Robin2
-
Posts
933 -
Joined
-
Last visited
-
Days Won
1
Content Type
Profiles
Forums
Events
Gallery
Blogs
Store
Posts posted by Robin2
-
-
Hi All.
Iam in the same boat at min myself. I have on Friday found the boat i wont. a 1987 48ft semi trad. That has been extremely well looked after. last had a survey in 2007 but had a hull suvey 8 months ago whilst being blackened. the boat gets blacked every year including bottom plate. has a new vetus engine in 2008!
I asked the advice of the broker. who said we would prefer you to have a survey but its my call!
Well don't fight over it - that will just push the price up
-
Well bang goes that theory.Found paperwork for engine from 1991-peak torque 85Nm approx at 2000rpm (approx).Max power 35bhp at 3000rpm only making 18bhp at 2000rpm.However same graphs show fuel consumption 3.5ltr p.h. at 1500 revs which is plain wrong.
So I have an engine which is nominally 35bhp but which for 95% of its life never gets above 18bhp.
Something wrong with the maths here.
If the maximum torque is at 2000 rpm and there is 18hp at 2000 rpm then there can't be more that 27hp at 3000 rpm.
Also (I hope my maths is right) 85Nm of torque at 2000 rpm = 8.9kW or 11.9 hp.
-
But that's not a 230 volt fridge.
The only difference between a 230v and 12/24v fridge is the inverter loss which has nothing to do with the manufacturer's estimate of annual energy consumption.
-
So...
After all that there seems to be a consensus that these brackets are the wrong way up
and this is the correct way
but there is still no rational explanation for either type.
C'mon historians --- help
-
Absolutely none at all. I linked it to the OP's question and when I hit the post button it only posted half of what I'd written. So I went back and edited it (you'll see that's marked) when I reposted it I didn't check that it was still linked to the right one. I removed the link completely as I believe my comments stand alone without need for any reference.
My mistake, apologies, have a cold beer on me
No problem!
-
I assumed that to be 320 watts over a 24 hour period.
This is actually 320 watt-hours over a 24 hour period, or an average consumption of 13.3 watts.
I agree with Gibbo's comment about the unreality of the manufacturer's figures - though mine does not seem to be as bad as 50% worse.
By the way are you using a fancy editor to create your posts or do you just enjoy the masochism of putting different font codes etc on each line?
-
If you look at the rudder on a butty you will understand the problem. The normal rudder on a modern powered narrowboat is far too small to have any useful effect without the flow of water from the propeller. The rudder is useless when reversing because the water flow into the propeller is spread over a large area and is not focused on the rudder.
-
All engines have sweet spots where they are happy to sit all day.I find that as a rule of thumb this is just below the point where secondary vibration and noise first begin to become irritating.You have probably sussed out where this is for your boat so stick with it.If you looked at a torque curve for your engine I would be very surprised if maximum relaxed cruising revs didn't bear a strong correlation to peak torque (and probably peak fuel economy).
Vibration has little to do with efficiency. It depends on how well the designers balanced the engine. With anything less than 6 cylinders there is going to be a lot of vibration and you are quite right to say that it is worst at certain engine speeds and smoothest at others. If the designers bothered I would expect them to try to minimize vibration at the speed the engine would usually operate - probably closer to full power than maximum torque. However they may in practice be more concerned to minimize vibration at maximum rpm so the engine does not break in the warranty period.
None of this is relevant for a boat unless the boat builder also carefully (or accidentally) matched the gearbox and propeller to obtain a suitable cruising speed at the smoothest engine rpm. What cruising speed should he choose? In practice it could well be that when the engine is at its most efficient point the boat goes too fast and wastes power, even though the engine is creating it efficiently. Alternatively if the gearbox and propeller are carefully matched for cruising the engine may not be able to attain full power and the boat would be underpowered on rivers.
The short answer is that the slower a boat goes the more mpg you get. You need to balance fuel against frustration.
-
Feel as justified as you like
but no way are they going to be used for lifting Here is a closer look for anyone who wants to copy them
In Steve Hudson's build spec I think they are referred to as bulkhead cabin rings.
Jeez ... all I meant was that my mistake was not unreasonable. I knew from the first glance that they are not actually suitable for lifting - but they might have been poor copies of brackets that were intended for lifting.
The pictures from the old boat suggest that the SH version is just a fanciful ornament.
And (referring to other comments) I'm still not convinced that the downward facing brackets were simply intended for convenience when mooring. That usage would not require them to be angled downwards, or to be as strong. It could well be that they were designed for another purpose but were used as convenient mooring points.
-
If efficiency in car engines is measured by mpg, then surely cutting edge engines must be the most efficient ? Take a look at e.g. BMW diesels - astonishing mpg and power compared with even 10 years ago. I think their 2 litre is some 163 bhp now whereas the Beta is around a 1/4 of that - I know that is a loose comparison and of power outputs not efficiency, but I imagine that the BMW engine would be more efficiently converting diesel to kWhs if each were put on a test jig.....
Nick
MPG measures the efficiency of the complete package taking account of power losses in the transmission, tyres etc and the effect of air resistance. The huge improvements that have been achieved are partly because they started from a very low base.
The relationship between 2 litres and 163 bhp says nothing about efficiency. Car engines are not designed to run continuously at their maximum power whereas the Beta and Isuzu etc diesel engines are - which is why their rated power outputs are much lower.
I would not expect much difference between the BMW and Beta engines in terms of specific fuel consumption - grams/kW-hr. If BMW have figured out a significantly better way the others will quickly copy them. Most of them use Bosch injection equipment anyway. I previously had a workshop manual for a Yanmar engine and I was amazed at the fine tolerances to which it was manufactured. I'm sure the Beta (Kubota?) and Isuzu engines are as good.
ETA why is it only after posting that you spot the typos?
-
I'm still not sure about this...?
I was hoping for some more knowledgable people to come along ..but here goes :
Still can't see your correlation between 240 volt and 12 volt ?
Sorry if I'm being thick...
If you draw 1 amp on 240volts...via an invertor...your invertor will take 20 amps from a 12 volt battery..to produce this 240 volt at 1 amp.
In other words..your 1.4 amp an hour fridge on 240 volt...over 24 hours...will take 1.4 x 24 x 20 = 672 amps from 12 volts.
It appears to me..(actual appearing may vary from description)....that you still need the 'hours' figure worked into this.
I 'think'..but am sorry if I'm wrong....that you think...(they think ?..nah)..that an amp on the 240 volt draws an amp from the 12 volt...but this is not so...
You come back to the wattage again...
Look on the back of your appliance...and see its wattage rating while running..
If its a microwave.....and it says '240 volt...1000 watts'...then it is drawing 4.16 amps while running on 240 volts...divide wattage by voltage = current (amps)
To supply this from an invertor..(ignore loss)...you must take 1000 watts from your 12 volt batteries...
BUT...instead of dividing the wattage by 240 volts..to get 4.16 amps..you have to divide the wattage by 12 volts...
That is a wopping 83 amps......and that is what you are taking (losses ignored)...from the 12 volt batteries..
If your mini freezer draws 2 amps while running...( and was continuous) and is 240 volts...that is 240 x 2 = 880 watts...in an ideal hour...
Running that on the invertor...from 12 volts...you divide 880 watts by 12v = 73 amps in an hour...!!
PLEASE...is there somebody more inteligent here...can help...a drownng Bob !!
bob
Gibbo selected a small piece out of this. Let me focus on a different piece.
The bit I have highlighted implies that the fridge consumes 336 watts. I'm sure you know this is far too much. Fridges are more likely in the 50 to 100 watt area while they are running and they only average maybe one third of that. Now if the above mentioned 1.4 amps is at 12v (rather than 240) it gives an average of 17 watts or about 50 watts when running if it runs for 20 minutes every hour.
On this basis I assumed that all of the amp-hour figures that Julynian quoted were at 12 volts, not 240v.
-
I moored near Sainsbury's for several days earlier this year without any trouble. I didn't try the area near Tesco's as that's a bit closer to the pubs. Tesco's is probably a little closer to the SVR but there's not much in it.
Enjoy the trains.
-
He will obviously do some calculations and I would have thought the question was to ascertain what worked for real paople than to be lectured on how to calculate consumption and conversion...
There seems to be circular logic here...
If you have an unlimited budget (for diesel, solar panels or batteries) you can blissfully ignore the watts and amps. If you want to get value for money they are unavoidable.
-
Efficiency ranging from 35% old engines to 50% new engines? I am no Diesel expert but from reading about engine efficiency I would be surprised if new diesels were not more efficient than older models. There is probably a trade-off though since older models were often 'over-engineered' to provide a long and reliable life. I came across this bit of info http://en.wikipedia.org/wiki/Diesel_engine#Power_and_fuel_economy
which also indicates that turbo and intercooling can make an engine more efficient - for a trade-off against servicing and reliability. I don't say that we should turbocharge though!
Efficiencies above 35% will be difficult to realize in practice. From reading the reference in the wiki article the higher efficiencies were in bigger engines. I think the low fuel consumption figure at the top of the article refers to a slow speed diesel in a large ship or power station.
Also bear in mind that engines are most efficient at a particular RPM and in boats and road vehicles it is unlikely that the engine will be working at exactly the right speed. For the Isuzu 3LB engine the specific fuel consumption varies between about 250 and 285 grams/kW-hr. That is an efficiency range of about 33% to 29%.
In a boat the greatest inefficiency is the propeller - even the best propeller - because it must slip in the water to create thrust - unlike a wheel which is in firm contact with the ground.
-
Hi Robin, I do understand that, I'll make sure I buy the best equipment too and even allow for additional panels in the future. I'm assuming of course that you don't have to purchase a separate MPPT for each panel. I would prefer to buy one unit say a MPPT at 500 watts but having only 400 watts of solar, so if I add an additional 100 watt panel I can do without purchasing another MPPT controller.
We have a solar shop locally I'm due to visit, so I'll get up to speed with all these options hopefully.
If you have space for more solar panels you might get more watt-hours for your £ by buying an extra panel rather than an mppt controller. And that would not prevent you from buying the mppt controller later. The economics require careful calculation unless investment funds are unlimited.
I have 3x80w panels that I got recently and I have no space for more - or I'm not willing to give up space for coal and bicycle. I am thinking carefully about mppt in my own perverse way.
-
I think if you tried lifting from those SH ones, you would quickly have a rather distorted cabin
Thats why I said "pretend" in post#4
As Alan (I think) said, they're for tying up, often temporary as you might with a centre line on a modern pleasure boat.
At that height they're clear of the deck and at a handy height for grabbing quickly, no stooping & no tripping hazard.
I'm not convinced. I can't see them being more convenient than a bollard at the bow or stern. To be useful at short notice they would need to have a rope through them all the time and the rope would get in the way. From that point of view an attachment on the roof and a rope on the roof would be better. Also I don't believe the working boats were managed so badly as to need anything done "quickly".
They look like the sort of connections you would need if you wanted to tie down the whole narrowboat e.g. as deck cargo on a bigger boat - but I don't imagine that was done very often
-
I also found the original chart for solarirradiance, really handy chart.
http://www.solarelectricityhandbook.com/solar-irradiance.html
Based on similar data these are the average daily amp-hr figures (at 12v) for each month for a 400 panel (assuming my spreadsheet is ok).
J 21.4
F 42.0
M 72.3
A 118.7
M 157.3
J 160.0
J 162.0
A 131.0
S 93.0
O 52.7
N 26.1
D 15.3
For planning purposes I believe these should be significantly reduced to allow for such things as being in a sub-average year, being moored in shade some of the time, birdsh*t on the panels etc etc.
-
If you don't have an mppt controller you will only get 20amps into your batteries (at 13v) or 260 watts.
We are talking peak/high noon amps here and I would say less up to 30% if you are not using a tracking/elevating system
I know, but that was not the point I was making. I had hoped to explain that the panels would not produce 400w in full sunshine unless the controller properly matches them to the batteries. I think Julynian understands the need to derate the maximum output (from 400w or from 260w) to allow for the UK weather.
-
Anyway, here's a genuine original pair of back end rings
I feel justified in my original supposition that the SH ones were for lifting.
I'm still not clear what the back end rings (as shown in the photo) were for. From the angle they're at they are clearly meant for a downward and outward load - such as fixing the boat to a mooring ring onshore. But doesn't the boat have cleats or bollards at the stern? And why would they design the mooring point so high up on the boat if it was meant to connect to something low down?
-
I am not sure that some of this is true. Surely the efficiency of the engine comes into the equation? If one engine is more efficient than the other then it will use less fuel for a given power won't it? All other factors being equal. This is mainly because the fuel is burnt less efficiently and some goes through without being burnt (or the power produced is not working towards turning the engine) - modern engines having pistons, chambers, exhaust etc refined for better fuel efficiency and should therefore propel a boat further for the same fuel. Where am I going wrong?
John
I did mention this in post#5
-
Perhaps it would be a good idea to ask the surveyor (before he earns any money) "If you give this boat a good report and we buy it and something goes wrong, what can we sue you for?". A good surveyor should not be offended and should be able to give a clear answer referenced to his draft contract.
Personally I would be happy with my own judgment of the condition of an engine and the electrical and plumbing systems - as well as the furnishings of course. What I can't do myself is measure the hull thickness and I don't have sufficient experience of poor welding quality or of propeller / shaft problems. Also I don't know the regulations so I would not spot an infringement that might make the boat hard to sell on.
So I would get a survey done and I would attend the survey and ask the surveyor any (vaguely relevant ) questions that sprang to mind.
Do what you want ....... it's your money.
If you're in the habit of spending large amounts of money on items which you yourself are not experienced in evaluating and it doesn't affect your ability to sleep at night, raise fears regarding your own safety or that of your family and friends or put a question in your head regarding how easy it will be to sell on afterwards then why break the habit of a lifetime?
In what way is your comment related to mine? If not, why make the link?
-
Hi Bob
The fridge is rated 117kwh per year It's a Bosch a+ rated so pretty economical. So I made that 117000 watts per year divided by 365 days is 320.54 watts per day divided by 24 hours = 13.35 watts per hour.
Is that the correct way?
I presume when you mentioned 27amps in your first post you meant 27 amps at 12v, not 27 amps at 230v.
You are using your terminology incorrectly - which may be adding to the confusion. Something that consumes 1 amp will consume 24 amp-hours in a day. One does not say "amps per hour" as that is meaningless. The correct expression would be "amp-hours per hour" but of course that is just "amps".
I believe it won't work to average the power consumption of your washing machine over several days. You need to do separate calculations for the days when you use the machine and the days you don't because the washing machine will seriously deplete your battery on the day it operates and if that is followed by several dull days you may found your battery SOC much lower than you bargained for.
You should be careful in interpreting the watts from your solar panels. What is the nominal voltage of the panels - lets assume its 20v to make the maths simple. That equates to 20 amps for 400 watts. If you have an mppt controller that should, in theory (but I have no practical experience yet) equate to 31 amps at 13v into your batteries. And I would assume at least a 10% efficiency loss from those figures. If you don't have an mppt controller you will only get 20amps into your batteries (at 13v) or 260 watts.
-
Perhaps it would be a good idea to ask the surveyor (before he earns any money) "If you give this boat a good report and we buy it and something goes wrong, what can we sue you for?". A good surveyor should not be offended and should be able to give a clear answer referenced to his draft contract.
Personally I would be happy with my own judgment of the condition of an engine and the electrical and plumbing systems - as well as the furnishings of course. What I can't do myself is measure the hull thickness and I don't have sufficient experience of poor welding quality or of propeller / shaft problems. Also I don't know the regulations so I would not spot an infringement that might make the boat hard to sell on.
So I would get a survey done and I would attend the survey and ask the surveyor any (vaguely relevant
) questions that sprang to mind. -
I advise that it's up to them whether to close the paddles whilst the gate is still open or to wait until it's closed, but I stress that whichever way they choose they should ensure that the paddles are fully closed before leaving the lock.
We followed a boat down the locks today who left all the pawls off and simply dropped the paddles by using the spindle...not very successfully, I may add!
Unfortunately there are quite a few paddles that won't fall by gravity because the mechanism is stiff and I have come across quite a few which were left slightly open - presumably because the last user did not check. In some cases it is necessary to use a windlass to make them close the last 50mm (deliberate anachronism
Seeking a part of a boat, but not knowing its name!
in Boat Building & Maintenance
Posted
I pressed "post" when I meant to press "preview" and then had to edit in public
That's only true if you know WHY you would put a load in one direction or the other. I am waiting for someone to propose a convincing explanation of what the brackets and rings were designed for - perhaps someone has a very old photo showing them in use?