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magictime

Steering basics - zigzag effect?

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My very first experience of steering a narrowboat was when the previous owner of our old 24-foot, outboard-engine boat passed the tiller over to give me a turn. As the boat began to drift to one side, I (over)corrected and it started drifting to the other, so I (over)corrected again, swinging from side to side in an ever-wider arc until we finally hit the bank. Not a great start, but I did fairly soon get a better feel for it!

Fast forward to the weekend just gone. I'm at a 'proper' tiller on a 'proper' 55ft, inboard-engine boat for the first time, after a 3-year break from boating... and I'm embarrassed to admit that I was having the same basic problem (albeit not as extreme):

Boat is heading towards one bank. Best guess at the right amount of steering to straighten up. Allow a few seconds for boat to respond, not wanting to overdo it. Nope -still heading towards the bank, which is now a lot closer. Steer more decisively to avoid collision, knowing this is overdoing it but not knowing what else to do. Surprise surprise, the boat swings too much and ends up pointing towards the opposite bank. Repeat as (un)necessary, travelling down the canal in a silly zigzag pattern until somehow the boat is back in a straight line.

Any suggestions? Do I just need to be more decisive in my steering at that first stage, before the boat is actually getting close to the bank? Maybe the unfamiliar weight/resistance of the tiller is making me reluctant to move it as far and as fast as I need to?

Ultimately I'm sure I'll get a 'feel' for it, but meanwhile I have gone aground for no good reason, had to hit reverse to avoid collision with a moored boat, and had rather more contact with tunnel walls than I might like. Anything I can do to accelerate the learning process can only be a good thing!

Oh, and I do plan to take a helmsman's course, but dates and geography mean a long journey before I do can't be avoided.

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it's just experience I guess, only being a shareboater with sometimes large gaps between time on the water it always takes me a little while to get out of the steering a car mindset where everything happens almost instantly and from the front, and back into the boat mindset where its not instant and pivots in the middle and carries on a bit after you've stopped turning.

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23 minutes ago, magictime said:

My very first experience of steering a narrowboat was when the previous owner of our old 24-foot, outboard-engine boat passed the tiller over to give me a turn. As the boat began to drift to one side, I (over)corrected and it started drifting to the other, so I (over)corrected again, swinging from side to side in an ever-wider arc until we finally hit the bank. Not a great start, but I did fairly soon get a better feel for it!

Fast forward to the weekend just gone. I'm at a 'proper' tiller on a 'proper' 55ft, inboard-engine boat for the first time, after a 3-year break from boating... and I'm embarrassed to admit that I was having the same basic problem (albeit not as extreme):

Boat is heading towards one bank. Best guess at the right amount of steering to straighten up. Allow a few seconds for boat to respond, not wanting to overdo it. Nope -still heading towards the bank, which is now a lot closer. Steer more decisively to avoid collision, knowing this is overdoing it but not knowing what else to do. Surprise surprise, the boat swings too much and ends up pointing towards the opposite bank. Repeat as (un)necessary, travelling down the canal in a silly zigzag pattern until somehow the boat is back in a straight line.

Any suggestions? Do I just need to be more decisive in my steering at that first stage, before the boat is actually getting close to the bank? Maybe the unfamiliar weight/resistance of the tiller is making me reluctant to move it as far and as fast as I need to?

Ultimately I'm sure I'll get a 'feel' for it, but meanwhile I have gone aground for no good reason, had to hit reverse to avoid collision with a moored boat, and had rather more contact with tunnel walls than I might like. Anything I can do to accelerate the learning process can only be a good thing!

Oh, and I do plan to take a helmsman's course, but dates and geography mean a long journey before I do can't be avoided.

 

You just need to practise to get used to it, but it's worth thinking on the fact that boats, being long, have significant angular momentum. This is just like the more familiar effect that things moving tend to keep moving in the same direction, but it refers to turning. Once the boat is turning, it will keep rotating even if you put the tiller back to the middle.

 

The trick is to be aware not only of where the boat is pointing, but also how that's changing. Once the boat is pointing in the right direction, it needs a distinct period of opposite tiller to stop is turning any further.

 

MP.

 

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A long steel narrowboat pretty much steers itself, shouldn't take you long to pick up. Now, steering a likle plastic boat on a windy day with an outboard motor, that's more difficult.

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Thanks for the reassurance everyone, and especially MoominPapa for that tip - very helpful in making sense of my experience.

Just from reflecting on things and watching a couple of YouTube videos, I'm already getting a fair idea of where I've been going wrong. Basically I think I've been too cautious in how much I move the tiller when only a small correction is needed, and too slow to bring it back to the middle even after a large correction; I need to be more timely and more definite both in stopping an initial drift to one side, and in making sure it doesn't then start drifting over to the other.

1 hour ago, rusty69 said:

Now, steering a likle plastic boat on a windy day with an outboard motor, that's more difficult.

I can imagine! Our old boat was steel, but small and with an outboard (as I say), and steering once winds got up to the mid-teens was always 'interesting'.

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Steering a boat with high precision is not about to have the boat pointing in the right direction only, but at the right moment, as when entering a lock. 

Before that, many small Quick rudder inputs to get the boat where you wanted is better then a few big inputs, so stay ahead of the boat (don't fly behind the plane)

The same in a narrow Canal, see what the wind is doing and suction from Canal side and try to stay ahead of it, or when sudden, a Quick responce.

To straighten a turn into a narrow passage it sometimes helps with a short input with the throttle to give the boat a new direction and help the rudder without giving it full angle.

There is centrifugal forces on a boats in a turn.

On a wide river/Canal without trafic you can relax a bit but try to be where you want the boat to go.

So, it is better to zig-zag the boat a Little then wait untill it is to late, in that way you are on top of it. just as a take of or landing roll with a taildragger, do not sitt still with your feet and wait for it to turn, small Quick input is the way to do it.

 

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As said, it is mostly about monitoring the RATE of turning, not just the current angle. The first thing that happens is a rate of turn starts. At that moment. the boat is still pointing the right way - but not for long! Correcting that initial rate of turn with a small tiller movement means the boat continues straight, in the middle of the cut. If you wait until it's pointing the wrong way and then try to correct, you need a much bigger input, you build up a rate of turn and chances are, you will overshoot and head towards the other bank.

Don't forget that once a boat is turning significantly, straightening the tiller won't really stop the turn, you are likely to need a bit of opposite rudder to do that.

Finally remember that the back of the boat tends to get "sucked" into the shallows if you have a lot of power on (Bernoulli). So if you have too much power on for the depth and width of canal, the stern will tend to get pulled into one side, makes the bow point at the other side, you correct and then stern gets pulled into the other side - repeat ad infinitum! Reducing power on a shallow canal will make steering much easier.

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On 25/09/2017 at 09:52, magictime said:

 

Boat is heading towards one bank. Best guess at the right amount of steering to straighten up. Allow a few seconds for boat to respond, not wanting to overdo it. Nope -still heading towards the bank, which is now a lot closer. Steer more decisively to avoid collision, knowing this is overdoing it but not knowing what else to do. Surprise surprise, the boat swings too much and ends up pointing towards the opposite bank. Repeat as (un)necessary, travelling down the canal in a silly zigzag pattern until somehow the boat is back in a straight line.

 

This has me wondering if you are simply going too fast for the width of canal and depth of the water. If my boat starts behaving like this (i.e. I'm finding it difficult to calibrate the degree of correction and I ind myself zig-agging) I just take some throttle off and calm control returns.

Try it next time this happens. Go slower and see if control returns.

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3 minutes ago, mross said:

And pay attention!  It's amazing how quickly it goes wrong just trying to put a coat on!

I have noticed that too - especially on one occasion a few years ago when I put my jacket on and managed to trap the end of the tiller arm in my side pocket!

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On 25/09/2017 at 12:31, bizzard said:

Or being glued to a mobile phone.

 

Yes this too. I can rarely type out a whole post on here without having to look up at least once for an emergency directional correction. :rolleyes:

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10 minutes ago, Mike the Boilerman said:

 

This has me wondering if you are simply going too fast for the width of canal and depth of the water. If my boat starts behaving like this (i.e. I'm finding it difficult to calibrate the degree of correction and I ind myself zig-agging) I just take some throttle off and calm control returns.

Try it next time this happens. Go slower and see if control returns.

I did find myself doing that, actually, and it did help, but we're talking about a speed barely above tickover. Maybe 900rpm. I can't cruise around like that forever!

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With zig-zag I mean just a few degree, if not more is needed to position the boat where you want it.

And as said, don't go so fast you lose Control.

Edited by Dalslandia

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On 25/09/2017 at 12:44, magictime said:

I did find myself doing that, actually, and it did help, but we're talking about a speed barely above tickover. Maybe 900rpm. I can't cruise around like that forever!

 

Which waterway are you cruising on? On the southern Stratford for example, a good proportion of it is shockingly shallow and narrow, and this effect can be very pronounced even at low speed.

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If you look at something like a tv aerial sticking up at the front of the boat, you can see how it is moving relative to the distant scenery. Thus gives a quicker sense of what's going on than just seeing where the boat us heading, or not :(

I'm OK at going forwards after decades of sailing and 6 years of narrowboating and tend to steer by 'feel' but, when reversing, I don't have the same feel and find that I can see what's happening much quicker by watching the relative movement of the bow compared to the scenery.

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You will get used to it.

Try to stay in the centre of the cut (unless there is another boat coming towards you) and try to keep the "gap" between the two banks and each handrail the same. As soon as the boat deviates from the centre correct it, and you will track a straighter course.

When steering through narrow bridges, particularly those on a bend, treat it as "a boat of two halves".

So concentrate on getting the front through the bridge first, then forget about the front and concentrate on not hitting the bridge with the stern. Then get the boat back to the centre of the cut. 

Remember the boat pivots at a point somewhere between a third and half way along it's length, and don't be afraid of temporarily using a lot of revs to improve the steering if things get to close for comfort.

In tunnels where you can the the point of light at the far end, use a centrally mounted mushroom vent or similar near to the front of the boat to help keep the boat centered in the tunnel.

Eventually it all becomes second nature.

Edited by cuthound
Clarification

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38 minutes ago, Mike the Boilerman said:

Which waterway are you cruising on? 

Leicester arm of the GU.

38 minutes ago, Mike the Boilerman said:

What engine, gearbox and final drive do you have?

Isuzu LC38, PRM150 and... erm... what's a final drive?:blush:

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On 25/09/2017 at 13:31, magictime said:

Leicester arm of the GU.

Isuzu LC38, PRM150 and... erm... what's a final drive?:blush:

Not a particularly thin or shallow canal then.

By 'final drive', I meant the reduction ratio on your gearbox. It's usually 2:1 on a modern boat.

I'm not familiar with that engine but it sounds like a marinised digger engine, in which case 900rpm probably isn't that fast. What would you consider 'normal' cruising speed on it?

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27 minutes ago, cuthound said:

You will get used to it.

Try to stay in the centre of the cut (unless there is another bost coming towards you) and try to keep the "gap" between the two banks and each handrail the same. As soon as the boat deviates from the centre correct it, and you will track a straighter course.

When steering through narrow bridges, particularly those on a bend, treat it as "a boat of two halves".

So concentrate on getting the front through the bridge first, then forget about the front and concentrate on not hitting the bridge with the stern. Then get the boat back to the centre of the cut. 

Remember the boat pivots at a point somewhere between a third and half way along it's length, and don't be afraid of temporarily using a lot of revs to improve the steering if things get to close for comfort.

In tunnels where you can the the point of light at the far end, use a centrally mounted mushroom vent or similar near to the front of the boat to help keep the boat centered in the tunnel.

Eventually it all becomes second nature.

What he says! 

Not too much power - more will probably just help you to dig a hole.

Keep an eye on where the front end is pointing, and constantly make small corrections to keep the boat going where you want.

 

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1 hour ago, mross said:

And pay attention!  It's amazing how quickly it goes wrong just trying to put a coat on!

Tip for that. Drop the engine revs right back to tickover: the stupid thing will stay in a straight line in the middle for much longer if you do. Possibly long enough to don both top and bottom waterproofs!

MP.

 

Edited by MoominPapa
Missing worm
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17 minutes ago, MoominPapa said:

Tip for that. Drop the engine revs right back to tickover: the stupid thing will stay in a straight line in the middle for much longer if you do. Possibly long enough to don both top and bottom waterproofs!

MP.

 

In my experience how striaght the boat stays whilst you put on your coat is very much dependent upon on the boat and whether it is in gear or not.

It was virtually impossible to do even in neutral on our first share boat (Pat Buckle hull).

The second shareboat would track a straight line whilst you put your coat on if it was put in neutral. (Graham Reeves hull)

My current boat stays perfectly straight at tickover for quite long distances, certainly for enough time to put a coat on.  (Alexander hull).

Generally the lighter the tiller feels, the more likely the bost is to deviate from a straight line.

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So, maybe, it depends on how much rudder is behind its pivot point compared to the amount in front - ie, how 'balanced' the rudder is.  I can certainly see that kicking it into neutral would eliminate prop-walk.

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