Navigation for Sea Kayakers

N A V I G A T I O N

Kayak Navigation

Kayak Navigation for Beginner to Advanced

Where am I now?

Navigation is easy all you need is a little practice Compass, Ruler, Pencil, Local Maps, Chart, Oileรกn, tide tables, weather forecast and plenty of Cop on

Navigation for Beginners to Advanced

David Carraher v5

Kayak Navigation

Navigation:     

Navigation is Knowing where you are.

Knowing where you are going.

Choosing a safe route.

Knowing how long the journey will take.

Allowing for the elements (wind, tide, visibility etc.).

OS Maps

The most common OS maps we use for kayaking and walking are the discovery series. The whole of the country is split up into small sections and each map 2 has its own distinct number. Each map is broken up into squares of 1km .

Ireland is broken up into 100 metre square grids. Each grid has its own letter to identify it. Normally when using grid references for kayaking or walking we use the map number of the discovery series.

Grid Reference David Carraher v5

Kayak Navigation

To identify particular points (places) on a map, a grid reference is used. The map is broken up into Grid boxes. A grid reference will give an accurate location on a map. When letting people know where you are or where you want to meet, it is much better to give a grid reference.

When reading a grid reference, read across the (bottom or top) of the map first, left to right. Then read up along the sides of the map to get the second part of the grid reference, bottom to top. (Walk down the hall and then up the stairs).

The discovery series of OS maps are very useful for both kayakers and hill walkers. The scale on these maps is 1:50000. This means that every centimetre on the map is equal to 500 metres on the ground. Each square on the map is 2 X 2 cm. Therefore each square on the map is 1 kilometre by 1 kilometre.

Each discovery series map has its own individual number (in this instance the number is 84). From the insert on the cover it can be seen which other maps either overlap or align with sheet 84.

2.

Each map is broken down into grids; each square on the grid is 1km Each square is identified by a grid reference. See diagram below. The square highlighted in red is referenced by the numbers 4538.

In the diagram below it can be seen that Dursey Head is in the square identified by grid ref 4538. This grid references the bottom left hand corner of the square.

Each square can be broken down further into tenths. This give us a grid reference for Dursey Head (see picture below) of 452388.

David Carraher v5

Kayak Navigation

David Carraher v5

Kayak Navigation

David Carraher v5

Kayak Navigation

Use of Compass A compass is basically a needle spinning freely and points to magnetic north when it comes to rest. The compass below is a Silva type 4 compass.

The needle rotates is a pool of liquid which helps bring it to a stop much faster than it would in air. The most important thing to remember about a compass is that the needle points to magnetic north.

The magnetic north needle always points north once the compass is held on the flat. In the above picture the floating needle has a red end and a white end, the red end is the end that points to north. Obviously then the white end of the needle is pointing south. The orienteering lines of the compass must be pointing north on the map before a compass bearing can be taken. The place to take the reading is where the direction of travel arrow is cut by the Nesmith’s ring. The direction of travel arrow is the arrow you follow when the north needle is aligned with the red needle pointing to N on the Nesmith’s ring. (See below for more detail on following a bearing).

Taking a Bearing.

Before taking a bearing using your compass, estimate the bearing you will get.

If you are going to be heading towards the top of the map, then your bearing will be north (i.e. 360 degrees or 0 degrees).

David Carraher v5

Kayak Navigation

If heading towards the right then the bearing will be 90 degrees. If you are heading towards the bottom of the map the bearing will be 180 degrees. If you are heading towards the left hand side of the map then the bearing will be 270 degrees.

A B

In the picture above we are trying to take a bearing towards the summit of a hill.

Before you start to use your compass, estimate your direction of travel. If travelling along line A then the estimated bearing will be approx 45 degrees. If travelling along line B then the estimated bearing will be approx 315 degrees.

Next you line up the edge of the compass with the object to which you intend travelling to. Next align the orienteering lines so that they are pointing north. In the above example the bearing for the compass on the left is 43 degrees and the bearing for the compass on the right is 301 degrees.

NORTH (Grid North) The top of the map always points to Grid north (on the OS series of maps we can take this as true north as the difference between Grid and True north is very small). The compass needle always points to magnetic north. The difference between magnetic north and true north is called magnetic variation. The magnetic variation is always given on the map, normally on the right hand side.

In Ireland magnetic variation is within the region of 4 to 9 degrees. The further north you go the greater the magnetic variation. I have paddled in parts of 0 Greenland where magnetic variation was 35 . In Ireland and most of Britain magnetic variation is west of true north at present.

Taking a Bearing from a Map David Carraher v5

Kayak Navigation

Remembering that if you are in the middle of the map the  Top of the map is North  Bottom of the map is South  Right hand side of the map is East  Left hand side of the map is West Before taking a bearing, first estimate the direction of travel (This reduces the risk of error). In this instance (see picture below) it is approx 200 degrees as you are heading in a South Westerly direction. We are heading from Cods Head to Garnish Island. (Incidentally if we were heading from Garnish Island to Cod’s Head then the approx. bearing would be 20 degrees). By estimating your

bearing helps eliminate errors when actually taking a bearing using the compass.

Now you can use your compass to get an accurate bearing. Careshould be taken here to ensure the highest degree of accuracy.

David Carraher v5

Kayak Navigation

Line up the edge of the compass with the two points on the map. Ensure the direction of travel arrow is pointing from where you are to where you want to go. From Cod’s Head to Garnish Island.

Ensure that the orienteering lines are pointing towards the top (North) of the map.

Use the lines of the map to ensure the

orienteering lines are parallel. The compass can now be lifted from the map to allow you to take your reading. compass reading in this case is 201 degrees.

Next check the magnetic variation on the map. In this instance it is six degrees. This is added to the reading on the compass, so the new compass bearing is now 207 degrees.

Once you have your bearing worked out you should write it down so that you don’t forget it. It is easy for the Nesmith’s ring to move and then you have lost David Carraher v5

Kayak Navigation

the bearing that you wish to follow. It is a good idea to have a piece of material on your deck that you can jot down notes on. Things like bearings, time of departure, Lights you should meet on your journey etc. When following a bearing, you should hold the compass as close to your body as possible, so that you are looking directly down on the compass. This reduces reading errors.

Once you have the compass aligned properly, look in the direction of the arrow and pick a point. Once you have a point in the distance that is on the bearing, you can move to that point. Make sure you do not lose sight of the point to which you are travelling. If you find that you are going to lose sight of the point, pick another point that is in line and go to this new point.

Ensure no metal is near the compass, as metal will affect the magnetic needle.

Likewise when packing a kayak, be aware of where your compass will be and ensure no cans, pots etc are placed near the location of the compass.

Travelling in Fog In the above example, if it is foggy and you cannot physically see Garnish Island then you should lay off a little i.e. either aim left or right (preferably left in this instance). Then once you reach land you will know which direction to go in order to hit Garnish Island. This idea of laying off is also used in the mountains.

Tidal flow will also have an effect on you while travelling on the sea. We will deal with tides later.

David Carraher v5

Kayak Navigation

Where Am I? When travelling on the open water it can be difficult to know exactly where you are. If you know your speed of travel and the direction you have been travelling in you can get a fix by dead reckoning.

Sometimes due to different circumstances you may not know how long you have been travelling. If you can locate places that you recognise then you can take a fix from them and work out your location. In the example below we have left the Fastnet Rock but now need to get a fix on our location.

We can identify the Fastnet Rock, The Bill of Cape Clear and Goat Island.

We take a compass bearing for each of these landmarks.

0 Fastnet Rock 214 0 The Bill Cape 83 0 Goat Island 350 Magnetic variation in this area is 4 degrees.

To translate these bearing, to the map we must take away 4 degrees. This 0 gives us Fastnet 210, The Bill 79 and Goat Island 346

David Carraher v5

Kayak Navigation

We now transfer these bearings to our map.

Set the bearing on the compass and lay the compass on the map pointing towards the Bill of Cape Clear. Align the orientating lines pointing north and draw a line along the edge of the compass.

Next set the bearing for the Fastnet rock and again align the compass on the map.

Draw a line from the Fastnet Rock. Do the Same Goat Island.

for

When all three lines have been drawn a small triangle (called cocked hat) will be formed. This indicates the position are in.

a

we

David Carraher v5

Kayak Navigation

At worse you are only a couple of hundred metres out. When travelling on the water this exercise should be carried out as quickly as possible to minimise the error caused by the flow of the tide and the speed of the wind.

Use of Charts Charts are very useful for the kayaker, they are very similar to maps except the information they give is only relevant to seafarers. They give direction of tidal flow, depths, areas where there are races and overfalls, light houses and cardinal buoys and their light sequence. They also give the magnetic variation for different parts of the chart.

Unlike OS maps they do not have grids, but use longitude and latitude for giving positions on the chart.

David Carraher v5

Kayak Navigation

Compass Rose On nautical charts you will most likely see a compass Rose. The compass rose shows both true north and magnetic north with magnetic variation. When taking a bearing on a chart you can read directly from the inner circle which allows for the magnetic variation. The outer circle shows true north.

If there is more than one compass rose on a chart, always use the nearest rose to the area in which you require the bearing.

The reason for this is that the magnetic variation will be different on different points of the chart, especially on large scale charts. Remember the further North you go, the greater the magnetic variation.

David Carraher v5

Kayak Navigation

Compass Rose

Contours on the Chart The contours on a chart denote areas which are the same depth below water.

The depths are normally given in metres. When paddling one should be careful of areas that suddenly become very shallow. Boomers can form in these areas especially at low tide. Boomers are waves that suddenly break out at sea or off David Carraher v5

Kayak Navigation

headlands, they can be quite violent. If you find you are approaching an area where there are boomers, it can be a very good idea to lay up somewhere and wait for the tide to rise. The more depth over the shallows the less boomers forming.

Latitude and Longitude Positions on charts are given in Latitude and Longitude.

Lines of Latitude are parallel lines measured from the centre of the earth. They are at an angle from the centre of the earth either North or South of the Equator.

Lines of Latitude never meet.

Longitude Longitude lines are the measure of the angular distance from the centre of the 0 earth east or west of 0 longitude which is the line of longitude which passes through Greenwich England. Lines of Longitude meet at both the north and south poles.

David Carraher v5

Kayak Navigation

Latitude is used to say how far north or south of the equator you are. Usually 0 expressed as N or S. Eg 30 N 0

Longitude is used to express how far east or west you are of 0 longitude.

0 0 Expressed as 30 E or 30 W One degree of Latitude is 60 nautical miles. One minute of Latitude is one nautical mile. When measuring distance on a chart, we only use the latitude scale nearest the position we want to measure. The latitude scale is on the sides of the chart.

We never use the longitude scale which is at the top and bottom of the chart as this scale is only accurate at the equator.

To define a position on a chart we give the Latitude and Longitude in degrees and minutes and decimal parts of minutes. Eg 0

0

53 18.65’N 5 55.542’W

Kish lighthouse is 0

0

0

0

Muglins

53 16.524’N 6 04.579’W

Fastnet

51 23.358’N 9 36.178’W

Note in Maritime matters it is convention to give Latitude first then longitude.

David Carraher v5

Kayak Navigation

Using Parallel Rulers In general charts are much larger than OS maps and they do not possess grid lines. Parallel rulers can be very useful when planning trips. The parallel rulers can be moved across the chart to the compass rose in order to allow you obtain both true north and magnetic north bearings. Again first thing to do is estimate the bearing you need to travel in.

Next align the parallel rulers between where you are and where you want to go.

In the picture below we are going to travel from Hook Head to Great Saltees.

The estimated bearing is approx 100 degrees

David Carraher v5

Kayak Navigation

Next carefully move the parallel rulers across the chart to the Compass rose. If the ruler moves off line then go back and line it up again.

David Carraher v5

Kayak Navigation

Carefully take your reading when the parallel rulers are cutting through the 0 centre of the compass rose. The magnetic bearing in this case is 102 and the true bearing 0 is 93 So now to travel from Hook Heat to Great Saltees you will need to follow a bearing of 0 102 on your compass.

Always note if the bearing is true or magnetic.

Portland Plotter David Carraher v5

Kayak Navigation

The Portland plotter can also be used to get a bearing. In this case we are travelling from Great Saltees to Hook Head.

Firstly estimate your bearing. The estimated bearing in this case is 0 approx 280 .

Place the edge of the plotter along the route you wish to travel. Ensure that the orienteering lines are pointing North. True North can be read directly from the plotter. In 0 this case it is 275 .

0 Next you need to add on for magnetic variation, which in this case is 8 50’ or 0 0 approx 9 . Therefore you will need to follow a compass bearing of 284 .

David Carraher v5

Kayak Navigation

Chart Symbols

Overfall. Caused by the tide flowing over submerged rocks.

Normally found at headlands and islands Flood Tide. Max speed 2 knots

Ebb Tide. Max speed 2 knots

Tidal Diamonds.

These give tidal strength and direction of tides in a given area.

These are in a table on the chart.

Drying heights above chart Datum. Note the figures have a line underneath them. This is what indicates drying height.

David Carraher v5

Kayak Navigation

Dangerous underwater rock of known depth.

Cardinal Buoy South Cardinal Buoy North Cardinal Buoy South marker indicates safe water to south.

South

North marker indicates safe water to north

North

Tidal Movement In general the tides around Ireland flow North up the Irish Sea and North along the West coast on the flood. The tides meet just south of Belfast. Tidal rates along the West coast are generally weaker than along the East coast. Tidal strengths will increase around headlands or where constricted between islands and the mainland or between two islands themselves.

Tidal streams are fastest during Spring Tides and the Tidal range is largest in Spring tides.

David Carraher v5

Kayak Navigation

Spring tides occur when the Sun, Moon and Earth are in line. Neap Tides occur when the Sun, Moon and Earth are at right angles to each other. The gravitational pull of the moon has much more effect on the tides that the suns gravitational pull. We get the biggest tides when the moon is closer to earth and all three (earth, sun and moon) are in line.

Tidal Flow The tidal flow is the speed of the water travelling up along the coast. It can be read directly from charts or tidal atlases.

Tidal Range To know if there is sufficient water to paddle in a particular area, you first need to look at the tidal range. This is the difference between High Water (HW) and Low Water (LW). Remembering that in general the tide rises for six hours and falls for six hours.

David Carraher v5

Kayak Navigation

st

From the tidal table we can see HW in the afternoon of 1 May is at 14:52 and tidal height is 3.4 metres. LW in the afternoon is at 21:23 and the tidal height is 0.9 metres. This gives us a tidal range of 3.4 – 0.9 = 2.5 metres. st

The 1 hour the tide will drop by 2.5/12 = 0.2 metres. Height left = 3.2 metres nd

The 2 hour the tide will drop by 2.5/6 = 0.4 metres. Height left = 2.8 metres rd The 3 hour the tide will drop by 2.5/4 = 0.625 metres Height left = 2.175 m The th 4 hour the tide will drop by 0.625 metres. Height left = 1.55 metres th

The 5 hour the tide will drop by 0.4 metres. th

The 6 hour the tide will drop by 0.2 metres.

Height left = 1.15 metres Height left = 0.9 metres.

This means there will be 0.9 metres of water above Chart Datum.

1.

2.

3.

4.

5.

6.

1st hours rise or fall = 1/12 of Range 2nd hours rise or fall = 2/12 of Range 3rd hours rise or fall = 3/12 of Range 4th hours rise or fall = 3/12 of Range 5th hours rise or fall = 2/12 of Range 6th hours rise or fall = 1/12 of Range Tidal Curves.

While the rule of twelfth’s is very useful it is not as accurate as using the Tidal Curve. Tidal curves are printed for all standard ports and can be used with the tide tables to work out the height of tide at any given time. Tidal curves are easy to use. They chart the rise and fall of the tide over a given period. From Low water to High water to Low water.

David Carraher v5

Kayak Navigation

To use the tidal curve you need to have the correct tide tables. From the tide tables find the 1.

2.

3.

4.

5.

The The The The The

time of High Water time of Low Water height of tide at High Water height of tide at Low Water range of the tide

The range of the tide is the difference between Low water height and high water height.

The range of the tide is the difference between Low water height and high water height.

Eg. The tide table for 3rd Feb 2011 Thu 3 Feb LW

HW

LW

05:15 11:52 17:43 David Carraher v5

Kayak Navigation

0.9 m 4.0 m 0.7 m From the table we see HW occurs at 11:52 and is 4.0m.

LW occurs at 17:43 and is 0.7m. Therefore the tidal range is 3.3m

Mark the LW and HW heights on the chart and drawn a line between them. Insert the HW time in the box marked HW and fill in the following hours in the other boxes.

If we want to know when we will have 2.1m of water above the depth marked on the chart we.    

Draw a line down from the 2.1m mark From where it meets the tidal range line draw a line across Where this line meets the tidal curve drop a line down.

Carefully read off the time In this instance it is 15:30 hrs

David Carraher v5

Kayak Navigation

Likewise we can find the height of tide at any particular time of day.

David Carraher v5

Kayak Navigation

From the image above we can see that the area south of Red island dries to a height of 1.2 meters. So if we wanted to paddle here the tide would have to be above 1.2 meters. If we want .3 meters of water to paddle in then we would have to be there before the tide fell below 1.5m We can use the tidal curve above to tell us that we would have to be there before 15:30

David Carraher v5

Kayak Navigation

Tidal Diamonds

Tidal Diamond This gives direction and strength of tide relevant to HW of reference port.

The tidal diamond can give a very good indication of when the tidal stream turns. The tidal stream does not always turn at HW or LW.

David Carraher v5

Kayak Navigation

The chart above show a tidal diamond with the letter C enclosed. The table above for HW at Dublin gives the tidal flows and directions at C. 6 hours before HW Dublin the direction of the tidal flow is 002 degrees. In Springs it flows at 1.3 knots and in Neaps it flows at 0.7 knots. In between Springs and Neaps the flow will be somewhere between 0.7 and 1.3 knots.

5 hours before HW Dublin the direction of tidal flow will still be 002 degrees. But in this instance the flow will be 2.1 knots in Springs and 1.1 knots in neaps.

It can be seen from the above example that the slackest water is approx 1.5 hours before HW Dublin. If heading out to the Kish from Bullock harbour the following must be taken into account.  

Distance Time of slack water at Kish David Carraher v5

Kayak Navigation



Speed of the flood.

It is approx 7 miles to the Kish, so this would take approx two hours to travel out to.

Slack water is approx 1 hr before HW Dublin.

Flood rate is approx 1kn over the time.

Therefore, the ideal time to head out to the Kish is approx 3 hrs before HW Dublin. This allows us to arrive at the Kish at Slack water. When heading out to 0 the Kish we should bear off 20 south to allow for the North going flood.

Trip Planning The above exercise is a quick trip plan. Wind, time of day, ferry times etc would also have to be taken into account.

It is important to plan trips well in advance of arriving at your intended departure point. The reason for this is you can determine what time you wish to pass any potential hazards.

For example if you wish to paddle around Dalkey Island with a group of novices, it is best to go around on the ebbing tide. If you have a group and you want some testing water it is best to paddle around Dalkey about 2 hours after the flood starts. The reason for this is that the overfall at the southern end of Dalkey is only there on the flood tide.

Paddling back from Dalkey on a Spring Evening

David Carraher v5

Kayak Navigation

Wicklow Head nd

For Saturday the 2 Feb HW Dublin is 08:06. The flood starts at Wicklow head at 11:51 and will run for approx six hours. The extract below is taken from Oileán. If you don’t want to be paddling against the flood, you would need to be past Wicklow head well before this time. However if you wanted to play in the overfall you could arrive any time after 11:50 Remember that the tide floods for 6 hours.

If planning a trip here to Maghermore then a 10 am start would get you from Wicklow harbour down well past Wicklow head before the flood tide commences.

Then after lunch you could return on the flood tide to Wicklow harbour

From Oileán At Wicklow Head, the N going flood starts earlier than on the Dublin/North Wicklow coast further N. The flood tide runs from Dublin HW +0345 to -0115 approximately. Downstream, expect long powerful run-offs. It is always possible to rest in eddies in the lee of the head, except when the wind is from the eastern quadrant.

Inshore tides all along the Wicklow and Wexford coasts generally follow the direction of the coast, and information on timing is unreliable. From Wicklow Head to Arklow, the flood is thought to run up to 3 knots in springs and the ebb at 1 knot.

Off Wicklow Head itself where big boats go, the flood is up to 4 knots, and the ebb 3 knots, but close by the rocks where kayaks go, the current gets seriously fast. Local paddlers say 6 knots, both ways. Bride’s Head at T339-931 is 1km N of Wicklow Head, and on the ebb, the flow can be almost as strong there.

David Carraher v5

Kayak Navigation

From Wicklow Harbour to Wicklow Head, the tide close inshore always runs SE. On the ebb, it runs strongly at up to 3 knots. On the flood, a major eddy system operates. Local paddlers report considerable struggles close inshore in springs. Going N, keep in the bumpy main flow for 1km at least and then keep at least 1km offshore until Wicklow Harbour.

Going S, on the other side of Wicklow Head, keep in the main flow as long as you can. A weaker eddy system operates, almost as far as Long Rock at Silver Strand at T338-910.

Dursey Tides (from Oileรกn) David Carraher v5

Kayak Navigation

The 14km circumnavigation is a challenging experience, and races may be expected off the twin outermost points, and elsewhere as tides and wind dictate. Tides flow up to 4kn in Dursey Sound and constantly boil, especially over a rock in mid-channel, under the cable-car wires. There is usually clapotis at the NE corner of the sound, which kayakers have found to extend 1.5km to Garinish Point to the NE. Beware flukey winds at the N entrance. The flood eddies on both sides of the southern entrance.

Off the outer tip of Dursey lie the Calf, the Heifer, the Cow and the Bull, mighty, remote and challenging rocks. Until recently, no kayaks had landed. Off these, the main tidal streams around Ireland split. One stream heads S through Dursey Sound and on to Cork, Wexford and Dublin.

The other heads N to Kerry, Mayo, Donegal and Antrim. The two streams meet again at the Isle of Man. The Bull has a huge lighthouse complex built on it. The Cow has nothing. The Calf has an abandoned stump of a lighthouse.

Tides flood E along both sides of Dursey Island and S through Dursey Sound, from HW Cobh 0500 to +0130. On the flood though, there is extensive eddying in the bay between the S entrance to Dursey Sound and Crow Head to the S. For the purpose of this exercise we will assume a wind of F2 to 3 from the SW From the tide tables we can get the times of HW and LW for Cobh on any particular day.

For example Sun the 4th May gives us a HW Cobh of 0502 and an afternoon HW of 1726.

Oileรกn states that the flood flows along both sides of Dursey from HW Cobh -0500. This means that the flood starts 5 hours before HW Cobh.

The flood continues until HW Cobh +0130 This means it continues to flood 1.5 hours after HW Cobh.

Therefore the flood on the 4th May starts at Dursey at 1226 and continues until 1916.

From Admiralty charts the tide floods up towards the Bull and Ebbs south from the Bull.

David Carraher v5

Kayak Navigation

This also means that the tide is ebbing from 0632 until 1226.

Flood starts at 12:26

From above information, if intending to paddle around Dursey it would be best to paddle out on the ebb to reach Dursey Head around one hour or so before slack water, this will allow time to paddle to the Bull. It will take around 1.5 hours to paddle to Dursey Head. Allow 1 hour for playing around or heading out to the Cow and the Bull. This means departing at approx 10am. This allows you David Carraher v5

Kayak Navigation

to paddle up the south side of Dursey with the flood. The wind may cause a bit of bump on the way back so this is a paddle for Level 4 paddlers.

Roaring Water Bay.

The harbour at Baltimore Tides The big picture is that the flood flows E from Mizen Head through the islands of the bay, and outside Cape Clear Island. Among the islands of the bay, the flood generally turns S and then E where circumstances suggest. In this way, the flood runs E along both the N and S sides of the islands, and generally S through sounds that run N/S. The reverse is also true, the ebb flowing generally W and N through the sounds.

This is particularly true of Gascanane Sound, between Sherkin and Cape Clear.

Important and predictable exceptions occur. The flood streams N through the sound between Long Island and Castle Island and ebbs S. This allows the large enclosed water area of Schull Harbour to the N to be filled and emptied. In the same way, the large enclosed water area of Baltimore Harbour fills from both sides, N and S. In the sound between Sherkin and the mainland, the flood is N and the ebb is S. David Carraher v5

Kayak Navigation

Tides The stretch of water around Cape Clear and Sherkin Islands is regarded by locals as serious, and not to be underestimated.

The tidal stream floods E on both the N and S sides of Sherkin Island. Baltimore Harbour fills from both the NW (between Sherkin and Spanish/Ringarogy Islands) and from the S between the mainland and Sherkin. These flood streams meet in the middle of the harbour at Lousy Rocks. After that, the combined stream heads E and then NE into Church Strand Bay, NE of the town. The ebb is the reverse. These flood tides begin at HW Cobh +0545, and the ebb at HW Cobh -0025.

Back of Sherkin

David Carraher v5

Kayak Navigation

In many places, especially Gascanane Sound, the tide runs fiercely, at up to 3kn, causing dangerous eddies and overfalls, especially near the rocks in the middle of Gascanane Sound, known as Carrigmore Rocks and Gascanane Rocks. The steep•to rock on the

In this example we will take Cobh HW as 11:00 hrs

Ebb starts at approx 10am Flood starts at 16:46

Sherkin side of the sound is Illaunbrock.

David Carraher v5

Kayak Navigation

This means that the flood North and south of the islands starts at 16:46 hrs and the EBB commences at 10:05 hrs. In Gascanane sound the tides start 30 minutes earlier.

Therefore the Ebb in Gascanane sound starts at approx 9:30 and finishes at around 16:15.

In the above example Slack Water in Gascanane sound is around 10am or 4:45 pm. If one wished to pass through the sound at slack water they would either have to start around 9am or else bypass the sound on the way out and return through the sound after lunch at approx 4:30pm to 5pm. If paddling during Neaps then the sound could be easily passed through if wind and tide are in unision.

Coming around Cape Clear

David Carraher v5

Kayak Navigation

Open Crossing (Donaghadee to Portpatrick)

This chart shows the area between Donaghadee and Portpatrick.

David Carraher v5

Kayak Navigation

Before undertaking any open crossing a number of factors need to be considered. 

Distance



Dangers (overfalls etc.)



Tides



Weather



Shipping



Time it will take to make the crossing.

From the above chart we can see there are overfalls marked near Donaghadee and Portpatrick. These areas should be paddled through at the slackest tides.

As the flood tide heads south and the Ebb tide flows north, it is best to paddle across on the Ebb. The distance is approx 19 nautical miles, so if the paddlers travel at 4knots then the time taken will be approx 5 hours. If the paddlers leave at HW Belfast they will arrive at Portpatrick approx 1 hour before LW.

This picture shows a line going from Donaghadee to Portpatrick.

Also making out each hour of travel using dividers

Using a ruler and a soft pencil (2B) draw a line from Donaghadee to Portpatrick as in picture above. Determine the bearing of this line. In this instance it is 53 degrees David Carraher v5

Kayak Navigation

Next measure out along the line each hour of paddling. Using the dividers measure out 4 nautical miles from the lines of Latitude. Each 4 nautical miles represent one hours paddling.

On this crossing the chart shows two tidal David Carraher v5

Kayak Navigation

diamonds in the area of which we are working. The first tidal diamond that affects us is F. The second is C, as we approach each tidal diamond we take our Tidal direction and strength from the tide table on the chart.

On the chart we draw in a line for the direction and strength of the tide for each hour. As we are leaving on HW Belfast, we start at HW Belfast.

In the diagram below we are looking at the second hour of paddling. The direction of travel is 359 degrees We draw in the direction of flow from the intended line of travel. The speed of flow is 2.3kn. We measure out 2.3 nautical miles on the line. We continue this for each hour as appropriate. Once we have all 5 lines draw we add the vectors together. We add each one, starting at the fifth.

A portland plotter is very useful for plotting the tide for each hour of paddling.

David Carraher v5

Kayak Navigation

Chart with all 5 vectors drawn for tidal direction and tidal flow.

Once we have all 5 vectors added together, we draw a line from Donaghadee to the end of the vectors.

This gives our position if we had taking a bearing for Donaghadee and followed that bearing. Now all we need to do is measure the angle between the two lines and add the difference to the bearing for Donaghadee.

Once we allow for magnetic variation we have a compass bearing to follow.

David Carraher v5

Kayak Navigation

Measure this angle to determine amount to lay off in order to allow for tidal

strength and direction. In this instance it is 18 degrees.

The chart shows all 5 vectors added together with the line drawn. After 0 measuring the angle (18 ) we add this to our original bearing and this gives us 0 the actual true bearing we need to follow. In this instance it is 71 , We now 0 need to allow for magnetic variation which in this area is 8 . This gives us a 0 compass bearing of 79 . To allow for slight errors and to ensure that we are on the correct side of Portpatrick when we reach land, we could use a bearing of 0 approx 84 . This ensures that if we don’t hit Portpatrick, at least we will only have to paddle with the flow to reach it. This makes the last hours paddling much easier than having to paddle against the flow.

David Carraher v5

Kayak Navigation

Basically all we did was 

Draw a line of the route we wish to travel.



Mark off on the line the distance we will paddle in each hour.



For each hour determine the speed and direction of tide.



Draw in the vectors for each hour at the relevant Mark.



Starting with the last vector add on each of the other vectors.



Draw a line from the starting point to the resultant sum of the vectors.



Determine the angle between the two lines.



Either add or subtract this angle from the desired direction. In this case add.



Allow for magnetic variation and set your compass.



Enjoy the paddle.

Paddling across Currents.

When paddling across currents allowances must be made for the current drift.

To do this with a degree of accuracy you must know your speed of travel and the speed of the tidal flow. If travelling at right angles to the tidal flow then a simple calculation can be used.

For example:  If your paddling speed is 3 knots and the tidal flow is one knot then you 0 would have to allow 20 for tidal drift.

David Carraher v5

Kayak Navigation



If your paddling speed is 3 knots and the tidal flow is 1.5 knots then you 0 would have to allow 30 for tidal drift.

From previous example of paddling from Donaghadee to Portpatrick the average flow is 1.5 knots approx nearly at right angles.

This would give us an offset bearing of 60/4x1.5 = 22.5 degrees, which means we are not too far off. It is another way of checking that our vectors are correct.

WIND One of the biggest factors affecting the kayaker is the wind. Depending on the strength of the wind the kayaker is required to take different actions. While looking at the wind we also need to look at the flow of the tide.

Fetch: The distance the wind travels over the sea. If the wind is blowing a long distance over the water then wind generated waves will be quite large. On the east coast any wind coming from the East will generate a big sea. Surfing conditions will be good in these conditions.

Tide: If the wind is blowing against the tide then the sea will also build up, depending on the speed of the wind and the flow of the tide. On the East coast if we have a southerly wind and an ebbing tide then the sea state will be quite big. If we have a southerly wind and a flooding tide then the sea state will not be so bad.

Effect of Wind on Paddling Speed.

Wind has a very big impact of the speed of travel of the kayaker. If the wind is coming from behind then your speed will increase. If paddling into the wind then your paddling speed will decrease.

If your paddling speed is 3 knots and you are paddling into a 25 knot wind then you will only move over the water at approx 1 knot. If the sea state is big, then you will probably end up going backwards.

Whereas if you are paddling with the wind your speed will increase to between 4.5 to 5.5 knots.

When going paddling in the wind a number of factors need to be taken into account. These are 

Strength of wind David Carraher v5

Kayak Navigation



Direction of wind



How long has the wind been blowing



Direction of Tide



Design of boat



Loading of boat



Paddles



Distance of Travel

Strength of Wind Novices will have difficulty in a force 2 wind and above. They will find it difficult to stay in a group or turn their boat.

Improvers will start to have difficulty in a force 3 and above. They will not be capable of turning their boats. If wind is against tide the sea state will also cause difficulties.

Intermediate paddlers will start to have difficulty with force 4 and above. They will have difficulty paddling across the wind and trying to keep their boat straight.

Experienced (level 4) paddlers will have difficulty with Force 5 especially when paddling across the wind. Going near overfalls or headlands will cause great difficulty for these paddlers.

Direction of Wind If Paddling with the wind then the difficulties decrease. It is very difficult to keep a boat straight when paddling across the wind and this type of paddling is very difficult to sustain over a period of time. If the distance to be travelled is far it may be wiser to paddle into the wind first and then paddle back to where you wish to go with the wind at your back.

When paddling with the wind behind you your speed of travel will increase How long has the wind been blowing When planning a trip it is important to know how long the wind has been blowing. If the wind has been blowing for a few days then the sea is more than likely to be quite big. This can cause problems when landing or launching.

David Carraher v5

Kayak Navigation

Direction of Tide.

When planning a trip check if the wind and tide are going in the same direction or are they opposing each other. If wind and tide are opposing each other there will be a lot of breaking waves and this can cause difficulties for most paddlers.

If tide and wind are going in the same direction there will be less of a confused sea.

Design of Boat Some boats behave better in the wind than others. It is important to determine how your boat behaves in different wind and sea conditions.

Loading of Boat A fully loaded boat is much easier to manoeuvre than a light empty boat in the wind. In a following wind or sea, some paddlers put extra weight in the front of their boats. This helps with the control of the boat.

Paddles Large bladed paddles are more inclined to catch the wind. Feathered paddles are less inclined to catch the wind. Long narrow paddles (Greenland paddles) catch the wind least, so are the best blades to use in big winds.

Distance of travel It is not wise to undertake long distance journeys if the wind is strong, unless you will be travelling with the wind and you have a safe place to land. The longer the distance the wind has travelled over the water the bigger the sea state will be.

David Carraher v5

Kayak Navigation

Micro Navigation: Micro Navigation basically means finding small points and knowing exactly where you are. Good quality maps and charts are necessary for this work.

Being able to follow a compass bearing is extremely important here and takes plenty of practice.

Understanding tidal flow and speed of flow is very important. Being able to make quick calculations is also very important.

Keep distance of each leg as short as possible. A couple of hundred metres for each leg would be ideal. Travel the leg and determine your exact location at the end of each leg.

Key to good micro navigation Know your speed over short distances. If you travel at 10kilometres per hour then you will travel 1 kilometre in six minutes see table below Distance

Speed 6km/hour

Speed 8km/hr

Speed 10km/hr

1 Kilometre

10 mins

7.5 mins

6 mins

500 metres

5 mins

3.75 mins

3 mins

400 metres

4 mins

3 mins

2.4 mins

300 metres

3 mins

2.25 mins

1.8 mins

200 metres

2 mins

1.5 mins

1.2 mins

100 metres

1 min

.75 mins

0.6 mins

From the above table if your travelling speed is normally 8km/hr and you have a tide of 2 km pushing you on and you are travelling a distance of 750 metres then to calculate your time, first look at your overall speed. Ie 8 +2 = 10km/hr.

Therefore the time taken to travel 750 metres is 500metres 3mins 200 metres1.2mins 50 metres 0.3 mins Total 4.5 mins Oilean David Carraher v5

Kayak Navigation

A book written by David Walsh which introduces you to the Islands of Ireland.

This book is well written and gives good description of the Islands, major headlands and cliffs. It describes Tides, landings, water availability, and items of special interest. This book is a must for paddlers who intend paddling around the coast of Ireland.

David Carraher v5

Kayak Navigation

Magnetic variation 90

14 B A

13

12 C A

11

A A

D A

10

09

08

David Carraher v5

Kayak Navigation

You are at grid reference 167123 stream junction.You are on a magnetic bearing of 290 and walking for 19mins, Locate yourself on the Map with a 6 figure grid.

Give a six figure grid reference for Points A,B,C and D. If going from point C to point D give the compass bearing you would use to take the easiest route. If you use more than one compass bearing give distance and time for each leg of the journey.

On the chart below calculate the distance from the red light on Dun laoghaire harbour to the south cardinal on the burford bank.

Explain the light sequence of the Bailey lighthouse

David Carraher v5

Kayak Navigation

Explain the light sequence for the Kish Bank light house and the North Kish Cardinal

David Carraher v5