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Tight Fit at Potter Heigham Bridge


Guest Brucec

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The height gauge was at less than 6 feet when I shot this video this afternoon. I know that to those not used to taking boats through here (i.e. most of us) the height can be deceptive, but I was very impressed that the pilot was lining up Juliette 2 to take her through. He did, I took some video, and I was very impressed by his skill! :clap:clap

http://youtu.be/oBeEDUs-AKs

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Very impressive indeed. Personally I would have ducked down a little earlier though. :lol:

cheersbar

Personally, Colin, I'd have been running in the other direction.

Risk assessment: 1. Bridge a gnat's whisker bigger than boat. 2. May destroy classic Broads cruiser. 3. May lose head. :o

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If you go down a narrow stretch of the river you notice the boat sucking the water down from the bank making the water level low so the same would happen going under a bridge making the boat lower as its sucking the water .....

Might not make any sence .... But what you go down a narrow sections of river look to the bank you will know what I mean

Jonny

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Ok. Jonny! now I'm really confused. :?

If the boat sucks water from the side of the river doesn't that mean it goes into the middle therefor raising the boat. :?

Sorry if I'm sounding thick but the grey matter is struggling with this. :roll:

Remember my boat does 4mph running with the tide and a tail wind. :grin:

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Ok. Jonny! now I'm really confused. :?

If the boat sucks water from the side of the river doesn't that mean it goes into the middle therefor raising the boat. :?

Sorry if I'm sounding thick but the grey matter is struggling with this. :roll:

Remember my boat does 4mph running with the tide and a tail wind. :grin:

Sounds rather stupid but when you go down a narrow stretch watch the bank lol

Jonny

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I can understand the speed helping with steering, but I'm confused with the taking the boat down ?

I always thought speed would raise the boat?

It depends on the hull form.

A planing boat will climb up and skim along the surface, but a displacement boat pushes itself through the water, so won't rise.

If the boat sucks water from the side of the river doesn't that mean it goes into the middle therefor raising the boat. :?

The propeller sucks water from under the boat, just in front of the prop.

In the main river channel, there is plenty of water each side, so it can slide quickly under the boat to replace what was sucked out without lowering the boat.

When the boat is going through a narrow channel however, as under Potter Bridge, there is much less water either side to replace the water being sucked away by the prop, so the boat drops.

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watch the clip shows you what i mean this happened when going down to rockland st mary with the narrow channel gives you an idea of what i mean .... so the same should happen when going under the bridge sucking the back end down which happens when the martham boat goes under potter

Jonny

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In '66, a pilot took our hire craft, 'Fiesta' through for us and he too

approached the bridge at speed. After getting the bow under the

first part of the arch, he shut the throttle quickly to idle and the

bow 'sat down' in the water. As the aft cabin, complete with the

cockpit roof lying on it, came close to the same point, he opened

it up to full throttle and the stern now 'sat down' in the water as

the bow came up and we cleared the bridge with ease! I have yet

to see anyone do it since :bow .....or me try it either :o

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Bill! the Pilot at Potter taught me to the exactly that back in 1985/6 with my Seamaster 25, when the screen was folded down onto the roof the roofline was as wide as the Hull, I took one look and chickened out from even trying it, I got talking to the Pilot and he said i'll go under easily I'll show you how to do it, the old Seamaster was a bit over propped as it came off the Thames so when he opened it up the Pullpit was 2ft higher than the arch of the bridge, The wife hid in the Cabin I prayed and was glad I had brown trousers on, but he did it exactly the way you descibe but I swear there was only an inch clearance when we went under, once we got to the other side he turned the boat around and said your go now once you do it the first time you'll be fine and made me take it back under, it was actually easier than I though but without his help and guidence it's something I would never have attempted alone, we spent many happy times the other side of Potter, but when I got rid of the boat around 1990/1 and bought a smaller Freeman23, I lost my nerve and to this day I've never taken one of my boats under Potter bridge,,

Regards Frank,,

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I'm lost!!! all I know is when the pilot took my Seamaster under about three feet from the bridge he throttled back and the bow visibly dropped below it's normal height, once the bow was about through he gave it full thottle and the stern dropped, I watched him take my brothers boat under that was the sister ship to mine and it actualy looked like the pilot curved the boat under the bridge, The Pilot called it digging a hole, I can't dispute what you say Rod, but wouldn't the length and weight of the boat make a difference, Surely the effect would be different when your talking hundreds of tonnes against a few tonne and hundreds of feet against 25/40ft plus I would think that 8 knotts on a 25/40 footer would and does handle completely different to one of your big boys, it's an interesting subject, next time I'm at Potter or Wroxham I'll have a chat with the pilots and see what their theory is, be interesting to find out,,,,

Regards Frank,,,,

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The truth of the matter is that we do it because it works. There is also an element of showmanship.

Aft cockpit Alpha 33s? (35s?) have ridiculously high pulpit rails and the bow rises at speed. (The speed is to get it all over and done with before the leakage occurs!) At steerage speed because the tidal current comes out of the arch at an angle the pulpit would be wiped out. The throttle was reduced at the very last moment. As soon as the pulpit cleared the arch on the other side of the bridge, the throttle had to be opened again because the helmsman's seat had a very tall back. The increased speed made the stern dip. I called it banana-ing the boat through. With most centre cockpit boats with sliding roofs the highest points of such boats are the extreme corners of the leading edge of their canopies. Speed seemed to get the stern deeper into the water. On the other hand, it may all be in the pilots' minds!

I will willingly teach forum members how to navigate the bridge safely in their own boats.

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Rod! sorry if I gave the wrong impression in my reply, as we all know most everything works in theory or on paper but real life gives different results, I just couldn't get my head around the size differences etc, lets face it most of the boats on the Broads are smaller than the tenders on the stuff you pilot, I wasn't questioning you for one minute,,,

Regards Mowjo,,,

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