Professional BoatBuilder - February-March 2018

FEBRUARY/MARCH 2018 51

design waterline beam of less than 7'

(2.1m). She has ample sail area for

excellent performance in light air, and

in normal conditions the  rst reef is

taken in at about 14 knots of apparent

wind.  e Seldén single-line ree ng

with cars inside the boom means the

 rst and second reefs are easily taken

in and let out as necessary.  e third is

main is therefore half the hoist of the

full main and 32% of its area.

 is is smaller than the O shore

Racing Congress’s and US Sailing’s

criteria for a deeply reefed main as a

trysail alternative. Petrel’s stability is

somewhat limited for a 32-footer

because of her shallow dra and a

Marchaj also researched the advan-

tages of crescent planforms and

observed this characteristic in nature,

notably in  sh  ns. He stated that

planforms with leading edges that

curved backward have better effi-

ciency in terms of induced drag, due

to bene cial interaction of the tip

vortex. With only minor amounts of

curvature, such bene ts are reduced,

but they certainly do not become

negative.

With respect to mast bend, the

P-32’s rig has a number of advantages.

Applying loads to bend the mast

results in a spar more stable—less

prone to pumping in a seaway—than a

straight stick. For a given increase in

area beyond a nominal triangular

planform, as characterized by the sail’s

midgirth with a curved mast, there is

less roach (curvature of the leech) and

thus lower compressive loads from the

full-length battens on their associated

mast cars. Perhaps the most signi cant

e ect of the P-32’s permanently bent

mast is the corollary to bending a rac-

er’s mast so as to  atten the mainsail in

heavy air.  e P-32’s main is cut rela-

tively  at to minimize side force when

sailing to windward, but as the main-

sheet is eased, the sail becomes fuller

for reaching.

Because all three of the main’s reefs

are laid out parallel to the boom, the

angles between the reefs and the back

of the mast decrease with height, so

the a end of the boom rises incre-

mentally with each reef, as it would

with a tripping reef:

• Th e fi rst reef of 4.5' (1.4m), which
  is two-fi ft eenths of the 33.75' (10.3m)
  hoist, reduces the area of the main by
  20%, with the headboard ending up at
  about the same height as the fractional
  forestay. So, from a distance, the reefed
  sail might make the boat appear to
  have a short masthead rig.


• Th e second reef of 5.625' (1.7m) is
  an additional one-sixth of the hoist,
  with a further reduction in area of 24%.


• Th e third reef, 6.75' (2.06m) and
  one-  h of the hoist, again reduces
  the area by 24%.  e triple-reefed

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