Morgan 462 (split backstays): rig report

DEMO: these results are replayed from the notebook study of this boat, stored in tests/reference/morgan-462-ketch-split-backstays.viewer.json. They don't change when the boat file changes. The list of estimates below does come from this boat file.

An engineering estimate, not a rig survey. From boats/morgan-462-ketch-split-backstays.yaml, rigframe 0.1.0.dev0, 2026-11-06.

Open the 3D viewer

Estimates: what to measure (68 of 93 inputs)

Input	Value used	Note
`hull.GZ30`	0.70 m
`sail_plan.headsail_LP`	130 %	Good Old Boat lists 130 % and 150 % genoas.
`sail_plan.reef_fraction`	60 %
`masts[0].step`	keel
`masts[0].heel_z`	-1.80 m
`masts[0].gooseneck_z`	1.80 m
`masts[0].above_hounds`	0.20 m
`masts[0].section.chord`	280 mm
`masts[0].section.width`	180 mm
`masts[0].section.wall`	5.5 mm
`masts[0].section.yield`	240 MPa
`masts[0].spreaders[0].height`	50 %
`masts[0].spreaders[0].length`	1.55 m
`masts[0].spreader_section.chord`	140 mm
`masts[0].spreader_section.depth`	40 mm
`masts[0].spreader_section.A`	7.0 cm^2
`masts[0].spreader_section.I_vertical`	20 cm^4
`masts[0].spreader_section.I_horizontal`	160 cm^4
`masts[0].spreader_section.J`	50 cm^4
`masts[0].shrouds.arrangement`	continuous
`masts[0].shrouds.cap.size`	7/16 in
`masts[0].shrouds.cap.chainplate.x`	-0.10 m
`masts[0].shrouds.cap.chainplate.y`	1.85 m
`masts[0].shrouds.lowers.forward.size`	3/8 in
`masts[0].shrouds.lowers.forward.chainplate.x`	0.50 m
`masts[0].shrouds.lowers.forward.chainplate.y`	1.80 m
`masts[0].shrouds.lowers.aft.size`	3/8 in
`masts[0].shrouds.lowers.aft.chainplate.x`	-0.75 m
`masts[0].shrouds.lowers.aft.chainplate.y`	1.80 m
`masts[1].x`	-7.00 m
`masts[1].hounds_z`	10.00 m
`masts[1].step`	deck
`masts[1].gooseneck_z`	1.70 m
`masts[1].above_hounds`	0.15 m
`masts[1].section.chord`	190 mm
`masts[1].section.width`	125 mm
`masts[1].section.wall`	4.0 mm
`masts[1].section.yield`	240 MPa
`masts[1].spreaders[0].height`	50 %
`masts[1].spreaders[0].length`	0.95 m
`masts[1].spreader_section.chord`	100 mm
`masts[1].spreader_section.depth`	28 mm
`masts[1].spreader_section.A`	3.5 cm^2
`masts[1].spreader_section.I_vertical`	5 cm^4
`masts[1].spreader_section.I_horizontal`	40 cm^4
`masts[1].spreader_section.J`	12 cm^4
`masts[1].shrouds.arrangement`	continuous
`masts[1].shrouds.cap.size`	1/4 in
`masts[1].shrouds.cap.chainplate.x`	-7.10 m
`masts[1].shrouds.cap.chainplate.y`	1.70 m
`masts[1].shrouds.lowers.forward.size`	1/4 in
`masts[1].shrouds.lowers.forward.chainplate.x`	-6.60 m
`masts[1].shrouds.lowers.forward.chainplate.y`	1.65 m
`masts[1].shrouds.lowers.aft.size`	1/4 in
`masts[1].shrouds.lowers.aft.chainplate.x`	-7.55 m
`masts[1].shrouds.lowers.aft.chainplate.y`	1.65 m
`stays[0].size`	7/16 in
`stays[1].bottom.x`	-9.60 m
`stays[1].bottom.y`	1.70 m
`stays[1].bottom.z`	0.40 m
`stays[1].size`	3/8 in
`stays[2].bottom.x`	-4.40 m	Forward end of the cockpit.
`stays[2].bottom.z`	0.60 m
`stays[2].size`	1/4 in
`stays[3].bottom.x`	-9.30 m
`stays[3].bottom.y`	1.20 m
`stays[3].bottom.z`	0.40 m
`stays[3].size`	5/16 in

All cases at a glance

Case	Solver	Governing wire	SF	Peak mast stress
Dock tune	Pynite P-Delta	cap V2 (port)	4.90	44 MPa · 18%
Full sails, RM ×1.0	Pynite P-Delta	cap V2 (port)	3.42	51 MPa · 21%
Forestay sag, RM ×1.0	OpenSees corotational	forestay	2.18	58 MPa · 24%