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Boat draught


MrsM

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1 hour ago, David Schweizer said:

 

David Mack's point is a good one. Having quite a deep draught we always stayed in the middle, until comparatively close to an appproaching boat, when we slowed a bit and moved about 4ft the right, assuming that the approaching boat would do the same. If they chose to move over more than 4ft, that was their decision, but unneccessary. People manage it easily in tunnels, so why not on an open canal?

 

 

I used to do this, but got tired of being bollocked of the better half, seems if you don't make it obvious you're moving over almost as you see another boat they will panic that you're going to ram them and head for the nearest bush/tree.

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Many boats have more draught than they should.  It is common to see them stationary, with the counter about 3 or 4 inches under water.  Apart from being bad for rope stern fenders, this makes for poor swimming, wastes fuel and causes worse wash.

The counter should be barely  immersed when still.  Just enough to stop the water slapping it when  the wind is astern.  It will draw down a bit when going along and work perfectly at stopping ventilation by the prop.

 

N

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32 minutes ago, BEngo said:

Many boats have more draught than they should.  It is common to see them stationary, with the counter about 3 or 4 inches under water.  Apart from being bad for rope stern fenders, this makes for poor swimming, wastes fuel and causes worse wash.

The counter should be barely  immersed when still.  Just enough to stop the water slapping it when  the wind is astern.  It will draw down a bit when going along and work perfectly at stopping ventilation by the prop.

 

N

 

Don't forget that the counter has to stay immersed in the most bow-heavy/stern-light configuration, such as a full bow water tank, an almost empty stern diesel tank, and several crew sitting in the bows (for a typical boat layout) -- and a full or empty pumpout tank if you have one, depending which end it's at. Move all the weights around (empty water/full fuel/crew at stern/opposite poo case) and the trim will change by maybe a couple of inches at both ends, perhaps an inch or so in the more typical case of everything midway.

 

But I agree that three or four inches typical is too much -- maybe in some cases the boat has been overplated and not had enough ballast removed, or has a lot of heavy stuff on board like coal/wood, or just more *stuff* than when it was ballasted...

Edited by IanD
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1 hour ago, IanD said:

 

Nope, a few have one or zero arms but AFAIK nobody has more than two -- so the average is slightly less than 2, that's how averages work... 😉

 

The same applies to legs, eyes, ears, testicles etc. -- but probably not nipples... 😉

I read a book once about a man with three balls, but maybe that was finction.

Life expectancy is another example where the average (mean) can be a bit misleading.

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1 minute ago, dmr said:

I read a book once about a man with three balls, but maybe that was finction.

Life expectancy is another example where the average (mean) can be a bit misleading.

 

Are you sure you're not getting confused with the limerick?

 

There once was a man from Devizes

Whose balls were of different sizes

One was so small it was no use at all

But the others were huge and won prizes 🙂

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It is a good point. I hadn’t really considered it. However I’m glad ours is deep draughted as it seems more stable in wind and turns very promptly.

 

We’ve not got too stuck yet, just once passing a boat in Nuneaton and once letting a boat past. Reversing got us out without the long shaft thankfully. 

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10 minutes ago, Stroudwater1 said:

It is a good point. I hadn’t really considered it. However I’m glad ours is deep draughted as it seems more stable in wind and turns very promptly.

 

We’ve not got too stuck yet, just once passing a boat in Nuneaton and once letting a boat past. Reversing got us out without the long shaft thankfully. 

 

I have hardly ever ever worked a shallow draught boat, and deep boats certainly seem to handle better, especially if they have long swims and a big rudder. Helvetia was 52ft long and had 15ft swims, which meant that underwater less than 20ft of the hull was parallel, making it very responsive to the rudder, reversing in a staight line was a doddle. The problem these days is that many builders want to maximise internal space, which creates short swims and compromises handling.

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4 hours ago, Owls Den said:

Without checking I’m pretty sure an average human has two arms.

 

But I get your point all boats are different. 
 

However.. There are a few types that seem pretty common, Liverpool, reeves etc and was wondering what their draught is like compared to 2ft 4’ !

 

3 hours ago, IanD said:

 

Nope, a few have one or zero arms but AFAIK nobody has more than two -- so the average is slightly less than 2, that's how averages work... 😉

 

The same applies to legs, eyes, ears, testicles etc. -- but probably not nipples... 😉

Nope to the latter.  The average human (median) has two arms.  The average number (mean) of arms will be a little under two.

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14 minutes ago, Tacet said:

 

Nope to the latter.  The average human (median) has two arms.  The average number (mean) of arms will be a little under two.

Did I get it right? Flukey bit like my maths gcse. This is my fav equation… Maths= 🤢🥴

 

 

 

 

3 hours ago, dmr said:

I read a book once about a man with three balls, but maybe that was finction.

Life expectancy is another example where the average (mean) can be a bit misleading.

My pal actually has three balls, another pal has one fake ball. Not even making that up!

Can someone explain what a counter is, and also a swims. TIA

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It's a funny thing but the more boating you do the less often you go aground - even on blasted supermarket trolleys and things and if you do you seldom get really stuck. It might just be some sort of instinct that you gather with time but we seldom get much trouble. Going too quick can make the boat 'sit down' at the back and also can make the boat difficult to steer in narrow and shallow places so perhaps that is a reason. Mind you clever clogs here tied in a short pound last year and the boat became part of the scenery for a night and a day when the levels dropped.

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5 hours ago, David Schweizer said:

 

David Mack's point is a good one. Having quite a deep draught we always stayed in the middle, until comparatively close to an appproaching boat, when we slowed a bit and moved about 4ft the right, assuming that the approaching boat would do the same. If they chose to move over more than 4ft, that was their decision, but unneccessary. People manage it easily in tunnels, so why not on an open canal?

 

 

I also do exactly the same, occupy the centre of the canal until the last moment then basically steer around the oncoming boat, i.e. once past the centre of their boat I then start to steer towards their stern which moves my stern out of their way.

 

I think there is a bit of a misunderstanding between 'pass on the left' and 'keep right'. I often wonder as I enter Netherton Tunnel, which I can see to be totally empty, there is a sign instructing,"Keep Right", why, if there is nothing there??:unsure:  The deepest part of a canal will invariably be the centre channel, why not take the fullest advantage of this?

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People can be odd. We finally met someone at Newbold Tunnel at the weekend, they were just entering at the pub end as we approached. Having never yet met anyone at a both-way working tunnel i was quite keen to see how things went.

But no, they turned their lights off and reversed out and onto the mooring by the entrance instead :( 

As we passed them at the other end the lady & gent of the boat both looked proper miffed. I was going to ask if they knew it was two way, but as they both had matching hat, coat and strides on i just said hello and pootled off and left them to their perceived righteous indignation at having their tunnel stolen.

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1 hour ago, Owls Den said:

Can someone explain what a counter is, and also a swims. TIA

This is extremely basic, but assuming it is a serious question, the 'swim' is the shape of the hull at the stern as it comes to a more or less pointed shape where the propellor is. The finer this shape is the easier it is for the water to be drawn by the propellor and the less 'drag' created. This means the boat has less wash, less turbulence, greater efficiency and greater speed. The counter is the deck platform above this where a steerer stands on an ex-working boat or anything based on that hull shape.

 

It is much cheaper and easier to build a straight-sided hull until the last moment and come to an abrupt pointy bit for the propellor, but that gives you a far less manoeuvrable craft. At the extreme you can have something that is simply a box shape with no swim at all - simply a propellor poked through the back of the box. You get more internal space but the boat is virtually unsteerable. Working boats have a fairly long and fine swim as ease of steering, fuel economy etc was of prime importance. Most people buying their first boat now only look at the internal space and price, but never do understand why boating is then such hard work for them.

 

Tam

Edited by Tam & Di
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29 minutes ago, Hudds Lad said:

People can be odd. We finally met someone at Newbold Tunnel at the weekend, they were just entering at the pub end as we approached. Having never yet met anyone at a both-way working tunnel i was quite keen to see how things went.

But no, they turned their lights off and reversed out and onto the mooring by the entrance instead :( 

As we passed them at the other end the lady & gent of the boat both looked proper miffed. I was going to ask if they knew it was two way, but as they both had matching hat, coat and strides on i just said hello and pootled off and left them to their perceived righteous indignation at having their tunnel stolen.

Many years ago I did that and the boater coming out remonstrated with me for not coming in. I told him I wanted to photograph the lights, not him.

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NB Earnest really is 24" draught plus skeg. We have never had trouble depth wise anywhere. We have just come over the Leeds and Liverpool, with Adlington pound down 8" inches (some of the locals where moaning it was a foot down) and had no trouble at all, even mooring up. Likewise with the Huddersfield Narrow, we got through the pound above Lock 1E with it down well over a foot.

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3 hours ago, Tacet said:

 

Nope to the latter.  The average human (median) has two arms.  The average number (mean) of arms will be a little under two.

Mean is the usual meaning of average, most people wouldn't know what the median was -- and certainly not the mode, which is of course also two... 😉

Edited by IanD
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7 hours ago, howardang said:

I am often surprised when some people speak about draught and yet have never checked that the figure they were given when they purchased is  l accurate. In some. In some shallower waterways a difference of few of inches can be important if you want to avoid running aground. Trim and fuel/water tanks full or empty can all affect the draught not to mention bags of coal on the roof, and other unaccounted weight such as additional internal wood paned etc.

 

A boats draught can, and does, vary depending on all these factors so boaters should at least be aware of this fact rather than always working of the same draught without mentally  allowing for any changes.

Howard

One other thing I forgot to mention is Squat which is the increase in aft draught when speed is increased and this increase in draught can mean the difference in touching the bottom or not. Squat effect is more noticeable in shallow water and that is why you may need to reduce speed in such condition.

Howard

 

 

 

 

 

 

 

 

 

 

 

 

 

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11 hours ago, ditchcrawler said:

Many years ago I did that and the boater coming out remonstrated with me for not coming in. I told him I wanted to photograph the lights, not him.

 

It's a "damned if you do, damned if you don"t" situation.

 

We go through Newbold tunnel each way pretty much every year and my approach now is to wait if they're not far from my end but go straight in otherwise. I've not yet had any complaints but the potential for someone to have a moan is always there whichever way you choose to do it. If you always wait then there's a good chance that by the time the boat you waited for has come out at your end another one has just gone in at the other end.

 

It's a dead easy straight two-way working tunnel with good visibility so I don't see why anyone should have a problem meeting someone half way. It''d rather meet someone there than in Braunston tunnel!

Edited by Lily Rose
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When we passed another boat in Newbold Tunnel, we were forced against the side with the safety chain which scraped some paint off our boat.  The other boat was bigger and heavier.  Obviously the board and safety chain will have made the tunnel slightly narrower. 

We certainly waited the time there was a canoe in there;  unfortunately the northern tunnel waiting area was very overgrown.  As the canoe was going away from us, it wasn't easy to see.  I don't understand why canoe-ers are only asked to display a forward facing light.  

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I went up the Ashby last summer when the level was perhaps 6" down and lots of people were reporting problems and advising not to go there. Yet it wasn't a particular problem for the act of simply navigating, it was just slower than it would have been. I managed to get into the side at the three or four different places I moored. Despite an air draught of about 4' 9" and a freeboard of 1' 0" Vulpes only has 2' 0" static draught by design. I can also tell the actual draught by virtue of having a continuous rubbing strake that is one foot below gunwale and two feet above the baseplate that in theory sits on the waterline.

 

What I did notice was a number of (mostly) hire boats out of channel on normal cruising power with water splaying out from under the counter in all directions and little forward momentum.

 

My first memory of the Oxford in 1978 was of running aground almost every time we passed another boat even in a shallow draughted hire boat. That didn't happen when I returned in 2022 on a much deeper boat.

 

I think it's wise to ease off power whenever you leave the deeper central channel and particularly so if you're forced to pass on the inside of a bend.

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11 hours ago, IanD said:

Mean is the usual meaning of average, most people wouldn't know what the median was -- and certainly not the mode, which is of course also two... 😉

Quite possibly.  But the average under discussion is the number of arms of the average person, which is unambiguously the median and not the mean.

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12 minutes ago, Tacet said:

Quite possibly.  But the average under discussion is the number of arms of the average person, which is unambiguously the median and not the mean.

 

No it isn't! We are discussing the average number of arms per person, not the number of arms on the average person. 

 

Two completely different things obviously. 

 

 

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