Professional BoatBuilder - February-March 2018

FEBRUARY/MARCH 2018 55

boat’s frontal area and the lower its drag

coecient, the lesser the impediment

to forward motion. Usually not recog-

nized is the signicant drag of compo-

nents with a circular cross-section,

such as rigging and tubular struc-

tures. As an amazing example of

this, an aerospace reference of mine

states, “e wing of a Boeing 747

has the same parasitic drag as a^1 ⁄ 2

inch [12.7mm] cable of the same

length” (Understanding Flight, by

D.F. Anderson and S. Eberhardt).

Hence, I took considerable eort to

reduce such windage on the P-32.

How does it all work? Writing about

his early test sail on Petrel, Charles

Doane noted on his website, Wa v e-

Train: “She is a very slippery vessel.

ough we had only working sails set

(the mainsail and a small club-footed

jib), she performed admirably in the

light conditions we had. Sailing close-

hauled in 10–12 knots of apparent

expected to be subjected to almost a

quarter of the hull’s righting moment;

so it will have a relatively robust spar

albeit with a hoist and foot smaller

than on most dinghies.

Optimizing Performance

In optimizing a sailboat’s perfor-

mance, one must consider not only the

li and drag components of the rig but

also the aerodynamic drag of the boat,

its hull, superstructure, and all the vari-

ous appurtenances that contribute to

the total windage. So the smaller a

Mizzenmast

I’ve also made provisions for Petrel’s

mizzen. Just aba the rudderpost, the

lazarette-hatch-base weldment has

the mizzen partners incorporated into

its forward portion. Below this,

the maststep captures the horn

timber and is tied into the rud-

derpost. is arrangement has

sucient depth to support a free-

standing carbon ber mizzen.

is type of mast avoids the com-

mon criticism of most traditional

yawls: a plethora of standing rig-

ging is necessary to support a

deck-stepped mizzen above an over-

hanging counter stern. e mast will

be laid up with built-in curvature pro-

portional to that of the bent main. e

mizzen is small relative to most yawls

but appropriate to balance the self-

tacking jib when sailing under jib and

jigger. Sailing with this conguration

in heavy air, the mizzen could be

The wing of a Boeing 747

has the same parasitic drag

as a^1 ⁄ 2 inch [12.7mm] cable

of the same length.

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