Narrow boat.....wide locks

Wide boats don't damage the seal/mitre on locks. If you think about it as the boat goes in it will initially contact the actual seal for a short time then it will start to rub against the non-sealing part of the edge of the gate because it as pushed the gate far enough open for it to be physically impossible for the seal to touch the side of the boat. The problem with narrow boats is that the other gate is in a closed position so the seal IS exposed to the boat and often the gate is drawn towards the boat.

The only time a vessel will damage gate seals is if the lock is twice as wide as the boat and the boat passes through one gate. Otherwise it won't be a problem*.

It categorically IS narrow boats which cause damage to lock gate seals.



The seal is only a seal at a certain angle and that angle is when the gate is closed (obviously) so unless the gate is in a closed position it is not possible for a boat to "scrape" the seal area. It can't happen - unless the boat is an unusual shape or has bits sticking out.

*eta this assumes the gate has been fitted with breast irons the vertical iron/steel guards protecting the edges of the gates by the seal. There has been a decline in the quality and durability of breast irons and some have come off. I've even seen them screwed on with pozidrive screws. Originally breast irons were 3 inch wide D strake pinned on with large iron spikes.

a boat wider than half the width of the lock will slide along against the breast irons. A boat half as wide as the lock will pass through one gate with the other gate in closed position thereby exposing the seal area to the passage of the boat causing damage.

No, MM is right, with the gates mostly but not fully open, the sealing surface is not exposed to scrapery and its impossible for a fat boat to damage the sealing surfaces. It will rub on other parts of the gate that are not responsible for the seal.

How can it not scrape the inner edge of the mitre?

The gates don't open.

Never mind.

Rog

The sealing surface is parallel to the lock side when the gates are closed and sealed. If you swing the gate by say 30degrees, that moves the sealing surface 30 degrees and brings a part of the gate not used for sealing parallel to the lock side (and hence the bit that can get scraped by a boat passing through.

Next time you pass through a wide lock, try opening both gates 1/2 way and you will see that you can’t scrape the part of the gate that seals, because you contact other parts of the gate first.

Nick is spot-on with what he's saying about the circumstances in which lockgate mitre post damage can occur.  Kris is also correct in what he said with regard to wide beam boats not contacting the mating faces/liners on gate mitre posts, and therefore, doing no damage.

There is in fact nothing new about narrowboats entering double (in excess of 14' wide) locks through just one gate, only the boats, their operating methods, and their design and construction, have changed. Due to these differences in hull design and construction, the practice/lock working method described immediately below did not have the same damaging effect on bottom gate mitres as do modern day steel pleasure craft using only one gate, . . . with their crudely constructed, slab-sided hulls, and protruding, sharp edged, bottom plating.

A bit too long winded to fully explain here at the moment, but briefly, the butty, of a pair of loaded working boats travelling singled out round short or shortish pounds and being towed off a 'snatcher' - a short towrope of about 20' length, would almost invariably enter an uphill lock with the motor's side gate closing alongside it somewhere between the mast and the middle beam. The reason for this happening was due partly to the fluid dynamics/hydraulics effects of loaded boats rapidly displacing large quantities of water out of lock chambers, and an advantage gained was that the hydraulic effects with one gate being forced shut by the water being displaced out of the lock chamber took a lot of way off a loaded butty before it was finally brought to a standstill with a 'uphill strap' - a length of rope for use round a 'strapping stump' to check a loaded boat to a halt. Due to the reduction in the butty's speed brought about by the motor's side bottom gate closing before the butty was fully past it, uphill straps weren't subjected to very much friction and heat as they passed/ran round the strapping stumps, and so were invariably used in a dry state. Due to the much higher speed of entry of a loaded butty into a downhill lock (again due to fluid dynamics/hydraulics of the water being displaced out of the lock chamber, but in this instance forcing and keeping the motor's side top gate open), 'downhill runners' (again, a length of rope used to check a loaded butty into a downhill lock) were invariably used wet and left trailing in the cut, behind the butty, between locks.

 Just curious - why are you going back to Shipley? Is it so you can do the Bingley rises with a new set of visitors? (Oh - Patty it be!).
 In Skipton we stopped just west of the last swing bridge by the railway station - those who park by the bus station get to regret it (local scrotes).
 In Skipton the 'Asian' boy who walks the towpath and asks for the bus fare back to Keighley doesn't live in Keighley - he lives in Skipton!

Having read everyone's views on the gates, I stand corrected (as the man in the surgical boot said).

It still seems wrong that forcing a wide beam through none opening gates will not damage the inside edges, but I accept you're all much wiser than I on the matter.

There was a six man C&RT team working the locks (actually lunching when we passed through) so hopefully this is one of the issues they're looking at.

A volunteer at the top lock told me that only one paddle was working on the bottom gates, so it was slow to empty. I asked if it had been reported and he replied it had been two and a half years ago!

There was also a huge void in the offside lock wall that dumped water straight into the cratch (cratch rolled up as it was so sunny). He said that had been reported too

He also said one of the lower locks was leaking into the adjacent fields.

I hope they all keep working. I know the lock on the Aylesbury arm with the huge waterfall void, eventually collapsed. Not good.

Anyway, we gave the Wigan lock keepers a four pack, we'd better get more in ready for the Bingley staircases.

How's Andy doing?

Okay we presume, as all's gone quiet on 'knackergate'.

Rog