The book cannot do all this for you but it can help materially with tide planning and navigational dangers.

Let us follow an example using an intended passage between Ramsgate and the Blackwater

A passage north from Ramsgate to the Blackwater can be broken down into a number of components:

• Passage from Ramsgate to clear the North Foreland
• From the North Foreland to one of three crossing points of the Long Sand
• Across the Long Sand
• Crossing the Black Deep
• Choosing a crossing point of the Sunk Sand
• From the Sunk Sand to the Spitway swatchway
• From the Spitway to the Blackwater

In the book, these separate components are known as sectors.  Each sector is identified by waypoints and hazards and other navigational issues are described.

Step 1 - read up on the route in the book and review the choices over your intended passage.  In this example, the first decision will be which crossing point you prefer for the Long Sand and the Sunk Sand.

Step 2 - using the tables provided, identify the sectors for the passage you prefer.  For this route, there will be seven sectors.  Transfer the sector numbers to the Planning Assistant that folds out from the rear cover of the book.

Step 3 - Select the right table for your intended day.

1.  Yellow pages for north bound passages; green for southbound;

2.  What is your expected average boat speed for the passage?  Select from 3, 4, 5, 6 or 7 knots;

3.  Is it Springs or Neaps?  Check on the tidal range at Sheerness for the day and select.  Mean Spring range at Sheerness is 5.1m; mean Neap range is 3.3m.  Interpolation for mid-range values will be necessary.

Step 4 - Select a start time.  There are a number of choices and here is where the flexibility of the tables will help you review each choice in very little time.  Here are some choices:

Choice 1 - scan the first sector duration times and select the start time that gives you the quickest progress.  Note the ‘time at end of sector’ (these are all related to HW Sheerness so the tables may be used perpetually).  Transfer that time to the start time of the next sector.  Interpolation may be necessary.  Remember that this is passage planning not an exact mathematical science.  Read off the ‘time of end of sector’ for this second sector and repeat the process until you have completed all seven sectors.  You have your plan!

Follow an Example

Solas V (Saving of Life at Sea Regulations - Chapter 5) gives guidance for Voyage Planning.  The regulations apply to small, privately owned pleasure craft. If you are involved in a boating accident and it is subsequently shown that you have not applied the basic principles outlined in the MCA leaflet, you could be prosecuted.  [common sense suggests a plan is necessary for these complex waters!]  These regulations require consideration of:

The weather

The tides

The limitations of the vessel

The experience and physical ability of the crew

Navigational Dangers, and

Information ashore

before you go!

SOLAS V

For Pleasure Craft

Now check that this plan suits you and makes sense.  You can quickly read off how helpful the tide is in each sector.  This choice will have given you a speedy passage to the North Foreland but what about elsewhere?  The impact of the tide will vary according to your average boat speed.  Some issues might be:

• Does this give you an adverse tide through the channels over the Long Sand?  The duration column of this sector will help you to judge this;
• What is the state of tide when you reach the Sunk Sand?  Do you want a rising tide at this point and a minimum period of flood before you cross?  Your timing will indicate if you are reaching there on a falling tide (+ values) or on the flood (- values).  Check the guidance in the book on the tidal differences at different parts of the Estuary;
• Does this give you an adverse tide across the Barrow Deep and Middle Deep?  The duration column will show;
• Do you have enough water at the Spitway?  Your timing will show whether the plan gets you there close to low water;
• You want to go all the way to the head of the Blackwater at Maldon or reach Heybridge in time for the lock opening?  Judge how much of the flood is left when you reach the River Blackwater landfall waypoint.  Is it enough for you?

You can quickly try alternative start times to see what your options are or go to -

Choice 2 - You determine the state of tide over the Sunk Sand is the most important feature of the passage to you.  Go to the sector for the Sunk Sand crossing and select what time you want to be there.  For example in the ‘Time’ column, select -1 if you want to be crossing just before high water (Sheerness).  Then work the sector times backwards to a start time and forwards to an ETA.

Bear in mind that the flood starts earlier at the Sunk crossing points than at Sheerness (see the text in the book for the estimates at relevant points).

[Here we work the table backwards.  We decide we want to be over the Sunk Sand no earlier than two hour before HW Sheerness.

A5 is the sector for the Sunk Sand.  Aiming for a -2.00 start time for this sector, we select the nearest value in the previous sector (A4) - here it is -1.57.  Reading back this tells us we start sector A4 at -2.30 and the previous sector (A3) at -3.45]

You can use the same system for any other sector requirement; sufficient water at the Spitway, enough flood left at the River Blackwater landfall waypoint and so on.

Choice 3 - Working backwards.  You want to arrive at the River Blackwater landfall waypoint around a certain time.  Select the ‘time at end of sector’ time you want in the final sector and work back across the sectors to find the estimated start time.  Once again review what this does to other parts of the plan.

Bear in mind that passage planning is an estimate.  Tide tables are predictions, tidal rate and direction data is averaged and constantly changing, and heights of tide and currents can be affected by wind and barometric pressure.  It is, therefore, not an exact mathematical exercise but a prediction and your progress should still be monitored as all prudent yachtsmen and women do.

As you become used to the tables, you will become aware of the inevitability of making a compromise.

• At typical yacht speeds (5Kts), the best favourable tide from Ramsgate will be excellent help but may well get you to the Sunk Sand at low water;
• From the North Foreland to the Long Sand, the tide does not simply flow backwards and forwards: it may turn west round the North Foreland, head north towards the Sunk Sand and later north-east or may be flooding south-west; all depending upon the time;
• Your choice of route across the Long Sand may well depend upon your choice of crossing the Sunk Sand;
• Over the Sunk Sand, you will encounter some of the shallowest water of the passage;
• Between the Sunk Sand and the Spitway, any adverse tide will add significantly to passage time; yet a slow yacht may need to choose this option if they want to carry a favourable tide all the  way to the top of the Blackwater at Maldon;
• The Spitway can be shallow for some at Low Water.

The planning tables provide vital information to help you through your preparations.

All tables are referenced to HW Sheerness and in consequence can be used perpetually.

[In this example, the quickest passage in the first sector is 38 minutes departing at HW+1.

The next sector starts at +1.38 (as it falls almost midway between +1.30 and +1.45 either could be used).  Using +1.30 ends at +2.04.  Then repeat the process with the next sector]

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