Slow Down!! "I Can't!!"

[mrsmelly]

3 hours ago, cuthound said:

 

Indeed. The depth and profile of the canal bed will also determine how badly affected the moored boat is.

 

I have had plenty of opportunity to observe this, having a canalside house with an end of garden mooring.

 

The canal, from the end of my mooring to the adjacent bridge, is only about one foot deep at its shallowest, presumably where boats have pushed the silt to the non-towpath side.

 

When a heavy, deep draughted boat speeds past you can actually see my boat drop by a few inches, and when water levels are low, like at present, hear it crunch as it makes contact with the bottom.

 

So as most people cannot know the profile or how shallow the canal is beneath moored boats, unless they travel that bit frequently, the best strategy to avoid verbal abuse is to pass slowly, by slowing down in plenty of time and being prepared to drop into neutral if you see the moored boat begin to drop in the water as you approach it.

Squat effect. Had to tell the bloke who took me for my 500 persons passenger boatmasters ticket all about it. QE2 was caught out by this. The boats have dropped and pushed the silt sideways.

[MtB]

9 hours ago, nb Innisfree said:

Just to reaffirm, it's not the bow wave that's the prob with heavy boats (though a canoe wave can be) it's the displacement of water which leaves a 'hole' in the water, water then returning into the hole creates a downhill flow which a moored boat tries to travel down and pulls on mooring ropes. It can't be avoided but it can be made to happen over a longer period of time by slowing down so reducing its effect. The heavier the boat the slower it needs to be. 

 

I disagree. I've only recently discovered this but by knocking the boat out of gear the 'hole' in the water you mention almost immediately disappears. The boat then passes the moored boat causing FAR less disturbance.

 

Have an experiment. The difference in effect on moored boats is remarkable. Well it is on my boat which is deep drafted and moves moored boats A LOT when passing even very slowly. It is a great improvement.

[nb Innisfree]

7 minutes ago, Mike the Boilerman said:

 

I disagree. I've only recently discovered this but by knocking the boat out of gear the 'hole' in the water you mention almost immediately disappears. The boat then passes the moored boat causing FAR less disturbance.

 

Have an experiment. The difference in effect on moored boats is remarkable. Well it is on my boat which is deep drafted and moves moored boats A LOT when passing even very slowly. It is a great improvement.

Where does it disappear to? 

[MtB]

5 minutes ago, nb Innisfree said:

Where does it disappear to? 

 

Where does the hole disappear to?

 

That is a very deep question best addressed by the philosophers on here.

[roland elsdon]

I dream of being asked to slow down, but i just cant go fast enough to achieve it. On most canals anything approaching a lazy stroll is met by the prop stirring up nappies, bin liners, bodies weed etc. if i rev hard enough i reach mud and coal dust. As i go aground on the detrius caused by some of the permanent moorings on the gu i have been known to exclaim look the use triangular tea bags still

[ditchcrawler]

23 minutes ago, Mike the Boilerman said:

 

Where does the hole disappear to?

 

That is a very deep question best addressed by the philosophers on here.

Well the prop is not dragging water from the sides and bottom of the boat for a start

[MtB]

Just now, ditchcrawler said:

Well the prop is not dragging water from the sides and bottom of the boat for a start

 

That's it exactly. When the hole disappears, the moored boat no longer falls into it. The reduction in effect on moored boats is remarkable, provided I disengage 'ahead' when my bow is a few metres short of the moored boat. Momentum carries me past.

[Lily Rose]

Mike, how does that work with a long line of moored boats, do you have to keep dropping in and out of gear?

 

Wear and tear on the gearbox?

[frahkn]

1 hour ago, Mike the Boilerman said:

 

I disagree. I've only recently discovered this but by knocking the boat out of gear the 'hole' in the water you mention almost immediately disappears. The boat then passes the moored boat causing FAR less disturbance.

 

Have an experiment. The difference in effect on moored boats is remarkable. Well it is on my boat which is deep drafted and moves moored boats A LOT when passing even very slowly. It is a great improvement.

 

My 31" draft boat does not move moored boats very much at all.  I have never been shouted at for speeding. Granted I am usually at tickover (about 800 revs for me) but I think the Orion hull has a better than average swim.

 

Of course this could be more imaginary than real but I genuinely have not been shouted at in the 5 years that I have owned the boat.

[cuthound]

11 hours ago, frahkn said:

 

My 31" draft boat does not move moored boats very much at all.  I have never been shouted at for speeding. Granted I am usually at tickover (about 800 revs for me) but I think the Orion hull has a better than average swim.

 

Of course this could be more imaginary than real but I genuinely have not been shouted at in the 5 years that I have owned the boat.

 

Hull shape definitely affects wash too. My Alexander hull rarely causes a breaking wave even on shallow canals at 3mph, and it too has long swims.

 

The square transom style narrowboats seem to leave big waves even was actually passing slowly past my mooring, whilst canoes generate huge waves even starting from a standstill (quite a few people use the bridge adjacent to my garden to launch them).

[MtB]

1 hour ago, cuthound said:

 

Hull shape definitely affects wash too. My Alexander hull rarely causes a breaking wave even on shallow canals at 3mph, and it too has long swims.

 

 

But we are not discussing wash. Wash is the waves on the surface. 

 

We are discussing the 'draw' created by the drop in water level by a passing boat, which makes the moored boat initially move in the same direction as the moving boat just before the moving boat arrives, then the moored boat lists slightly and drops vertically by an inch or two when the passing boat draws level, then finally the moored boat surges back in the opposite direction to the moving boat and again strains on its mooring lines. 

 

Wash just make a boat rock a little, if anything at all. 

[cuthound]

22 minutes ago, Mike the Boilerman said:

 

But we are not discussing wash. Wash is the waves on the surface. 

 

We are discussing the 'draw' created by the drop in water level by a passing boat, which makes the moored boat initially move in the same direction as the moving boat just before the moving boat arrives, then the moored boat lists slightly and drops vertically by an inch or two when the passing boat draws level, then finally the moored boat surges back in the opposite direction to the moving boat and again strains on its mooring lines. 

 

Wash just make a boat rock a little, if anything at all. 

 

Both draw and wash affect the stabity of a moored boat, wash as evidenced by the movement generated by canoes, which draw very little and weigh little more than the weight of the paddles.

[doratheexplorer]

1 hour ago, Mike the Boilerman said:

 

 

 

Wash just make a boat rock a little, if anything at all. 

That's not true.  My boat rocks around a lot when kayaks go past.

[MtB]

45 minutes ago, cuthound said:

 

Both draw and wash affect the stabity of a moored boat, wash as evidenced by the movement generated by canoes, which draw very little and weigh little more than the weight of the paddles.

 

Even so, they are two different effects. They both move the moored bot but in different ways and by different mechanisms. 

 

And as I said, we were discussing the draw we create when passing a moored boat, not our wash.

[cuthound]

57 minutes ago, Mike the Boilerman said:

 

Even so, they are two different effects. They both move the moored bot but in different ways and by different mechanisms. 

 

And as I said, we were discussing the draw we create when passing a moored boat, not our wash.

 

I know I mentioned this in posts #12 & #23 ?

[furnessvale]

3 hours ago, Mike the Boilerman said:

 

Even so, they are two different effects. They both move the moored bot but in different ways and by different mechanisms. 

 

And as I said, we were discussing the draw we create when passing a moored boat, not our wash.

Both of which are virtually eliminated by a boat being correctly moored.

 

The OP himself is the first to admit that his vessel was incorrectly moored.

 

George

[howardang]

4 minutes ago, furnessvale said:

Both of which are virtually eliminated by a boat being correctly moored.

 

The OP himself is the first to admit that his vessel was incorrectly moored.

 

George

Exactly, which is the point I was trying to make in post number 5! I do idly wonder  what the OP's reaction would have been if the roles were reversed and he approached a badly moored boat such as his, after duly slowing down? Would we have had an email regarding inconsiderate moorers? 

At least the post has given the theorists a chance to educate we lesser mortals in the hydrodynamics of canals and boats therein.

 

Howard

[cuthound]

1 hour ago, furnessvale said:

Both of which are virtually eliminated by a boat being correctly moored.

 

The OP himself is the first to admit that his vessel was incorrectly moored.

 

George

 

Not necessarily, my boat is securely moored on bollards using springs at either end, and speeding, deep draughted boats suck the water from underneath it causing it to hit the bottom. 

[furnessvale]

20 minutes ago, cuthound said:

 

Not necessarily, my boat is securely moored on bollards using springs at either end, and speeding, deep draughted boats suck the water from underneath it causing it to hit the bottom. 

The way that mud gathers under a permanent mooring means that almost any vertical movement will result in a boat touching bottom.

 

Indeed, when I had a permanent mooring, on returning from a long cruise I often could not get fully in to the side because passing boats had moved mud into "my" space.  A couple of days of passing boats and tightening my lines would see me back in place having tamped the mud beneath the hull.

 

To me, a "speeding" boat had to be making a breaking wash past my permanent mooring to make me raise an eyebrow.

 

George

[cuthound]

17 minutes ago, furnessvale said:

The way that mud gathers under a permanent mooring means that almost any vertical movement will result in a boat touching bottom.

 

Indeed, when I had a permanent mooring, on returning from a long cruise I often could not get fully in to the side because passing boats had moved mud into "my" space.  A couple of days of passing boats and tightening my lines would see me back in place having tamped the mud beneath the hull.

 

To me, a "speeding" boat had to be making a breaking wash past my permanent mooring to make me raise an eyebrow.

 

George

 

The bottom under my mooring is hard, not mud. It is only the gap after my mooring and before the bridge that is muddy.

 

 At normal water levels there is usually 3-4" of water under my boat.

Edited July 17, 2018 by cuthound
To add the last sentance

[nb Innisfree]

In the, very, wet spell of '07/' 08 we were moored bankside on the K&A, the towpath was so muddy it was near impossible to moor securely,  2 lines at 45° + 2 spring lines, 8 pins in total and still they were being dragged,. I politely asked a passing boat to slow down a bit more but was met with "If it's moored properly it would be all right" Obviously he'd been moored on rings or bollards so had no idea of the conditions.

 

The only solution I could think of was large flat plates with lots of spikes underneath to spread the load and a hole in the centre for a couple of mooring pins, maybe a sheet of chequer plate with 6mm stainless coach bolts. Never did get round to trying it. 

 

[NB Esk]

4 minutes ago, nb Innisfree said:

In the, very, wet spell of '07/' 08 we were moored bankside on the K&A, the towpath was so muddy it was near impossible to moor securely,  2 lines at 45° + 2 spring lines, 8 pins in total and still they were being dragged,. I politely asked a passing boat to slow down a bit more but was met with "If it's moored properly it would be all right" Obviously he'd been moored on rings or bollards so had no idea of the conditions.

 

The only solution I could think of was large flat plates with lots of spikes underneath to spread the load and a hole in the centre for a couple of mooring pins, maybe a sheet of chequer plate with 6mm stainless coach bolts. Never did get round to trying it. 

 

Probably would have worked.  We had a bigger version, when I was in the army, known as ground anchors.  Used them for winching from.

[nb Innisfree]

24 minutes ago, NB Esk said:

Probably would have worked.  We had a bigger version, when I was in the army, known as ground anchors.  Used them for winching from.

We used them in the fire brigade, there was an unaccounted one in the station stores complete with pins for years, soon after launching our boat I went back to the station to, erm, borrow it, but it had just been returned to HQ stores! Grrr! 

[Neil Smith]

I have a ground anchor that I used for winching my off roader out of the mud when stuck the harder you pull on it the deeper it digs in, might put it on the boat for soft banks.

 

Neil

[MtB]

5 hours ago, Neil Smith said:

I have a ground anchor that I used for winching my off roader out of the mud when stuck the harder you pull on it the deeper it digs in, might put it on the boat for soft banks.

 

Neil

 

What does it look like?!

 

I've often wondered about an oversized ronde anchor with an enlarged flat blade tip to do the same thing in soggy ground. They dig in deeper the more they are dragged, too.