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Wroxham - a question


DaveS

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Dave, wait until it's not too busy and poke your nose up to it, you'll either get under it or not and if not then reverse off and go somewhere else, it's surprising where you can get under if you just try, we used to get under St. Olaves bridge even though the sight gauge said no way in Kingfisher quite regularly and not always at low water either. We have also seen the shock on peoples faces as we emerged the other side of Ludham Bridge in Genji with the radar still attached, just go at it gently. :naughty:

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I did 'nose up' to St Olaves bridge at HW springs, and we couldn't fit under.

The tide was on the flood, so we had excellent control, being able to 'hold station' with ease.

I'm with Gretsky, if Wroxham Bridge is just an historic ornament, then take it down and sell it to the Americans, as we did with London Bridge :lol:

Dave

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Just to clarify, the bridge pilot at Wroxham, they will only take craft from the hire fleets through!

I even offered to pay them but they said that Loynes (who now have control of the pilots)wouldn't

let them.

The gauge on Avalon says 6' 10", but I measured it at 6' 8", but would like someone with more

experience of our type of boat to take her through before I do it! The pilot says try it at 7' 2"

and she will go through ok. I need to go through as we do miss that stretch of river a lot.

We went under Beccles with the gauge reading 6' 10" and had at least 4" to spare and more like 6"

and it is common knowledge that the Wroxham gauge is about 3" short!

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I have often look at Wroxham bridge and thought I am sure my boat will go under that with the arch down, but never had the gut to try it! Does anyone have any ideas wide the clearance of the posted hight is? i.e 7'6" at 12' or 11'? thanks

The 64,000 dollar question !

I'd heard somewhere that the Pilots at Potter Bridge know how wide the arbitrary rectangular boat profile is for there's but have never heard it mentioned for Wroxham Bridge.

I guess if someone could take a closeup photo of each arch, exactly square on, just before going under, and note the actual height gauge reading at the same time, we could scale it off easily enough.

Quite a useful piece of information for all the Broads Guides !! :)

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For reference my centre cockpit Alpha 35ft will go under a flat bridge at 6ft6in with about an inch to spare. Last September I took it through Wroxham bridge when the downstream guage was showing 6ft6in and I had just under an inch spare on the shoulders of the sliding roof. I am guessing that the downstream guage is not that accurate and will always take it very easy when the clearence is that low, in case they reset the guage :o

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Just to add for comparision, the pilots at Potter want the guage to be showing 6ft9in - 6ft10in, before they will take her through. The Potter bridge pilot guage is the most accurate, and whilst I don't know at which point on the arch it is measured from, they still require 3-4ins more than the boat needs under a flat bridge. Thinking about it, I wouldn't be surprised if the Potter guage is measured to the top of the arch.

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The 64,000 dollar question !

I'd heard somewhere that the Pilots at Potter Bridge know how wide the arbitrary rectangular boat profile is for there's but have never heard it mentioned for Wroxham Bridge.

I guess if someone could take a closeup photo of each arch, exactly square on, just before going under, and note the actual height gauge reading at the same time, we could scale it off easily enough.

Quite a useful piece of information for all the Broads Guides !! :)

Cant be that hard, British Waterways publish the air draft of a bridge with the span of the quoted air draft.

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Guest DAYTONA-BILL

The easiest way to see if you`ll get under the bridges is to look at the underside of the bridge from a little (about 3-4ins) above the highest point of your boat, and if you can see BOTH sides of the underside of the bridge, then you`ll get through. That`s what we always do, and it`s NEVER failed. It`s at this point, you can see just how much difference there is between the "stated" and the "actual" airdraught of your boat. Regards to all ............. Neil.

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Have been watching this thread with interest. I have an Aqufibre 33 with higher grabrails on the sun deck that usual. As such I am not certain of the airdraft. What I do know is that the boat goes under Wayford Bridge with 4 to 6 inches to spare. Does that mean I will get through Wroxham?

Incidentally, is there anyware I can go and get the airdraft of the boat measured?

Thanks

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Guest DAYTONA-BILL

Hi Soundings, i would have thought the answer to that is yes. However, it pays to check what the height gauge says, and check the height gauge at Wroxham. Wayford is a flat bridge whereas Wroxham has an arch, but a widish arch at that. I think at average high water, Wayford is much about the same as Wroxham, but i wilfully stand to be corrected by anyone who knows better. Have you checked the bridge heights in any of the Broads navigation publications, such as the Broadcaster, or the Hamiltons guide?, it should tell you in them. Regards ................. Neil.

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Thanks Daytona-Bill, it was people saying the bridge height measurement is based on a box passing through the bridge that got me thinking. Up until then I had always thought the measurement was from water level to highest point of the bridge. In such a circumstance the arch of the bridge would almost certainly stop me passing through.

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Up until then I had always thought the measurement was from water level to highest point of the bridge

Yep, me too, as I said earlier.

If you look at the bridge height listed on the BA website, it makes no reference to any 'box section', only being the clearance at average high water.

Very informative :roll:

Dave

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I haven't got many photos of Wroxham Bridge, but do have quite a few of boats transiting Potter.

It's surprising how much "safety margin" the gauges have, as well as not being based on the maximum height at the centre of the arch.

Although most of these shots show a 6ft 9" clearance, you can see quite a bit of clearance at cabin roof edges on quite wide beam boats.

There's another factor though.

The Guys at Martham Boats told me that when you drive a large, long boat through at speed, the prop sucks water from under the boat whilst going through the restricted width and depth opening, dropping the boat by as much as 3 inches.

You just have to be brave enough to try it, unlike me :shocked )

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Your credentials on such matters are cast-iron Rod, as further proven by your very detailed explanation.

I did once see a Martham Judith boat "limboed" under by expert use of the throttle, accelerated up to the bridge, then decelerated to dip the bow, then accelerated to drop the stern. I wish I'd videoed it, most impressive to watch. :)

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Here’s a couple of pictures of Rod’s chains at Wroxham.

I agree with Rod, there is s bit of latitude as we just glanced one the chains going through last time but had plenty of room as it turned out. As has been mentioned the main thing with Wroxham is to be aware that it is offset – if you centre up on the arch and ignore the footbridge and the bank you can’t go far wrong. We take a centre cockpit Alpha through and with the gauge showing 7 feet you have loads of room.

cheersbar

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