, ju-u-st backstays; this second set could have been running
enough to miss the mizzen, so the two masts are backs led right to the stern for a more favorable
independently stayed. There’s a jumper stay, à angle, but that would have meant more strings to
la the Jenny Ives, but here the lower end of the tend in a sometimes-shorthanded boat. Instead, the
stay comes clear down to the base of the mast, so spreader-less uppers angle far enough aft for good
it doesn’t buckle the middle. This has the added support, yet are far enough forward that the mizzen
advantages of lessening compression on the jumper boom can swing out on a broad reach.
strut and getting the turnbuckle down where it’s Two lower shrouds per side fix the lower panel
easy to adjust. in all directions. Notice how the wire ends go to dif-
Mast shape has changed, too. The previous ferent heights; they’re independent of each other
masts in this chapter were round, but Portunus has a as redundancy in case one should break, and they
rectangular mast, with the long side running fore- spread the load over a wider area of mast than if
and-aft. This makes the mast stiffer in this plane, they both went to the same tang.
where the strongest buckling forces are. And the The big news on this mast is the jumper stay/
mast is big and stiff enough in both planes at the radar housing setup. The double jumpers, angled
lower end that the long unsupported panel below diagonally forward, hold the masthead forward,
the spreaders is no problem. Now the lower shrouds prevent the middle of the mast from buckling for-
can go way up, to stabilize things in the way of the ward, and help stay the masthead laterally.
jumper strut. The upper shrouds hold the masthead Just above the radar is a springstay leading to
laterally, while their spreaders stabilize the mast the mainmast. This does tie the masts together, but
below the lower shrouds. With so much fore-and-aft it’s a calculated tradeoff. The compression load from
stiffness, the running backs are practically vestigial, the radar/jumpers wants to push the middle of the
set up far less often than for Cirrus. mast aft, and those aft-leading uppers don’t lead far
By playing rig configuration and mast size and enough aft to counteract with sufficient compres-
construction off against each other, the Concordia’s sion-bow forward. The springstay takes the excess
designer, Raymond Hunt, was able to come up with jumper compression and delivers it to the mainmast.
a mast that could take a lot of load, yet be quite The aft-leading lower shrouds assist the aft-leading
simple. uppers in preventing the entire mast being pulled

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