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What RPM should I be cruising at?


Herdwick

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6 minutes ago, Ronaldo47 said:

From fluidics lectures at college many years ago, I learned that, counterintuitively, the streamline configuration for lowest flow resistance, for sub-sonic flow at least, is a round nose facing the flow and a tapered tail downstream.  I noticed that that is how the footings of the piers of the railway viaduct that crosses the (non-tidal) River Chelmer in Chelmsford are constructed.  

That's exactly why submarines are shaped like that, but this only really applies for submerged bodies -- which a narrowboat isn't, hopefully ?

 

When a hull pierces the surface and creates a wake the lowest drag shape for a bow is different, and depends on speed. For relatively slow/weak wake displacement ships like big container ships (and narrowboats) a sharp bow isn't needed, which is why big container ships (where lowest drag is critical) don't have one, they're relatively blunt and rounded. For high-speed vessels with a big wake a sharp bow is preferable, but a narrowboat would probably need to get up to tens of knots for this to happen...

 

At the stern it's important for any speed to have a gradual taper with a clean water entry to the prop, and there are well-known rules about this which many narrowboat hulls completely ignore ?

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1 hour ago, Ronaldo47 said:

From fluidics lectures at college many years ago, I learned that, counterintuitively, the streamline configuration for lowest flow resistance, for sub-sonic flow at least, is a round nose facing the flow and a tapered tail downstream.  I noticed that that is how the footings of the piers of the railway viaduct that crosses the (non-tidal) River Chelmer in Chelmsford are constructed.  

Classic 'cod's head, mackerel tail', or in the old boat design cliches, 'a fine run aft' to which there must be all sorts of jokes none of which I can think of right now.

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Your hull is a tubby boat, no pretense of swims at the stern and a blunt bow. It also looks to be a shallow draught with a small prop.

It is what it is, enjoy it.

 

Look at the hull shape of a true old Josher boat, its totally different which is why they swim so much better.

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12 minutes ago, ditchcrawler said:

I still bet there is something wrong and it will go faster

Not so sure, when we were on the Lancaster in 2019, I doubt we went above 2.5 mph, it is quite a shallow canal.  With the same rpm we were doing down stream on the Avon today at 4.5 mph, say 4 mph through the water.  We had no issue crossing the Ribble, and the OP’s boat may well be be fine too.  It is all down to what it does in deep water, and as I suggested, he has Glassom dock as a convenient test ground. That will give an idea how it performs, if he can get say 5mph there I would suggest it would be OK for the Ribble.  If it will only do 2.5 mph in deep water, then there is something wrong of course.

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3 hours ago, john6767 said:

Not so sure, when we were on the Lancaster in 2019, I doubt we went above 2.5 mph, it is quite a shallow canal.  With the same rpm we were doing down stream on the Avon today at 4.5 mph, say 4 mph through the water.  We had no issue crossing the Ribble, and the OP’s boat may well be be fine too.  It is all down to what it does in deep water, and as I suggested, he has Glassom dock as a convenient test ground. That will give an idea how it performs, if he can get say 5mph there I would suggest it would be OK for the Ribble.  If it will only do 2.5 mph in deep water, then there is something wrong of course.

Racing round Glasson dock is also very exhilarating, especially a hand brake turn to line up for the jetties!   

 

 

 

glasson2.jpg

Edited by Chagall
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On 16/06/2021 at 15:42, Tony Brooks said:

 

As advised by someone else. Go to Glasson docks and see what it will do on wide deeper water. Even a car satnav will give you a decent indication of speed.

Get the GPS test app for your phone. Mine is set for 0-10mph and I get a good idea of average speed - usually 3mph so 20 min between mileposts.

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  • 2 years later...

Sorry for an off topic, I have tried to send you a personal message but as I am new to the forum rules doesn't allow it. Anyway I have Nanidisel engine and some "electrician" who was trying to fix control pannel has messed up all wiring. As engine has almost 40 years I have lost the manuals and couldn't find anything online. During my search I have found your photo of the rpm meter which looks the same as mine so I guess the control pannel should be the same. Could you please take a photo of the back side of the control pannel so I can see how wirinig is done. Thank you in advance.

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3 minutes ago, frankof said:

Sorry for an off topic, I have tried to send you a personal message but as I am new to the forum rules doesn't allow it. Anyway I have Nanidisel engine and some "electrician" who was trying to fix control pannel has messed up all wiring. As engine has almost 40 years I have lost the manuals and couldn't find anything online. During my search I have found your photo of the rpm meter which looks the same as mine so I guess the control pannel should be the same. Could you please take a photo of the back side of the control pannel so I can see how wirinig is done. Thank you in advance.

@Herdwick has not logged in to the site for over a year. I've tagged them to increase the possibility that this question might be seen.

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4 minutes ago, frankof said:

Sorry for an off topic, I have tried to send you a personal message but as I am new to the forum rules doesn't allow it. Anyway I have Nanidisel engine and some "electrician" who was trying to fix control pannel has messed up all wiring. As engine has almost 40 years I have lost the manuals and couldn't find anything online. During my search I have found your photo of the rpm meter which looks the same as mine so I guess the control pannel should be the same. Could you please take a photo of the back side of the control pannel so I can see how wirinig is done. Thank you in advance.

 

I suspect that it may be easier to trace your cables and understand how the circuits work, rather than copy another boat's panel wiring that may or may not be the same as yours.

 

All instruments will normally have a positive and negative feed from the ignition switch, these are often looped from one to the next. There will be another terminal that has a wire from the sender, or in the case of  rev counter from the W or a phase tap on the alternator. There may or may not also be an illuminating bulb in each but a canal boat does not really need those. If you do I would presume the positives would be looped from the Tunnel lamp switch.

 

The warning lamps are a but more complicated if you have a single warning lamp buzzer, but if not or if you are happy with more than one buzzer you need a positive feed from the ignition switch, again usually looped. Another wire to the relevant switch (temp or oil pressure) while the charge light's second cable will normally go to the alternator D+ terminal.

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18 hours ago, Tony Brooks said:

 

I suspect that it may be easier to trace your cables and understand how the circuits work, rather than copy another boat's panel wiring that may or may not be the same as yours.

 

All instruments will normally have a positive and negative feed from the ignition switch, these are often looped from one to the next. There will be another terminal that has a wire from the sender, or in the case of  rev counter from the W or a phase tap on the alternator. There may or may not also be an illuminating bulb in each but a canal boat does not really need those. If you do I would presume the positives would be looped from the Tunnel lamp switch.

 

The warning lamps are a but more complicated if you have a single warning lamp buzzer, but if not or if you are happy with more than one buzzer you need a positive feed from the ignition switch, again usually looped. Another wire to the relevant switch (temp or oil pressure) while the charge light's second cable will normally go to the alternator D+ terminal.

Thank you very much. Unfortunatelly I don't know almost anything about electric and I don't want to touch anything. The electrician who tried to repair the mess didn't found how the wirings go so if I got that photo I would show it to him for a help. I will show your answer to him, hope it will be of a help.

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8 hours ago, frankof said:

Thank you very much. Unfortunatelly I don't know almost anything about electric and I don't want to touch anything. The electrician who tried to repair the mess didn't found how the wirings go so if I got that photo I would show it to him for a help. I will show your answer to him, hope it will be of a help.

It may be easier to find another electrician 

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8 hours ago, frankof said:

Thank you very much. Unfortunatelly I don't know almost anything about electric and I don't want to touch anything. The electrician who tried to repair the mess didn't found how the wirings go so if I got that photo I would show it to him for a help. I will show your answer to him, hope it will be of a help.

 

The electrical course notes on my website might help you understand what goes where, they deal with the individual circuits rather than one big diagram, because I think that way is easier to understand. You are free to print them out for our own use.  www.tb-training.co.uk.

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I am in Garstang with similar Hallmark Inlander boat and a fair bit of cruising experience canal and tidal. I haven’t time for long reply but please PM me if interested  for a chat. I too did speed trials at Glasson a few years ago!

I am in Garstang with similar Hallmark Inlander boat and a fair bit of cruising experience canal and tidal. I haven’t time for long reply but please PM me if interested  for a chat. I too did speed trials at Glasson a few years ago!

I am in Garstang with similar Hallmark Inlander boat and a fair bit of cruising experience canal and tidal. I haven’t time for long reply but please PM me if interested  for a chat. I too did speed trials at Glasson a few years ago!

I am in Garstang with similar Hallmark Inlander boat and a fair bit of cruising experience canal and tidal. I haven’t time for long reply but please PM me if interested  for a chat. I too did speed trials at Glasson a few years ago!

I am in Garstang with similar Hallmark Inlander boat and a fair bit of cruising experience canal and tidal. I haven’t time for long reply but please PM me if interested  for a chat. I too did speed trials at Glasson a few years ago!

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5 minutes ago, Peugeot 106 said:

I am in Garstang with similar Hallmark Inlander boat and a fair bit of cruising experience canal and tidal. I haven’t time for long reply but please PM me if interested  for a chat. I too did speed trials at Glasson a few years ago!

I am in Garstang with similar Hallmark Inlander boat and a fair bit of cruising experience canal and tidal. I haven’t time for long reply but please PM me if interested  for a chat. I too did speed trials at Glasson a few years ago!

I am in Garstang with similar Hallmark Inlander boat and a fair bit of cruising experience canal and tidal. I haven’t time for long reply but please PM me if interested  for a chat. I too did speed trials at Glasson a few years ago!

I am in Garstang with similar Hallmark Inlander boat and a fair bit of cruising experience canal and tidal. I haven’t time for long reply but please PM me if interested  for a chat. I too did speed trials at Glasson a few years ago!

I am in Garstang with similar Hallmark Inlander boat and a fair bit of cruising experience canal and tidal. I haven’t time for long reply but please PM me if interested  for a chat. I too did speed trials at Glasson a few years ago!

 

 

You seem to be a regular visitor to Garstang !

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35 minutes ago, Alan de Enfield said:

 

 

You seem to be a regular visitor to Garstang !

Yes mooring is there or are you being sarky re repetition of reply!  Wrote long reply to Herdwick but it crashed and am short of time hence asking for pm if he’s still interested.

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Just picked up on this one, yep, there are problems with the top of the water being too close to the bottom, but when I had a 30 ft boat I found it went  a lot better in the summer when the water tank (front mounted) was full and kept the bow down, than in the winter when it was empty and the bow was up......avoiding the bow trying to 'sit' on the water. - 30ft boat, 1.5BMC ......Tring Summit.

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20 hours ago, ditchcrawler said:

It may be easier to find another electrician 

I have also thought about that idea, I will give him one more chance and if he don't suceed I will have to find somebody else.

20 hours ago, Tony Brooks said:

 

The electrical course notes on my website might help you understand what goes where, they deal with the individual circuits rather than one big diagram, because I think that way is easier to understand. You are free to print them out for our own use.  www.tb-training.co.uk.

Thank you for your help. There is a lot of stuff on your website. This will be a good material for learnong about electric. I will try to check it out but it is quite comprehensive and it would take a long time to find a solution to my problem. For now I will try to find another electrician after I give one more chance to this one. Just to congratulate you for sharing all this knowledge on your website without any compensation.

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the chances are that the solution is likely to be fairly simple, so give us a rough location in case a more knowledgeable member is able to pop over and take a look. I trust that you are aware that there are no qualification for a so-called marine electrician working on inland boats.

 

I think that all we know is that the rev counter is not working, but are there any other symptoms. how many other instruments and warning lights are not working. 

 

Are you aware that a faulty alternator, that may still appear to be charging, will cause the rev counter not to work.

 

If you are within about 30 miles of Reading WITH close by car PARKING, I would happily pop over and take a look FOC. (you to do any work under instruction).

 

PS often the rev counters will "stick" at whatever reading it was showing the instant the engine/ignition was turned off. That is normal, it should drop to zero revs the moment the ignition is turned on again.

Edited by Tony Brooks
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