Sail Dimensions for Early Potters

(U.S. gunter rigs and "Mk I’s" and UK "A-types" and B-types)

Someone on the Trailer Sailor Potter Forum needed the sail measurements for an early gunter-rigged Potter. The original sails for my 1967 gunter-rigged U.S. West Wight Potter were still in fair condition, so I laid them out on the lawn and measured them. Here are the results. I used an on-line triangle calculator to determine the triangle areas and tack angles.

Note that I measured the sails corner to corner as they lay. If I had pulled them tight from corner to corner I would probably have gained an inch or two on each one. I included the triangular area of the main roach but disregarded any other rounding or fullness that would have added to the total area. Thus my calculated triangles total less area than the advertised sail area.

Jib

Luff: 120" (10')

Foot: 51" (4'3")

Leech: 98" (8'2")

Calculated tack angle: 52.8 deg

Calculated triangle area: 16.9 sq ft

Advertised sail area: 20 sq ft

Main

Luff: 147" (12'3")

Foot: 93" (7'9")

Leech: 171" (14'3")

Roach: approx 1' at mid-leech

Calculated tack angle: 87.9 deg

Calculated triangle area: 6831 sq in

Plus roach triangle area: 85.5 sq in =

Combined triangle sail area: 6916 sq in (48.2 sq ft)

Advertised main sail area: 52 sq ft

The advertised sail area for the UK original WWP (now called the "A-type"), the UK B-type, both versions of the U.S. gunter-rigged Potters, and the first non-gunter U.S. P14s (now referred to as the "Mk I") was the same, i.e., main, 52 sq ft; jib, 20 sq ft. It appears the sail dimensions were approximately the same also.

The gunter rig sails had bolt rope in the foot and luff to fit in the grooved wooden spars. The Mk I main was set loose footed on an aluminum spar like the later, larger Mk II main, so it had bolt rope only in the luff (for the grooved aluminum mast), not in the foot.

The classic "WWP" sail emblem was used only on the gunter rigs; the "Mk I" was the first to use the (HMS Marine/International Marine) spinnaker emblem used on all U.S. Potters since then. My sail had a black emblem and red numbers, although. I’ve seen photos of gunter Potters with red emblems and black numbers.