Wednesday 6th February 2013

Housing and Marina at Knapp House - Ships for Yalland

mv BALTIYSKIY 202 due Thursday to load logs at YELLAND has been delayed by bad weather and a cut in tide height at DUNDALK. She remains at anchor off the port awaiting an improvement in conditions. She should berth at DUNDALK tonight and sail for YELLAND tomorrow (Thursday 7th) for a Friday pm arrival.

mv WELSH PIPER is due for YELLAND next week from mid week onwards to import building sand from the Bristol Channel to Notts Contractors.

Two ships are due for BIDEFORD at the end of the month.

A decision ref the proposed marina at Knapp House should be made tomorrow at the Town Hall Plans Commitee.

Much local opposition has been made ref the development.

The Harbour Master has been asked re access to the marina, and to comment on the latest Tidal Assessment made by consultants.

Several enquiries have also been made ref the access periods to the marina from the general public. A copy of my reply to the enquiry is shown below.

The document is an attempt to explain the accessibility to the marina, and as such is at least somewhat confusing.

I am happy to run through the document with anyone, but at this eleventh hour, then it is likely too late.

The best way to get an idea of the accessibility to the proposed marina is to do practical observations, since admiralty intermediate tidal heights within the estuary do not allow for the effect of banks and constrictions in the river.

In light of this I did a few days of tidal observations on the recent 'neap tide.

As you will realise that as Pilot  I work to small clearances for the ships that come and go into Bideford,  and Appledore and so it is critical to know what tide heights are both here in Bideford and at Appledore.

To that end we have a tide board at Bideford set to Bideford chart datum and two  tideboards at Appledore also set to Bidefords tidal datum height. (Bideford datum is 1.38m below ordnance datum Newlyn)

At high water the tidal reading at the Bideford tide board corresponds with the tide board reading at Appledore.

There is therefore no gradient at slack high water as the document states – if there was obviously  there would be a tidal flow.

During intermediate times then there is most definitely a changing gradient throughout the river.

My observations over a tidal cycle on a moderate 4m neap tide show the following;

That on 5th of February that the Knapp house flap tidal gate would have been open for 5 hours and five minutes allowing passage for vessels in and out of the marina..

This is based on the corrected  drawing supplied by Alex Beere last week with a cill height of -1m (below Ordnance datum) with a 2m high tide gate.

Observation in the river from the Pilot boat show that the banks at the site (approach channel) start to uncover when there is approx. 3.1m on the Bideford tide guage indicating that the channel to the marina would need to excavated by 3 metres of mud.

In conclusion with the short study and with my experience of the river is that the marina will be workable for boats over a period of at least 4 hours on most tides. And that on the smallest neaps that this may be reduced to 2.75 hours subject to actual observation. ( I did it by extrapolating my own tidal curve for a 4m tide.)

The channel off the marina is wide and relatively deep, and currents will be easily manageable by boats approaching and leaving the marina.

Atmospheric pressure has an effect on tide heights, and on Spring tides levels can be reduced by over half a metre when the pressure is around 1030 mbs. Also wind can reduce the tide heights (eg a strong northerly) and at times other than high water the fresh water when the river is in spate  will increase heights at intermediate tide times.

There has been a lot of misinformed comment re the estuary from some surprisng sources eg that the estuary and Bristol Channel is especially 'dangerous' for small craft. It is not more dangerous than many other estuaries  and all 'Bars' must be treated with caution including Padstow which have many visitors and Chichester bar where many thousands of yachts are based to mention but two locations.

Dredging of the marina and  especially the approach channel will need regular attention to maintain designed depths. This can be achieved with a plough type attachment to a small tug.

Careful monitoring of removed spoil would need to be made as happens at the Shipyard approach channel and annually at the Hanson berth at Bidna.

I cannot comment on the desirability of the large housing estate, but it is clear that to object on the usability of a properly designed and run marina will not be valid for this would indicate that any marina development within the estuary would be undesirable or unworkable, which is not the case.

R.T.Hoad Pilot HM Bideford.