How do they go so slowly?

[Wanderer Vagabond]

10 hours ago, mrsmelly said:

You must have asmall prop?? My 18 x 12 has us running at 1000 to 1100 revs at normal cruising speed and 1600 would be river mode. Nowt wrong with more revs though as it will charge yer batteries and work the engine a little more. The downside is that some numpties will shout slow down just because the engine is spinning faster.

How small is a small prop? I measured mine last time I blacked the hull (March) and each blade is about 9". Normal cruising speed, between 3 and 3.5mph has the engine running at 1600 rpm, a speed it sounds comfortable at and burns about a litre of fuel an hour. If I try to run at less than 1000rpm it really doesn't sound comfortable and below 900 just kicks out of drive. it is what I thought was a fairly slow boat since it would never get to 5mph under its own power no matter how deep the river (tried on the Ouse this year and best speed was about 4.7mph according to satnav).

 

Having said that, I'm quite happy with it.

 

 

Edited October 13, 2020 by Wanderer Vagabond

[Arthur Marshall]

I have been known to get up to rudder length of very slow boats who appeared to object to going at 3mph.  I'm mostly more tolerant these days and just stop foir a bit and make tea, but I did blast past a hire boat on the Llangollen this year without any contact at all.

He had hit a swing bridge and a boat, just after the Pontywotsit, and then hit every bridge he came to before stopping dead and letting the bloke at the pointy end push the nose into the bridgehole with the bargepole. In between bridges he went at tickover. About seven of us behind him, me immediately. I nearly hit him the first time he stopped, I was so surprised. After half a dozen bridges there was a wide enough bit and I just went past him at possibly slightly more than my usual revs.

And, as my max speed is not very high, I tend to let boats past whenever possible.

[PhilR]

I regularly see boats creeping past at little more than 1 mph. Whilst it is obvious to me viewing from the bank that they have fouled propellers, they are usually unaware and unable to interpret the change of their prop wash.

[Alan de Enfield]

55 minutes ago, Wanderer Vagabond said:

How small is a small prop? I measured mine last time I blacked the hull (March) and each blade is about 9".

Next time you are 'out' it may be worth having a look on the prop 'boss', the size is usually marked there.

 

Consecutive numbered pair (for when one is not enough)

 

 

 

 

 

 

Edited October 13, 2020 by Alan de Enfield

[cuthound]

15 hours ago, robtheplod said:

Interesting as we have an 18" prop but the stopping on Water Lily is pretty dire compared to our shareboat......

 

What pitch is It?

 

The pitch determines how far forwards the boat moved for each revolution of the prop.

 

You need to compare both diameter and pitch with that of your share boat.

 

IIRC from my one day out on her, Aurora had an 18" x 12" prop.

Edited October 14, 2020 by cuthound
Share not shire

[robtheplod]

31 minutes ago, cuthound said:

 

What pitch is It?

 

The pitch determines how far forwards the boat moved for each revolution of the prop.

 

You need to compare both diameter and pitch with that of your share boat.

 

IIRC from my one day out on her, Aurora had an 18" x 12" prop.

Thanks for the reply. I'm not sure with Water Lily - is there a relatively easy way to find out?  I know its 18" but dont know the pitch. The only photos i have are when she came out for blacking but they are not very good:

 

 

Edited October 14, 2020 by robtheplod

[Mike Tee]

Prop size is usually stamped on the bit where the shaft goes in (boss?) - do you have an old survey? If an out of water survey was done at any time, the surveyor will normally mention prop size in his / her report.

[robtheplod]

7 minutes ago, Mike Tee said:

Prop size is usually stamped on the bit where the shaft goes in (boss?) - do you have an old survey? If an out of water survey was done at any time, the surveyor will normally mention prop size in his / her report.

I don't have any previous surveys, and our survey just says:

 

"An 18” Turbine type propeller is fitted, which appears to be in a serviceable condition where visible with some light damage to the blades"

 

this 'light damage' is just scratches as we chatted to the surveyor...

[Mike Todd]

14 hours ago, robtheplod said:

ok, going to sound stupid here, whats fishtail?

A means of steering a boat at slow speed using the rudder and taking advantage of the fact that water resistance is non-linear wrt to speed. 

 

So, push the rudder hard in one direction and slowly back again - this will exert a net force on the stern and hence rotate the boat about its turning axis. It was, I believe, mainly used by butties and is helped by the extra size of the rudder - which in any case is needed to allow the butty to turn as well as the motor. The latter uses the speed of the water from the prop over its rudder to give much greater turning force than that obtained just by moving through the water (as with the butty).

 

I find it is useful occasionally, not often, when - for example - drifting to await a lock being prepared and the wind or current takes the boat out of position but it is often just wishful thinking and the engine proves to be necessary!

[Alan de Enfield]

7 minutes ago, Mike Todd said:

A means of steering a boat at slow speed using the rudder and taking advantage of the fact that water resistance is non-linear wrt to speed. 

 

So, push the rudder hard in one direction and slowly back again - this will exert a net force on the stern and hence rotate the boat about its turning axis. It was, I believe, mainly used by butties and is helped by the extra size of the rudder - which in any case is needed to allow the butty to turn as well as the motor. The latter uses the speed of the water from the prop over its rudder to give much greater turning force than that obtained just by moving through the water (as with the butty).

 

I find it is useful occasionally, not often, when - for example - drifting to await a lock being prepared and the wind or current takes the boat out of position but it is often just wishful thinking and the engine proves to be necessary!

 

Think of sculling where a single oar is 'rowed' side to side over the stern of a boat.

 

Far more efficient that trying to do it with a rudder as you can alter the angles of the blade on the return stroke.

 

 

 

[BWM]

Unique to this time of year are those travelling with a ball of leaves on the prop, there seem to be many who are unaware of the build up and its effects on progress. 

[alias]

3 hours ago, Alan de Enfield said:

Far more efficient that trying to do it with a rudder as you can alter the angles of the blade on the return stroke.

Single oar sculling is also really handy for maintaining an appearance of control after incompetently losing one of the oars while attempting to row.  Similarly I seem to recall on a rented punt in Cambridge there was a small paddle that by the same technique allowed recovery of the pole that I had left vertically stuck in the mud behind me.  Sadly you'll spot there's a theme emerging there.

 

Doing it with the rudder, what works best for me is to do a stroke in the direction I need, then to let the rudder return to central at its own speed before the next stroke.

[gatekrash]

On 12/10/2020 at 21:24, Wanderer Vagabond said:

For the second time in a week I've found myself behind a chronically slow boat and I'm getting curious just how people can go so slowly.Now I am in no particular rush and on the first occasion, 10 days ago on the GU near Nether Heyford I just moored up for the day and left them to it. Today I caught up with another boat going at the same speed (slooooow). Now running my boat at the slowest it will go (about 900rpm on the tachometer, less than 2mph on the satnav) I just repeatedly kept catching up with them. The only 'solution' was to run in gear for a bit, then knock into neutral and drift for a bit and keep repeating (which gets a bit tedious). The query is just how do boats go that slowly (less than half my tickover speed)? Do they fit them with tiny propellers? do they have specially low gears in their gearbox they can change to? how do they do it? (and why).

Just had exactly the same, all the way from Tardebigge to Alvechurch the entire way at tickover catching up with the boat in front. Thing is my boat has quite a slow tickover, 800 rpm and snail pace, but we still kept catching it and even the Mrs (who is really steady with the throttle) was getting frustrated with the continual neutral / tickover thing. Then again today with another boat from the same hire company from one end of wast hill through the tunnel to Kings Norton doing the same thing. Perhaps they're trying to save diesel !

[Tracy D'arth]

18 minutes ago, gatekrash said:

Just had exactly the same, all the way from Tardebigge to Alvechurch the entire way at tickover catching up with the boat in front. Thing is my boat has quite a slow tickover, 800 rpm and snail pace, but we still kept catching it and even the Mrs (who is really steady with the throttle) was getting frustrated with the continual neutral / tickover thing. Then again today with another boat from the same hire company from one end of wast hill through the tunnel to Kings Norton doing the same thing. Perhaps they're trying to save diesel !

Its what the kettle is for, put it on the gas, when it boils brew up, stand on the back with boat out of gear till cooled. Drink tea, back in gear till the next brew.

[gatekrash]

I'd have been drinking a hell of a lot of tea...then, there'd have been a lot of stopping to empty the toilet cassettes so might have worked...

[Detling]

On 13/10/2020 at 16:49, Tracy D'arth said:

Boat moving forward, slowing down, will still steer if the rudder is sufficient. Ellums worked quite well with no engine chucking water back.

just try turning an Ellum with a prop wash over it, maybe desperate Dan could, but he would probably break the tiller.  Most boats can steer at 2 mph without the propwash, at 1 mph it is very iffy and before now when following a slow boat past a row of moored boats I have had to go alongside one, and hold on, whilst the slow coat got ahead because I did not have steerage way.  Murphy ruels that the one you choose its the only one in the line with the owner aboard.

[Wanderer Vagabond]

34 minutes ago, gatekrash said:

Just had exactly the same, all the way from Tardebigge to Alvechurch the entire way at tickover catching up with the boat in front. Thing is my boat has quite a slow tickover, 800 rpm and snail pace, but we still kept catching it and even the Mrs (who is really steady with the throttle) was getting frustrated with the continual neutral / tickover thing. Then again today with another boat from the same hire company from one end of wast hill through the tunnel to Kings Norton doing the same thing. Perhaps they're trying to save diesel !

I dodged a similar bullet a few years back on the GU. I'd been behind another chronically slow boat but eventually passed him before Stoke Bruerne, where we stopped for lunch. He later caught up with me and moored behind. We had lunch and just as we were finishing I realised that he had started up again and, not intending to sit behind him through Blisworth tunnel dropped everything, cast off and set off to and through the tunnel. Just as well, I got to the other end of the tunnel and moored up in Blisworth for the day. It's about 2.5 miles from Stoke Bruerne to Blisworth and it had taken me about an hour and 15 minutes, so I cannot be accused of rushing. This slow boat arrived an hour and a half after I got there followed by a convoy of 5 other boats. Once again he moored up behind me, he later commented how he had been subjected to some abuse from the boats behind him, I told him I had no idea why they would do that.

13 minutes ago, Tracy D'arth said:

Its what the kettle is for, put it on the gas, when it boils brew up, stand on the back with boat out of gear till cooled. Drink tea, back in gear till the next brew.

Doesn't it say something like,"...Don’t smoke or use cookers and heaters. Turn off the gas except pilot lights...." in tunnels?

[PhilR]

24 minutes ago, Wanderer Vagabond said:

This slow boat arrived an hour and a half after I got there followed by a convoy of 5 other boats. Once again he moored up behind me, he later commented how he had been subjected to some abuse from the boats behind him, I told him I had no idea why they would do that.

 

Maybe you should have given an honest reply? The guy might think it is acceptable and normal practice to prevent other boaters from making *normal progess*

[Wanderer Vagabond]

7 minutes ago, PhilR said:

Maybe you should have given an honest reply? The guy might think it is acceptable and normal practice to prevent other boaters from making *normal progess*

I think he had already been in receipt of a number of 'honest opinions' from the boats behind him in the tunnel. I have to say that would be my worst nightmare, taking an hour and a half to get through a tunnel that shouldn't really take much more than 40 minutes whilst sucking in diesel fumes all the way.

[PhilR]

1 hour ago, gatekrash said:

Just had exactly the same, all the way from Tardebigge to Alvechurch the entire way at tickover catching up with the boat in front. Thing is my boat has quite a slow tickover, 800 rpm and snail pace, but we still kept catching it and even the Mrs (who is really steady with the throttle) was getting frustrated with the continual neutral / tickover thing. Then again today with another boat from the same hire company from one end of wast hill through the tunnel to Kings Norton doing the same thing. Perhaps they're trying to save diesel !

There have been several posts along similar lines. Just a thought, but didn't any of you attempt an overtaking manoevre?

[Wanderer Vagabond]

Just now, PhilR said:

There have been several posts along similar lines. Just a thought, but didn't any of you attempt an overtaking manoevre?

I passed the slow boat on the GU but if they decline to co-operate it becomes problematic. I passed him on a decent straight stretch but as my (minimal) bow wave pushed against the stern of his boat it deflected his boat towards me, similarly as the bow wave pushed against his bow it then deflected him off into the bank. Overtaking is fine on rivers, but on canals it does really need the co-operation of the boat being overtaken.

[GUMPY]

13 minutes ago, PhilR said:

There have been several posts along similar lines. Just a thought, but didn't any of you attempt an overtaking manoevre?

Passing in a tunnel can be interesting

I've done it in Blisworth in the "new" section, the other steerer wasn't impressed.

 

[PhilR]

15 minutes ago, Wanderer Vagabond said:

I passed the slow boat on the GU but if they decline to co-operate it becomes problematic. I passed him on a decent straight stretch but as my (minimal) bow wave pushed against the stern of his boat it deflected his boat towards me, similarly as the bow wave pushed against his bow it then deflected him off into the bank. Overtaking is fine on rivers, but on canals it does really need the co-operation of the boat being overtaken.

We have to thank Bernoulli for his explanation of that effect!

 

But, yes overtaking on the canals does need co-operation

[Rob-M]

On 14/10/2020 at 10:58, BWM said:

Unique to this time of year are those travelling with a ball of leaves on the prop, there seem to be many who are unaware of the build up and its effects on progress. 

Met several boats last week where the steerer appeared to be oblivious to the build up of leaves they must have been dragging along with them, they were moving very slowly with most of their prop wash going sideways.

[PhilR]

1 minute ago, Rob-M said:

Met several boats last week where the steerer appeared to be oblivious to the build up of leaves they must have been dragging along with them, they were moving very slowly with most of their prop wash going sideways.

I see it every day at home. We are surrounded by oak, beech and ash trees. It is easy to see whether the boats have left hand or right hand props, although most boaters seem oblivious to it.