Passing moored widebeams

[peterboat]

I have the Exol Pride [1000 ton tanker] pass my boat twice a week all the yogurt pots move everywhere the narrowboats nearly roll over if it goes to fast and the widebeams move about a bit does that answer your question Mike?

[Alan de Enfield]

53 minutes ago, Robbo said:

That depends, for the same moored boat weight, the water removal from around the boat will pull the boat more, but the wake will effect a narrow boat more.   Of course this depends on the boat that is passing as small boats cause more wake than heavier long boats which cause more surge.  So there is no right or wrong answer, but for the average canal boat, the average widebeam on the average canal, I think the narrowboat will be more effected.

Many have been using 'effected' when they actually mean 'affected' sorry to use you post as an example - it just happens to be the latest one, and I can no longer resist.

 

Think of Edgar Allen Poe and his RAVEN: Remember Affect Verb Effect Noun. ... Most of the time, you'll want affect as a verb meaning to influence something and effect for the something that was influenced.

The wake will affect the narrowboat, but, the narrowboat will be effected.

[WotEver]

6 minutes ago, Alan de Enfield said:

Many have been using 'effected' when they actually mean 'affected'...

Not me sir

[mark99]

56 minutes ago, Dingle said:

What about Speed?

A vessel just making way has a lot less effect on the water it shoves around than one going at full pelt...

Yes because it's displacing more mass per unit time. And depending upon the cross sectional area of the waterway will change the hydraulic gradient .......but that's not the question.

[WotEver]

15 minutes ago, mark99 said:

... but that's not the question.

There's a lot of that going on

[mark99]

3 minutes ago, WotEver said:

There's a lot of that going on

We call it scope creep at work..... 

[Scholar Gypsy]

Sorry if these points have been made before, I have skimmed this thread but am behind CWDF as I have been out boating for five days

1) Some comments above are about surface waves, eg the effect of a passing canoe or a trip boat on a wide and deep stretch of river.  This is different to the hydraulic effect which is what this posting is about, namely the effect of moving X tonnes (the displacement of the boat) from in front of the boat to behind for each length travelled. Narrowboats usually create minimal wash but can create a significant hydraulic effect, even at low speed.

2) The average speed of the water current (backwards) is the speed of the boat divided by (ratio of boat cross section to canal cross section - 1)

3) In a narrow channel a wide boat will occupy more of the channel, so the "backwards" water current will be greater.

[WotEver]

18 minutes ago, Scholar Gypsy said:

Sorry if these points have been made before, I have skimmed this thread but am behind CWDF as I have been out boating for five days

1) Some comments above are about surface waves, eg the effect of a passing canoe or a trip boat on a wide and deep stretch of river.  This is different to the hydraulic effect which is what this posting is about, namely the effect of moving X tonnes (the displacement of the boat) from in front of the boat to behind for each length travelled. Narrowboats usually create minimal wash but can create a significant hydraulic effect, even at low speed.

2) The average speed of the water current (backwards) is the speed of the boat divided by (ratio of boat cross section to canal cross section - 1)

3) In a narrow channel a wide boat will occupy more of the channel, so the "backwards" water current will be greater.

Whilst interesting that still isn't the question being asked...

A narrowboat is proceeding down the cut. Moored at the bank side are another narrowboat and a little further on, a wide beam. Will the moored wide beam move more than the moored narrowboat or less?

My money is on less. 

[Peter-Bullfinch]

On the Lancaster today I took special note as we went along looking at how boats were affected with this relatively shallow saucer shaped bed canal. Yes, narrowboats moved...yes..widebeams also moved...but well tied up boats didn't really seem to move at all. 

[howardang]

25 minutes ago, Peter-Bullfinch said:

On the Lancaster today I took special note as we went along looking at how boats were affected with this relatively shallow saucer shaped bed canal. Yes, narrowboats moved...yes..widebeams also moved...but well tied up boats didn't really seem to move at all. 

Wow!  What a soilsport! You've ended a debate that could have run and run......or have you?

 

Howard

Edited April 17, 2017 by howardang

[NickF]

5 hours ago, WotEver said:

Yes of course the flow will differ but that's not what's being discussed. We have been talking about the difference in the effect that flow will have on a narrowboat vs a wide beam. 

Or are you suggesting that the ratio of the effect changes along with the cross section of the water course?

Ok to correct my post from earlier .... what I was saying is the effect changes .... not the ratio of the effect, I mis interpreted your post ..... and so as you say that's not what was being discussed!

32 minutes ago, Peter-Bullfinch said:

On the Lancaster today I took special note as we went along looking at how boats were affected with this relatively shallow saucer shaped bed canal. Yes, narrowboats moved...yes..widebeams also moved...but well tied up boats didn't really seem to move at all. 

So Peter, does that mean you have proved that widebeams are better at tying up!?

[Lord Gadbury]

Not read all messages, personaally I slow down for any moored boat, surprised me this weekend how many owned boats did not give a flying fick.

When attempting to tell one individual to slow down, he put his hand to ear, then cut the engine to idle in able to hear, cruiser club flag happily flying, so I gather from that experience, that you should only slow down when passing a cruising club, or permanent mooring, not a designated 48 hour mooring.

Funny thing about this is it was an approach to a narrow bridge, followed immediately by a busy junction, yet the amount of boaters that slowed down was poor.

We are all in the same boat so to speak, we are never going to get any where fast, so show a bit of respect for others, treat others the way you would like to be treated. 

Not difficult is it ? All boaters know what happens when an inconsiderate person doesnt bother slowing down.

 

[Drayke]

Yes widebeams will move backwards and forwards but not so much from side to side, even if moored up correctly as the ropes always seem to stretch a bit.

When I was in Thames & Kennet Marina some of the canoeists that went past you could feel the boat rocking bow to stern.

[Scholar Gypsy]

2 hours ago, WotEver said:

Whilst interesting that still isn't the question being asked...

A narrowboat is proceeding down the cut. Moored at the bank side are another narrowboat and a little further on, a wide beam. Will the moored wide beam move more than the moored narrowboat or less?

My money is on less. 

Well suppose the narrowboat occupies 1/5th of the cross section of the canal, then if it passes a moored NB then the current will be 1/3rd of the speed of the boat (each boat occupies 1/5th, leaving 3/5ths). If it is passing a WB, that occupies 2/5th  of the cross section, then the current will be 1/2 of the speed of the boat. So I would reckon for boats of equal displacement, the short fat boat will suffer more disturbance than a long thin boat. 

As others have noted, the quality of mooring will make the most difference. Do wideboaters moor better or worse??

[Alan de Enfield]

3 minutes ago, Scholar Gypsy said:

Do wideboaters moor better or worse??

I guess it depends if you mean 'wide beam boats' or 'wide skips with lids on'.

Boaters tend to 'tie up' better than 'skip drivers'.

[Tacet]

37 minutes ago, Scholar Gypsy said:

Well suppose the narrowboat occupies 1/5th of the cross section of the canal, then if it passes a moored NB then the current will be 1/3rd of the speed of the boat (each boat occupies 1/5th, leaving 3/5ths). If it is passing a WB, that occupies 2/5th  of the cross section, then the current will be 1/2 of the speed of the boat. So I would reckon for boats of equal displacement, the short fat boat will suffer more disturbance than a long thin boat. 

As others have noted, the quality of mooring will make the most difference. Do wideboaters moor better or worse??

Sounds right to me.  But the force required to pass a wider boat (resulting in a smaller cross section of channel) will be greater if the same speed is to be achieved.

Put another way, with the speed wheel/morse lever at the same setting (or even the same revs), the travelling boat will, of necessity, pass a tied-up WB (i.e a greater displaced cross sectional area) slower across the ground than a NB.  But just how much will depend on some complex interaction of several factors.

 

[sharpness]

5 hours ago, Alan de Enfield said:

The wake will affect the narrowboat, but, the narrowboat will be effected.

Surely that should be "the narrowboat will be affected" 

[Alan de Enfield]

1 minute ago, sharpness said:

Surely that should be "the narrowboat will be affected" 

No - the NB is the object / subject - you could say "...the effect on the NB will be that it rocks...."

[Scholar Gypsy]

6 minutes ago, Tacet said:

Sounds right to me.  But the force required to pass a wider boat (resulting in a smaller cross section of channel) will be greater if the same speed is to be achieved.

Put another way, with the speed wheel/morse lever at the same setting (or even the same revs), the travelling boat will, of necessity, pass a tied-up WB (i.e a greater displaced cross sectional area) slower across the ground than a NB.  But just how much will depend on some complex interaction of several factors.

 

Good point - the initial momentum of the narrowboat will be the same in both cases, when it first reaches the moored boat, but as you say will drop faster when passing a widebeam. A complex problem!

[MtB]

On 17/04/2017 at 21:27, F DRAYKE said:

Yes widebeams will move backwards and forwards but not so much from side to side, even if moored up correctly as the ropes always seem to stretch a bit.

When I was in Thames & Kennet Marina some of the canoeists that went past you could feel the boat rocking bow to stern.

 

When I was moored in Thames and Kennet Marina I never had a single canoe go past.

[Drayke]

7 minutes ago, Mike the Boilerman said:

 

When I was moored in Thames and Kennet Marina I never had a single canoe go past.

I was moored down by the entrance from the Thames and canoeists practised from hard standing and all the way across Dutch Barges and widebeams. 

[sharpness]

34 minutes ago, Alan de Enfield said:

No - the NB is the object / subject - you could say "...the effect on the NB will be that it rocks...."

Agreed, you could say "...the effect on the NB will be that it rocks...." but then the narrowboat has been affected, not effected.

[WotEver]

7 minutes ago, sharpness said:

Agreed, you could say "...the effect on the NB will be that it rocks...." but then the narrowboat has been affected, not effected.

Unless it has acquired an affectation and now rocks along to any passing music. 

[Tacet]

11 hours ago, Scholar Gypsy said:

Well suppose the narrowboat occupies 1/5th of the cross section of the canal, then if it passes a moored NB then the current will be 1/3rd of the speed of the boat (each boat occupies 1/5th, leaving 3/5ths). If it is passing a WB, that occupies 2/5th  of the cross section, then the current will be 1/2 of the speed of the boat. So I would reckon for boats of equal displacement, the short fat boat will suffer more disturbance than a long thin boat. 

As others have noted, the quality of mooring will make the most difference. Do wideboaters moor better or worse??

 

10 hours ago, Tacet said:

Sounds right to me.  But the force required to pass a wider boat (resulting in a smaller cross section of channel) will be greater if the same speed is to be achieved.

Put another way, with the speed wheel/morse lever at the same setting (or even the same revs), the travelling boat will, of necessity, pass a tied-up WB (i.e a greater displaced cross sectional area) slower across the ground than a NB.  But just how much will depend on some complex interaction of several factors.

 

 

10 hours ago, Scholar Gypsy said:

Good point - the initial momentum of the narrowboat will be the same in both cases, when it first reaches the moored boat, but as you say will drop faster when passing a widebeam. A complex problem!

I think its more complex still as the reverse flow 1/3 and 3/5th thing, could take longer to refill the void behind the boat than thee passage time.  That is the travelling boat might force a head of water ahead of it that will take a while to find its way back.