There is over-riding factor when planning any cruise around the Island, and particulary from the club's premises at Gallows Point - the Admiralty Tide Tables!
North Wales is one of those places where, without tide tables, you might as well stay at home.
The local pilot contains a complete Tidal Atlas based on local knowledge (there is little other published data for the region) and tidal flows of 5 knots are common, flows of 8 knots are "not uncommon" !
For tidal flow rates in the Menai Strait, 
For Tidal Predictions for the year from Bangor University,
For UKHO (Admiralty) Tidal Predictions for Beaumaris,
A number of factors contribute to these tides, perhaps the most significant being the meeting of up to five tides at the one place (in several places!).
Constricting the tidal flows of the Irish Sea into the confines of the gap between Anglesey and Isle of Man, Bardsey Sound, River Mersey and the Menai Strait doesn't help. In the particular cases of the Menai Strait and Bardsey Sound, the tide is still flowing out of one end when it is entering the other - resulting in water level differences of over a metre, and a serious downhill torrent.
For simiilar reasons, HIGH water and SLACK water do not always co-incide, this being most apparent in the Menai Strait.
The adjoining Table (taken from the pilot) shows the effects throughout the area.
| Constants on Dover | Height (metres) | Range | ||||||
| HW | Slack | MHWS | MHWN | MLWN | MLWS | Sp. | Np | |
| LIVERPOOL | 0015 | 0015 | 9.3 | 7.4 | 2.9 | 0.9 | 8.4 | 4.5 |
| Mostyn Dock | 0000 | 0000 | 8.5 | 6.7 | - | - | - | - |
| Colwyn Bay | -0005 | -0005 | 7.8 | 6.1 | - | - | - | - |
| Llandudno | -0015 | -0015 | 7.4 | 5.9 | 2.4 | 0.7 | 6.7 | 3.5 |
| Conwy | -0015 | -0015 | 7.7 | 6 | 2.3 | - | - | 3.7 |
| Puffin Island. | -0015 | -0015 | 7.5 | 5.9 | 2.5 | 0.9 | 6.6 | 3.4 |
| Beaumaris | -0025 | 0110 | 7.6 | 6 | 2.5 | 0.8 | 6.8 | 3.5 |
| Menai Bridge | -0020 | -0150 | 7.3 | 5.8 | 2.3 | 0.7 | 6.6 | 3.5 |
| Swelly Rock | -0055 | -0215 | - | - | - | - | - | - |
| Port Dinorwic | -0105 | -0120 | 5.6 | 4.4 | 2 | 0.8 | 4.8 | 2.4 |
| Caernarfon | -0130 | -0130 | 5.2 | 4 | 1.9 | 0.6 | 4.6 | 2.1 |
| Belan Pt. | -0115 | -0115 | 4.6 | 3.5 | 1.8 | 0.6 | 4 | 1.7 |
| Porth Dinllaen | -0240 | -0240 | 5.6 | 4.4 | 2 | 0.7 | 4.9 | 2.4 |
| Llanddwyn Is. | -0210 | -0210 | 4.9 | 3.9 | 1.9 | 0.7 | 4.2 | 2 |
| Trearddur Bay | -0100 | -0100 | 5.2 | 4 | 2 | 0.8 | 4.4 | 2 |
| Porth Trecastell | -0050 | -0050 | 5 | 3.8 | 2 | 0.7 | 4.3 | 1.8 |
| Holyhead | -0045 | -0045 | 5.6 | 4.4 | 2 | 0.7 | 4.9 | 2.4 |
| Cemaes Bay | -0040 | -0050 | 6.6 | 5.1 | 2.3 | 0.8 | 5.8 | 2.8 |
| Amlwch | -0030 | -0030 | 7.2 | 5.7 | 2.5 | 0.9 | 6.3 | 3.2 |
| Moelfre | -0035 | -0035 | 7.5 | 5.8 | 2.5 | 0.9 | 6.6 | 3.3 |
| Porth Dinllaen | -0240 | -0240 | 4.6 | 3.4 | 1.8 | 0.5 | 4.1 | 1.6 |
| Bardsey Island | -0305 | -0305 | 4.4 | 3.2 | 1.5 | 0.6 | 3.8 | 1.7 |
| Aberdaron | -0305 | -0305 | 4.6 | 3.3 | 1.9 | 0.5 | 4.1 | 1.4 |
| St. Tudwel's Roads | -0315 | -0315 | 4.8 | 3.3 | 1.8 | 0.5 | 4.3 | 1.5 |
| Pwllheli | -0315 | -0315 | 5 | 3.4 | 1.9 | 0.5 | 4.5 | 1.5 |
