From the master of stupid questions - another one

Blackfeather

Blackfeather

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www.blackfeatherboatcharter.com
Another noobie question - bridge heights.

So I have had the radar arch hinged and, when down, this reduces the air draught to 12' 6'. I have looked carefully at all the bridge heights and, in theory, that seems to get us under all of them. Forgetting the current horrendous conditions, and assuming a range of normality (is there such a thing?) can the published bridge heights be taken as safe ie with a bit of latitude for higher levels? Also is there a river height gauge system at all so that one can calculate whether there is sufficient height at any particular time?

I was traumatised a couple of years ago seeing a lovely old cruiser smashing its roof under Henley Bridge and I don't want to experience that first hand.

Apologies for yet another question and thanks to everyone so far for your help and patience.





PS. I haven't finished with the questions yet
 
The bridge heights are typically measured from a level in the river called 'headwater' which you can call zero.

Most locks run at X above headwater , usually between 3 and 6 inches .

So for an accurate measurement you would need to either phone the lock before the bridge and ask them how much above headwater they are running at , or look on the levels page and then subtract it from the bridge height given.

Lower thames levels ....


http://www.environment-agency.gov.u...580.aspx?RegionId=9&AreaId=25&CatchmentId=157
 
Wow a good answer TD, so if Bridge heights are published at Headwater = zero why don't lockies control to that rather than always +3-6inches?
 
My airdraft with radar down in also 12 6".Have had no problems getting under anything on the Thames.
You can also get under both bridges in Maidstone Town centre,which proves boaters doing so are either
(a) foolhardy or
(b) keen. :)
Mind you at the moment you could probably not get a matchstick through the arch.
 
12,6" is going to be tight at Cookham lock cut bridge. I'm about 12'3", and occasionally struggle if the water is up a bit.

Good news is that there is a sighting pole at Cookham lock, if you ask the lockie nicely he can check as you leave the lock upstream and advise.

You'll also have to be very careful at Windsor and Eton bridge as it's arched, so you have to be bang in the middle.
 
rosssavage said:
12,6" is going to be tight at Cookham lock cut bridge. I'm about 12'3", and occasionally struggle if the water is up a bit.

Good news is that there is a sighting pole at Cookham lock, if you ask the lockie nicely he can check as you leave the lock upstream and advise.

You'll also have to be very careful at Windsor and Eton bridge as it's arched, so you have to be bang in the middle.
Click to expand...
My previous boat had an air draft of 12'6" with the fly screens in place and I couldn't get under Windsor & Eton or Cookham lock cut. As Ross points out the bridges are arched (although Cookham only marginally so). My problem was my 12'6" air draft went the full width of the flybridge so while I might have enough to spare in the middle, I didn't at the extremes of the flybridge. Even with the fly screens removed, lockie at Cookham had to drop the level more than once to get me under.
 
Wavey said:
My previous boat had an air draft of 12'6" with the fly screens in place and I couldn't get under Windsor & Eton or Cookham lock cut. As Ross points out the bridges are arched (although Cookham only marginally so). My problem was my 12'6" air draft went the full width of the flybridge so while I might have enough to spare in the middle, I didn't at the extremes of the flybridge. Even with the fly screens removed, lockie at Cookham had to drop the level more than once to get me under.
Click to expand...

My fly is very narrow and falls away sharply to either side. Probably accounts for difference ?
 
Chris_d said:
Wow a good answer TD, so if Bridge heights are published at Headwater = zero why don't lockies control to that rather than always +3-6inches?
Click to expand...

I thought the targets were actually -3 to +6 - not +3 to +6 ? I do know that specific intent to keep within this range was taken out of the Customer Charter a couple of years ago which now simply says
5. Managing water levels
We manage water levels to balance the many uses of the river,
including boating, retaining enough for water companies to extract,
managing flood risk and ensuring conservation sites, fisheries and
water quality are protected. We measure water levels at lock sites
and monitor them 24/7.
We operate the weirs and other structures to provide the best
conditions possible for all uses of the river. Our ability to control
water levels may change in flood or drought conditions.
Click to expand...
 
Well its certainly a tad more than +6 today - LOL

Joe just sent me a pic of my boat at Penton this morning - I usually walk down onto that pontoon !

penton080114.jpg
 
Last edited:
boatone said:
Well its certainly a tad more than +6 today - LOL

Joe just sent me a pic of my boat at Penton this morning - I usually walk down onto that pontoon !

penton080114.jpg
Click to expand...

I am probably one of the few who had a short cruise on the Thames today , from my mooring to the lift out area at Penton Hook. For those who know the marina the water level was almost at the same level of the top of the lift out area. Good to have a word today Tony [B1] , and as I said your boat looks fine if a little marooned.
 
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