POINTS FROM THE BILGES - A FEW THOUGHTS

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The idea of this page is a bit of a blog to record thoughts on various topics and list my top tips.  Some items are on the design process and which drove me in a particular direction, others are on any topic, some may not be connected with barges.

 Hulls, Superstructures and Seaworthiness

Hull strength is probaby the most important consideration for any vessel that is going to operate on anything rougher than a UK canal and can only really be checked by a qualified marine architect or a surveyor.  The best way is to use Classification Society rules such as Lloyds or DNV rules for small craft.  However, the American Bureau of Shipping (ABS) has a very simple rule of thumb:

"The thickness of the hull plating should not be less than 1/100th of the distance between the transverse frames or longitudinal stringers."

For example using typical 6mm plate for the hull side means that there should be frames or stringers with centres at every 600mm.  On old dutch barges the standard frame spacing is 500mm, so in practice 5mm plating should be sufficient.  In many barges the acceptable minimum thickness is 4mm, as determined by insurance companies.  I personally would be wary of subjecting any hull that does not meet the ABS rule of thumb to waterways rougher than inland canals.  Even on a calm day at sea, the swell can induce hogging and sagging stresses that the vessel will not have been designed for.  On a new construction barge not being constructed to Classification Society rules, I would insist on meeting the ABS rule for the entire hull - bottom plates, chine plating, hull sides and weather deck up to the gunwhale.

Superstructures also have a marked effect on a vessel's seaworthiness and the wheelhouse construction of a dutch barge in particular has a considerable impact on seaworthiness.  In many ways the superstructure and wheelhouse must be as strong as the hull.  This is particularly important if considering building a vessel to cope with more severe weather and larger waves.    Survivability requires water tight integrity of all openings such as windows and hatches, etc.  Despite this fairly obvious requirement it is quite common for dutch barges to have a relatively large wheelhouse windows in a large lightly built wood or aluminium wheelhouse structure.  Hulls may be reasonably strong, but see the comments above.  True survivability can hardly be claimed for boats with big picture windows and lightly built superstructures...! or the sake of achieving a good view

On the other hand, a 180 degree range of positive stability for power vessels that do have strong and rugged superstructures and with small and robustly constructed window and door openings will not ordinarily be an excessive claim.   If structure is approached conservatively, if the openings are designed with an adequate support structure, and if the glazing is of the right materials and adequate thickness, this degree of survivability amounts to only a slight penalty in terms of weight and cost.

I think it unreasonable to expect any form of folding wheelhouse with large windows to cope with waves that the hull may be able to cope with.  Most hulls can be built to a MCA standard.  A folding wheel house probably will not be.  A reasonably sized chunk of water that might come off a 4m wave weighs the same as a small car.   Would a folding/collapsing wheelhouse support a car on the roof?? or resist a car hitting the front or side at say 5 mph??.  I think not.

Round Bilge/Hard Chine debate

A thought on the round vs double hard chine debate. Round chines are useful if you want to maximize hull cargo capacity but they also mean greater hull volume so greater displacement which probably means more ballast for our vessels.  The hull does do not "grip" the water as well as a double hard hard chine hull, so less longitudinal stability and roll resistance which can be overcome with bilge keels or leeboards, but then more bits stiking out to snag on canal sides etc.  Also more expensive to produce - the wretched curved sections plus additional keels.  So unless you are a stickler for complete authenticity, I would suggest go with a double/multi hard chine if going for a new build.

V bottom/flat bottom considerations (Dec 08)

There is much discussion on the merits of having a traditional flat bottom vessel or a v bottom on a new build.  The traditional flat bottom vessel will probably require additional ballast and a 22m vessel may require between 10 and 25 tons to achieve the correct draft, which does have a small knock on effect on handling and fuel consumption.  However, a flat bottom vessel can have an enormous amount of useful storage space under the flooring for some or all of the following - fresh and dirty water tanks, fuel tanks, chest deep freeze, cool room, battery compartment, general storage, coal and log store, paint store.  

KEI has 6000 litre fresh water tanks, 2 x 3000 litre black and grey water tanks, 85 litre underfloor chest deep freeze, 1.5m x 1.5m x 0.7m cool room, wine and beer store, 2.2m x 0.6m x 0.35m battery compartment, 250kg coal store, 1.25m3 log store, 3 x 4.5m x 0.5m x 0.7m general storage spaces, 1 x 3m x 0.5m x 0.5m carousel storage for paint, fresh water, grey water and trash pump space, storage for useful come in handy wood.  Most of this is under the galley and saloon floor which is approx 0.7m above the bottom plate.  A modern V bottom no ballast design will not have space for all or most of this and consequently require storage somewhere else, invading the living accommodation.  As a guide each person uses 100l per day, so 6000 litres lasts the two of us up to 30 days.

A further consideration is handling at sea and there is a consideration that the V bottom will ride the seas more comfortably with less roll.  This may be so, but after 2 channel crossings, I can say that KEI's sea keeping qualities are fine.  The roll rate is slow and unsecured items have not fallen over, for example bottles of wine.  Being a multi hard chine with a substantial skeg, longitudinal stability and "grip" in the water is also good and I do not think that a "V" bottom has any advantage here either, being essentially a hard chine hull.

Hydraulic Drive

Hydraulic propulsion is most often promoted in order to enable placement of the main propulsion engine in a location other than amidships, in other words to make use of an unfavorable location in terms of trim and pitching moment.  Although ordinarily highly reliable, any hydraulic propulsion system must be engineered correctly or it will be very unsatisfactory.  Even if engineered and installed correctly, the use of hydraulics for primary propulsion is expensive to install, highly complex, ordinarily very noisy, and incredibly inefficient when compared to a simple direct shaft drive. This can hardly be viewed as a "feature."

On the other hand, one might very rationally consider a modest hydraulic drive system for a get-home installation, primarily to save weight and to provide flexibility of machinery location.  A PTO on the generator might for example be used as the motive force.   In this case, the hydraulic propulsion equipment will still be somewhat expensive, noisy, and inefficient, but it will not be asked to operate continuously, nor at full vessel speed.

A  UK designed and recently built  barge of approx 24m was fitted with a very sophisticated, and I recall very expensive, hydraulic drive system.  The vessel's hull form is very similar to the example of a UK replica shown on the Hull Statics page.  The owner has punlished the following comment on his system:

This certainly bears out the comment on inefficiencies at para one above.  The vessel is fitted with a single engine of 245Hp, so using 2 smaller engines might have been better but possibly negating the space advantage, plus a 32kw genset.  The hull form also needs considering and it is likely that the drag penalty of the UK design over the dutch vessels (1920s hull and ESS hull) is contributing to the fuel consumption.  It probably puts the vessel's energy efficiency towards the "Z" end of the alphabet.

Which Voltage

This refers to the voltage of equipment carried.  I decided at an early stage to have all essential systems working at 24 volts,  This includes fresh water pump, fridge, freezer, deckhead lighting and sump tank pumps.  The rationale was based on several reasons.  We intended to spend considerable time underway, so much of our electrics whilst running would come from the 28 volt alternators.  This would charge the battery and essential systems would run direct from that instead of using the inverter.  I also planned to fit solar panels and again it made sense to get best efficiency from the system without the losses associated with using the inverter.  I even converted the gas hob from a 240 volt igniter to a 1.5 volt D cell battery igniter.  In practice it works well, and the inverter can be switched off for long periods when 240v is not actually required.    Of course, some 24 volt items are more expensive than their 24 volt counterparts, such as the fridge, but it is easier to build a modular deep freeze with 24 volt items than 240 volt ones.

For a more static vessel using shore power, then the use of predominantly 240 volt equipement begins to make more sense. [Nov 08]

Upper deck layout

The upper deck layout is key to safe, flexible and efficient working ropes during berthing evolutions whether entering a lock or going alongside.  I consider the following points to be essential requirements:

1500 or 3000 rpm Generator

There is an ongoing debate on whether it is better to have a slow revving 1500 rpm or fast running 3000 rpm generator.  A 3000 rpm machine is smaller and lighter than the equivalent power 1500 rpm.  The 1500rpm also generates lower frequency vibrations which transmit more energy than high frequency vibrations.  The lower frequencies are also more difficult to attenuate.  Thre is not a great deal of difference in engine life of a 1500 or a 3000 rpm machine and manufacturers of both quote 10,000 hours (equiv to 400,000 car miles).

Washing Machines (WM) and Tumble Dryers (TD)

Can use huge amounts of electricity.  A modern cold fill machine will use approx 1kwh for a 60C wash, an old hot fill machine will use 0.3kwh for a 60C wash.  A tumble dryer cycle takes 3 - 4 kwh.  A cold fill machine can be filled with hot water, but the machine is still likely to heat up the water at some stage in the washing cycle as the drum etc cools the wash water. Cannot be avoided except by disconnecting the heater, which may not be that satisfactory as inbuilt error detection may stop the machine working at all.  When motoring, using the machine as a cold fill is not normally a problem as there is normally enough electricity.  Cold fill heating takes around 8A at 230v, 80A at 28 volts, for short periods, so if the alternator or shore power is not sufficient, the inverter should cope - especially those that can "parallel the shore supply".

The tumble dryer is even thirstier, taking around 12/13A for extended periods.  This requires around 130A at 28 volts, which in turn requires hefty DC generation.  Bearing in mind that often the alternator(s) will not always be developing max power, then the alternator capacity needs upsizing.  With a total of 205A at 28 volts from two Leece Neville alternators, or around 20A at 230 volts from the inverters, at high revs both the WM and TD can be run at the same time.  This was the case crossing the Channel.  However, at typical canal engine revs, only 135A is available, approx 13A.  Running both the WM and TD at the same time whilst at canal revs dragged the battery voltage down to 24.5 volts, and both alternators, working hard, got fairly hot.  The alternative is to run the generator.

When alongside and on a meagre shore supply, the TD can be used as a useful load for the generator.  For example, the oven takes 3kw of my nominal 11kw capacity.  The battery charger may take another 2 kw , which still leaves the generator lighlty loaded.  The TD adds another 3kw, putting a respectable total load of 8 kw on the generator.  As cooking the roast and a large TD load takes much the same time, it all works out quite well.  Another consideration is to make up a small electric calorifier in the central heating circuit and use a 3kw, or larger, immersion heater.  This would put a load on the generator and at least pre heat the CH water and in conjunction with generator heating of the CH circuit, would provide enough heating for the calorifiers .  Using  just the tank immersion heater is not that satisfactory as invariably it does not stay on that long.  [Nov 08]

In summary, well sized 28v alternators and a cunning power management strategy are required,  plus possible serious consideration of a 240v AC Travelpower.   [Nov 08]

Colin's Top Tips

In no particular order:

Tip 1.  When filling with diesel, get the supplier to put a splash into an empty glass jar - jam jar is possibly too small, Tesco gherkin jar is ideal.  Check that fuel is clear and bright with no obvious bits or water at the bottom.  Check for moisture with water finding paste.  Label jar with supplier and date.  Keep in cool dark place and observe.  If fuel was contaminated with microbes, then they will be seen multiplying in the jar.

Tip 2.  Digital charting is excellent and I use laptop compatible chart software and charts.  However, if relying on a digital charting system, then it is best practice to copy the commercial world and you really should have 2 independent systems - eg 2 laptops and 2 GPS receivers.  With 2 independent systems, one can dispense with paper charts.  I use USB GPS "mice" with laptops or a feed from the main ship GPS.  The coxswain needs a chart to steer by and a second system is ideally used by the navigator who can look ahead and provide guidance of features coming up - bearing of new buoys, light characteristics etc etc.  Another consideration is to use charting on a car type GPS navigator or PDA.  Navman GPS units are Win CE devices which opens up the possibility of "unlocking" them and installing WinCE charting software, such as Oziexplorer.

Tip 3.  Use the engine to heat central heating.  Fit a heat exchanger into the central heating circuit so that when the engine is running, the central heating circuit is heated up.  Cruising in late Oct 08 was no problem with lashings of heat from the radiators.  This also has the added benefit of providing redundancy of systems, in this case engine cooling via central heating system.  May be more costly but the added flexibility means problems are not show stoppers.  We travelled down the Thames in Aug 08 for 4 days with the primary engine cooling system, the keel cooling, inoperative due to an airlock.  Engine cooling was achieved by using central heating system and turning on all the radiators.

Tip 4.  If you use wet batteries, topping up can take a fair quantity of water and the traditional 1 litre filling bottle is not really up to the task.  The answer is a basic garden pressure sprayer.


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