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RayandCarole

By RayandCarole
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ranworthbreeze

ranworthbreeze

Posted
Posted

Thanks Ray,

Looking at this report, I noted the following:-

"The most common place this year for smashes has been at Vauxhall bridge in Great Yarmouth, where five out of the reported seven incidents took place. The other two were at Thorpe railway bridge and Beccles bridge. Five of the incidents involved hire boats.

In a bid to combat the problem, the Broads Authority has adjusted the gauge board at Vauxhall bridge by three inches to give the impression there is less headroom than there is."

What we need is the correct height at all bridges with bridge height boards that are clearly marked at the lower levels and well in advance of the bridges, so crews can make informed decisions before getting to the bridges. The height boards going down river through Great Yarmouth are almost unreadable.

With higher air-draft boats calculating the tides and the height at low & slack water is imperative and misinformation on the approach to a bridge does not help anyone. 

Regards

Alan

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RayandCarole

RayandCarole

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Posted (edited)
  • From the BA website:
  •  
  • Time your arrival in Great Yarmouth to coincide with the right tide - slack, low water or just after, which is approximately one hour after low water at Great Yarmouth Yacht Station. To find out when low or slack water is check the tide tables.

so the tide would already be on the rise one hour after low water.

 

cheers

Ray

 

Edited by Tangara
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kfurbank

kfurbank

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Would it be correct to assume that the difference in clearance under the bridges  between low water and slack water is almost zero?

No, at slack water it is usually a few inches higher than at low water. At places such as Reedham and Burgh Castle it is not unusual to see the water still flowing out at low water and then the boat will rise fairly quickly by about 6 inches before the water goes slack. Basically the incoming tide starts to restrict and hold back the outgoing flow causing the water to rise. At the point the incoming tide matches the outgoing, otherwise known as slack water the water has already risen. This effect is much more noticeable after heavy rain fall. Its certainly strange to witness the boat rising whilst the current appears to be going out. Its a little known fact but the Thames Barrier has actually been deployed to prevent fluvial flooding on more occasions than to prevent flooding from surge tides, the purpose it was originally built for. To help with fluvial flooding, the barrier is often raised just after low tide stopping any on the incoming tide, thus creating more capacity upstream of the barrier for rain water to fill and not be pushed back upstream. Then just after high water the barrier is gradually lowered to allow the rain water to flow out with the outgoing tide.

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kfurbank

kfurbank

Posted
Posted

I note the increase in extra large boats is seen as part of the problem but I wonder how many of the bridge strikes involved these larger boats?

The Beccles bridge strike involved Sandfly from Sandersons. Yes its a tall boat, but hardly new. The bridge strike at Thorpe involved an Alphacraft boat that is some 15 years old. Also interesting to see that the figures disprove the often quoted effect of social media whereby it is assumed that these events are not on the increase, but just being reported more often. I have often disagreed with that theory and it will be interesting to see the figures for groundings when they are published. I suspect they are also truly on the increase, not just being reported more.

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Hockham Admiral

Hockham Admiral

Posted
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Would it be correct to assume that the difference in clearance under the bridges  between low water and slack water is almost zero?

It's the Twelfths Rule, Eric. The tide rises 1/12 in the first hour, 2/12 in the second, 3/12 in the third and fourth, 2/12 in the 5th and 1/12 in the 6th.

So if the total rise over a whole tide is, say, 6ft, then you'd expect it to rise 6ins in the first hour.

We used it all the time when entering North Sea harbours abroad.

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LondonRascal

LondonRascal

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I doubt a damage waiver or not would have solved these issues – let’s face it even a £200.00 deposit would not go far to putting right the damage, and there is still liability allegedly on the hirer despite the damage waivers, thing is that is going to be down the costly road of the law so it is easier for a boatyard to accept ‘accidents happen’ and get on repairing the damage than chasing the hirer for money.

I think adjusting height markers is ridiculous! 

I wrote to the Broads Authority earlier in the year covering a number of topics such as boats going aground and hitting bridges (I’ll scan their reply at lunchtime).  We all have an opinion on this, as does the Broads Authority which seems to be to leave it to the Hire Federation to go around to their member yards likely ‘cap in hand’ for some money to get a production company to produce a DVD to give to hirers. Meanwhile the Broads Authorities quick fix is to make it seem there is less height than there really is. Charming.

So is it now the case that those passing through Yarmouth can take it as gospel there is ‘actually’ 3” more clearance than the gauge actually reports – these things I believe should be either as accurate as they can be, or universally ‘liberal’.  I don’t mean that such is published in the public domain but that the gauges at any bridge all give (for example) 3” extra so the Broads Authority themselves and contractors know what to set the gauges at when they are put in. Otherwise we will have some on the liberal side and others pretty much bang on. 

As for the DVD forgive me but people are on holiday, not a course.  If such a DVD was produced it is not going to be a case of people ushered into a back room and sat down for 20 minutes to watch how to plan tides and bridges – it will no doubt be left in the Skippers Manual and reliant upon people watching it – perhaps being told on take over  “would you, when you have some time tonight, watch the DVD in the book as it contains important information about bridges”.

DVDs cost money to make, get taken, scratched lost you name it and are very much these days a format on the way out – what is needed if any video was produced is on the online – sent out embedded in the email confirmation for booking.  People then at home, on their tablet, phone, computer you name it can watch it even on the bus or train and boatyards can have it on their website and Facebook pages easily and once produced for free – spread everywhere.  Far more sensible in my opinion.

Finally though I still think universal, clear signage at each bridge would not be a bad thing along with universal signage on every hire boat helm – same format, same colour, same size and same wording but I’ve said enough on this in the past.

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ranworthbreeze

ranworthbreeze

Posted
Posted

Eric, put it this way, I can get under Beccles and Potter Heigham with two inches difference in clearance. Doesn't sound much but it means that I don't trust the height gauges. Does it matter? Yes, when sometimes people slide under with literally one inch clearance.

I total agree Peter, these boards have be correct.

Eric, re low and slack water, lets put it this way a limited number of very high draft craft can traverse the Yarmouth bridges say once or twice a year if well planned and at low water not slack water.

The reason for going through the bridges at slack water is that the the fast flow of the outgoing tide should have slowed down to make a controlled passage down river, coming up river it is not so much of a problem other than using more revs and diesel.

Regards

Alan

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Guest

Guest

Posted
Posted

........In a bid to combat the problem, the Broads Authority has adjusted the gauge board at Vauxhall bridge by three inches to give the impression there is less headroom than there is............

I agree with the others that this is very wrong.

If some people are going to try to squeeze under bridges when there's insufficient clearance, then lying about the clearance is unlikely to stop them.

Such a stupid thing to do, now even responsible people will have to start guessing what the unknown "safety margin" is.

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Poppy

Poppy

Posted
Posted

IMHO, the bridge gauges and their accuracy has little to do with the problem. I'm afraid that like the increase in hire craft navigating after dark, boats aground, etc. can partly be put down to ignorance, to an unwillingness to read instructions (or listen to them and a wider attitude that can be summed up as 'don't ******G well tell ME what I can and can't do. 

All too prevalent in society today, and not just on the Broads I'm afraid. Yes, take a 'swipe of their credit card, just as is done when hiring a car or checking in to a hotel !

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Mark

Mark

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Robin re the damage waiver:  You are 100% right that  even £200 wont put right the damage to the boat, but the point is that for the  Hirer who stands to  lose the £200 , it can be a fairly  large chunk of his/her money for nothing, and  may  (granted  its only a may) make some think twice before taking a risk on the basis  of "ah well my damage waiver will cover any damage risk  so its   not my loss... so  I,ll go for it "   

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JennyMorgan

JennyMorgan

Posted
Posted

A little bit of clarification on the newspaper report that may not have been that well researched......

 

 

http://thebroadsblog.blogspot.co.uk/2015/10/gauge-boards-should-be-taken-as.html?m=1

Now the seeds of doubt have been cast can we really be sure? 

If there is to be any departure from reality then perhaps it should be on hire boats, just don't tell the hirers!

Why of why, when they were renovating that blessed bridge, did they not jack the blessed thing up onto a couple of bricks, making both bridges the same height?

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Arthur

Arthur

Posted
Posted

I totally agree with your comments regarding Vauxhall Bridge Alan,

After all they removed the old bridge further upstream that used to carrry the railway line to Yarmouth Beach.years ago.

I can understand the occassional error when trying to negotiate arched bridges like Potter and Wroxham where the width is also a significant factor.  However this has been long recongnised and the pilot has been required for hire boats at Potter for many years and more recently at Wroxham.

A lot of the more recent bridge strikes seem to involve hirers either misjudging the clearance or I am sure on some occassions not even looking at the gauges.  

I hired from Aston Boats for many years and all of their boat carried the boatyard penant on a flagstaff mounted on the bow of the boat.

This was deliberatly set at the height needed for the boat to safely clear a bridge.

Ie if the flagstaff hit the bridge then the boat would not pass through.

Even if you did not get close enough to the bridge to put it to the test it gave a very good indication to the helmsman when approaching.

 

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diesel falcon

diesel falcon

Posted
Posted

I ve said it before but i think ba should invest in electronic real time display boards, at a loose end tonight so had a think of how to do it, got as far as the sensor, which would work mounted over a tube set on the bank with an open end and large perperations(so it woul dn,t block up!) then link it to a display mounted on the bridge....https://www.apgsensors.com/ultrasonic-level-sensors/iru-3430, simple !!

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