Grand Union and Paddington Arm

[DBA Forum (WGBAI) - Laurence Williams]

Useful info for boaters! We only made it as far as bridge 206a, the railway bridge about 2 miles North West of Brentford!
Thick muddy silt stopped us in our tracks. Depth of water here was about 2 feet. As we have raw water cooling and a draught of 1 meter the inevitable blocking of the filter with mud and weed occurred. After clearing the filter and allowing the engine to cool, we gave it one more go through the deepest channel but stuck fast. After another filter clean and cooling, we luckily managed to turn down-canal with the bow thruster, which isn't as deep as the prop, and freed ourselves.
CnR Trust said that area had been dredged last year! Seems like they need to get out again.
End of adventure for this year anyway.
It is worth mentioning the bridge clearance at the Brentford High St Bridge just before the key operated gauging locks. (after the Thames Lock)
The clearance is reduced at high tide, and there is a useful? marker which only measures to 8 ft. We waited for the tide to drop but even at lowest water, the max clearance was around 9 ft. With our Air Draught of 9ft 2ins, we ended up dismantling the wheelhouse.
The Trust bridge clearance info for the GU between Brentford and Bulls Bridge (Paddington Arm turn) does not mention this bridge!!! It is lower than the Western Rd Bridge (9ft 7ins)that they regard as the lowest on this section.

[DBA Forum (WGBAI) - Adrian]

On Tue, 13 May 2014 07:36:34 +0100, "DBA Forum (WGBAI) - Laurence

Post by DBA Forum (WGBAI) - Laurence Williams
Useful info for boaters! We only made it as far as bridge 206a, the railway bridge about 2 miles North West of Brentford!
Thick muddy silt stopped us in our tracks. Depth of water here was about 2 feet. As we have raw water cooling and a draught of 1 meter the inevitable blocking of the filter with mud and weed occurred. After clearing the filter and allowing the engine to cool, we gave it one more go through the deepest channel but stuck fast. After another filter clean and cooling, we luckily managed to turn down-canal with the bow thruster, which isn't as deep as the prop, and freed ourselves.
CnR Trust said that area had been dredged last year! Seems like they need to get out again.

There is a long, and sad, history to this.

This section of the waterway is actually the canalised River Brent.
The Brent enters the navigation at the foot of Hanwell locks, i.e. in
the pound above the one you had trouble in.

The Brent carries a lot of silt, which it deposits as soon at hits the
slackish water in the canal. I believe that in the freight days, this
section, especially the pound above Osterley lock, was dredged at
least annually. Now, not so much.

To make matters worse, a predecessor of the Environment Agency decided
it had to do something about the Brent's flooding in this area. So,
it lowered the crest of Osterley weir, and thus of the
Osterley-Hanwell pound. When Osterley lock is full, you can see the
water is well below the top of the lock masonry. Of course, this
reduces the depth "cushion" of the pound, making it necessary to
dredge the pound more often (when it is actually being dredged less
often). The weir should be raised again, perhaps with a crest that
can be lowered during heavy flows.

The silt you hit has undoubtedly come through the lock when it was
worked (the movement of the water above the lock when it is worked
puts silt into suspension).

If you can get into Hanwell bottom lock, you will have passed probably
the shallowest bit of the Grand Junction. However, the whole canal is
considerably shallower than it was in the freight days, so even above
Hanwell a barge steere should expect to have to go slowly in general.
This is very likely to get worse, now that C&RT has abandoned its
"original profile" dredging promise.

Post by DBA Forum (WGBAI) - Laurence Williams
It is worth mentioning the bridge clearance at the Brentford High St Bridge just before the key operated gauging locks. (after the Thames Lock)
The clearance is reduced at high tide, and there is a useful? marker which only measures to 8 ft. We waited for the tide to drop but even at lowest water, the max clearance was around 9 ft. With our Air Draught of 9ft 2ins, we ended up dismantling the wheelhouse.
The Trust bridge clearance info for the GU between Brentford and Bulls Bridge (Paddington Arm turn) does not mention this bridge!!! It is lower than the Western Rd Bridge (9ft 7ins)that they regard as the lowest on this section.

Yes. And further north you will find other bridges that even if
passable with a wheel house up are a lot more comfortable with it
down.

Adrian


Adrian Stott
Tel. UK (0)7956-299966