Celestial navigation simulator

NAVIGATE
BY THE
STARS

Receive a daily astronomical observation computed from USNO ephemerides. Reduce it with HO 249 tables, plot your line of position, and submit your fix. The platform calculates your error in nautical miles.

19
Passages
3
Oceans
±0.5'
Nautical fidelity
→ Start for free
Magic link signup · No credit card
Today's observation — D4
HALIFAX BERMUDA
Day 4 of 7 · North Atlantic · Window open
The low-pressure system has passed. The wind veered northwest behind the front — the Sailcasted is sailing a beam reach, eight knots in the gusts. 318 miles from Halifax. You are halfway.
Body Sun — Lower limb
UTC Time 15:23:47
IC (index error) –2.3' on the arc
Dip (eye 3.2 m) To correct
Three Ho readings
41°12.3'
41°12.7'
41°11.9'
Your turn Consult the Almanac, reduce with HO 249, plot your line of position, submit your fix.
Actual position revealed in
44:17:03
Profiles

WHO IS SAILCASTED FOR

C
Certification student
Preparing for your Transport Canada, RYA, or STCW exam? Practice on realistic observations before the big day.
S
Experienced sailor
You know how to sail but your sextant is gathering dust? Refresh your skills with a 7-day passage.
I
Instructor
Teaching celestial navigation? Create a cohort and track your students' progress in real time.
How it works
4 STEPS
TO YOUR FIX
No software to install. No GPS. Just your tables, your pencil, and your reasoning.
01
Step 01
Sign up

Choose a passage. Receive your departure briefing with vessel parameters and your initial position.

02
Step 02
Receive your observations

Every day, an astronomical observation arrives by email. UTC time, observed altitude, correction data — everything you need.

03
Step 03
Calculate your position

Sight reduction with HO 249, AP 3270 or HO 229 tables depending on your certification. Plot your line of position. Determine your fix. On paper, like at sea.

04
Step 04
Submit and compare

Enter your estimated position. Compare with the actual position. Track your accuracy day after day.

USNO/JPL Ephemerides · Haversine Algorithm · Accuracy ±0.5' · No software required
Available passages

CHOOSE
YOUR PASSAGE

Real routes, simulated observations, accuracy to prove.

FREE
Tier 1 — Sun
7 days · North Atlantic
HALIFAX BERMUDA

Seven days from Dartmouth wharf to St. George's Harbour. Observe the Sun at meridian, reduce each line of position with HO 249, submit your position. Your delta is revealed when the 48-hour window closes — just like at sea.

7Days at sea
±30 nmTarget tolerance
1Narrative VHF fix
HO 249AP 3270 · HO 229
0 $
No credit card required
→ Start for free
Magic link · No password
19$
Passage · Tier 1–2
CAROLINAS → BAHAMAS

Cape Hatteras, Gulf Stream, turquoise shallows.

Tier 1 7 days
→ Enroll ±30 nm
7J
19$
Passage · Tier 1–2
EUROPE → AZORES

Europe's first Atlantic crossing, made yours.

Tier 1 10 days
→ Enroll ±30 nm
10J
View all 19 passages
Save with bundles

CROSS
EVERY OCEAN

Three thematic bundles to progress through a coherent learning arc. Buy the set — save on every passage.

–30%
Average savings
→ View all passages
Learning progression
PROGRESS
AT YOUR PACE

From beginner to confirmed navigator — each tier raises the complexity of celestial bodies, the expected accuracy, and the richness of the night sky to decipher.

Automatic unlock
by performance
over 7 consecutive days
1
Initiation
DECKHAND
Sun only
1 observation per day
Simple line of position
Short passages (5–14 days)
±30 nm
Target tolerance
Entry point — unlocked on signup
→ Start at Tier 1
1
2
Intermediate
WATCH OFFICER
Sun · Moon · Polaris
2 observations per day
Fix by crossing lines
Medium passages (14–28 days)
±15 nm
Target tolerance
Average < 30 nm over 7 consecutive days
→ View Tier 2 passages
2
3
Advanced
NAVIGATOR OFFICER
Sun · Moon · Stars · Venus
3 observations per day
Twilight multi-star fix
Long passages (21–90 days)
±10 nm
Target tolerance
Average < 15 nm over 7 consecutive days
→ View Tier 3 passages
3
4
Expert
CAPTAIN
All bodies · Eclipses
Rare oblique bodies
Degraded conditions
Long passages (35–90 days)
±8 nm
Target tolerance
Average < 10 nm over 7 consecutive days
→ View Tier 4 passages
4
FAQ

FREQUENTLY ASKED QUESTIONS

Do I need a sextant?
No. Observations are provided to you by email. You need a nautical almanac, reduction tables (HO 249, AP 3270 or HO 229), a worksheet and a pencil.
How much time per day?
Between 20 and 45 minutes depending on your level. The submission window is 48 hours — you work at your own pace.
What is the Tier system?
Four levels of increasing difficulty. You start at Tier 1 (sun only, ±30 nm). By maintaining good accuracy over 7 days, you automatically unlock the next tier with new celestial bodies and tighter tolerance.
For certified instructors

TEACH
CELESTIAL NAV
DIFFERENTLY

Create a cohort, invite your students, follow their daily progress. Sailcasted becomes the practice lab between your classroom sessions.

Cohort dashboard with per-student delta
Manual observation triggering (Workshop mode)
Narrative VHF fix to re-engage struggling students
Compatible with TP 15136F, RYA Yachtmaster, US Sailing, ASA
→ Submit my application
Manual validation · Limited to certified celestial navigation instructors
Solo navigator

NO NEED FOR
AN INSTRUCTOR
TO GET STARTED

Sign up directly, choose your passage, receive your observations. Progress at your pace — join a cohort later if you wish.

Immediate access without approval
Halifax → Bermuda completely free
Progress from Tier 1 to Tier 4 by performance
Join a cohort at any time
→ Start for free
Magic link · No password · No credit card
Your first observation arrives tonight

YOUR NEXT FIX
STARTS TONIGHT

Free signup. First observation within 24 hours. No software to install — just your HO 249 tables and a pencil.

→ START FOR FREE
Halifax → Bermuda · Free · 7 days · Tables HO 249 / AP 3270 / HO 229