The southerly entrance to the channel between Holy Island and Anglesey itself is called Cymyran Inlet. It lies between Silver Bay to the west and RAF Valley to the east. Glazebrook's Anglesey Pilot (out of print) is very positive about it: as the only safe haven on a large stretch of coast
The chartlet in Glazebrook's 1961 Pilot shows lots of detail.
Depths in the Cymyran Inlet are in fathoms after one hour of flood tide.
TVS means tide very strong (especially ebb).
click for image.
His chart suggests that there was 3 ft depth at one hour after LWS if the correct
route in is taken.
There is no buoyage and there are a lot of rocks lurking. Away from HW, the current could be quite strong also.
So a challenge: I tried to enter it a few years ago, see here. I did not get far because I had no idea of the correct location of the deepest channel. Google Earth has the option to look at historic images and I found the 2006 image was taken at close to LW. I used this to set up waypoints to aid my access.
2006 Google Earth image (close to LW) with my waypoints:
On Thursday 6 July 2017 near HW (Holyhead HW 9:39 4.8m; Porth Trecastell
HW 9:04 4.2m) from 9:08 until 9:25 I explored. Current was slack. My tracks are shown
superimposed on the chart here:
The depths shown are below my keel, so 0.7m less than the full depth
at that tidal state, namely 4.2m above CD. Note that LWS would be 3.5m less than
at that tide state. So a depth reading of 2.8m on the plot corresponds
to seabed at LWS level. Also shown are my waypoints (depths in metres;
distances in metres):
I seem to have lost the channel a bit while turning near the "pool" - most probably because I tried to stay clear of moored vessels. In my experience, near HW one can get in with more than 2m depth. The moorings in the "pool" restrict options for staying. Taking the ground somewhere suitable (for example after exploration at LW on foot - though that would entail a long walk) is an option.
Images of my 2017 trip:
Entrance from seaward (at left of image); in channel looking out.
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Boats in Pool; rocks in entrance offshore(looking outwards).
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This can be a very sheltered and peaceful spot - though not in mid-week 9-5 when RAF Valley is practising and very very noisy at times.
I would be interested to hear from anyone with more experience than me of this challenging "port".