In the last blog we looked at how the tidal range is directly affected by the position of the Moon, Sun and Earth to create either spring or neap tides. We also looked at how the equinox also influences the size of tides with greater ranges found in the March and September. In this blog we are going to look at the rate in which the tide moves which is directly proportionate to the range of water going in and out.
In the last blog we identified that a tidal range can vary from 1.8 m to 4.6 m of water coming in or out. This amount of water makes a massive difference and a big tide can be clearly seen racing in or out the harbour mouths of Langstone and Portsmouth. The time taken for the tide to come in (flood) or out (ebb) takes roughly 6 hours and the rate varies during this time. In simple terms it starts of slow and speeds up before slowing down again. We break this down into what’s known as the rule of twelves. Table 1 shows the amount of water travelling with the two middle hours (in yellow) having the most amount of water travelling and therefore the fastest and strongest time of the tide.
To relate this to kayaking journeys in the harbours it is always easiest to travel with the tide and greatest benefits will be had during a spring tide and during the middle two hours. If you ever choose to paddle against the tide a neap tide would be favourable and during the first or sixth hour of the tide. There are also other areas to consider, such as:
- Is the tide high enough to provide access without trapesing through mud?
- Is the wind working with or against you?
- A strong or weak tide can greatly affect the amount of time paddling from one to several hours.
direction several problems can occur. The wind could end up pushing you in an undesired location or creating a rather choppy service making it harder for beginners to stay upright. It is concerning if you have a capsized kayaker in the water when you have wind over tide as they could end up going in opposite directions. As seen in figure 1 the boat will stay on the service and get blown by the wind across the service of the water, whereas the swimmer will be pushed by the tide.
