Island Packet 40: rig report
DEMO: these results are replayed from the notebook study of this boat, stored in tests/reference/island-packet-40-1996.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/island-packet-40-1996.yaml, rigframe 0.1.0.dev0,
2026-11-06.
Estimates: what to measure (33 of 58 inputs)
| Input | Value used | Note |
|---|---|---|
hull.GZ30 | 0.70 m | No stability curve found. |
sail_plan.J2 | 3.90 m | Staysail stay tack on the foredeck. |
sail_plan.staysail_LP | 100 % | Self-tending staysail on a boom. |
sail_plan.reef_fraction | 60 % | |
masts[0].heel_z | -1.60 m | |
masts[0].gooseneck_z | 1.95 m | |
masts[0].above_hounds | 0.20 m | |
masts[0].section.chord | 254 mm | Maker not known. |
masts[0].section.width | 165 mm | |
masts[0].section.wall | 5.0 mm | |
masts[0].section.yield | 240 MPa | |
masts[0].spreaders[0].height | 50 % | |
masts[0].spreaders[0].length | 1.45 m | |
masts[0].spreader_section.chord | 130 mm | |
masts[0].spreader_section.depth | 38 mm | |
masts[0].spreader_section.A | 6.0 cm^2 | |
masts[0].spreader_section.I_vertical | 16 cm^4 | |
masts[0].spreader_section.I_horizontal | 120 cm^4 | |
masts[0].spreader_section.J | 40 cm^4 | |
masts[0].shrouds.arrangement | continuous | |
masts[0].shrouds.cap.chainplate.x | -0.10 m | |
masts[0].shrouds.cap.chainplate.y | 1.80 m | |
masts[0].shrouds.lowers.forward.chainplate.x | 0.55 m | |
masts[0].shrouds.lowers.forward.chainplate.y | 1.72 m | |
masts[0].shrouds.lowers.aft.chainplate.x | -0.80 m | |
masts[0].shrouds.lowers.aft.chainplate.y | 1.72 m | |
stays[0].size | 3/8 in | Not in the rigging table. |
stays[1].top.at | 50 % | Tang at the spreader root. The input most likely to change the answer. |
stays[1].bottom.x | 3.90 m | |
stays[1].size | 5/16 in | |
stays[2].bottom.x | -7.40 m | |
stays[2].bottom.y | 1.10 m | |
stays[2].bottom.z | 0.45 m |
All cases at a glance
| Case | Solver | Governing wire | SF | Peak mast stress |
|---|---|---|---|---|
| Dock tune | Pynite P-Delta | cap V2 (port) | 4.91 | 46 MPa · 19% |
| Full sails, RM ×1.0 | Pynite P-Delta | cap V2 (port) | 3.28 | 51 MPa · 21% |
| Full sails, RM ×1.5 | Pynite P-Delta | aft lower D1A (port) | 2.50 | 69 MPa · 29% |
| Genoa only, RM ×1.0 | Pynite P-Delta | cap V2 (port) | 2.64 | 48 MPa · 20% |
| Staysail + reefed main (60% of P), RM ×1.0 | Pynite P-Delta | aft lower D1A (port) | 2.49 | 128 MPa · 53% |
| Reefed main only (60% of P), RM ×1.0 | Pynite P-Delta | aft lower D1A (port) | 2.57 | 160 MPa · 67% |
| Stay sag, RM ×1.0 | OpenSees corotational | forestay | 2.26 | 78 MPa · 32% |
| Stay sag, RM ×1.5 | OpenSees corotational | forestay | 1.81 | 105 MPa · 44% |
| Staysail + reefed main, stay sag, RM ×1.0 | OpenSees corotational | aft lower D1A (port) | 1.71 | 166 MPa · 69% |