Cill Time

[system 4-50]

This is not nearly as much fun as some other threads but I would be grateful if somebody could give me an idea of the time taken for there to be a difference of 1 foot in the height of the bow to the stern for a 60ft boat that has parked its behind on the cill of an emptying lock.

Obviously locks vary but I'd like to have an idea of the time for an "average" lock and also for the quickest locks, where locks are standard CRT inland canal locks.

The foot difference is over the normal float level of the boat.

I am trying to knock some electronics together to make myself a "tilt alarm" and I need this information to decide how sensitive it must be.

[Ray T]

What about damage to the skeg and or rudder? Just a thought.

[Guest]

This is not nearly as much fun as some other threads but I would be grateful if somebody could give me an idea of the time taken for there to be a difference of 1 foot in the height of the bow to the stern for a 60ft boat that has parked its behind on the cill of an emptying lock.

Obviously locks vary but I'd like to have an idea of the time for an "average" lock and also for the quickest locks, where locks are standard CRT inland canal locks.

The foot difference is over the normal float level of the boat.

I am trying to knock some electronics together to make myself a "tilt alarm" and I need this information to decide how sensitive it must be.

Interesting idea but as you say it will be very variable. Surely better to have something that goes off at a specific angle of tilt rather than build something based on rate of the tilt developing?

[DeanS]

considering that a boat should always be perfectly horizontal, I'd say a variance of almost anything would be an indicator, but not only back to front, but also front to back, left to right and right to left, as a lower front pound can be low, and cause the bow to jam on the cill exiting a lock, and also extrusions on the lock walls can easily tilt a boat...happened to me....very scary.......so you need 4 of your contraptions....possibly set to 5degree tilt each?

[RLWP]

Absolutely impossible to predict

 

Richard

[Stilllearning]

My only ever experience of near disaster in a lock was catching the stem under the top beam of a gate on the K&Awhile going uphill. There was almost no time from realising it had happened (by seeing it happen) and almost sinking the boat, so I am not sure a buzzer would have helped, far better to keep an eye on things, and concentrate on what you are doing. As Dean says, it's not as simple as just one direction of tilt.

[SamKingfisher]

Narrow boats are rarely perfectly horizontal. Bow up trim means bilge water runs to the stern.

 

This seems like a technological solution for an observational problem.

[WJM]

I think you need to go for a specific angle, regardless of how long it is held - not deflection plus time.

 

There will be very rare occasions when this approach could generate a false alarm - but too rare to seriously consider!

 

Edited January 6, 2015 by WJM

[DeanS]

Narrow boats are rarely perfectly horizontal. Bow up trim means bilge water runs to the stern.

 

well done...I had missed that completely...of course the boat itself changes in the water due to pump out volume, diesel volume, water tank volume....

 

*slapping my forehead.*

 

[dave moore]

What happened to common sense and the knack of keeping an eye on the boat as it descends? Cilling seems to be a more frequent occurrence than it used to be, a point agreed by another long term boater I was with recently. Perhaps the OP is happy to be dependent on technology, a state that sits less readily with this old fart. Sorry.

 

Dave

[boathunter]

Great pictures!

I'd go for angle too, but I think you'd notice something was amiss before it went off unless it was so sensitive it caused lots of false alarms as well in which case you'd be self-trained to ignore it? Like the fire alarm going off when you burn your toast. Can't hurt though?

What happened to common sense and the knack of keeping an eye on the boat as it descends? Cilling seems to be a more frequent occurrence than it used to be, a point agreed by another long term boater I was with recently. Perhaps the OP is happy to be dependent on technology, a state that sits less readily with this old fart. Sorry.

Dave

Depending on how long ago "used to be" was, might that be because there are more narrowboats?

[matty40s]

I have a tilt sensor, it is me.

 

coming into most locks, the cill will be just below the rear of your boat, low pound levels and sometimes you scrape over the cill (HNC and this is where the problems start)

A narrow lock can go from full to empty in just a few minutes, it would be seconds before your rudder or skeg sits on the cill in some cases.

 

Keep your eyes open, be alert to the risks, and don't stand with your back to the lock chinwagging with Gongoozlers.

[BD3Bill]

This is not nearly as much fun as some other threads but I would be grateful if somebody could give me an idea of the time taken for there to be a difference of 1 foot in the height of the bow to the stern for a 60ft boat that has parked its behind on the cill of an emptying lock.

Obviously locks vary but I'd like to have an idea of the time for an "average" lock and also for the quickest locks, where locks are standard CRT inland canal locks.

The foot difference is over the normal float level of the boat.

I am trying to knock some electronics together to make myself a "tilt alarm" and I need this information to decide how sensitive it must be.

 

Maybe something like a parking sensor / electronic eye, fixed to the stern, giving you warning of how close you are to the top gates? ( i know some cill's project up to a yard out from the gates).

 

Agree with those that say all round awareness is better though.

[Ray T]

What happened to common sense and the knack of keeping an eye on the boat as it descends? Cilling seems to be a more frequent occurrence than it used to be, a point agreed by another long term boater I was with recently. Perhaps the OP is happy to be dependent on technology, a state that sits less readily with this old fart. Sorry.

 

Dave

 

Dave, according to CRT's Press Briefing on the 5th November 2014.

 

"This is the third worst year for boat “hang ups” in locks in 10 years of recording, 2007 being the worst at 15. There were 12 in 2013, with 10 so far this year. The accounting year for this is a calendar year".

Edited January 6, 2015 by Ray T

[James Owen]

considering that a boat should always be perfectly horizontal, I'd say a variance of almost anything would be an indicator, but not only back to front, but also front to back, left to right and right to left, as a lower front pound can be low, and cause the bow to jam on the cill exiting a lock, and also extrusions on the lock walls can easily tilt a boat...happened to me....very scary.......so you need 4 of your contraptions....possibly set to 5degree tilt each?

What nonsense.

[billS]

 

Maybe something like a parking sensor / electronic eye, fixed to the stern, giving you warning of how close you are to the top gates? ( i know some cill's project up to a yard out from the gates).

 

 

Excellent idea - they could be disguised as rivets...

[system 4-50]

Ok.

The normal attitude of the boat is not a problem as the gadget takes that as its base line & resets itself every time the engine is switched on so water usage etc won't bother it.

It will give an alarm at a certain angle up from that.

It needs a few seconds to be sure that the boat is actually tilting and not just riding a surge caused by water moving in the lock, and to eliminate the effects of eg engine vibrations.

I need it because I'm single handing and people distract me.

I am the primary tilt sensor but I'm human and sometimes fail. A gadget properly designed will be more reliable.

I haven't given up using my eyes because I wear glasses. (poor analogy but you get the idea.)

The gadget will handle up/down & left/right.

I've only cilled once and was able to rev the engine & slide off. Yes, a passer-by had asked me a question.

[Tony Dunkley]

This is not nearly as much fun as some other threads but I would be grateful if somebody could give me an idea of the time taken for there to be a difference of 1 foot in the height of the bow to the stern for a 60ft boat that has parked its behind on the cill of an emptying lock.

Obviously locks vary but I'd like to have an idea of the time for an "average" lock and also for the quickest locks, where locks are standard CRT inland canal locks.

The foot difference is over the normal float level of the boat.

I am trying to knock some electronics together to make myself a "tilt alarm" and I need this information to decide how sensitive it must be.

That's one of the daftest ideas I've ever heard. If you're watching as carefully as you should be while a lock's emptying then you'll spot a change in trim of much less than a foot as soon as it starts to happen.

[dave moore]

Perhaps a change to locking technique might help? I too single hand regularly, agree it's not hard to be distracted. Down hill is more arduous. Often I'll use ropes to keep the boat close to the bottom gates, having opened them as the water makes a level you can then use it to start the boat moving out of the lock....just a thought.

 

Dave

[The Lockie]

When training seasonal lockies or volunteers I tell em never to take their eyes off the boats in the lock. Still need to explain to some that no matter what the distraction that this is a golden rule. It is doable to answer a question or phone call. Just never take your eyes off the pointy things:-) :-) :-)

Edited January 6, 2015 by The Lockie

[jake_crew]

1 foot in 70 is less than 1 degree, and I'd be worried about a 1 ft hang up.

 

I reckon that could happen less than 30 seconds if you're unlucky.

Edited January 6, 2015 by jake_crew

[sirweste]

I have nothing to add other than I think this and the parking sensors are a cracking idea.

[system 4-50]

... If you're watching as carefully as you should be while a lock's emptying then you'll spot a change in trim of much less than a foot as soon as it starts to happen.

I totally agree!

[DHutch]

As said, the rate of decent, and hence the rate at which the boat will tip will vary from lock to lock, and will also not be linear over the fall of the lock as they change level faster initially when the difference in water is greater.

 

The boat can also hang up or be held down on a range of thing at almost any time, and in both directions, not just on the cill. Infact, I have have the boat hang or get held down under my watch about three times in ten years, and to date none of them have been a classic cilling occurrence.

 

Unless I know the person standing on the boat well, or it is myself, I aim to always watch the boat carefully until it is within about 18inchs of the water coming level. Due to the fill/empty not being linear as above, while this accounts for the majority of the fall and almost all the risk, it only takes a minute or so.

 

On an average lock, where you have got all paddles up as fast as practical, I expect you could draw the first foot off in around 5 seconds, given as one end goes up the other goes down by an amount, should if the boat caught up straight away you would have to be bloody fast on most boats! Don't forget, that when then re-filling, the first foot becomes the last foot, is hence the slowest!

 

 

 

The few times I have had a boat get stuck, one was getting stuck under a top gate going up, all three paddles open, and the bow was about 18inchs under with the uxeter plate 6 inches out by the time it came unstuck by itself, the crew had only just started reacting.

Second time the bow was held up when going down, I think by the track that the paddle runs in, the bow was about a foot up and the rear 4inchs or so under at the time, we stopped and refilled, but that was also right near the bottom of the fall when we had all but stopped watching it.

Remaining time was very like the first, only it was the leading edge of the baseplate catching on a rsj protecting the cill, I was inside at the time and was unaware until the floor jumped up a foot or so when it came upstuck, wasn't able to witness the reaction of the only other crew but the water had again come up 18inches and I expect he was moving as fast as he could to stop it before it sorted itself out.

 

 

 

 

Daniel

[nicknorman]

I think it could take as little as 5 seconds to drop a foot. Deeper locks will have the greatest differential pressure across the paddles at the point where the stern catches the cill so these are likely to be the fastest drainers at the critical point. Don't forget that a sudden forward acceleration or decelleration is indistinguishable from a tilt in terms of a gravity - seeking sensor like a tilt gauge (ie bumping the bank etc), or are you planning to use a gyro or vibrating beam angular rate sensor?