Tricky rivers: Tactics to get upstream and back again

Generations of small boat sailors have enjoyed the tidal estuaries of South Cornwall and Devon, with their hospitable towns and villages, fine scenery and secure shelter.

This makes for a very popular cruising ground, good for relaxation, but it is still possible for a yacht to venture away from the crowd, into peaceful corners where she is likely to be the only visitor, or even the only vessel in sight.

On a recent West Country cruise, Mary and I planned to re-explore two of these unfrequented places, in order to update our local knowledge.

Then relaxation turned into drama, but it allowed me to improve my knowledge of how to anchor in shallow water and strong currents.

We were aiming first for Weir Head, at the tidal limit of the River Tamar.

I first went there as a boy, on the Southern Belle, which was a fast, sleek excursion boat in the 1950s.

Holiday trips to Weir Head had been a regular feature of local life since Victorian times, when paddle steamers provided the transport and the river was also busy with sailing coasters, some serving the mine workings and wharves that lined the banks in the upper reaches.

At one time, barges could also go beyond the tidal limit by a short canal that led to Gunnislake.

Nowadays, not only have the old industries died but the excursion boats have grown plump and hardly ever venture past the pubs and chip shop at Calstock.

I featured Weir Head in my book Channel Havens, but most pilot books are pessimistic about taking yachts into the upper reaches and I had read a couple of reports suggesting that the channel might have become obstructed by trees or debris.

Then, while we were at anchor in Cawsand Bay, on the western side of Plymouth Sound, we spoke to Chris Pollard, who runs Calstock Boatyard and therefore seemed like the ideal person to consult about the upper Tamar.

However, although he had been up to Weir Head in a dinghy he had not recently tried in anything larger.

It seemed our duty to go and check.

Tricky Rivers: Heading inland

For boats cruising within the Tamar estuary there are plenty of anchorages but few all-tide landings with useful shore facilities.

The most convenient place to top up provisions is Saltash, where the Town Council has taken control of the once-decrepit Jubilee Green pontoon, just north of the twin bridges.

This is now in good order and fitted with sound mooring cleats, although the attendant who issues key fobs for the gate is only present between 0900 and 1800.

Saltash Sailing Club has a water tap and it may be possible to moor at the club’s pontoon for a short period. A passage into the upper Tamar is always a grand experience.

North of Weir Quay the river valley squeezes between Dartmoor and Bodmin Moor, forming a series of magnificent loops where thick woods overhang the river and old mine buildings peep out from the undergrowth.

Cotehele Quay has 15th-Century heritage and enough depth for anchoring close downstream.

Continues below…

At Calstock, landing is muddy except at high tide, but the boatyard may be able to offer a drying berth alongside its jetty or pontoon.

After that the surroundings are wild. It is essential to do some tidal calculations, because the channel beyond Halton Quay is nominally dry at chart datum.

In fact, there are several places where current scour has created deeper holes, some with enough depth for a yacht to lie afloat at low water.

A further complication is that the chart datum actually steps up with the rising bed level, but only the first step is acknowledged on UKHO chart 0871, where MHWS for Cotehele is given as 1.1m less than at Plymouth.

The other steps on the table below are calculated from our own soundings, although it does not show all the smaller lumps and dips. (This diagram first appeared in YM in 2006, after discussions with
UKHO, and I have made a couple of minor improvements.)

In practical terms, this means that, for instance, the bed level close upstream of Calstock, at point X on the diagram, is 2m higher than chart datum at Plymouth.

The chart shows a low water depth of 0.2m but that is only the river water trickling down the channel at low tide.

During the next flood the depth will not increase until the height of tide at Plymouth has risen to more than 2m.

On the other hand, that shallow patch also acts as a dam to retain water in the next scour hole, which has a low water depth of about 3m.

Tricky Rivers: Upper Reaches

The tides were springs, so we expected strong currents, and as high water times would be ‘morning and evening’ we planned the trip in two stages, intending to anchor overnight in the second scour hole above Calstock, where depths of around 2m should allow us to lie afloat.

The channel bed between the mud banks is gravel and stones, so the holding would be uncertain and I preferred to use a single anchor, reasoning that the boat would gently swing upriver with the very first of the flood, allowing the anchor to realign itself before the main rush of current.

When we reached the intended anchorage, the deepest part was overhung by a large tree, which would have threatened our rig as we swung, so we continued a short distance further upstream to a spot clear of foliage.

We anchored in the channel, close to the Devon bank, and alongside ruined buildings on a levelled patch of ground that used to be a loading wharf known as New Quay.

The evening was perfect, the river surface like brown glass as the current slowed.

High water came 45 minutes later than at Plymouth and we enjoyed a peaceful night while the tide ran gently back towards the sea.

There was less depth than in the middle of the scour hole but I convinced myself – fingers crossed – that we would still have just enough water to float at low tide. Big mistake!

We really should have retreated to anchor in the 3m-deep pool.

When I rose early to watch the first of the morning flood we were not quite floating, and both keels were just touching the bed.

As London Apprentice began to feel the new tide she lifted and started to swing but her deep skeg scraped on the mud close to the bank and then we were drifting sideways (see Diagram 4).

I started the motor to push us clear but it was too late, as the starboard keel snagged the anchor chain, trapping it between keels and skeg so that we were effectively anchored amidships, with the anchor on a very short scope so that it was scrabbling over the gravel as our stern tore through overhanging bushes. What a shambles!

We attempted to motor out of trouble but the increasing current was too strong.

Eventually, our second anchor saved the day; we dropped it on a long warp then snubbed the warp to stop the drag and allow the first anchor’s chain to fall clear of the keels.

The whole episode would have qualified for YM’s ‘Confessions’ page and I was glad there had been no spectators.

Foggy start

At breakfast time the valley was full of mist but we waited until the flood slackened, to reduce the risk of becoming tangled with any waterlogged debris, and by the time the anchor came up the haze was clearing with the promise of another fine day.

At Morwellham Quay, which has been restored as a tourist attraction, we passed the schooner Garlandstone in her old berth and then chose the Devon side of a small island, which has been gradually eroding and will soon become a concealed bank in mid river.

There was lots of swerving around big trees but no serious obstructions.

At the precipitous Morwell Rocks we could just make out a narrow carriage track, between cliff and river, on which Queen Victoria went sightseeing.

Soundings were gradually decreasing but we had more than 2m depth as we approached a house in the trees that was once the lock keeper’s cottage for the Gunnislake canal.

Patches of bubbles drifted from the upper weir, which was out of sight around a bend, but two lower weirs were submerged and the first one was close upstream of the house.

Warm sunlight was slanting down through a cool jungle. The tide continued to rise slowly but the river’s fresh water had baulked the current and we were able to linger, drinking in the atmosphere while floating motionless on a liquid mirror.

Yes, yachts can still reach Weir Head and it’s well worth making the effort.

River of sand

And that would have been that, but a couple of days later we had a second chance to practise anchoring in a restricted space.

We were calling at the River Avon, which dries upstream of its mouth but is a wonderful place for family holidays because the bed is almost entirely of sand, rather than the usual West Country mud (Diagram below).

Bantham village also has a shop and the Sloop Inn.

The main drawback is that the river entrance can be dangerous in onshore winds and swell, particularly during the ebb, when yachts should either stay away or stay inside.

The two houses that serve as entry transit marks are still obvious but old white pilotage marks on the rocks have faded and we followed the first curve in the channel by simply steering close to the cliff, while watching the echo sounder carefully, until we could see the sand on the seaward side.

After the narrows, this estuary has another example of a retained pool of deeper water, extending as far as Bantham village, with low tide depths of around a metre.

Most visitors anchor on the drying banks but we wanted to use the pool because that would enable us to make an early departure against the morning flood and then ride an east-going stream around the coast to Salcombe.

However, a row of boats was on fore-and-aft moorings along the north side of the pool, so swinging room was limited and we would have to copy them by anchoring fore-and-aft.

As the bed of the pool is uncompacted sand, I was confident that neither of our Delta anchors would drag and we laid the bow anchor towards the entrance so that the stern anchor could be lifted first on departure; that was on a long warp with a chum weight about half way down.

Simple solution

When the ebb stream started to run it steadily increased to about 3 knots and our boat’s design began to cause a problem.

One of the best features of the Sabre 27 is its deep rudder and skeg, set well aft so that it has plenty of leverage.

This is a great comfort in nasty sea conditions, especially when off the wind and carrying a bit too much sail, but in this anchorage all that lateral resistance, close to the stern, meant that the hull was sheering from side to side as the current from aft caught the rudder blade.

This obviously increased the chance of dragging and I tried moving the warp to another fairlead, then securing it amidships, but London Apprentice was still lunging across the stream.

Finally, we found the answer by joining the warp to a bridle rigged between the quarter fairleads; it was simple but it worked and we could finally relax while the river emptied and golden banks emerged into the sunshine.

Remember the summer of 2018? At low tide the pool made a fine lido, with water temperature 23ºC.

We have anchored in hundreds of places during our time, often fore-and-aft, but there is always something new to learn and these unspoilt estuaries are certainly delightful classrooms in which to be taught.

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