Water Rescue
Water-rescue difficulty is graded by water type (still/slow/rapid/sea/ice/flood) combined with water temperature, flow velocity, distance to shore and victim condition, yielding method, equipment and warning advice.
1. Reach（延伸）：从岸边用竹竿/绳索延伸够及被困者
2. Throw（抛掷）：抛投救生圈/抛绳包
3. Row（舟艇）：使用冲锋舟/橡皮艇接近
4. Go（入水）：最后手段，救援人员入水接近（需最高等级防护）
>20°C：安全 | 15~20°C：低温风险 | 10~15°C：失温风险高 | <10°C：失温风险极高
冷水 immersion shock（入水休克）可在 1~3 分钟内致命
| Item | Formula / Note | Source / Standard |
|---|---|---|
| Water force | F = 0.5ρC_dAv², C_d≈1.0 | Drag equation |
| Safe current | >1.5 m/s no wading | Water rescue SOP |
| Throw bag | 15–25 m throw range | Rescue equipment spec |
| Live bait rescue | 45° tether angle | IRIA standards |
| Capsize moment | M = ρgV·GM | Ship stability |
| Cold water | Cold shock <15 °C | IMO guidance |
综合水域类型、流速、水温、距离和被困者状态，评估救援难度等级，推荐救援方法与装备清单。