ONBOARD CARD 04 — Gulf Stream Entry
Phase: Approaching and entering the Gulf Stream north wall. Typical elapsed time: Race start +24–40 h Location: Approximately 36.5°N to 38.5°N (varies by year and route)
TL;DR
- Set the sail BEFORE entering the Stream. A peel inside is the skipper's call, not a watch default.
- Every crew member physically locates reef line, kite sheets, kite halyard, tack line, foreguy — in daylight.
- First-time maneuver at night ≠ right time. Conservative sail; accept the speed loss.
- Squall ladder canonical 30/20/10 (see
crew_orientation.md— Squall Protocol). Pre-Stream: 30-nm rung is active trigger. - Adverse current >2.5 kts unforecasted → calculate bash-vs-deflect (Card 10 — Adverse Current section).
- Wake Skipper when squall forces tactical hold or route change.
DATA TO CHECK
Before entry (SST gradient still >50 nm north): - Latest RTOFS/HYCOM current at entry latitude — direction and magnitude - GRIB forecast wind for crossing window - CAPE overlay if available — convective risk in crossing zone? - SST isotherm position from most recent imagery - Radar: any echoes within 30 nm W–SW–NW? - GPS/log: are you already seeing Stream influence?
At the SST gradient: - Sea surface temp every 30 min - Boat speed: 2–5% increase at entry is typical - Current experienced: GPS SOG minus log STW = current speed/direction - Wave character: chop increases if wind is opposing current
TRIM / SAIL
Before entry: reduce to entry sail; do NOT enter mid-peel; douse kite immediately if squall echo is developing.
| Conditions | Preferred sail | Notes |
|---|---|---|
| SW 10–16 kts, reaching | Code 67 or A3 | Code 67 at 80–120°; A3 if it broadens past 110° |
| SW 16–24 kts, reaching | A3 or J3 | A3 if chop manageable; J3 if gear-shy |
| SW 24+ kts, any angle | J3 or J4 | J4 at 28+ kts; reef ready |
| NW 10–20 kts, broad reach | A3 | A2-1 only if running past 140° |
| NW 20–30 kts, running | A3 or SS | SS only if crew is confident |
| Light <8 kts | A1-1 or Code 67 | Code 67 if tight angle; A1-1 if open reach |
| Upwind in adverse current + chop | J3 or J4 — conservative | Do not carry J1 upwind in Stream chop |
TACTICAL OPTIONS
- Enter on planned latitude — execute pre-race routing hypothesis
- Enter early (north) — if current on rhumb is adverse and CCR western limb is within reach
- Enter late (south) — if Stream has shifted north and current at planned entry is weak
- Hold at gradient — if squall line or frontal passage is imminent (30 min or less); do NOT enter the Stream in that window
RED FLAGS
- Radar echo within 30 nm W–NW: GET KITE DOWN. REEF #1 READY.
- Water temp change >5°F in <2 nm: you are in the north wall — full crew awareness
- GPS/log current showing adverse >1.5 kts: possible meander — check position vs pre-race Stream analysis
- Wave height/period abruptly changes (steeper, shorter): wind-against-current — assess sail choice immediately
- Log boat speed drops >1 kt unexpectedly: adverse current — are you in the wrong lane?
DECISION THRESHOLD
Adverse current >2.5 kts on rhumb, unforecasted: - Calculate: bash through or deflect 15–20°? - Run routing detour scenario onboard. If detour saves >2 h on corrected time, seriously consider it.
Squall threat forces hold at north wall: - Can hold up to 60–90 min south of the wall; costs less than a blown kite inside. - Brief crew: "waiting for the squall to clear."