Why do so many people tie up their boats like this?

[nicknorman]

We always pass moored boats at tickover. In general they don't move much. Some tip wildly and they are the ones whose ropes go to piling hooks or stakes placed at right angles to the boat. The modest fore-aft pull is translated to a massive rolling force by the mechanical advantage. Crazy but you see a lot of it! Since the main force is fore-aft, surely the angle of the ropes should be at least 45 degrees?

[RLWP]

At 45 degrees going out from the boat too, not back towards the middle.

 

I think they do it so they aren't 'invading someone else's space' with their ropes

 

Richard

 

Not so they can get irate and scream "SLOW DOWN"

[MtB]

I think a significant proportion of boaters have no concept of the fore/aft movement created in a moored boat when a boat passes.

 

I regularly notice in the threads about slowing down past moored boats posters who seem to think the problem is the waves caused by the wake of the passing boat. It also takes a bit of 'spacial awareness' to imagine how best to tie to resist the fore/aft forces. Not everybody has this in abundance.

[steelaway]

We always pass moored boats at tickover. In general they don't move much. Some tip wildly and they are the ones whose ropes go to piling hooks or stakes placed at right angles to the boat. The modest fore-aft pull is translated to a massive rolling force by the mechanical advantage. Crazy but you see a lot of it! Since the main force is fore-aft, surely the angle of the ropes should be at least 45 degrees?

 

 

Hi

To be honest I dont notice the massive rolling force you mention even though my ropes are usually fixed as short as possible.

 

The longer the ropes the more they seem to stretch or loosen. Keeping them short alleviates this. Its the distance the boat travel backward or forward, before being stopped by the ropes is the worst problem

 

Alex

[Tiny]

I notice a lot of first timers use a straight out rope with pin hardly in the ground - and go off leaving it for hours. Watching all the racing boats don't seem to have any effect on it. But next door the pins will be at 45 degrees, well knocked in and even there may be a spring - yet a few boats pass them and they are loose. Of course there are exceptions to these observation, garnered over many years. But it does make us wonder if moorers who know know better have their own angel looking out for them while for others God like to have a laugh.

[alan_fincher]

At 45 degrees going out from the boat too, not back towards the middle.

 

Do you actually think the latter makes a significant difference, (unless it's a very short boat ?).

 

I must admit we regularly tie with the ropes "inwards" rather than "outwards", if that works out better for available rings, bollards, or pilings to put chains through.

 

Never found it to be a problem, although I can see the geometry could result in the boat being able to move a bit more.

 

I agree about the 90 degree thing though - far too many people are happy to do this, then probably moan (to themselves at least!), if they move!

[nb Innisfree]

Do you actually think the latter makes a significant difference, (unless it's a very short boat ?).

 

I must admit we regularly tie with the ropes "inwards" rather than "outwards", if that works out better for available rings, bollards, or pilings to put chains through.

 

Never found it to be a problem, although I can see the geometry could result in the boat being able to move a bit more.

 

I agree about the 90 degree thing though - far too many people are happy to do this, then probably moan (to themselves at least!), if they move!

 

Agreed, we don't notice any difference between inwards or outwards tying, if we are forced to tie at right angles we then use centrelines backwards and forwards as springs to minimise any surging and keep rocking to a minimum.

[RLWP]

Do you actually think the latter makes a significant difference, (unless it's a very short boat ?).

 

I must admit we regularly tie with the ropes "inwards" rather than "outwards", if that works out better for available rings, bollards, or pilings to put chains through.

 

Never found it to be a problem, although I can see the geometry could result in the boat being able to move a bit more.

 

I agree about the 90 degree thing though - far too many people are happy to do this, then probably moan (to themselves at least!), if they move!

 

Yes, I do think it makes a significant difference

 

For a start, it prevents your mooring lines chafing on the hull

 

Richard

[MtB]

Agreed, we don't notice any difference between inwards or outwards tying, if we are forced to tie at right angles we then use centrelines backwards and forwards as springs to minimise any surging and keep rocking to a minimum.

 

 

Surely using centre lines as springs, being attached to the roof of the boat, would make the rocking worse?

[RLWP]

Surely using centre lines as springs, being attached to the roof of the boat, would make the rocking worse?

 

By pulling the boat sideways - I agree

 

Richard

[nicknorman]

Hi

To be honest I dont notice the massive rolling force you mention even though my ropes are usually fixed as short as possible.

 

The longer the ropes the more they seem to stretch or loosen. Keeping them short alleviates this. Its the distance the boat travel backward or forward, before being stopped by the ropes is the worst problem

 

Alex

Have you considered the geometry? Assuming the ropes are at 90 deg and tight, how much does it have to stretch to allow say 1" fore aft movement. Maybe 1mm? Rope twice as long, but at sensible angle, same force = 2mm stretch which equates to perhaps 3 mm fore aft movement. Maybe they don't teach geometry at school these days?

[alan_fincher]

Yes, I do think it makes a significant difference

I'm surprised, (in movement terms), particularly if your boat is full length.

 

For a start, it prevents your mooring lines chafing on the hull

Ours always rub "somewhere", as they pass over something. It just transfers the "somewhere, to "somewhere else".

 

The only reason I tie "outwards" rather than "inwards" if all other things are equal is to keep the ropes clear of where you might be stepping on or off the boat. That's significant, of course, but otherwise I have no preference.

[jonk]

Have you considered the geometry? Assuming the ropes are at 90 deg and tight, how much does it have to stretch to allow say 1" fore aft movement. Maybe 1mm? Rope twice as long, but at sensible angle, same force = 2mm stretch which equates to perhaps 3 mm fore aft movement. Maybe they don't teach geometry at school these days?

 

Surely it is not Geometry you need to worry about, it is Statics and Dynamics? The Geometrical diagrams will show both moorings will leave the boat motionless since stretch doesn't come into Geometry!

Taking stretch into account and understanding that theory does not always apply in practice, 45 outwards and 45 towards the centre of the boat should have no difference on forward and aft movement since the same force will be applied to the pins, but there might be a higher 'pivot' force with pins inside the length of the boat - take the extreme example of both ropes going to a central pin which will result in one triangle with the boat pivoting about the securing pin. The use of spring lines creates two triangles and also splits the pulling force into two. Triangles are good! halving force is also good!

 

 

John

[NigelJ]

For along boat (ours is 70ft) it definitely makes a lot of difference and I avoid mooring with ropes slanted 'inwards' if at all possible. Although the boat is theoretically fastened tight against any movement, in practice it can pivot about ropes slanted inwards but is almost entirely prevented from doing so whent the ropes are 45 degrees 'outwards'. A very obvious difference when boats are passing.

 

Also, not everyone seems to realise the 'drag' on a moored boat is not initially created by a boat actually passing. The first, and quite noticeable, effect occurs when the passing boat is still 100 yards or more away. If it doesn't begin slowing down at that distance it will be too late to prevent moving a boat on its moorings.

[David Schweizer]

To be honest, I get a bit fed up with these "the way I do it is best" threads, and tying up is one where you cannot make hard and fast rules, because it also depends on the underwater shape of your hull, and how well you fender your boat to absorb movement.

 

If you have one of these modern shallow draught, slab sided boats with virtually no swim, then you need all the help you can get to stop it rocking about when a boat passes, but if you have a boat with a deep draught and long swims, and you use decent sized fenders, the requirements are no where near as critical.

 

Frankly there is no correct way for all boats, and the experienced boater will soon work out what works for their boat. The best system for our boat does not comply with any of the examples given above.

Edited August 6, 2011 by David Schweizer

[jonk]

For along boat (ours is 70ft) it definitely makes a lot of difference and I avoid mooring with ropes slanted 'inwards' if at all possible. Although the boat is theoretically fastened tight against any movement, in practice it can pivot about ropes slanted inwards but is almost entirely prevented from doing so whent the ropes are 45 degrees 'outwards'. A very obvious difference when boats are passing.

 

I am sure there can be since with 'inpointing' mooring the force is taken on the REAR rope (when water is flowing from the front), whereas with 'outwards pointing' mooring the force is taken by the FORWARD rope - bound to be different in practise I would think.

 

To be honest, I get a bit fed up with these "the way I do it is best" threads, and tying up is one where you cannot make hard and fast rules, because it also depends on the underwater shape of your hull, and how well you fender your boat to absorb movement.

 

If you have one of these modern shallow draught, slab sided boats with virtually no swim, then you need all the help you can get to stop it rocking about when a boat passes, but if you have a boat with a deep draught and long swims, and you use decent sized fenders, the requirements are no where near as critical.

 

Frankly there is no correct way for all boats, and the experienced boater will soon work out what works for their boat. The best system for our boat does not comply with any of the examples given above.

 

The theory applies to ALL boats, the amount of individual affect will vary because of the differences you describe (such as hull shape).

What method do you use, I am at a loss to think others, other than dropping an anchor/weight?

 

John

[nicknorman]

I am sure there can be since with 'inpointing' mooring the force is taken on the REAR rope (when water is flowing from the front), whereas with 'outwards pointing' mooring the force is taken by the FORWARD rope - bound to be different in practise I would think.

Yes, it depends on whether you want J-Lo derriere wiggling motion for your boat or not!

 

To be honest, I get a bit fed up with these "the way I do it is best" threads,

is their a duty rota to play "Mr Grumpy" on CWDF? If so, can I get on it please?

[David Schweizer]

The theory applies to ALL boats, the amount of individual affect will vary because of the differences you describe (such as hull shape).

What method do you use, I am at a loss to think others, other than dropping an anchor/weight?

 

John

Theory is fine, but that is all it is. If I moored our boat with lines at 45 degrees or more, it will move backwards and forwards everytime a boat passes.

 

Or boat is 33" deep at the back and 18" deep at the fromt, and has 15ft swims. I have found, through trial and eror, that a forward line at a little less than 45 degrees and a rear line at just over 90 degrees, both moored tightly, fendered with two small tyres suspended from the cabin side steps, prevents any backwards and forwards movement and without any rolling.

 

I am not suggesting that anyone else should copy me, but that configuratuion works for us, and I am bemused by people suggesting that they know better.

Edited August 6, 2011 by David Schweizer

[nicknorman]

Surely it is not Geometry you need to worry about, it is Statics and Dynamics? The Geometrical diagrams will show both moorings will leave the boat motionless since stretch doesn't come into Geometry!

Taking stretch into account and understanding that theory does not always apply in practice, 45 outwards and 45 towards the centre of the boat should have no difference on forward and aft movement since the same force will be applied to the pins, but there might be a higher 'pivot' force with pins inside the length of the boat - take the extreme example of both ropes going to a central pin which will result in one triangle with the boat pivoting about the securing pin. The use of spring lines creates two triangles and also splits the pulling force into two. Triangles are good! halving force is also good!

John

the geometry describes the relationship between fore/aft travel vs change in rope length when the angle is not 180deg. It doesn't explicitly include or exclude stretch as being the source of the change in length.

[jelunga]

Just to throw my hat in the ring we try to moor with outward facing ropes. I find this is best to stop fore & aft movement. I also deploy two spring ropes from an almost central cleat at gunwale height, tied to a convenient ring, bollard or pin as necessay. These have the greatest effect in stopping movement. An even bigger effect would be for all those miserable impatient arrogant bums would slow down. Last night at Hawkesbury junction we suffered greatly from speeding boats(rushing to get through Hillmorton lox?), bloody kids on noisy trail bikes on the towpath and then loud music from a nearby boat on a permanent mooring. It was not just me pissed off, about 3 other boaters asked them to turn it down without result. Went on till 2200 at least. I did think of taking my bugle across and Playing reveille at 0500 but couldn't really be arsed.

[Theo]

We always pass moored boats at tickover. In general they don't move much. Some tip wildly and they are the ones whose ropes go to piling hooks or stakes placed at right angles to the boat. The modest fore-aft pull is translated to a massive rolling force by the mechanical advantage. Crazy but you see a lot of it! Since the main force is fore-aft, surely the angle of the ropes should be at least 45 degrees?

 

The fact that the ropes are at right angles will not cause the boat to roll. It is the vertical position of the attachment point that is critical here. If you use a centre line attached to the roof that will cause the boat to roll.

 

Nick

[nb Innisfree]

Surely using centre lines as springs, being attached to the roof of the boat, would make the rocking worse?

 

Not really, preferred method if available would be to tie springs at deck level but we find that using centre lines back to the mooring points does reduce rocking quite a bit as the pull is more longitudinal than lateral. In fact we find the lateral pull at deck level on a 90deg mooring is much higher.

Edited August 6, 2011 by nb Innisfree

[howardang]

For those who think that it is a boats wash that causes the problem, look at this short video. There are no waves but the movement of the moored boat is substantial when the boat passes. The vessels in the video are very similar in weight snd dimensions to canal boats.

 

 

Howard

[Sunset Rising]

There is more to mooring a boat than just stopping it moving forward and backward. If ropes are tight enough to prevent movement ( at whatever angle ) what happens about water level dropping ? More important on a river I know but even canals can drop overnight.

Edited August 6, 2011 by Sunset Rising

[boatyboy]

Do you actually think the latter makes a significant difference, (unless it's a very short boat ?).

 

I must admit we regularly tie with the ropes "inwards" rather than "outwards", if that works out better for available rings, bollards, or pilings to put chains through.

 

Never found it to be a problem, although I can see the geometry could result in the boat being able to move a bit more.

 

I agree about the 90 degree thing though - far too many people are happy to do this, then probably moan (to themselves at least!), if they move!

I agree that it makes no differance if your ropes are inwards or outwards.(As long as you don't have one in and one out of course)Reason being the pivot point is the bollard on the deck.therefore its ok to do it both ways(IMHO).I've done both ways for years.Main reason for being inboard is mooring between other boats when space is tight.

Edited August 6, 2011 by boatyboy