Boat hierarchy

[cuthound]

1 hour ago, Alan de Enfield said:

That is surface charge you are measuring, not the 'battery voltage'.

After you have run the engine, wait 2 hours with NOTHING either going in or out of the battery. That then is the battery voltage.

 

To check the capacity of the battery (a rough method) :-

Charge the battery to what you consider full.

Wait for the surface charge to be absorbed.

Put a known load (around 4 - 5 amps is ideal) onto the battery.

Continuously check the battery voltage until it gets down to 12.1 volts.

 

That has then used (roughly) 50% of its capacity.

 

If it has taken 10 hours, with a 5 amp load,  to get  to 12.1 volts then you have used 50Ah so your battery capacity is 100Ah

If it has taken 5 hours, with a 5 amp load,  to get  to 12.1 volts then you have used 25Ah so your battery capacity is 50Ah (assuming a 110Ah battery - when new - it is now virtually knackered as it only retains 50% of it original capacity)

 

Old fashioned car halogen headlights are 55-60 watts so if you use one of those you have a 'nominal' 5 amp

 

https://uk.rs-online.com/web/p/products/0579146/?grossPrice=Y&cm_mmc=UK-PLA-DS3A-_-google-_-CSS_UK_EN_Lighting-_-Halogen_Lamps|Automotive_Halogen_Lamps-_-PRODUCT_GROUP&matchtype=&pla-546053811838&gclid=Cj0KCQjwkoDmBRCcARIsAG3xzl9U5eeDCkO1AAeJow9YXLmhTdPTMr6IZuX_5M14NwhH9gN6waNa7o8aAgY6EALw_wcB&gclsrc=aw.ds

.

 

Ideally to measure battery capacity accurately you need something more variable in resistance then a bulb. That way you can keep adjusting the current back up to 5 amps (in your example) because the dropping battery voltage will cause the current to drop too.

[Alan de Enfield]

39 minutes ago, cuthound said:

 

Ideally to measure battery capacity accurately you need something more variable in resistance then a bulb. That way you can keep adjusting the current back up to 5 amps (in your example) because the dropping battery voltage will cause the current to drop too.

Ideally - yes.

But it is just a rough and ready indicator and is simple for someone with a limited understanding of battery management to do.

 

It the real world it doesn't make much difference if your battery is 45% - 48% - 50% or 52% of its original capacity it is still knackered (as far as use as a domestic battery is concerned)

[Sea Dog]

2 hours ago, Mike the Boilerman said:

 

The mechanism is very unlikely, but is a log fouling a propeller blade and getting pulled sideways through the gap between the prop and the leading edge of the rudder. The leading edge of the rudder (the flight blade, I think its called) gets shoved forcefully across to one side, along with the tiller arm. 

 

In astern, the most common mechanism is simply the boat going backwards into the bank, wharfside, pontoon or other obstruction that is to low for the stern fender to hit first. The rudder blade protruding from the back gets shoved over to one side, along with the tiller arm. and in goes the person standing within its arc. 

 

The astern one is particularly nasty though as with the engine still in gear, the flow of water the victim falls into is under the boat and into the blade, so the victim gets sucked into the blade. I was present when a woman died this way, so I've given it a LOT of thought...

 

 

Couldn't agree more with the risks when going astern Mike. I go further and (particularly when single handing through locks) never leave (or board) the boat in gear. It only takes a slip...

 

Going ahead, I don't really see anything on it's way through a propellor rotating at hundreds of rpm making it far enough in a straight line to reach the rudder and then cause it to react violently. Still, it fits into the low likelihood / high impact bracket. Falling in and mixing it with the prop doesn't bear thinking about - so I'd say you're right to give it a lot of thought! 

 

[Sea Dog]

2 hours ago, Alan de Enfield said:

Old fashioned car halogen headlights are 55-60 watts so if you use one of those...

Generously sharing another one of your bright ideas Alan?

 

[system 4-50]

39 minutes ago, Sea Dog said:

Going ahead, I don't really see anything on it's way through a propellor rotating at hundreds of rpm making it far enough in a straight line to reach the rudder and then cause it to react violently.

I thought that until it happened to me.  Fortunately I have a lot of space behind the tiller.

[Chris Williams]

I used a NiFe battery on my boat - lasts forever and no worries about abuse.  Start anything.  Anyone else got one? 

[cuthound]

1 hour ago, Alan de Enfield said:

Ideally - yes.

But it is just a rough and ready indicator and is simple for someone with a limited understanding of battery management to do.

 

It the real world it doesn't make much difference if your battery is 45% - 48% - 50% or 52% of its original capacity it is still knackered (as far as use as a domestic battery is concerned)

 

Indeed, with a boat battery it is time for replacement when you can no longer live with its reduced capacity.

 

In the commercial world of data centres they are replaced at 80% of capacity and capacity is over specified by 25%. If you let a battery go below the 80% capacity and a customer suffers a loss you csn expect a big law suit to follow.

 

1 minute ago, Chris Williams said:

I used a NiFe battery on my boat - lasts forever and no worries about abuse.  Start anything.  Anyone else got one? 

 

Great batteries providing you can live with the wide voltage difference between charges and flat.

 

Almost indestructible.

[Sea Dog]

46 minutes ago, system 4-50 said:

I thought that until it happened to me.  Fortunately I have a lot of space behind the tiller.

Really? Then you'd fit into the "low likelihood" bracket but, very happily, not the "high impact" one!  Do please share your experience so we can all learn from it.

[system 4-50]

1 minute ago, Sea Dog said:

Really? Then you'd fit into the "low likelihood" bracket but, very happily, not the "high impact" one!  Do please share your experience so we can all learn from it.

Not much to add really.

I was steering the boat.

Something firmly attached to the canal bed hit the rudder. It had not disturbed the passage of the boat previously.

The tiller swung over with a force and a speed that I had not believed possible.

It struck me and pushed me back.

I have a lot of space at the back but it pushed me with some momentum further back than I was comfortable with. I was concerned that the speed it gave me would take me too near to the back of the boat.

I did not discover the nature of the obstruction.

I continued on, somewhat wiser than before.

Edited April 24, 2019 by system 4-50

[tree monkey]

3 hours ago, Alan de Enfield said:

I learnt that as a youngster hand starting Dumpers more than once felt as if my wrist was broken - tell that to the kids of today ………………………………….

Diesel  Howard gem rotovators,  oh what fun they were to start

[WotEver]

6 hours ago, roland elsdon said:

Im also not sure if you are better with less capacity fully charged or more capacity partialy charged ( which rapidly becomes less capacity through sulphation).

It takes exactly the same time in Absorption to charge 400Ah as it does to charge 100Ah. The only difference is how long you’ll be in Bulk prior to Absorption due to the size (or lack of size) of your charging source. 

[WotEver]

8 hours ago, ivan&alice said:

So all of this stuff about 2 hours a day killing batteries is not true as long as you charge for 10 hours once a week in order to keep your batteries healthy?

Not really. The 10 hours once a week will slow the sulphation but it won’t eliminate it. Spending 6 days at less than fully charged will undoubtedly cause the battery to sulphate; it’s all a balance between time/engine wear/fuel usage/replacement battery cost. 

[Chris Williams]

2 hours ago, cuthound said:

providing you can live with the wide voltage difference between charges and flat.

Ah, that explains why my lighting would slowly dim!  A bit anti-social to start the engine late at night to charge up.

[Chris Williams]

After a long day's boating, I went into the engine 'ole to turn off the engine, to find it full of fumes from the overcharged lead-acid battery.  Knowing nothing about batteries, I made enquiries.  Apparently the controller had been set for a hire boat, using lots of lighting.  I was on a working boat with just one bulb in the cabin, the charging rate was much too high.

 

[haggis]

6 hours ago, ivan&alice said:

To be fair, no one has commented on the fact that the seat diagram I posted shows the tiller arm sweeping underneath the seat, rather than into the seat/steerer as in all of these comments and pictures. If you are perched on a seat that is positioned out of the way of the tiller arm as such, the risk will be significantly reduced, I think.

Even the boaters handbook on page 11 merely says "On a traditional or semi-trad narrowboat, stand in front of the small rear deck and not beside the tiller so you won’t fall off when making sharp turns or going into reverse. Don’t let passengers stand or sit in the way of the tiller."

What more do you want, seat belts??

 

If the tiller arm sweeps below your seat you must have quite long arms to reach the tiller comfortably when you are seated and will your legs not be hanging down and could possibly be hit by the sweeping tiller? The tiller hitting your dangling legs hard could perhaps unseat you.

 

haggis

[Sea Dog]

1 hour ago, haggis said:

If the tiller arm sweeps below your seat you must have quite long arms to reach the tiller comfortably when you are seated and will your legs not be hanging down and could possibly be hit by the sweeping tiller? The tiller hitting your dangling legs hard could perhaps unseat you.

 

haggis

The usual scenario involves the tiller moving violently through a full sweep to the left or right. I would have thought having that having your hand disappear under your seat at lightning speed would do the job pretty well too!

 

[roland elsdon]

9 hours ago, cuthound said:

 

This ardvark of yours, presumably it is some kind of ampeater? 

 

https://en.m.wikipedia.org/wiki/Aardvark

 

???

No its a small scaled animal which someone has cunningly put in a black box. After 15 mins running it injests bad lazy volts and excretes bigger volts. After 15 minutes it gets a bit hot and sleeps for a while. After a short nap it gets going again and excretes more bigger volts. It does this for a while and then goes back to sleep. 

When you start the rotating noisy thing again it wakes up and starts again.

thats what they told me in the shop.

 

mine got a bad stomach one day after too many volts, but it was fixed free.