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Boat draught


MrsM

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11 hours ago, howardang said:

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

 

I have never heard it called "squat", but I recognise the effect. On the Southern Oxford, in Autumn, the leaves used to gather under the narrow bridges, attracting other debris as well. I used to adopt a practice employed by working boatmen to stop me running aground under these bridges, simply knock the revs back to tick over as the stern goes under the bridge, and watch it lift several inches. As soon as  the boat was through, the revs could be brought up again, without collecting half a forest on the prop.

 

 

1 hour ago, Lily Rose said:

 

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!

 

Talking of Braunston Tunnel, I once met a working boat, not displaying any lights. coming towards me in Braunston Tunnel. I could hear it but could not see it until we were quite close (just a simple 45w tunnel light pointing at the roof) We managed to pass each other quite easily without hitting the sides, or each other. We both chose to proceed at a modest pace, and as we passed, the captain apoligised as his electrics had failed after he entered the tunnel.

Edited by David Schweizer
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1 hour ago, Captain Pegg said:

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.

Although I have steered Song of the Waterways before, I haven't crewed her for any length of time before last weekend's BCN Challenge. She draws 2'9" static, so a bit less than Oates (3'1"). We went round the Wyrley & Essington and the Walsall, so definitely the lesser used end of the network, shallow in part and quite a bit of weed, although nothing like as bad as on last year's Challenge, even on the Main Line.

 

Two of the crew were running app-based speed measurements which were reasonably consistent with one another. We know that on a deep, clear stretch of canal such as the northern SU we would be doing 3.5mph, 3mph on the southern section. On the W&E we were mostly doing 2.5-2.6mph which produced a prop wash which looked like a folded in trail with almost no splash. If the speed dropped to 2.2-2.3mph it was worth checking the wash. There were conditions where the wash would start to splay slightly wider and if that corresponded with kicking up silt or rotting weed then we were fine - it was a sign that the channel had got shallower and was only just deeper than the boat. Only if we started to get wash out from the side of the prop was it worth checking for fouling. The only place where we felt significant drop in speed due to channel depth was on the Walsall near the entrance to the Bradley Locks branch. There you could feel it pushing the silt.

 

Alec

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16 hours 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.


Try Braunston tunnel for plenty of experience, you get a bonus for over ten 🤣

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10 minutes ago, Stroudwater1 said:


Try Braunston tunnel for plenty of experience, you get a bonus for over ten 🤣

Got that next week, she's off for grit blasting and blacking at Debdale, so was hoping to not be a two way tunnel virgin 😱😭🤣

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4 hours ago, David Schweizer said:

 

I have never heard it called "squat", but I recognise the effect. On the Southern Oxford, in Autumn, the leaves used to gather under the narrow bridges, attracting other debris as well. I used to adopt a practice employed by working boatmen to stop me running aground under these bridges, simply knock the revs back to tick over as the stern goes under the bridge, and watch it lift several inches. As soon as  the boat was through, the revs could be brought up again, without collecting half a forest on the prop.

 

 

Squat is a very well known phenomenon in ship handling and of course happens to a lesser extend with smaller craft such as canal boats especially in shallow water. .  It may be of interest that a few years ago QE2 was cruising off the East Coast of the States with a pilot on board who decided to save time by crossing over a fairly shallow patch near Martha's Vineyard.  During the  port approach  she experienced  a noticeable vibration. and it was suspected that she may have touched bottom.  This led to an unplanned drydocking in New York and it was found that the ships bottom over a large extent of the hull was extensively damaged with the repairs costing a very large sum. On calculation it was found that she had squatted  around six feet or so - a very costly event.

This Wikipedia article describes the event. In more detail. 

 

https://en.wikipedia.org/wiki/Squat_effect

 

Howard

Edited by howardang
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5 hours ago, David Schweizer said:

 

I have never heard it called "squat", but I recognise the effect. On the Southern Oxford, in Autumn, the leaves used to gather under the narrow bridges, attracting other debris as well. I used to adopt a practice employed by working boatmen to stop me running aground under these bridges, simply knock the revs back to tick over as the stern goes under the bridge, and watch it lift several inches. As soon as  the boat was through, the revs could be brought up again, without collecting half a forest on the prop.

 


This is very useful to avoid picking up plastic and other prop fouls through bridges on the BCN, up to Coventry from Hawkesbury or in the Manchester area. Really it’s best to potter on tickover between locks on the Rochdale up the 9 and  to the top of Failsworth locks. 

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24 minutes ago, Stroudwater1 said:


This is very useful to avoid picking up plastic and other prop fouls through bridges on the BCN, up to Coventry from Hawkesbury or in the Manchester area. Really it’s best to potter on tickover between locks on the Rochdale up the 9 and  to the top of Failsworth locks. 

The opposite is useful to know but takes a modicum of courage! Some working barges in the North used to use squat to squeeze under low bridges by putting on the power on the approach to what would otherwise be impassible to pass. The stern would squat sufficiently to allow them wriggle through before slowing down again once clear. In fact I think that still happens occasionally but you need nerves of steel!😀

 

Howard

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On 02/06/2023 at 14:54, MtB said:

 

Bear in mind 'average' is rather meaningless in this context. After all, the 'average' human being has slightly fewer than two arms.

 

 

 

6 hours ago, MtB said:

 

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. 

 

 

Make up your mind!

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18 minutes ago, howardang said:

The opposite is useful to know but takes a modicum of courage! Some working barges in the North used to use squat to squeeze under low bridges by putting on the power on the approach to what would otherwise be impassible to pass. The stern would squat sufficiently to allow them wriggle through before slowing down again once clear. In fact I think that still happens occasionally but you need nerves of steel!😀

 

Howard

One of my favourite boat engine sounds and I have the utmost respect for this skipper..

 

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In 1985 we had no problems going right to the end of the Ashby canal. When we repeated the exercise a few years ago, we gave up half way as progress was so slow..Winding our 60 footer hire boat at a very badly silted up winding hole took ages and required the assistance of  the bargepole to lever the boat round. 

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12 minutes ago, Ronaldo47 said:

In 1985 we had no problems going right to the end of the Ashby canal. When we repeated the exercise a few years ago, we gave up half way as progress was so slow..Winding our 60 footer hire boat at a very badly silted up winding hole took ages and required the assistance of  the bargepole to lever the boat round. 

I assume you don't mean you actually used the pole as a lever? That's a good way to break them.

 

Tam

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On 02/06/2023 at 10:28, dmr said:

 

A deeper boat with a chine would be a nice option but that does loose a bit of interior space, but can work well on widebeams. Avoid "Birmingham Square".

We have a Jonathon Wilson 57 foot Birmingham square boat with a 3 feet draught. We get to most places around the midlands and southern parts of the country without great difficulty ( the Ashby is about the limit but we can get to the end without difficulty). We tried the Langollen but gave up at Whitehouse tunnel as we were scraping along the bottom and risked getting stuck.

A draught of 2' or so as per the OP should have little difficulty. 

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On 03/06/2023 at 22:07, jonesthenuke said:

We have a Jonathon Wilson 57 foot Birmingham square boat with a 3 feet draught. We get to most places around the midlands and southern parts of the country without great difficulty ( the Ashby is about the limit but we can get to the end without difficulty). We tried the Langollen but gave up at Whitehouse tunnel as we were scraping along the bottom and risked getting stuck.

A draught of 2' or so as per the OP should have little difficulty. 

2' was fine on the Llangollen and we are currently on our way back from a trip there. We moored in the basin with 2 deeper draughted boats who were scraping the bottom a fair bit. One of them had been wrongly told they wouldn't make it. Can't recall their exact draught but believe it was around 32". 

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16 minutes ago, MrsM said:

2' was fine on the Llangollen and we are currently on our way back from a trip there. We moored in the basin with 2 deeper draughted boats who were scraping the bottom a fair bit. One of them had been wrongly told they wouldn't make it. Can't recall their exact draught but believe it was around 32". 

This boat draws a bit more than 2 foot, One of Kevin Maslin's photos

image.thumb.png.c72a6515d348f85cb2babd00de9ece8e.png

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7 minutes ago, ditchcrawler said:

This boat draws a bit more than 2 foot, One of Kevin Maslin's photos

image.thumb.png.c72a6515d348f85cb2babd00de9ece8e.png

Gorgeous.  I'm in awe of their skill! Is that a fuel boat? I understand a fuel boat makes regular visits to the basin so it must be achievable. 

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2 minutes ago, ditchcrawler said:

No its a Tug towing a butty


Yeah, but is it the tug or the butty that draws a bit more than 2’? (Me thinks the tug).

 

ETA - I realised your choice of words was probably ironic so how much do you think Governor draws?

Edited by Captain Pegg
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1 hour ago, Captain Pegg said:


Yeah, but is it the tug or the butty that draws a bit more than 2’? (Me thinks the tug).

 

ETA - I realised your choice of words was probably ironic so how much do you think Governor draws?

image.thumb.png.8ba2a87f372c4ca6be25ce85889facdd.png

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On 02/06/2023 at 15:37, 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’ !

Our Liverpool narrowboat was 2'5" at the last survey.

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On 02/06/2023 at 11:20, MrsM said:

 please bear in mind the boat's draught

I have been a bit obsessed with that at the outset of my research, but now very decisively settled on a vintage engine as a must, a deeper draught it will be. A lot of varied feedback on the topic. I watched "The Narrowboat Pirate"  YouTube vlogger Heidi go up and down the length of the Llangollen with 3 foot draught this past autumn/winter. I hadn't thought that possible but then she has 10 years of CC'ing and so experience is everything.

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43 minutes ago, nealeST said:

I have been a bit obsessed with that at the outset of my research, but now very decisively settled on a vintage engine as a must, a deeper draught it will be. A lot of varied feedback on the topic. I watched "The Narrowboat Pirate"  YouTube vlogger Heidi go up and down the length of the Llangollen with 3 foot draught this past autumn/winter. I hadn't thought that possible but then she has 10 years of CC'ing and so experience is everything.

One of the boats in the phot I posted is 34 inches 

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