Ludham Bridge Clearance

[wooster]

HI

I know the bridge is about 8'6" at high water and my boat has an airdraft of exactly 8'6". I also believe the water only moves about 3" or 4 " so 'I'd need to be picky about time.

My question is, would I have ample opportunities to move past Ludham ( ie at some point most days in spring, summer and autumn ) to get to Stalham and back or not?

I'm really a South Broads type of guy and haven't spent much time north.

[Chelsea14Ian]

Our boat is the same height and we've always  gone through ,no problems .

[BrundallNavy]

8ft6 is rear nowadays was only 8ft the other day.  

[Ray]

My boat is 8'3" and I was advised by George at Ludham Bridge boatyard that for most of the seson I'd get through but there would be times in the winter I won't

As my boat is new to me this year and BA reset the marker boards fairly recently I've been paying a lot of attention to guage it for myself.

Last week the height boards nearest the bridge, both upstream and downstream, read 8' 

It was quiet enough and calm enough to take her gently up to the bridge itself (travelling upstream) It was safe to pass and my crew reported about one inch to spare.

Obviously every helm on every pass has to make their own decision but personally I have found that I can (cautiously) add 3 inches to the height board readings. (I haven't compared the further out ones)

Grendel took some measurements which you can find on an older thread by searching the forum. My findings appear to match his... which also of course come with the proviso that it's up to the helm on the day to decide.

[annv]

Hi Wooster when going through Ludem use full throttle to dig the water from under the boat if you dawdle/creep through the boat can rise as you are restricting the flow, this can happen if you have a wide boat (12Ft)or more this will raise the boat up by several inches which can cause you to contact the bridge, found this out with my last boat when i first took it through, only happens at Ludham duo to it being narrow. And if you site along highest part of boat at the rear if you can see far side you will clear if only front then you will hit.  John

[Lulu]

It was showing 8ft this morning at 7.30

[RS2021]

I hired a boat which measured 8'6"and have been through Ludham with no problems. I compared the gauge to actual clearances and also to the EA gauges at Barton and Ranworth. I also downloaded 12 months worth of data from the EA sites. Based on that I recon that if the EA gauges are showing 0.5m or more you will get through Ludham with an 8'6" boat (obviously if there are stronger flows on the rivers these can vary from Ludham, but its a very useful guide to check before you travel). Also based on the 12 months of data I recon you will get through on 90% of days between April and October, or 97% of days between May and September. Winter, obviously will be more difficult. 

[CambridgeCabby]

On Cerise Lady , airdraft of 8ft, the only times we were unable to pass were in the winter when it had been very wet and it was spring tides , normally we would have over 4inches of clearance at high tide 

[wooster]

I could have sworn I'd replied to this but I can't find it anywhere! 

Anyway, I am taking a positive view on the basis that

1. The BA height measurements are very cautious

2. Most low tides would give me the required clearance

My boat's stern also leans back and moves downwards a fair bit when I apply some throttle and she has a 10' 1" beam so that should also help.

I hope I'm not being too optimistic though .... 

[Broads01]

7 hours ago, annv said:

when going through Ludem use full throttle to dig the water from under the boat

You're a braver man than me, knowing how narrow it is.

[RS2021]

14 hours ago, RS2021 said:

0.5m or more

correction - should read 0.5m or less!

[rightsaidfred]

I agree with annv regarding use of throttle, 1 point to remember is that due to the restriction of the bridge the water level upstream is slightly higher than below the bridge and this reflected by the gauge furthest upstream.

Fred

[wooster]

Folks, on a related but tangential point, I need a lesson on tide table reading. Maths isn’t my strong point so bear with me please.

According to my app, today the time Ludham Bridge is at low water is 11.37 and this is followed by  the reading 0.37m. High water is 18.10 followed by the reading 0.91m.  I had thought these readings related to water height above Chart Datum -with that being the lowest "normal" tide. It might not be the correct definition but at any event, CD will be a constant point from which tide height is measured. 

If I’m right here, then the water at Ludham today moves between 0.37m above CD and 0.91m above CD which is a rise and fall of 0.64m or roughly 25”. Clearly this isn’t the case so what am I getting wrong?

[grendel]

depends where the chart datum is taken and how near to Ludham Bridge that is, if the chart datum is taken at great Yarmouth, then that rise and fall would be seen at great yarmouth, not ludham bridge.

 

[wooster]

HI Yes I see that but I'm assuming it's local to each location as each one gives different figures with eg Great Yarmouth Yach Station showing substantially larger differences between high and low water of approximately 4ft which kind of surprises me as I always assumed the tide rise and fall there was more.

On reflection, maybe I should have started a new thread on this

[annv]

Hi Wooster I use it to tell me that on that day (no storms etc) that when it gives the higher figure the tide will comply with it ie higher on the day it says higher and lower rise and fall applied where you are when a lower figure, just read the board at the site and site along highest part of your boat, your going to get through most times in summer as Cambridge Cabby said Alternatively there is a foot path/ledge at bridge measure with a tape your boat height from top down and see what is showing at your height a crack,  bolt, something on brick/concrete then just check it each passage this will 100% accurate as it cant move this is what i did as i needed 8'6". John Oh and write it down with sketch.

[wooster]

Thanks John. That's a good tip about getting a marker to ensure the tide height. Thanks.

I'm still a bit baffled about these tide tables though

[annv]

Just buy a tide table from BA for a £1=00 and keep at helm. John

[Smoggy]

BA tide tables use a different datum than regular tables so worth bearing in mind, don't rely on the tables too much as wind speed and direction and air pressure all make a difference on times and heights.

CD on a proper chart and table refers to lowest astronomical tide which is very rarely reached, not sure what ba go by.

[annv]

They work very well for me and at a £1=00 a year and kept open at the currant page on the helm infallible aide. John

[Scotty]

Please correct me if I'm wrong has this is going to be close for me also with an air draft of 8ft6" with all the weather we could have in between now and when I get to stalham with regards to ludham bridge height Datum of Yarmouth Bar is 4hrs in front of ludham bridge so ie if low water at yarmouth bar is 07:47 then that would be 11:47 according to ba tide table and location 

And in previous topics grendel has measured the bridge to 8ft with the concrete path showing 

Kind regards scott

[wooster]

I use this free app here and I find it very useful. I also have a copy of the Broads Tables. My question about the tables and the app and tables in general, is really if I'm reading them incorrectly, because whatever BA use for datum the tidal difference is a lot more than a few inches. Can anyone help with my understanding?

[grendel]

4 hours ago, annv said:

Alternatively there is a foot path/ledge at bridge measure with a tape your boat height from top down and see what is showing at your height a crack,  bolt, something on brick/concrete then just check it each passage this will 100% accurate as it cant move this is what i did as i needed 8'6". John Oh and write it down with sketch.

I did this and posted it to the forum somewhere, would have been almost a year ago as I did it en route to lads week last year.

[grendel]

 

[ranworthbreeze]

I go onto the Broads Authority website to check out  the tide tables, I have done this for years since we first started coming to the Broads.