Daily Navigator Brief Template - Newport to Bermuda Race

Instructions

Copy this template for each briefing cycle. Name files: YYYY-MM-DD_Tminus_N_brief.md Example: 2024-06-11_Tminus10_brief.md

Complete ALL sections. Do not skip sections. If data is unavailable, say so explicitly. Mark the brief PRE-RACE RESEARCH - NOT for use as race-period routing advice.

Brief date: __ Brief time (UTC): __ T-minus: ___ days to start Briefing by: __ GRIB cycles used: GFS ___ z / ECMWF ___ z SST product date: __ Altimetry product date: ___

EXECUTIVE SUMMARY

3–5 sentences max. What is the dominant feature, what is the routing implication, and what is the headline change since last brief?

Pattern type (analog code): Primary: ___ Secondary (if applicable): ___ Analog confidence: HIGH / MEDIUM / LOW Best historical analog years: ___ (primary), ___ (secondary) Key difference from analog years: ___

SECTION 1 - Dominant Weather Feature

Feature name and description:

Position and movement:

Expected timing relative to fleet: | Race elapsed hours | Expected conditions | |-------------------|---------------------| | 0–12h | | | 12–24h | | | 24–48h | | | 48–72h | | | 72–96h | |

What would change this picture:

SECTION 2 - Gulf Stream Situation

North wall position at ~67°W: °N Data source: SST / RTOFS / altimetry / all three RTOFS vs SST agreement: YES / NO - if NO: ______

Stream meander present: YES / NO (A meander is a bend in the connected Stream - distinct from a CCR. 2024 analog: southerly meander delivered up to 5 kts NE favorable current on the eastern limb.) If YES: - Meander direction: southerly / northerly / complex - Favorable limb position: °N °W - Expected favorable current: ___ kts - RTOFS confirmed: YES / NO - SST confirmed: YES / NO - Pre-calculated exit latitude: °N (calculate BEFORE committing to meander entry) - Routing strategy: T-ME - enter favorable limb, exit at above latitude - Routing implication: ______

Cold core ring (CCR) present: YES / NO (CCR = detached cold-water ring; NOT connected to main Stream. Position uncertainty ±20–30 nm. 2016 cautionary tale - RTOFS alone is unreliable.) If YES: - Center position: °N °W - Diameter estimate: ___ nm - SST anomaly: °F - Altimetry confirmed: YES / NO - if NO: do not commit - Favorable (western) limb position: ___ - Routing implication: ______

Warm core eddy (WCE) present: YES / NO (WCE south of Stream - adverse on western/southern limb. 32–34°N is typical location.) If YES: - Center position: °N °W - Diameter estimate: ___ nm - SST anomaly: °F - Altimetry confirmed: YES / NO - Adverse limb extent and bearing from rhumb: ___ - Routing implication: ______

Expected current on rhumb line crossing: - Speed: ___ kts - Direction: ___ - Duration of significant current exposure at rhumb crossing speed: ___ h

Wind-against-current risk: YES / NO / POSSIBLE If YES/POSSIBLE: ___

Optimal crossing window: - Latitude range: °N to °N - Timing: ___ - Why: ___

Stream situation change since last brief:

SECTION 3 - Model Agreement / Disagreement

GFS vs ECMWF comparison: | Feature | GFS | ECMWF | Agreement | |---------|-----|-------|-----------| | Ridge axis position | | | | | Front timing (if applicable) | | | | | Wind speed at crossing | | | | | Post-stream wind | | | | | Bermuda approach wind | | | | | Routing result (rhumb, elapsed) | | | |

Model delta (elapsed time, rhumb route): GFS: h / ECMWF: h / Delta: ___h

Which model is preferred this cycle and why:

Confidence in forecast: - 0–24h: HIGH / MEDIUM / LOW - 24–48h: HIGH / MEDIUM / LOW - 48–72h: HIGH / MEDIUM / LOW - 72–96h: HIGH / MEDIUM / LOW

What would change model preference:

SECTION 4 - Likely Race Phases

First 12 Hours (Newport to offshore)

Expected conditions: __ Dominant sail: __ Key tactical issue: __ Watch for: __

Gulf Stream Crossing Window

Expected entry time: Race elapsed ___ h (approximately) Expected conditions at entry: __ Stream crossing strategy: __ Contingency if crossing conditions are worse than forecast: ___

Post-Stream to Bermuda

Expected conditions: __ Dominant sail: __ Key tactical issue: ___

Bermuda Approach

Expected conditions in final 150 nm: __ Shutdown risk: YES / NO / POSSIBLE Approach angle: __

SECTION 5 - Routing Hypothesis Status

Primary Strategy: ___

Label: H-RH (rhumb) / H-PF (pressure) / H-CF (current) / H-ME (meander) / H-CCR (cold ring) / H-CL (conservative) / H-HR (high risk) Tactic tags: __ Elapsed time estimate (S3, 10% degradation - planning default): ___ h Sensitivity: robust at S4 (YES / NO / BORDERLINE) Key assumption: __ Failure trigger: ___

Backup Strategy: ___

Label: __ When to activate: __ Estimated time cost vs primary: ___ h

Discarded Strategies and Why:

___ - reason: ___
___ - reason: ___

SECTION 6 - Sail Inventory Implications

Based on this forecast, the following sails should be prioritized:

Essential (must have on board and in top condition): - ___

Probably needed: - ___

Likely not needed but carry if space allows: - ___

Consider leaving ashore: - ___

SECTION 7 - Crew and Watch Implications

Expected rest windows (periods of predictable, simple conditions): | Time window (elapsed h) | Conditions | Rest potential | |------------------------|------------|----------------| | | | |

High-alert windows (all hands or experienced watch): | Time window | Reason | |-------------|--------| | | |

Watch schedule considerations:

SECTION 8 - Tactical Decision Points

List the 3–5 key decisions the navigator must make, in chronological order:

Decision #	What decision	When to decide	Key data needed	Fallback if wrong
1
2
3
4
5

SECTION 9 - Top 3 Navigator Questions

The three most important unresolved questions for the next briefing cycle:

SECTION 10 - What Changed Since Previous Brief

Item	Previous brief	This brief	Significance
Pattern type
Stream north wall
Stream meander
Cold core ring
Warm core eddy
Primary strategy
GFS elapsed estimate
ECMWF elapsed estimate
Model agreement

APPENDIX - Raw Model Data Summary

(Paste key numbers from model runs here for archiving)

GFS rhumb elapsed: ___h
ECMWF rhumb elapsed: ___h
GFS primary strategy elapsed: ___h
ECMWF primary strategy elapsed: ___h
Stream north wall (RTOFS): ___°N
Stream north wall (SST): ___°N

PRE-RACE RESEARCH - NOT for use as race-period routing advice Template version: 1.1 - Stream meander field added; H-ME hypothesis label added; CCR/WCE clarifications added