Cill Time

[p6rob]

last time I went up some single locks (Lapworth 5-2) I noticed my boat seemed to go up at the back then the front. It's only a 40 footer and was centred in the lock. It was quite interesting watching it see-saw up. Only a couple of inches difference either end but it was definitely visible.

[Neil2]

I'm struggling to understand why the time it takes is relevant. Surely what you want to know is the point at which the boat has altered its trim by a foot regardless of time? If you imagine a 60 foot boat as the radius of a circle, with the skeg stationary and the bow describing the circle, the circumference of that circle would be near enough 360 feet so one foot is one degree. All you need is some electronic device to tell you when the trim of the boat has changed by one degree.

 

Or you could just get one of those jumbo fenders that keeps the stern well away from the cill.

[system 4-50]

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?

both

[ditchcrawler]

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?

I often watch or boat with amazement how much it pitches and roles in a filling lock. mind you we dont tend to hang about when filling locks.

[Machpoint005]

I'm struggling to understand why the time it takes is relevant. Surely what you want to know is the point at which the boat has altered its trim by a foot regardless of time? If you imagine a 60 foot boat as the radius of a circle, with the skeg stationary and the bow describing the circle, the circumference of that circle would be near enough 360 feet so one foot is one degree. All you need is some electronic device to tell you when the trim of the boat has changed by one degree.

 

Or you could just get one of those jumbo fenders that keeps the stern well away from the cill.

 

As Neil2 says, it is the rapid change in angle that indicates a problem. That is what a human observer would notice, and it doesn't matter whether the boat is trimmed by the head or by the stern -- whatever the angle of trim, that is the baseline condition.

 

My first reaction to Nick Norman's 5 seconds to drop a foot was 'no, not as quickly as that' but on reflection, of course the OP would want to design for the extreme worst case or there'd be no point in having a device in the first place. The typical 'drop one foot' time might be around 20 seconds, provided you are not in the habit of flinging the paddles wide open straight away?

 

ETA: but you would not want it to be too sensitive as there is a certain amount of 'normal' fore-and-aft rocking which is perfectly OK.

Edited January 6, 2015 by Machpoint005

[WJM]

I am so impressed with the many posters on here who are capable of 100% infallible attention. Your abilities far exceed mine!

 

 

The only time I have hung my boat, I had my back to it winding the paddle. Fortunately it was a rare occasion when I was not single-handing. I was altered by my passenger shouting. That saved the day!

 

The only time I have ever seen a boat hang on the cill it was being locked through by two or three CaRT staff with the owner stood at the tiller. Nobody seemed to notice until a pronounced angle had developed.

 

In both cases, the OP's proposed alarm would have greatly helped.

 

I have an alarm that rings if my oil pressure drops. Does that make me an inattentive lightweight wuss?

Edited January 6, 2015 by WJM

[Machpoint005]

I am so impressed with the many posters on here who are capable of 100% infallible attention. Your abilities far exceed mine!

 

 

The only time I have hung my boat, I had my back to it winding the paddle. Fortunately it was a rare occasion when I was not single-handing. I was altered by my passenger shouting. That saved the day!

 

The only time I have ever seen a boat hang on the cill it was being locked through by two it three CaRT staff with the owner stood at the tiller. Nobody seemed to notice until a pronounced angle had developed.

 

In both cases, the OP's proposed alarm would have greatly helped.

 

I have an alarm that rings if my oil pressure drops. Does that make me an inattentive lightweight wuss?

 

I agree. Nobody is suggesting the tilt alarm will replace proper observation, no more than the oil pressure light is the only thing you should rely on fro engine health.

[Keeping Up]

Perhaps a switch fitted to the bottom of the skeg would stand a better chance of sensing a hangup as soon as it starts to happen. Or a depth-sounder at the stern?

[nicknorman]

The typical 'drop one foot' time might be around 20 seconds, provided you are not in the habit of flinging the paddles wide open straight away?

 

Why would you not want to fling the paddles wide open straight away when going downhill?

[cuthound]

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.

 

I'd of thought a parking sensor at the front, to warn you when you are too close to something would be more useful, and use the mark one eyeballs to check you are not too close to the cill.

[blackrose]

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.

Exactly. If your eyes and the semi-circular canals of your inner ears are working properly (for when you're onboard)，then you've already got all the sensors you need.

Edited January 6, 2015 by blackrose

[Arthur Brown]

I'd probably also look at the possibility of echo sounding in say two places. and when the stern and stem readings differ by much there's a problem. Not too sure about narrow waters though, and there could be issues with the transducer being aft of the prop and getting a thrashing.

[furnessvale]

I'd of thought a parking sensor at the front, to warn you when you are too close to something would be more useful, and use the mark one eyeballs to check you are not too close to the cill.

So far as locking is concerned, I know when I am close enough at the front, I feel a (slight) bump and there the boat remains otherwise I am in danger of ending up on the cill.

 

George ex nb Alton retired

[Tony Dunkley]

I just can't believe how many people are taking this seriously enough to be posting suggestions about how to either put into practice or improve an idea that should have been saved for the first day in April.

Anybody who thinks trim sensors are either necessary, or would work better than simply paying attention when working locks, really ought to give some very serious thought to taking up something other than boating, or swapping their existing boat for a static houseboat. They should also consider the advisability of driving any kind of motor vehicle or even venturing outside their home unless accompanied by a responsible adult who's aware of what's happening around them.

[FadeToScarlet]

So far as locking is concerned, I know when I am close enough at the front, I feel a (slight) bump and there the boat remains otherwise I am in danger of ending up on the cill.

 

George ex nb Alton retired

Even more hairy with an extra 18"!

 

I've found that, as long as e fore end is near the bottom gates when the paddles are wound, it will happily sit against the gates and run down for the first 3 feet or so, by which time the rudder is below the level of the cill, and safer.

Why would you not want to fling the paddles wide open straight away when going downhill?

Indeed, it's best to, because it will hold the boat against the bottom gates, away from the cill.

I often watch or boat with amazement how much it pitches and roles in a filling lock. mind you we dont tend to hang about when filling locks.

In a filling narrow lock, I've found the boat pitches up and down as the lock fills. The one time it hung up (so far) from the end of the baseplate catching on a cill, it was hard to see because the boat had been pitching a bit before, and the first sign of trouble was when I expected the fore end to come up, and it didn't.

[system 4-50]

I just can't believe how many people are taking this seriously enough to be posting suggestions about how to either put into practice or improve an idea that should have been saved for the first day in April.

Anybody who thinks trim sensors are either necessary, or would work better than simply paying attention when working locks, really ought to give some very serious thought to taking up something other than boating, or swapping their existing boat for a static houseboat. They should also consider the advisability of driving any kind of motor vehicle or even venturing outside their home unless accompanied by a responsible adult who's aware of what's happening around them.

Tee Hee!

[furnessvale]

Even more hairy with an extra 18"!

 

 

Are you 72' 6" then? :-)

 

George ex nb Alton retired

[nicknorman]

In a filling narrow lock, I've found the boat pitches up and down as the lock fills. The one time it hung up (so far) from the end of the baseplate catching on a cill, it was hard to see because the boat had been pitching a bit before, and the first sign of trouble was when I expected the fore end to come up, and it didn't.

The risk of catching the bow / fender on something going uphill is why we keep our boat nearer the back (we can afford to at only 59'). As you say, the inrush of water under the bow typically causes the nose to pitch down whilst the back goes up (Bernoulli at work I guess) followed by some pitching up and down as the water sloshes back and forth. Quite difficult to differentiate that initial pitch down from a stuck bow - by the time it is definitely a stuck bow I doubt there is much "fixing" time left. Of course for 99.99% of locks there is nothing to catch on, it is the 0.01% I worry about. It only takes one to trash your boat.

[Loafer]

I think locking is a bit like having a poo.

 

Make sure you position yourself correctly in the facility.

 

Don't go too far forward, or there's a risk of getting summat caught under the gate. (If on the rise)

 

Don't go too far back, or you'll rub your back end on summat, and leave a bit of a stain.

 

Don't talk to anyone.

 

If there's anyone watching you, just ignore them and continue texting.

 

If there's a massive tilt developing, get off and stand clear. The bog has probably come loose.

Edited January 6, 2015 by Loafer

[FadeToScarlet]

Are you 72' 6" then? :-)

 

George ex nb Alton retired

I thought Joshers were 70'6"?

[Guest]

I just can't believe how many people are taking this seriously enough to be posting suggestions about how to either put into practice or improve an idea that should have been saved for the first day in April.

Anybody who thinks trim sensors are either necessary, or would work better than simply paying attention when working locks, really ought to give some very serious thought to taking up something other than boating, or swapping their existing boat for a static houseboat. They should also consider the advisability of driving any kind of motor vehicle or even venturing outside their home unless accompanied by a responsible adult who's aware of what's happening around them.

The thing is Tony it really isn't for you or anybody else for that matter to dictate what people want to fit to their boat and nothing posted in this thread so far constitutes reason enough for anybody to consider giving up boating, nor to deserve your rather mocking response above.

 

I read it as an interesting idea but not as an entirely serious one, something perhaps akin to a bit of an experiment but not something that one would totally rely on but rather a bit of an aid should you become distracted whilst in a lock. Yes it might be described as a bit of a 'solution for a problem yet to be invented' but what the heck nobody is forcing you to have one fit to your boat.

[BGA]

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.

you could base this on a gyro from a RC helicopter they are very small and adjustable, that would give you X, Y and Z axis detection,

[bargemast]

This sounds like a very necessary gadget, maybe with a sort of adaptor I could fit something simular to my car, to inform me that I've a pedestrian on the bonnet of my car which would change the angle possibly a bit aswell, that would help me keeping concentrated while sending messages on my phone

 

I wonder why there are hardly any accidents like this listed from the days that the canals where only (mainly) used by commercial boats in the old days.

 

Peter.

[BGA]

This sounds like a very necessary gadget, maybe with a sort of adaptor I could fit something simular to my car, to inform me that I've a pedestrian on the bonnet of my car which would change the angle possibly a bit aswell, that would help me keeping concentrated while sending messages on my phone

 

I wonder why there are hardly any accidents like this listed from the days that the canals where only (mainly) used by commercial boats in the old days.

 

Peter.

Now you're being silly, everyone knows you don't let the pedestrian or cyclist get as far as your bonnet you fit bull bars so they bounce off without damaging the paint work.

[Neil2]

The thing is Tony it really isn't for you or anybody else for that matter to dictate what people want to fit to their boat and nothing posted in this thread so far constitutes reason enough for anybody to consider giving up boating, nor to deserve your rather mocking response above.

 

I read it as an interesting idea but not as an entirely serious one, something perhaps akin to a bit of an experiment but not something that one would totally rely on but rather a bit of an aid should you become distracted whilst in a lock. Yes it might be described as a bit of a 'solution for a problem yet to be invented' but what the heck nobody is forcing you to have one fit to your boat.

I agree. I don't really care whether the OP is being serious or not and I don't care to analyse why I find these threads interesting except I suspect a lot of very useful inventions have started out as a seemingly wacky idea. You kick something around for a while and there's no knowing where you might end up.

 

As for getting hung up it's happened to me twice, once the rubbing strake got caught on a lock wall and I realised immediately that something was wrong but the other time was the bow fender getting caught when descending and I'm not ashamed to admit I didn't sense the change in the boats orientation at all until the fender broke loose and the bow suddenly dropped. Like many members on here I have done thousands of locks and I was shocked how easily a serious incident could have occurred.