Caernarfon Notice to Mariners 22/2025
Aid to Navigation Aber Menai Point is on station and showing it’s appropriate lights.
The land marks position is 53°7.619 N 004°19.715 W
David John O’Neill
Harbwr Feistr Caernarfon Harbour Master
Sailing in Company since 1928
Aid to Navigation Aber Menai Point is on station and showing it’s appropriate lights.
The land marks position is 53°7.619 N 004°19.715 W
David John O’Neill
Harbwr Feistr Caernarfon Harbour Master
Aid to Navigation Aber Menai Point is not on station.
The charted position is 53° 7.619 N 004° 19.715 W
Mariners are advised to navigate with caution in this area.
David John O’Neill
Harbwr Feistr Caernarfon Harbour Master
Mariners are advised of the current positions of the Aids to Navigation listed below.
| Yellow Highlight = | Change of position since last |
| Aid to Navigation | Depth (5 metres off correct side of AtoN, adjusted to CD). | Latitude | Longitude | Light |
|---|---|---|---|---|
| LLANDDWYN ISLAND SW ROCK BUOY S CARDINAL | 8.5m | 53ᵒ 07’.89 N | 004ᵒ25’.15 W | Unlit |
| LLANDDWYN ISLAND NE ROCK BUOY S CARDINAL | 2.02m | 53ᵒ 08’.04 N | 004ᵒ24’.47 W | Unlit |
| SAFE WATER MARK | 7.64m | 53ᵒ 06’.95 N | 004ᵒ25′.14 W | L Fl.10s |
| C 1 STARBOARD | 5.38m | 53ᵒ 06’.96 N | 004ᵒ24’.71 W | Fl.G.5s |
| C 2 PORT | 0.34m | 53ᵒ 07’.12N | 004ᵒ24’.71 W | Fl.R.10s |
| C 3 STARBOARD | 1.7m | 53ᵒ 07’.23 N | 004ᵒ 23’.88 W | Q.G |
| C 4 PORT | 1.8m | 53ᵒ 07’.12 N | 004ᵒ22’.72 W | Q.R |
| GRAMPIAN CASTLE S CARDINAL | N/A | 53ᵒ 07’.26 N | 004ᵒ 22’.96 W | VQ(6)+LFl.10s |
| C 5 STARBOARD | 1.93m | 53ᵒ 07’.19 N | 004ᵒ23’.37 W | Fl.G(2).5s |
| C 6 PORT | 2.3m | 53ᵒ 07’.16 N | 004ᵒ21’.91 W | Fl.R.5s |
| MUSSEL BANK PERCH | 5.59m | 53ᵒ 07’.32 N | 004ᵒ20’.92 W | Fl.R(2).5s |
| C 8 PORT | 3.76m | 53ᵒ 07’.63N | 004ᵒ19’.43 W | Fl.R.3s |
| C 10 PORT | 2.1m | 53ᵒ 07’.95 N | 004ᵒ18’.22 W | Q.R |
| C 7 STARBOARD | 2.3m | 53ᵒ 08’.14 N | 004ᵒ18’.13 W | Q.G |
| C 12 PORT | 3.03m | 53ᵒ 08’.50 N | 004ᵒ17’.38 W | Fl(2)R.10s |
| C 9 STARBOARD | 3.58m | 53ᵒ 08’.57 N | 004ᵒ16’.88 W | Fl.G.2s |
| CHANGE BUOY S CARDINAL | 2.19m on station 6.09m in channel | 53ᵒ 08’.81 N | 004ᵒ16’.72 W | VQ(6)+LFl.10s |
| SEIONT RIVER BIFURCATION | -1.21m | 53ᵒ 08’.55 N | 004ᵒ16’.79 W | Unlit |
| TRAETH GWYLLT STARBOARD | 6.04m | 53ᵒ 09’.29 N | 004ᵒ16’.08 W | Fl(2)G.10s |
| C 13 STARBOARD | 3.74m | 53ᵒ 09’.54 N | 004ᵒ15’.89 W | Fl(4)G.10s |
| C 11 STARBOARD | 4.2m | 53ᵒ 09’.88 N | 004ᵒ15’.63 W | Fl(2)G.5s |
| C 14 PORT | 7.38m | 53ᵒ 10’.23 N | 004ᵒ15’.41 W | Fl.R.5s |
| C TEMP | 53ᵒ 10’.53 N | 004ᵒ14’.67 W | FL(2)R.5s | |
| C 9 STARBOARD PORT DINORWIC | 1.29m | 53ᵒ 10.69 N | 004ᵒ13’.81 W | FL(3)G.10s |
David John O’Neill
Harbwr Feistr Caernarfon Harbour Master
Notice of Commencement of Works- Oyster deployment
Wild Oysters: Conwy Bay Project – Native oyster (Ostrea edulis) Habitat Restoration, Conwy Bay.
The deposit of native oysters, Ostrea edulis for Wild Oysters: Conwy Bay Project is due to take place between 17 June 2025 until 24 June 2025. The works will involve depositing oysters on the seabed undertaken by the Conwy Harbour Authority, using the vessel Jac-Y-Do. Temporary buoys will be in place to aid deployment within the site. It should be noted that these are not for any navigational warning purposes.
See the attached document for more information.
Matthew Forbes
MSc LLB (hons) BSc AFNI
Conwy Harbour Master
All mariners are advised that 4 orange buoys will be positioned in Conwy bay to aid in the cultch deployment for the Bangor University oyster regeneration project. Please see attached detailed information of the planned cultch deployment works issued by Bangor University.
Works are scheduled to commence on the 9 th June 2025 for a period of 20 days.
A further notification will be issued on completion of the Cultch deployment.
Matthew Forbes
MSc LLB (hons) BSc AFNI
Conwy Harbour Master
Three Seasonal Race Marks have been established in the following positions.


David John O’Neill
Harbwr Feistr Caernarfon Harbour Master
Temporary Aid to navigation Port “T” Fl (2) R 5s is now on station in the position below.
53°10’.53 N 004°14’.55 W
David John O’Neill
Harbwr Feistr Caernarfon Harbour Master
The Aber bridge is now operational.
Notice to Mariners 15/2025 is hereby cancelled.
David John O’Neill
Harbwr Feistr Caernarfon Harbour Master
Notice of temporary restriction to enter or depart the Afon Seiont. due to mechanical failure of the Aber Bridge.
The bridge is not mechanically able to open for vessels. Emergency work will be completed as soon as possible. Once the bridge is repaired a cancellation notice will be issued.
For vessel requiring safe haven. Please make contact with the Dock Master. Ch 80. 01286 672346
David John O’Neill
Harbwr Feistr Caernarfon Harbour Master
Notice of temporary change to current operational procedures at the Aber Swing Bridge.
On the 10/05/2025
The bridge will open as required to river traffic on each hour between the hours of
09:00 – 1430
For vessel requiring safe haven.
Please make contact with the Dock Master. Ch 80
01286 672346
David John O’Neill
Harbwr Feistr Caernarfon Harbour Master