grendel

busy getting on with their holiday i guess.

I think you would be better occupied looking after mrs Griff this evening, and you have posted your evidence before, but I am sure somewhere out there is the surveyed data for the depths, but the question is then can we find similar river depth data from the 1970's or 1980's that would help prove the case. empiratical data such as well they dredged all year round in the 1980's and they dont now, is fine and dandy, but actual hard numbers speak volumes more to prove the point, with numbers the actual volume of the flow could be calculated and the reduction in that flow could then be factored into the equation.

we must remember that the stones we see that have moved are only the facing stones on the outside of the bridge structure, the fact that they were able to realign them in the repairs shows that the underlying structure of the bridge had not altered, just on the visible face the missing stone allowed those surrounding it to also shift slightly.

I do however take exception to the elevation drawing in the report, as it fails to show the difference in height of the two side arches, this is an obvious feature as can be seen by the photographs, so to represent it on the survey drawing as the same height could well cause issues at a later time, as a draughtsman it offends my eye to see such a casual misrepresentation called an elevation drawing, it also leads me to wonder if they even measured the clearances on the side arches.(though I can appreciate with changing river levels taking a comparative level might be difficult as you would need to measure all 3 arches in a short span of time.

not to mention spotting anything fouled in the prop

While I probably agree with you Griff, we are trying to find hard data to prove the point, and we are eliminating sea level change (4" over the period we were looking at) and the bridge sinking from the causes, " something else" could well be the bure hump, but we need uncontrovertible data to prove that this is so.

surely something like that would have been reported in the survey, it was after all only someones opinion that they though it might have sunk on one side, it could of course easily been an optical illusion caused by the angle of viewpoint. It is very easy to just pick and choose the bits of a post that we would like to believe, but we have now seen the sea levels data and the bridge survey, so if the bridge isnt sinking, and the sea hasnt risen as much as the clearance has dropped, that just leaves "something else" as the cause, once the known causes have been deducted. as for one side sinking, the picture in the report does show one arch lower than the other, but then again so does this one from 1926, clearly the herbert woods side arch is lower than the other, and yes there does appear to be more clearance in 1926 than 2011, but then sea level in 1926 was some 75mm below average UK MSL whereas in 2011, it was 100mm above UK MSL, a difference 0f 175mm.

How about placing it on Hydraulic platforms, then the condition of the stonework can be more easily inspected ( as well as allowing a lift to get more boats through the bridge.)

PH currently looks to be 6 foot at low tide

does that involve first passing under Potter Heigham?

was his name Donald Campbell?

I cant see the picture from work as its probably off somewhere thats blocked, but if its the one i saw on facebook last night, no its not me, though even my daughter remarked on the passing resemblance (bald, beard, shorts)

following the analogy further, you have drains that overflow and wash back up the plughole too, bringing with them everything in the drains - or in reality - saltwater surges

actually, its the lack of the weight of ice after the last ice age, the weight has reduced so scotland is rising again

correct, the north pole location is slowly moving (the magnetic one anyway) and there is evidence in the past of the magnetic poles flipping N to S, the mechanism is not understood completely, but its not a quick process, so I think we can rule out the wobble as a cause of variance. the graph clearly shows the general trend is a rising sea level since 1900.

perhaps we should arrange for a drop in sea levels as that can be attributed as part of the cause, so ST i suggest a stint as King Canute is called for (though to be fair on that fair regent he wasnt out to actually stop the tides, but to demonstrate the fallibility of even a king, and that nobody could control nature.)

well we now have sea level data represented, expilot says there have been regular surveys of the bridge, so i guess we need to find that data too as it must be out there somewhere, it does strike me that the reported boat sizes that used to get through (shall we assume during the late 70's when the sea levels were lower) compared to the boat sizes that get through nowadays that there is a discrepancy of not just a few inches between the 4" of sea levels and shall we add the 4" difference of the tides, is still less than the difference between what could get through and what no longer can, so tidal levels and rising sea levels dont appear to account for the difference, we are told that level surveys show the bridge isnt sinking, so what other factors are there?

looking at the graph, you will notice quite a large dip (nearly 50mm) through the 1970's until the late 1970's, so going back to our childhood memories for the bridge clearances clearly is putting those memories in a significant dip of sea levels, the level then climbed steadily through the 1980's until it dropped again sharply around 1990 before starting a steady rise to today, looking at the pattern, it could be about to have another sharp drop soon (fingers crossed)

here is a pdf that contains the data graphs for sea level for the UK from about 1900 https://www.ntslf.org/sites/ntslf/files/pdf/images/bslindex.pdf this shows that on average the sea level has risen about 100mm (4") from here - https://www.ntslf.org/products/sea-level-trends

so filing finished and double sided tape added, ready for when the second coat of varnish dries on the well deck

so with an hour or so on my hands waiting until a reasonable hour for a routine appointment, i have bought the well deck area back in from its first coat of varnish, and am about to do some more filing on the stainless steel hatch surround. This was cut out of 0.3mm stainless steel sheet with scissors, and the inner section removed using a diamond cutting disc in the dremel, more pics when i have completed the work.

Lynsey, I think you are referring to the dyke to Catfield from Hickling, I think paladin was referring to a dyke just up river from How Hill, off the Ant, that leads to Cromes Broad (but is in Catfield parish). I too took a judith up to Catfield Staithe and yes its a tight turn up the top there by the staithe, when I went up there Tumblehome was moored up at the staithe.

Google earth still shows a vessel up the dyke as late as november 2017, so it could well still be there.

I suspected when I hired Jayne II from Martham boats that they had future proofed her a little bit as they had rebuilt the entire topsides, by rebuilding it a couple of inches lower than originally, this was backed up by heading through Potter Heigham Bridge at less than 6 foot, with several inches to spare.

well the first coat of varnish is on, so next up is the stainless steel hatch surround in the well deck over the rudder. a bit more trimming to get the edges straight, then manage to keep it flat.