How do I find a good boat builder?

[Athy]

1 minute ago, Nightwatch said:

Mike. Please accept my apologies. I know you're not a naff person.

I really can't see that any apology is necessary! As for my level of naffness, the description I like is "slightly imperfect real person", bestowed on me by a fellow forum member some months ago. But then he hadn't seen my sweater.

We think we're coming over to the boat this weekend. I'll be in touch by p.m. when we have fixed our plans (which, with us, can be a last-minute thing), but typically we would put in an appearance in the Brasenose Arms about 6 p.m. on either Friday, or Saturday, or both.

[MtB]

I made no comment about any naffness or otherwise of Mr Athy's Trojan jumper. I simply asked if he was wearing it!

[Ampen Spekersohn]

24 minutes ago, cuthound said:

When a battery is flat it will, provided the alternator can supply it, take a huge amount of current, hundreds of amps even for a relatively small battery. The more amps the alternator has to deliver, the more difficult it is to turn, hence the more power needed to turn it.

If the engine has a low power rating, its output will be mainly taken up driving the alternator,  leaving less power available to drive the boat.

To avoid this problem it is best to use a modern relatively high powered engine, such as a Beta 43 rather than an asthmatic old one 

Hate to disagree with this comment, but the alternator can only ever deliver up to its maximum rated output. Even then, achieving maximum output depends upon it being rotated at very high speed, typically 6,000-8,000rpm. So if you have say, a 70A alternator, it will take 70*12= 840W. Allowing for system losses, belt friction, heat, etc, at maximum output, the total power requirement would be around 1000W, or 1.3HP.

A loading of 1.3HP on an engine of 20-odd HP shouldn't really make that much difference. Also, bear in mind that you are unlikely to have a pulley ratio which will deliver anything like 6,000rpm at a fast tickover, so an alternator rated 70A @ 6,000rpm will probably only deliver around 40A.

There are specialised marine alternators (e.g. Balmar) which unlike an automotive one, are designed to produce full output at much lower revs. But they are wallet-busting expensive, typically £900+. But this graph shows a typical performance curve for an automotive unit:

http://www.balmar.net/why-cdi/the-balmar-difference/

If you have a 230V alternator, such as a Travel Power, this could load up your engine rather more. At full power, 3.5KW equates to 4.6HP, which is going to consume a bigger chunk of your engine output, but it still shouldn't be enough to stop you moving!

[cuthound]

Just now, Ampen Spekersohn said:

Hate to disagree with this comment, but the alternator can only deliver up to its maximum rated output.

That is why I said "provided the alternator  can supply it" in the first line of my post. 

I am sure Athy won't mind me saying that he isn't technically minded, so I was trying to provide him with a simple explanation of why an alternator demands more power to rotate it when an engine is first started.

Also as I am sure you must know, an engine will only deliver its rated power over a fairly narrow rev range, typically near to maximum rpm. Most engines in narrowboats rarely if ever get to the revs necessary to develop their maximum power, so the loading effect of an alternator will be more pronounced. 

My Beta 43 can be heard to labour when a large electrical load is suddenly imposed on it at tickover,  for example plugging in an electric kettle.

[Alan de Enfield]

17 minutes ago, cuthound said:

an engine will only deliver its rated power over a fairly narrow rev range, typically near to maximum rpm

My engines RPM Vs HP ( I have RPM vs fuel consumption and BHP Vs RPM plotted out on numerically and on graphs on excel spreadsheets)

RPM	HP
1000	8.6
1100	10.0
1200	14.3
1300	17.9
1400	22.9
1500	27.2
1600	34.3
1700	39.3
1800	47.2
1900	55.8
2000	65.8
2100	76.0
2200	87.2
2300	97.2
2400	111.5
2500	126.6
2600	143.0

Edited July 10, 2017 by Alan de Enfield

[Ampen Spekersohn]

2 hours ago, Mike the Boilerman said:

Yes people often don't realise the electricity from an alternator is not free. The alternator pulley resists being turned according to the electrical load on it, and the effort to turn it has to be paid for in diesel. Lets run some numbers.

When my alternator is delivering 45A at 26v just after starting the engine, that is 45V x 26A= 1170W. This is enough to stop the engine revs rising above about 200rpm.

1170W converted to HP is however is 1170 / 746 = 1.6hp. So if we assume an alternator efficiency of say 80%, this means my engine is only producing 2hp at this balance point where full throttle won't make the engine spin any faster than the 200rpm.

This surprises me given it is a 22hp engine at 750rpm. Given the torque curve is roughly straight and flat, 200rpm ought to equate to 5.8hp. So I must conclude power output when stone cold IS substantially reduced. To 2hp in fact! This must be due to losses caused by thick oil, and other minor loads on the engine like the oil and water pumps. Or more likely possibly poor and incomplete combustion in a cold combustion chamber. Surprising figure though. Can anyone spot an error in my figures?

Anyway I was getting off the point. The 2hp my alternator is drawing at this point is being supplied by burning diesel. Given that a boat cruising at a steady 3mph typically uses about 6hp for this and burns a litre an hour, 2hp is probably using about 1/3 of a litre an hour just to charge my battery. 

This is one of the reasons I'm veering towards the JP3 - to give a bit of surplus for power generation, battery charging, etc. I wouldn't want to find that I'm heading up a river and then slow to a crawl because her ladyship is using the microwave!

I fully accept that generated power is not free. In fact this is the reason I will go for a fuel tank of at least 600L capacity - to enable a direct delivery of red from Boiler Juice - currently at around 50p/L with no 60/40 split, instead of the scary prices demanded by many marinas. At least at that price, it will cause less angst to use a few 'luxury' appliances!

 

[MtB]

On 10/07/2017 at 12:14, Ampen Spekersohn said:

This is one of the reasons I'm veering towards the JP3 - to give a bit of surplus for power generation, battery charging, etc. I wouldn't want to find that I'm heading up a river and then slow to a crawl because her ladyship is using the microwave!

I fully accept that generated power is not free. In fact this is the reason I will go for a fuel tank of at least 600L capacity - to enable a direct delivery of red from Boiler Juice - currently at around 50p/L with no 60/40 split, instead of the scary prices demanded by many marinas. At least at that price, it will cause less angst to use a few 'luxury' appliances!

 

 

Do they sell red diesel then? Sounds to me as though they are flogging heating oil which is similar, but not the same. 

A JP3M will probably run fine on it but other things like Ebersputters won't. 

[Athy]

4 minutes ago, Mike the Boilerman said:

 

Do they sell red diesel then? Sounds to me as though they are flogging heating oil which is similar, but not the same. 

 

This surprised me too: we use them to supply the heating oil (kerosene 28) for our Rayburn, but I was not aware that they dealt in red diesel.

However, their web site confirms that they do.

[cuthound]

17 minutes ago, Ampen Spekersohn said:

This is one of the reasons I'm veering towards the JP3 - to give a bit of surplus for power generation, battery charging, etc. I wouldn't want to find that I'm heading up a river and then slow to a crawl because her ladyship is using the microwave!

I fully accept that generated power is not free. In fact this is the reason I will go for a fuel tank of at least 600L capacity - to enable a direct delivery of red from Boiler Juice - currently at around 50p/L with no 60/40 split, instead of the scary prices demanded by many marinas. At least at that price, it will cause less angst to use a few 'luxury' appliances!

 

"Boiler juice" is not the same as gas oil (AKA red diesel). Heating oil is actually kerosene and is thinner than gas oil. It is often know as 35 second oil, because it that is its viscosity when measured at a second temperature throughost a standard sized hole.

A more detailed explanation of the various oils is here.

https://www.crownoil.co.uk/faq/fuels-the-what-who-why-of-fuel/

24 minutes ago, Alan de Enfield said:

My engines RPM Vs HP ( I have RPM vs fuel consumption and BHP Vs RPM plotted out on numerically and on graphs on excel spreadsheets)

RPM	HP
1000	8.6
1100	10.0
1200	14.3
1300	17.9
1400	22.9
1500	27.2
1600	34.3
1700	39.3
1800	47.2
1900	55.8
2000	65.8
2100	76.0
2200	87.2
2300	97.2
2400	111.5
2500	126.6
2600	143.0

Thanks Alan, your table demonstrates my point perfectly, even though your engine(s) are not typical canal boat engines 

Edited July 10, 2017 by cuthound
To unmangle the effects of autocorrect.

[Ampen Spekersohn]

17 minutes ago, Mike the Boilerman said:

 

Do they sell red diesel then? Sounds to me as though they are flogging heating oil which is similar, but not the same. 

A JP3M will probably run fine on it but other things like Ebersputters won't. 

Oh yes. You just specify it on the quote page. Current price is £249.38 for 500L delivered. Under 50p/litre.  

9 minutes ago, cuthound said:

"Boiler juice" is not the same as gas oil (AKA red diesel). Heating oil is actually kerosene and is thinner than gas oil. It is often know as 35 second oil, because it that is its viscosity when measured at a second temperature throughost a standard sized hole.

Boiler Juice is the name of the company. They also sell red diesel. Have a look! https://www.boilerjuice.com/

[MtB]

On 10/07/2017 at 12:39, Ampen Spekersohn said:

Oh yes. You just specify it on the quote page. Current price is £249.38 for 500L delivered. Under 50p/litre.  

 

Blimey that's cheap! Shame my diesel tank is a ridiculous 90 litres exactly.

(Can you guess how I know this?)

[cuthound]

3 minutes ago, Ampen Spekersohn said:

Oh yes. You just specify it on the quote page. Current price is £249.38 for 500L delivered. Under 50p/litre.  

Boiler Juice is the name of the company. They also sell red diesel. Have a look! https://www.boilerjuice.com/

Sorry, my misunderstanding. When you referred to boiler juice I thought you meant heating oil. 

[WotEver]

1 hour ago, Ampen Spekersohn said:

bear in mind that you are unlikely to have a pulley ratio which will deliver anything like 6,000rpm at a fast tickover

Au contrair, many decent narrowboat setups are pulleyed to achieve just this. 

[Athy]

6 minutes ago, cuthound said:

Sorry, my misunderstanding. When you referred to boiler juice I thought you meant heating oil. 

They are a company which sees to act as a sort of umbrella organisation or agent for many regional oil suppliers. When we place an order with them, they search for the local supplier who offers the cheapest price on that day - so our oil may be delivered to our house by any one of three different companies. In addition, if several orders are placed in the same area - on the same tanker run, I suppose - they often apply a further price reduction. But, as noted above, their minimum order is for 500 litres. They WILL deliver less in an emergency but the cost per litre is much higher. We've used them ever since our first Rayburn was installed nigh on ten years ago.

[Ampen Spekersohn]

Really? If you have a vintage engine spinning at say, 380rpm at tickover, you'd need a pulley of 15:1! Alternators also have a maximum rotation speed, which must not be exceeded when the engine is going maxi chat. So if you had a 15:1 pulley setup, this would go way beyond its limits. Even with a vintage engine maxxing at 1,000rpm, this would give 15,000rpm to the alternator. So as ever, a compromise is needed.

One way to overcome this conundrum (this is my planned approach) is to have a single 230V alternator of 3.5KVA to 5KVA connected to a DSR regulator. This gives stable 230V AC at a wide range of engine speeds. The output from that can be fed to a high power battery charger which can deliver up to 120A @ 12V. E.g. Victron Combi. This setup can also charge the starter battery and can use combined generator/inverter power to cope with high AC loading.

[MtB]

This doesn't really match my personal experience. My alternator pulley ratio is 2.5:31 (I just measured it!) or 12:1. 

My alternator reaches its maximum specified output at about 250rpm on the engine from memory. Certainly no more than 300 rpm, so that's full output at a pulley speed of no more than 3,700rpm.

Edited July 10, 2017 by Mike the Boilerman

[Ampen Spekersohn]

7 minutes ago, Athy said:

They are a company which sees to act as a sort of umbrella organisation or agent for many regional oil suppliers. When we place an order with them, they search for the local supplier who offers the cheapest price on that day - so our oil may be delivered to our house by any one of three different companies. In addition, if several orders are placed in the same area - on the same tanker run, I suppose - they often apply a further price reduction. But, as noted above, their minimum order is for 500 litres. They WILL deliver less in an emergency but the cost per litre is much higher. We've used them ever since our first Rayburn was installed nigh on ten years ago.

Exactly. Obviously, their main business is heating oil. Which conveniently brings me to my next big design dilemma. I would really like the new boat to be gas-free. I accept it has its advantages, particularly for cooking, but I don't like the stuff. It's potentially dangerous and it's getting very expensive. If I can get my diesel at a sensible price, it makes sense to use it for all my energy needs. 

So I've been looking at diesel-fired ranges, such as the Heritage. The distributors assure me it can run successfully on red diesel, as long as higher pressure is supplied to the burners. A range like this would do all the cooking, as well as hot water and heating. Does anyone have any real-world experience of these machines? Are they reliable? I like the look of Heritage because it's well insulated (not too much excess heat in summer) and fast to cooking temperature. But are they noisy? If this can be made to work successfully, it eliminates the need for gas bottles and will free up the gas locker for other storage too. The cost of a Heritage is not much more than a Hurricane plus a decent gas cooker.

My plan is to install a boiling water tap which will take care of the urgent early morning cuppa.

The other line of thinking is to (reluctantly) revert to a gas cooker plus a Hurricane for heating, which is apparently more reliable on red diesel than other makes.

Input welcomed!

[Nightwatch]

1 hour ago, Mike the Boilerman said:

I made no comment about any naffness or otherwise of Mr Athy's Trojan jumper. I simply asked if he was wearing it!

Mike. I was just wriggling out of a corner I thought I was in. Apparently not though. 

Mike (Athy). We will probably have moved on by Friday AM as we are venturing onto the K&A. We want to be near Newbury by about the 8th of next month. Goodness knows how long it'll take us as we have a great variations of progress. Sometimes slow,sometimes very slow.

Would have been great to touch base with you.

Martyn & Margaret.

[WotEver]

49 minutes ago, Mike the Boilerman said:

This doesn't really match my personal experience. My alternator pulley ratio is 2.5:31 (I just measured it!) or 12:1. 

My alternator reaches its maximum specified output at about 250rpm on the engine from memory. Certainly no more than 300 rpm, so that's full output at a pulley speed of no more than 3,700rpm.

Exactly. An 'average' alternator will give around 75% of its rated output at around 3000rpm. So a 150A alternator will be supplying 120A at that speed. A slow-revving vintage engine is unlikely to do much more than double its tickover speed at max revs (rarely 3 times) so the alternator at that time would be rotating at somewhere between 6000 and 9000 rpm. Well within its design limits. 

'Correctly pulleying' the alternator doesn't mean to 'make it do 6000 rpm at tickover'. That would be a perfect example of incorrect pulleying. 

[WotEver]

51 minutes ago, Ampen Spekersohn said:

My plan is to install a boiling water tap which will take care of the urgent early morning cuppa.

Which uses around 240Wh/day even when not used (to keep the water hot in the tank). That's over 20Ah/day on a 12V system. 

Not necessarily a problem, just something to bear in mind. 

[MtB]

On 10/07/2017 at 14:06, WotEver said:

Exactly. An 'average' alternator will give around 75% of its rated output at around 3000rpm. So a 150A alternator will be supplying 120A at that speed. A slow-revving vintage engine is unlikely to do much more than double its tickover speed at max revs (rarely 3 times) so the alternator at that time would be rotating at somewhere between 6000 and 9000 rpm. Well within its design limits. 

'Correctly pulleying' the alternator doesn't mean to 'make it do 6000 rpm at tickover'. That would be a perfect example of incorrect pulleying. 

 

K series Kelvins are the exception which proves your rule. 

They tick over at 170rpm, and run up to peak power at 750rpm. A ratio of 4.4:1.

[Athy]

8 minutes ago, Mike the Boilerman said:

 

K series Kelvins are the exception which proves your rule. 

 

Duly noted.

[MtB]

On 10/07/2017 at 14:49, Athy said:

Duly noted.

 

Good. Got one over on Teacher as my use of the term is clearly logically inconsistent. 

As n e philosopher kno.

[Athy]

Just now, Mike the Boilerman said:

 

Good. Got one over on Teacher as my use of the term is clearly logically inconsistent. 

Oh, not to me - I glazed over when the technical discussion got under way.

 

[WotEver]

13 minutes ago, Mike the Boilerman said:

 

K series Kelvins are the exception which proves your rule. 

They tick over at 170rpm, and run up to peak power at 750rpm. A ratio of 4.4:1.

Ahhhhhbuttt... yours is 'correctly pulleyed' so that you have the compromise of high-enough output at double-tickover without over spinning the alt at full chat. 

Which proves my point about a correctly set up system having the correct pulley ratio.