“Zip” - a 23’ Tabloid Tri
A small racer/cruiser, Zip combines light weight with power: at 20’ (6.1m) wide, the ability to carry sail is greatly increased with the crew well upwind of the leeward hull... especially with two on trapezes! Construction is of wood/foam core/carbon (a little)/‘glass, with simple and strong rig and demountable (not folding) amas and cross arms.
Two features reduce weight and increase strength: the cross arms are bolted together at the centreline, and are secured at the main hull side, creating a lighter, stronger and wider setup than with a folding system, and the almost-vee main hull shape above the spray rail provides more interior volume but has less hull surface area than that of a typically complex-curved tri topsides. Foam core may be used to good effect here, though the cruiser may be all-plywood. The spray rail provides good lift at speed (both forward and aft), and keeps the high pressure water from rising up the side of the vee hull. That is, will increase speed and allow the main hull to fly easier than without the rail. With 135% (of main hull) ama volumes, a racing Bruce Number of 175, Bruce Foils, and canted and fenced (to reduce cavitation at speed) rudders in each outer hull, it’s clear this boat is meant to be sailed with two hulls flying. The cruiser may have an offset main-hull daggerboard only, to keep the amas simpler. The all-out racer can have 3 boards.
Length -
Beam -
Beam Demounted -
Sailing Displacement -
Lightship Displacement -
Mainsail -
Jib -
Spinnaker -
Bruce Number (main + jib) -
Particulars - With cruising rig
23’
20’
10’
1,400 lbs.
1,000 lbs.
215 sq. ft.
87 sq. ft.
267 sq. ft.
1.55
7.01 m
6.1 m
3.05 m
635 kg
454 kg
20 m^2
8.1 m^2
24.8 m^2
Definition of tabloid used - “concentrated, easily assimilable”
The living space includes 4 berths (2 singles, 1 double), galley, and camping head. The one drawback of the great beam and non-folding setup is the boat is less simple to trailer than folding tris - it is more suitable for people who usually sail from their home port... who sail more and trailer less!
With racing rig
1,300 lbs.
900 lbs.
271 sq. ft.
93 sq. ft.
300 sq. ft.
1.75
590 kg
408 kg
25.2 m^2
8.6 m^2
27.9 m^2
Stern View
Bow View
Copyright 2001-2011 inclusive McGowan Marine Design, Inc.
Mk. IV (below) - to eliminate cavitation in the rudders, they’ve been moved forward of the ama
transoms and are now in lifting cassettes. The aft ends of the amas have a small flat to allow the
tops of the rudders to remain tight to the hulls for most of their swing.
