ONBOARD CARD 05 — Inside the Gulf Stream
Phase: North wall entry to south wall exit. Typical elapsed time: 8–18 h inside (boat-speed and current dependent) Location: Approximately 35°N to 38.5°N (varies by year)
TL;DR
- Default: hold the entry sail — a Stream peel is the skipper's call, not a watch decision. J4 / Code 67 furl if you must.
- All crew on deck clipped in. No exceptions.
- Squall ladder stepped from 30-nm to 20-nm rung at the north wall. Per-rung procedure in Card 09.
- Track current core via GPS/log delta every 30 min; SST every 30 min.
- Adverse >4.5 kts = meander or wrong lane — immediate Navigator attention.
- Wake all watch on Stream entry, squall ≤20 nm, or SST change >5°F in 5 nm.
DATA TO CHECK
Every 30 min: - GPS SOG vs log STW: difference = net current vector. Record it — it should increase toward the core. - Water temperature: note at every speed change. Core is often warmest. - Radar: check for convective echoes; development can be rapid (10-min cycles) inside the Stream.
Every hour: - Course made good (CMG): are you being set? Compensating correctly? - Update dead reckoning for current set. - On track to exit at planned latitude?
Every 3–4 hours: - Compare observed current to pre-loaded routing analysis. If significantly different → what does this mean for exit latitude and strategy?
TRIM / SAIL
Core of the Stream: - Not the time for aggressive sail changes. Prioritize the sail that is working now. - If wind builds to crossover: go conservative and take the sail down now. - If you dropped reef pre-entry: resist shaking it out in the core.
Squall management (see also Card 09): - At ANY squall echo within 20 nm: douse the kite if flying. - Reef #1 pre-rigged in mast throughout daylight in the Stream; no exceptions at night. - A 15–30 min squall gust at 35–45 kts with a kite up can end your race.
TACTICAL OPTIONS
- Track the favorable current core — steer to maximize northward set via GPS/log vector
- Follow north wall — if CCR western limb: stay tight to north wall for additional favorable current before diving S
- Cut straight south — if adverse current: get through the core as fast as possible; extra distance costs less than more time in adverse
- Angle for exit latitude — if current is pushing you off planned exit, correct heading to compensate
Important geometry: The Stream flows NE. Heading south (160–180°T), the current adds a NE component to your actual position. You will be set ENE of your intended track if you don't compensate. Confirm GPS/CMG offset before entry.
RED FLAGS
- GPS/log delta >4.5 kts adverse: meander or wrong lane — immediate Navigator attention
- Water temp drops rapidly while in intended current zone: may be inside a cold-core ring — check position
- Wave character shifts from running/reaching to steep choppy: wind-against-current developing — reduce sail NOW
- Squall gust >30 kts: kite should already be down if Card 04 was followed
- Any crew member showing extreme fatigue, confusion, or physical distress: all hands wake; safety first
DECISION THRESHOLD
Crossing taking >2 h over estimate: - Likely cause: stronger adverse current or wind shift. - Adverse current: consider angling 20–30° toward the favorable side. - Wind shift: update strategy for post-Stream leg.
Crossing faster than expected: - Confirm exit latitude is still correct relative to post-Stream plan. - Don't exit too far east or west of planned post-Stream waypoint.
Stream Crossing Log
| UTC time | Lat | Lon | SST °F | SOG | STW | Current (calc) | Wind TWS/TWA | Notes |
|---|---|---|---|---|---|---|---|---|
| Entry | ||||||||
| Core | ||||||||
| Exit |