Compact but comfy

[Timleech]

I've given this some thought:-

 

The 30 bhp engine will give 30bhp at ca. 4,000 rpm. the bhp is proportional to rpm, so at 1,000 rpm it will be giving 7.5 bhp. About 4 bhp will move the boat at 4 mph the extra 3.5 bhp is used to drive fuep, oil and cooling water pumps; these are overheads and fairly constant.AT 1,000 RPM 4/7.*100=53% of your fuel is beingused for producing power.

 

At 4,000 rpm the engine will produce 30 bhp, 3.5 bhp will still cover overheads and 26.5/30 * 100 = 88.3% of your fuel is being used for producing power.

 

your motor is producing 20kw of storable electricity, is that a shed load?

 

Bill Adam

 

Even if it were proportional to rpm, that'll be what the engine is capable of producing at that speed. Deducing that anything not used goes to ancillaries is simply not true. The engine will produce what's required of it, up to a maximum of what it's capable of. If the demand is less, it will simply use less fuel and produce less power.

 

Edit to add - 'Propeller (power) law' follows approximately the cube of rpm, so by my reckoning if the prop is absorbing 30 bhp @ 3000 rpm, it'll only be using just over 1 bhp @ 1000 - which is not far wrong for pushing a narrowboat gently along a canal.

 

Tim

Edited November 28, 2012 by Timleech

[jelunga]

You don't "need" plumbing, hot or cold. I don't have any plumbing in my house!

Yeh, but you are Swedish so it does count.

[Bill2]

power isn't proportional to rpm - its not far off, but it isn't proportional

 

where did you get the 4bhp requirement to move the boat at 4mph from? Reference please

 

where did you get the 3.5bhp requirement to drive pumps from - once again, a reference is needed.

 

Without the references, your 53% is a figure plucked out of thin air.

 

at 4000rpm, the accessories will need more power to drive them than at 1000rpm - for example, for pumps, power requirement is proportional to the cube of shaft speed.

 

Why later mention something in kW when you started in bhp?

 

 

"Not far off, sounds near enough to me.

 

Just 2 horse power propels a narrowboat at about 3mph http://solarboat.co.uk/faq.shtml

 

the lower bhp figure I refer to makes the "standing charge" even bigger.

 

Hard sum, Total power (7.5 bhp) minus power used to drive the boat ( 4bhp) equals power used to run

 

ancilliaries (3.5 bhp). That this "standing charge" is small compared to the working load is shown by the

 

effect of sudden removal of the working load.

 

Your turn. Reference please.

 

Normal practice has been to refer to motor power out put in bhp and electric powe available in kW.

 

Bill Adam

[Paul C]

What is a standing charge?

 

What about the fact that pumps, and the prop, require power proportional to the cube of rotating speed?

Edited November 30, 2012 by Paul C

[Bill2]

What is a standing charge?

 

What about the fact that pumps, and the prop, require power proportional to the cube of rotating speed?

A standing charge is a cost entailed whether a facility is made use of or not. If your engine is run without going anywhere you incur the cost of fuel to run pumps, charge full starter battery, turn camshaft etc.

 

What about he "fact" that pumps, ...etc. reference required.

 

It is self evident that the anciliaries place a much smaller load on the engine than does the primary load ( driving the boat, charging the ton of batteries or whatever). Sudden removal of which (eg broken propshaft) has a dramatic affect on the engine. Whereas removal the water pump (broken fanbelt) has a neglidgeable effect until overheating occurs.

 

Bill Adam

 

P.S.

The stresses in reciprocating parts (eg. pistons) do increase with the cube of rotating parts.

Edited December 1, 2012 by Bill2

[Paul C]

Not much to add really, its clear that you don't fully understand the physics of this, and you've been deceived into thinking that a hybrid system is good for a canal boat. Its not. (see posts 15, 16, 17 etc) Its possible you have a partial understanding of some of the stuff, though.

[RLWP]

Not much to add really, its clear that you don't fully understand the physics of this, and you've been deceived into thinking that a hybrid system is good for a canal boat. Its not. (see posts 15, 16, 17 etc) Its possible you have a partial understanding of some of the stuff, though.

 

Remember this, Paul?

 

Bill2, I could be up for a discussion on this, except you really want to do this, so your mind is closed to the drawbacks and limitations

 

Richard

 

 

Richard

Edited December 1, 2012 by RLWP

[Paul C]

Apologies if I didn't quote the right posts which tried to dissuade the original poster from the idea. TBH the vast majority of posters on this thread have been in agreement that its not such a good idea. I'm all for people being innovative and coming up with new ideas and that 'its traditionally always been done like this' isn't a good enough reason in itself to poo-poo a new concept.

[RLWP]

Apologies if I didn't quote the right posts which tried to dissuade the original poster from the idea. TBH the vast majority of posters on this thread have been in agreement that its not such a good idea. I'm all for people being innovative and coming up with new ideas and that 'its traditionally always been done like this' isn't a good enough reason in itself to poo-poo a new concept.

 

Just in case that was addressed to me, what I meant was that I stepped out much earlier as I couldn't see how to remove the blinkers of desire from Bill's eyes. Your arguments are sound and well presented and I appreciate them

 

Richard

[Bill2]

 

- You'll still need plumbing for hot water.

- 10x less ventilation ISN'T 10x less heat loss, heat loss will occur in many places other than the vents. A lot of boaters seem to get by with a solid fuel stove and 'free' wood foraged from the environment, and with the small interior size of a narrowboat, no issues at all with heating the interior up to a comfortable level.

 

Don't forget that 35 foot boat length (half of a 70 footer) doesn't mean half the cabin space, it means less than half, because you can't reduce the open areas at bow/stern that much. 35' is pretty small for a liveaboard. There's a reason why liveaboard boats tend to be around 57 feet.

 

 

plumbing for hot water is to 3 taps

My post reads

"No plumbing or boiler for central heating"

Cost of boiler? > £1,000

Cost of radiator?

Cost of pipework?

 

In a narrow boat the recomended ventilation far outweighs any other heat loss so 10x less ventilation is about 10x less heat loss.

As a share holder in a narrow boat I spent years trying to convince my fellow owners that the demanded BSS ventilation was excessive, to no avail. Now the authorities have changed it from compulsory to recomended that's as near as one can expect to an admission that they were wrong.

 

The cabin space is around 9 foot long but is triple functional. QThat makes it equivalent to 35+18=53 foot.

 

The major attraction of hybrid drive is a (literal) ton of batteries and a big generator. A major snag in boats is flat leisure batteries. You have a nominal 100Ah but ifyou go below half full they get sulphated so 100Ah is only 50Ah, but it's hard to know their charge state so allow a big margin for error and you daren't use more than half that, leaving only 25Ah.

[bottle]

A major snag in boats is flat leisure batteries. You have a nominal 100Ah but ifyou go below half full they get sulphated so 100Ah is only 50Ah, but it's hard to know their charge state so allow a big margin for error and you daren't use more than half that, leaving only 25Ah.

 

Fit a Smartgauge, then you will know.

 

A major snag in boats is flat leisure batteries.

 

Never had that problem, I wonder why.

 

 

below half full they get sulphated

 

I do not think so batteries sulphate because they are not re-charged sufficiently,

[Bill2]

If the "smartgauge" works as well as their web site you're going to have flat, sulphated batteries.

 

Bill Adam

Edited December 7, 2012 by Bill2

[bottle]

Mmmmm.

 

Does seem a little slow, usually works well.