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Local Notice to Mariners 19/2025
04/07/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Cynghorir morwyr am safleoedd cyfredol y Cymhorthion Mordwyo a restrir isod.
Mariners are advised of the current positions of the Aids to Navigation listed below.
| Aid to Navigation | Depth (5 metres off correct side of AtoN, adjusted to CD). | Latitude | Longitude | Light |
|---|---|---|---|---|
| Change of detail since last report. | ||||
| 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 |
Local Notice to Mariners 18/2025
01/04/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Y Felinheli – Port Dionorwic
Mae tri Marc Rasio Tymhorol wedi’u sefydlu yn y safleoedd canlynol:
CHYF 3 – 53˚10.867N 004˚ 13. 476W
CHYF 4 – 53˚11.110N 004˚ 13. 095W
CHYF 5 – 53˚11.326N 004˚ 12. 936W
Three Seasonal Race Marks have been established in the following positions:
PDSC 3 – 53˚ 10.87N 004˚ 13. 47W
PDSC 4 – 53˚ 11.11N 004˚ 13. 09W
PDSC 5 – 53˚ 11.32N 004˚ 12. 93W
Local Notice to Mariners 17/2025
12/05/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Y Fenai – Menai Strait
Mae cymhorthydd mordwyo drots dro Port “T” Fl(2) R 5s nawr ar ei safle yn y lleoliad isod.
53ᵒ10.53′ Gog 004ᵒ14.55′ Gor
Temporary Aid to navigation Port “T” Fl (2) R 5s is now on station in the position below.
53ᵒ10.53′ N 004ᵒ14.55′ W
Local Notice to Mariners 16/2025
12/05/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Aber Seiont
Mae Pont Aber nawr yn weithredol.
Mae Hysbysiad i Forwyr 15/2025 yn cael ei ganslo drwy hyn.
The Aber bridge is now operational.
Notice to Mariners 15/2025 is hereby cancelled.
Local Notice to Mariners 15/2025
10/05/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Aber Seiont
Hysbysiad o gyfyngiad dros dro i fynd i mewn i Afon Seiont neu ei gadael, oherwydd methiant mecanyddol Pont yr Aber.
Nid yw’r bont yn gallu agor yn fecanyddol ar gyfer llongau.
Unwaith y bydd y bont wedi’i hatgyweirio, bydd hysbysiad canslo yn cael ei gyflwyno.
Ar gyfer llong sydd angen hafan ddiogel:
Cysylltwch â’r Doc Feistr. Ch 80
07483 072851
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
07483 072851
Local Notice to Mariners 14/2025
30/04/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Aber Seiont
http://www.gwylfwydcaernarfon.cymru/2025-festival.html
Hysbysiad o newid dros dro i weithdrefnau gweithredu presennol Pont Yr Aber.
Ar 10/05/2025.
Bydd y bont yn agor yn ôl yr angen i draffig yr afon bob awr rhwng yr oriau
09:00 – 14:30
Ar gyfer llong sydd angen hafan ddiogel:
Cysylltwch â’r Doc Feistr. Ch 80
01286 672346
http://www.gwylfwydcaernarfon.cymru/2025-festival.html
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 – 14:30
For vessel requiring safe haven.
Please make contact with the Dock Master. Ch 80
01286 672346
Local Notice to Mariners 13/2025
29/04/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Mae Hysbysiad i Forwyr 17/2022 yn cael ei ganslo drwy hyn.
Notice to Mariners 17/2022 is hereby cancelled.
Local Notice to Mariners 12/2025
03/04/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Bar Caernarfon Bar
Mae cymhorthydd mordwyo Starboard Rhif C11 Fl(2)G.5s nawr yn ddangos ei siâp dydd priodol ac nawr yn arddangos ei nodweddion golau priodol.
53ᵒ09.88′ Gog 004ᵒ15.64′ Gor
Cynghorir morwyr bod yr hysbysiad hwn yn dileu Hysbysiad 10/25.
Aid to navigation Starboard C11 Fl(2)G.5s is now demonstrating its appropriate day shape and is exhibiting its appropriate light characteristics.
53ᵒ09.88′ N 004ᵒ15.64′ W
Mariners are advised that this notice herby cancels Notice 10/25.
Local Notice to Mariners 11/2025
01/04/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Bar Caernarfon Bar
Longddrylliad “Grampian Castle” Wreck
Mae Cardinal De sefydlog newydd VQ(6) + LFl 10s (Castell Grampian) wedi osod ar longddrylliad “Grampian Castle”.
53ᵒ07.30′ Gog 004ᵒ22.99′ Gor
A new Fixed South Cardinal VQ(6) + LFl 10s (Grampian Castle) has been affixed to the wreck of the “Grampian Castle”.
53ᵒ07.30′ N 004ᵒ22.99′ W
Local Notice to Mariners 10/2025
13/03/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Bar Caernarfon Bar
Mae cymhorthydd mordwyo Starboard Rhif C11 Fl(2)G.5s nad yw’n dangos ei siâp dydd priodol ac nad yw’n arddangos ei nodweddion golau priodol.
53ᵒ09.88′ Gog 004ᵒ15.64′ Gor
Aid to navigation Starboard C11 Fl(2)G.5s is not demonstrating its appropriate day shape and is not exhibiting its appropriate light characteristics
53ᵒ09.88′ N 004ᵒ15.64′ W
Local Notice to Mariners 09/2025
19/03/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Swellies
Cynghorir morwyr bod yr hysbysiad hwn yn dileu Hysbysiad 08/25.
Mariners are advised that this notice herby cancels Notice 08/25.
Local Notice to Mariners 08/2025
19/03/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Swellies
Bydd dau fwi angori yn cael eu lleoli o amgylch Swelly Rock o 13:00 ar 21/03/25 hyd nes y cyhoeddir Rhybudd Morwriaeth yn dileu. Mae’r rhain er mwyn caniatáu mynediad ar gyfer gwaith atgyweirio arferol i’r AtoN.
Nid yw’r angorfeydd yn addas i’w defnyddio a gwaherddir Morwyr rhag defnyddio’r angorfeydd.
Cynghorir morwyr i fordwyo gyda gofal yn yr ardal hon.
Two mooring buoys will be situated surrounding Swelly Rock from 13:00 on the 21/03/25 until a cancellation Notice to Mariners is issued. These are to allow access for routine repairs works to the AtoN.
The moorings are not suitable for use and Mariners are prohibited from making use of the moorings.
Mariners are advised to navigate with caution in this area.
Local Notice to Mariners 07/2025
17/03/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Bae Caernarfon Bay
Cynghorir morwyr y bydd y cwch “Seven Guardian” yn cynnal arolwg gwyddonol ar raddfa fach (samplu cydio) rhwng y dyddiadau isod yn yr ardal Bae Caernarfon gan gynnwys y ffyrdd tuag at Gaernarfon. Bydd samplu yn cymryd oddeutu 2 ddiwrnod a bydd yn golygu gostwng ac adfer samplwr cydio gwaddod bach mewn lleoliadau ar draws y bae o borth Dinllaen i o amgylch Bar Caernarfon.
Gwaith arolwg: arolwg “benthig” Bae Caernarfon
Cyfnod yr Arolwg: 31/03/2025 – 18/04/2025
Hyd yr arolwg: 2 ddiwrnod
Amser yn yr orsaf: 15-60 munud
Lleoliadau sampl: ynghlwm
Cwch Arolwg: Severn Guardian
Dim ond ar gyfer y dyddiadau uchod y mae’r Hysbysiad hwn yn ddilys.
Mariners are advised that the vessel Seven Guardian will be undertaking a smallscale scientific survey (grab sampling) between the dates below in the Caernarfon Bay Area including the approaches to Caernarfon. Sampling will take approximately 2 days and will involve lowering and retrieving a small sediment grab sampler at locations across the bay from Porthdinllean to around the Caernarfon Bar.
Survey work: Caernarfon Bay benthic survey
Survey Period: 31/03/2025 – 18/04/2025
Survey duration: 2 days
Time on station: 15-60 mins
Sample locations: attached
Survey Vessel: Severn Guardian
This Notice is only valid for the above dates.
Local Notice to Mariners 06/2025
13/03/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Bar Caernarfon Bar
Mae cymhorthydd mordwyo Bwi Tramwyo L FL 10s ar ei safle priodol.
53ᵒ06.95′ Gog 004ᵒ25.14′ Gor
Aid to navigation Fairway Buoy L FL10s is now on station.
53ᵒ06.95′ N 004ᵒ25.14′ W
Local Notice to Mariners 05/2025
13/03/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Ynys Llanddwyn Island
Mae cymhorthydd mordwyo “Graig Dde dwyrain” Ynys Llanddwyn Cardinal De, Melyn a Du nawr ar ei safle priodol.
53ᵒ08.04′ Gog 004ᵒ24.46′ Gor
Cynghorir morwyr i fod yn ofalus iawn yn y ardal hwn.
Aid to navigation Llanddwyn Island “South East Rock” South Cardinal, Y.B is on its appropriate station.
53ᵒ08.04′ N 004ᵒ24.46′ W
Mariners are advised to exercise extreme caution in this area.
Local Notice to Mariners 04/2025
12/02/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Bar Caernarfon Bar
Mae cymhorthydd mordwyo Port Rhif C12 Fl(2)R.10s nawr ar ei safle priodol.
53ᵒ08.49′ Gog 004ᵒ17.39′ Gor
Aid to navigation Port No C12 Fl(2)R.10s is now on its appropriate station.
53ᵒ08.49′ N 004ᵒ17.39′ W
Local Notice to Mariners 03/2025
12/02/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Bar Caernarfon Bar
Nid yw cymhorthydd mordwyo Port Rhif C2 Fl. R 10s ar ei safle priodol.
53ᵒ07.12′ Gog 004ᵒ24.43′ Gor
Lleoliad presennol: 53ᵒ07.10′ Gog 004ᵒ24.13′ Gor
Cynghorir morwyr i fordwyo gyda gofal yn yr ardal hon.
Aid to navigation Port No C2 Fl. R 10s is NOT on its appropriate station
station.
53ᵒ07.12′ N 004ᵒ24.43′ W
Present position: 53ᵒ07.10′ N 004ᵒ24.13′ W
Mariners are advised to navigate with caution in this area.
Local Notice to Mariners 02/2025
10/01/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Bar Caernarfon Bar
Nid yw cymhorthydd mordwyo “Graig Dde dwyrain” Ynys Llanddwyn Cardinal De, Melyn a Du ar ei safle priodol.
53ᵒ08.04′ Gog 004ᵒ24.46′ Gor
Cynghorir morwyr i fod yn ofalus iawn yn y ardal hwn.
Aid to navigation Llanddwyn Island “South East Rock” South Cardinal, Y.B is not on its appropriate station.
53ᵒ08.04′ N 004ᵒ24.46′ W
Mariners are advised to exercise extreme caution in this area.
Local Notice to Mariners 01/2025
10/01/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Bar Caernarfon Bar
Mae cymhorthydd mordwyo Port Rhif C2 Fl.R 10s nawr ar ei safle priodol.
53ᵒ07.102′ Gog 004ᵒ24.133′ Gor
Aid to navigation Port No C2 Fl.R 10s is on its appropriate station.
53ᵒ07.102′ N 004ᵒ24.133′ W
Local Notice to Mariners 29/2024
05/11/2024 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Bar Caernarfon Bar
Nid yw cymhorthydd mordwyo Bwi Drylliad yn nodi Castell Grampian Fl (4) Y10s ar ei safle priodol.
Y safle siartredig llongddrylliadau yw 53ᵒ07.30′ Gog 004ᵒ22.98′ Gor
Mae’r cymhorthydd mordwyo wedi derfynwyd dros dro ar gyfer y gaeaf.
Aid to Navigation Temporary Wreck Buoy marking the Grampian Castle Fl(4) Y10s is not on station.
The Wreck’s charted position is 53ᵒ07.30′ N 004ᵒ22.98′ W
The Aid to navigation has been temporarily discontinued for the winter.
Longterm Notices to Mariners
Local Notice to Mariners 11/2025
01/04/2025 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Bar Caernarfon Bar
Longddrylliad “Grampian Castle” Wreck
Mae Cardinal De sefydlog newydd VQ(6) + LFl 10s (Castell Grampian) wedi osod ar longddrylliad “Grampian Castle”.
53ᵒ07.30′ Gog 004ᵒ22.99′ Gor
A new Fixed South Cardinal VQ(6) + LFl 10s (Grampian Castle) has been affixed to the wreck of the “Grampian Castle”.
53ᵒ07.30′ N 004ᵒ22.99′ W
Local Notice to Mariners 24/2024
30/08/2024 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Bar Caernarfon Bar
“BANC CREGYN GLEISION”
Mae nawr Cymorth Mordwyo Port newydd ar Mussel Bank, ac mae bellach yn dangos siâp dydd priodol a golau Fl R(2)5s yn y sefyllfa ganlynol.
53ᵒ07.320′ Gog 004ᵒ20.926′ Gor
“MUSSEL BANK”
A new fixed Port Aid to Navigation on Mussel Bank, has been completed and is now demonstrating an appropriate day shape and light Fl R(2)5s is the following position.
53ᵒ07.320′ N 004ᵒ20.926′ W
Local Notice to Mariners 19/2021
02/07/2021 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Cynghorir morwyr bod yr ardal a amlygir isod ar y siart, yn benodol o amgylch C7 ac C12 wedi datblygu banc tywod sydd rhyw 1 metr yn uwch na Chart Datwm.
Cynghorir morwyr i gymryd rhybudd a rhoi sylw dyledus i’r dyfnder dŵr sydd ar gael wrth fordwyo yn yr ardal hon.
Mariners are advised that the area highlighted below on the chart, specifically around C7 and C12 has developed a sand bank that is approximately 1 meters above Chart Datum.
Mariners are advised to take caution and have due regard for the available depth of water when navigating in this area.
Local Notice to Mariners 12/2021
01/04/2021 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Harbour Master’s General Direction
5 Knot Speed Limit
By virtue of the provisions of Sec. 52 Harbour, Docks and Piers Clauses Act 1847, Port and harbour of Caernarfon Harbour Master has made the following General Direction:
1. This Direction is given to Masters (see note a) and persons having command or charge of any vessel (see note b) other than those vessels listed in paragraph 4(i) to 4(v).
2. This Direction applies at all times and in the area north of the existing and active speed limit at Y Felinheli. (Now known as the “Y Felinheli to Garreg Ginnog” Area of General Direction). The “Y Felinheli to Garreg Ginnog” means the area below the level of mean high water spring tides bounded by a line drawn along the northern extent of the existing charted speed limit at Y Felinheli and through to a new line drawn from a point 53ᵒ12.30’N 004ᵒ12.44’W to a point 53ᵒ12.40’ N 044ᵒ12.82’W. (Illustrative chart extract at end of NtoM).
3. At the Northern and Southern extent of the entire speed limit. Special Marks will be positioned to demark the area.
4. This Direction is not given to Masters and persons having command or charge of vessels:
(i) used by search and rescue organisations
(ii) of the Caernarfon Harbour Authority
(iii) of HM Customs and Excise
(iv) vessels under sail.
(v) used as safety boats by Yacht and Sailing Clubs and other such organisations when engaged in operations where complying with this Direction would inhibit their ability to fulfil their function as a safety boat
5. No vessel, except those listed in paragraphs 4(i) to 4(v), shall proceed at a speed of greater than 5 knots.
6. This Direction is given notwithstanding the requirements of the International Regulations for Preventing Collisions at Sea (see note c) and The Port and Harbour of Caernarfon Bylaws 1991 (see note d).
7. Not to comply with this Direction is a criminal offence for which the person having command or charge of the vessel may be prosecuted (see note e).
8. The Harbour Master or his deputies will be actively monitoring the compliance with this General Direction.
David John O’Neill
Caernarfon Harbour Master
Notes
a Sec.3 Harbour, Docks and Pier Clauses Act 1847
b As defined in the Port and Harbour of Caernarfon Bylaws 1991.
c Merchant Shipping (Distress Signals and Prevention of Collisions) Regulations 1996 [SI 75/1996]
d Port and Harbour of Caernarfon Bylaws 1991.
e Sec.3 and Sec.53 Harbour, Docks and Piers Clauses Act 1847
Owners, Agents Charterers, Marinas, Yacht Clubs and Recreational Sailing Organisations should ensure that the contents of this Notice are made known to the master or persons in charge of their vessel or craft.
Blue area denotes existing speed limit. Yellow area denotes new area of General Direction.
Local Notice to Mariners 14/2019
16/05/2019 – Y Fenai – Siart 1464 – Menai Strait – Chart 1464
Menai Strait
Cynghorir morwyr bod yr ardal a amlygir isod ar y siart, yn benodol o C11 er i C9 wedi datblygu banc tywod sydd rhyw 0.5 metr o ddŵr yn is na Chart Datwm.
Cynghorir morwyr i gymryd rhybudd a rhoi sylw dyledus i’r dyfnder dŵr sydd ar gael wrth fordwyo yn yr ardal hon.
Mariners are advised that the area highlighted below on the chart, specifically from C11 though to C9 has developed a sand bank that has approximately 0.5 meters of water below Chart Datum.
Mariners are advised to take caution and have due regard for the available depth of water when navigating in this area.
