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fishtone

Going under Wroxham Bridge

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I have a boat with a 6ft 4inch air draft and 8ft beam. what minimum height would members recommend to go under Wroxham bridge. I have been under at 7ft 3in but would like to go under more often so there fore would like some advice.

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With a beam of 8ft you are narrower than most. So my sensible correct answer would be 6ft 5" (Or more) all day long.

However I once measured the gap between our spotlight which I know for a fact to be at 6ft7"  The airdraft gauge on the bridge stated 6ft 8" and yet I had around 5" clearance - so the gauges are not calibrated correctly.  I use this data to my advantage and normally keep it to mysen, if they ever re-calibrate the airdraft gauge without informing all and sundry - I'll be in trouble

Griff

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At 6ft4" Air Draft you should excuse the pun, sail through Wroxham Bridge,( just make sure you are centre) more often than many when high tides there. Before the powers that be forced us hirers to use a Pilot I often took my hire boat through with the gauge showing a lot less than 7ft 3". There is a bit of give in that height gauge how much is open to discussion!

 

cheersIain

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I can remember ( I think I can!) when hire boats, years ago had a little mast on the bows, upon which flutterd the flag or pennant which denoted the yard where the boat came from. I liked that. They also produced a enamel badge which hirers were given and displayed with pride. I liked that.

The flag pole or mast which displayed the boatyard flag was secured on a rubber mounting. The flag mast was the exact height of the airdraft of the boat. So, if the pole/mast hit the bridge it did not break. However, it did tell you, that if you decided to continue, you would be in the doo, doo!

I liked that.

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I can remember ( I think I can!) when hire boats, years ago had a little mast on the bows, upon which flutterd the flag or pennant which denoted the yard where the boat came from. I liked that. They also produced a enamel badge which hirers were given and displayed with pride. I liked that.

The flag pole or mast which displayed the boatyard flag was secured on a rubber mounting. The flag mast was the exact height of the airdraft of the boat. So, if the pole/mast hit the bridge it did not break. However, it did tell you, that if you decided to continue, you would be in the doo, doo!

I liked that.

We have exactly the same on Friday Girl's pulpit. If the RAFSA Burgee goes through then so will the boat...

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Yes I liked that as well.

i remember the old Broom Navigator had the flag. 

If we saw a boat we liked we could look at the flag (don't remember them being called burgees then but I was only young ha ha !) then look in Hoseasons or Blakes brochures to se if we could afford them.

 

ah the good old days

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The NBN burgee makes an ideal height gauge.

Regards

Alan

I'll second that, ours is on the cabin roof, if that can get through, we don't need to drop the windscreen. We also use it as a gun sight, I look over the top of the screen, line it up with the top of the flag, observe the parallax as we get closer to the bridge .... works every time... so far.

 

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Sorry to take over your post fishtone :bow

if I have a airdraft off 7ft 4 ins. Wroxham bridge  is 7ft 6ins according to another thread  it can fall between 4- 6inches. Assuming the worst it only falls the 4 inch stated and not 6 inch . That would give me 6inch to play :shocked with. Is it worth risking it for a biscuit . if it fell the full 6inch  I would have 8inch to spare two guns

karl

Ps

confused. Com  tag on boats says 7ft 4 is this the hire company adding a bit ? 

paper work says 6ft 8inch.

think I'll just line it up and full throttle it and shut my eyes :hardhat:

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Karl - ignore the plaque that was fitting to the boat when in hire and don't hope for the best, be accurate.  Do the following:

Items to get:

  • Tape measure
  • Felt tip pen
  • String
  • Weight to tie to one end of string
  • Spirit level
  • Straight bit of wood about 4/5 feet long - I am sure you can find something suitable to borrow
  • Yourself
  • A helper

Find the highest point of your boat with your screen folded down - note it may be the screen itself, or something fore or aft of it.  Once located, place the wood on this and ensure it is kept level with the aid of the spirit level and your handy helper holding it in place and level.

The wood has to extend from this point and out over the side of the boat.  Tie the string to the end of the wood (or hold it to it but keep it from slipping) pay out the string until the weight touches the surface of the water. 

Mark string with a felt tip pen.  Allow you and your helper to relax and measure from the bottom of the weight to the mark you made on the string.  You've now accurately* measured the air draft of your boat.

*You may wish to repeat with different combinations of people and things like full water and fuel tanks so you have some idea of how much the figure may fluctuate.

Once this is done you can have your own air draft plate engraved from somewhere like this: Link to buy

 

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Guest

This image shows the arched profile height relative to the gauge heights three years ago.

 

wroxham bridge profile downstream.jpg

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If you have any boat whether ex-hire or private, take any airdraft given as suspect!

If you are told 7' for instance, do as Robin says and measure it. Next, go through the bridge when it has it's most clearance, which is usually late spring, where it can show 7'6" or more, (Iv'e seen it show 8' last year) and note how much spare room you have. The next time, go through with a little less and so on.

Soon you will know what you, and the boat, are capable of. You also need to note that the bridge does not sit square to the river and you will need to go more towards the Hotel Wroxham side when going upstream.

If need be, stand in the middle of the boat if your arms are long enough to reach the wheel and use that to align with the 'key stone' in the centre of the bridge.

And DO remember to use the horn :shocked 

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