Electrification big picture

As I wrote previously, we are going to make our lovely Blu Emu into a parallel hybrid. The key though is how we want to be a hybrid. A hybrid sailing vessel can plan on using their electrical propulsion only when entering or leaving a harbour or mooring, essentially only a small part of the time. Sailing Uma is one of the preeminent YouTube examples of this. They don’t need much power and crucially they don’t need it for very long.

Blu Emu though is a powered vessel only: no sail. So the benefit of electrification is to get as much as possible for as long as possible. Some powered vessels go the Uma route, like the smaller Greenline hybrids. Given the expense of adding electric propulsion, we want to use it as much as possible, so our goal is:

For short trips, upto 50nm, and where time permits:

For coastal multi-day trips, and where time permits:

For long journeys, like crossing seas/oceans:

Whenever time is crucial, because of weather, sea state or anything else, we will use the diesels!

use electric propulsion only (small motors, large battery bank).

use a combination of diesel-electric (small-medium motors, large battery, fast recharge)

watch the weather and use either diesel alone, or a combination diesel-electric as needed to get to the destination safely.

We think our boating will be 70% of the short trips, 20% of the second, and less than 10% of the third. But instead of going entirely electric, we want to give us the option of the longer journeys by keeping our lovely old, functional and functioning, diesels.

To go hybrid for our uses, we will need to:

Generate power:

  • Add solar, so we get some “free” energy and don’t have to use a diesel engine for everything
  • Add big alternators, so we get storable electric power from the diesel engines while we have to use them
  • Don’t use a generator! A big enough generator is another diesel engine in the boat, and the noise, cost, maintenance of such engines is something we are trying to steer away from. Instead of a generator, we will use large alternators off the main engines which, as our main propulsion, will be on much of the time we travel (unlike a sailing vessel) while at anchor the solar array is more than sufficient for non-moving needs.
  • Store power
  • Use the power

Add a large lithium battery bank (why lithium is explained but is really for another blog post!)

Add a parallel electric motor to each diesel, and electrify as much as possible. This includes getting rid of potentially dangerous gas-powered cooking.

  • Make it all work
  • Check whether it does work!

Redo the entire electrical system, buy all the stuff and install it.

Generate Power


Essentially the idea is to get as much solar as possible. Given we are a power boat, we don’t have the limitations many sail boats have wherein their mast and sails shade the solar panels reducing output considerably. On the other hand, more panels equals more space that can’t be used for anything else, more cost and more weight up high, increasing the moment of the boat (movement side to side) and windage, both of which should be as low as possible. For us, the benefits of large amounts of solar are such that the cost and space are accepted.

The weight issue goes hand-in-hand with the “as much solar as possible” end goal. Flexible panels are extremely light, but aren’t as efficient so the same area delivers less solar power. So we have decided that the weight penalty of the heavier panels, like are used on houses, is worth it as we have such a limited space (compared to a house: compared to other boats, we have heaps!).

One other point about solar panels is that their directionality can impact their performance: if you can keep them cool, and pointed at the sun, then the power they provide is maximised. Unlike a house though, a boat moves around while travelling, at anchor or moored. So careful angling of the panels, or having them turn continuously to face the sun, is very difficult and would require solar tracking mechanisms electronics which aren’t suited to the marine environment and are heavy – and incidentally would have to move a lot as the boat moves a lot on a mooring or anchor!

Blu Emu would just be able to have 9.6sqm on the roof above the internal steering position. Once we have designed the flybridge we may have upto another 20sqm. A further sliding extension over the front 9sqm could provide another 9sqm or so.

Solar panels above inside steering position before Hurricane Irma

The panels we are evaluating are probably the 20.4% efficient, LG Neon 2. They are a good mix of efficiency and cost and are 204W/sqm. Sunpower Maxeon 3 are higher efficiency at 22.6% and 226W/sqm, but are a lot more expensive and harder to get. Panasonic HIT are possible too at 203W/sqm. The LG panels though meet our sizing well to pretty much perfectly use up the 9.6sqm space. 9.6sqm would just accommodate 6 panels, making 2.1kW. The sliding extension would add another 4-6panels, or 1.4-2.1kW making a total (excluding flybridge) or 3.5-4.2kW. I’ve made the calculations since on an average of 3.8kW.

The typical daily ability to collect power from solar panels is 4-5 times their power depending on where on the globe you are and winter/summer. Averaging to 4.5 for simplicity, 4.5×3.8=17kW of solar input per good sunny day. There is a loss in conversion from higher voltage at the panels to the battery, but using MPPTs and series connections for higher voltages and earlier in the day power should minimise this. We have allowed an 8% loss in calculations.


Apart from the sun, we do need other means to create electricity if we want to use it for propulsion. Typically, alternators are used in most motor vehicles to make sure the starting battery is charged. However, since we are a motor vessel our diesel engines are going to be on a lot, and instead of using a third diesel engine in the form of a generator we will use large alternators on the main engines.

Our main engines are Perkins M135 naturally aspirated. They are 600kg big lumps of metal. Perkins states that the PTO (power takeoff) at the non-prop shaft end can handle 6kW/8hp being taken. This will slightly increase fuel usage (10-15% at our guess), and would certainly be a problem if we ran the engine anywhere near the maximum power. Luckily, we are already purposely downrated from 2600rpm to a maximum 2400rpm, or 132hp maximum down to 100hp per engine. So there is plenty of room to take off 8hp.

While in theory 6kW/8hp can be “taken off”, an alternator only works at a certain level of efficiency. Average ones are 50-60% efficient only. But there are some that are more like 80-85% efficient. This turns the 6kW/8hp into an actual 5.1kW/6.8hp to go into the batteries (with a little loss in transmission).

Most alternators are small: 12V units for cars and trucks, from 50amp to 100amp (or 0.6-1.2kW). These can be driven from V-belts between the engine and the alternator. Large-frame alternators though may be 180amp or more (2.1kW), and most then need serpentine belts to take off the power successfully, and are usually externally regulated. Some boats even run twin alternators, one on either side of the back of the engine so that the radial loads – the sideways pull on the PTO shaft – is offset by an equal pull from the other side for another alternator.

As the battery will be 48V to cater for the largest use, propulsion using a 48V motor, the alternator has to be 48V as well or a step-up transformer (with loss!) is needed. We have found an Australian company, Rapid-Power, who make alternators for the mining industry and have 48V, 100amp (4.8kW) 85% efficient units. We will likely ask them to make us a 48V, 125amp (6kW) unit (their webpage show a 28V 200amp 5.6kW unit, the RP5, which is close).

Importantly, alternators can be irreparably damaged if they suddenly lose their load, such as the battery “saying” it is full, or misuse of the 1-2-both switch (Marine HowTo has some excellent information on why not to use a 1-2-both switch). So the external regulator usually will turn off (aka regulate) power from the alternator to suit the needs of the battery. The older regulators just used voltage to decide what do: they were programmed for lead-acid batteries and their particular needs. But there are now new ideas and products to cater for lithium batteries and even combination of chemistries. Options we have looked at for a regulator include: a Wakespeed WS500, fairly basic but known Balmar, and something with much more “smarts”: a digital CANbus controller. The particular controller, or regulator, is important as it can limit the amount of power that goes to the battery, making charging longer or even impossible especially for new large lithium batteries with 0.5C charge possibilities. So matching the alternator, battery and regulator/controller is very important!

If (and that’s still in question) a separate lead-acid starter battery is needed, there is also the option of a Victron Argo FET 200A Charging Splitter with ignition switched activation to ensure the different battery chemistries charge properly. We would probably use the Argo FET anyway to protect the alternator from sudden shutdown.

Store Power

Power is stored in a battery. Interestingly, you can have a battery made out of many things – a spring is a type of battery! The Baghdad Battery was made in 200BC or so and made from pottery and copper. In our case, as a catamaran we need light weight, lots of power storage so we can run on electricity for a long time, the ability use the power stored when needed, make sure it is safe on a vessel that’s moving about sometimes violently, and is cheap. Hmmm, that’s hard!

Fortunately, battery technology is changing very fast. Lithium iron phosphate (LiFEPO4) is our chosen battery technology and meets all the needs. It is much lighter weight the old AGM or other chemistries, it has vast storage for its size and weight, some examples can be charged at 0.5C or even 1C, and discharged at 1C. But it has some safety issues, and some thermal runaways and explosions have been experienced for some installations and particular chemistries. Marine Howto has some good points.

With the chemistry choice made (and watching for the many changes happening in the field!), the next choice is then whether to work with a respected manufacturer (like Victron) and use their batteries, or DIY. The cost difference is substantial! We will keep watching, but the cost savings of DIY mean we are leaning that way: making up our own battery from purchased cells and a BMS (battery management system).

Right now (early 2021), the 280ah cells from EVE and Lishan are looking good (DIYsolar has some excellent information and people who are doing similar things for boats and RVs; Marine Howto has great information on how to make your own battery cables). These 280ah 3.2V cells x 16 to make up 48V, would make a battery bank of 13.4kW. For Lithium, discharge to 80% is generally ok meaning a usable 10.8kW of storage. These cells have a 2000+ cycle lifetime (so 80% or 90% of their initial size), or about 7 years of usage where every day is discharged and recharged once. Discussions with some gurus seem to indicate that regular charge-discharge in an electric boat sense (perhaps hourly even switching between electric (using power) and diesel (generating power)) may not constitute an entire cycle.

Use the Power

The two uses of the power is electric propulsion, and things working on the boat (cooking, anchor winch, fans, recharging phone and computer, etc.). These uses are split into the voltage each needs, and then whether they are always-on or “switched”. Some items are 12V, some are 48V, and some are 240V.

  • 12V DC is common in cars and smaller boats. There are a lot of 12V products. 12V won’t kill you, but also is typically low powered. If a 12V thing needs a lot of power, it needs a lot of amps which means heavy, expensive cables and connectors and so more 12V products don’t use too much power.
  • 48V DC seems to be the sweet spot between “high enough for small amperage and good enough power” and “not quite high enough to kill you if something goes wrong” which seems to cut in at about 50V. Anything over 50V needs a qualified installer and extra care. There are a variety of 48V products available now, including anchor winches (which take a lot of power), and electric motors for propulsion.
  • 240V AC is the Australian standard for home electrical. This covers various goods we may use aboard like air-conditioning, fridge/freezer, microwave, induction stove top, etc. These typically need big amounts of power, even if used for shortish periods of time.

Propulsion is the main reason though that we want to go down this path – if we were doing it only for the purpose of using induction cooktops and other high-draw electrical items then our choices may be different. But for propulsion, the stakes are higher.

There are many options for electric propulsion: electric outboards, electric motors connected to straight propeller shafts, electric motors connected to sail drives, and then serial hybrid or parallel hybrid. We have thought about electric outboards, which would entail no internal changes to the boat but are severely limited in their prop size. At the moment, a parallel hybrid is preferred, a bit like Beta marine is marketing.

The motor is planned to be 48V. This limits our continuous power quite a lot to less than 16kW because of the cabling size (amps) and runs required: 333amps is enormous! Fortunately, we have had a quote from Oceanvolt which gives a general indication of the power we will need for particular speeds:

This graph immediately demonstrates the limitations of electric power for a semi-displacement (and displacement) hull shape: the power required to go fast rapidly goes exponential. While some hydrofoils and specialty boats may be able to go faster than 9-10kn using electric only, most vessels won’t be able to – and certainly not using 48V!

So we are limiting our electric usage to between 4 and 7 knots. A cut down version of the graph is easier to understand:

This shows the amps (at 48V) required for 3,4,5,6 and 7kn. So 5kW of power would draw 100amps from the battery to go about 4.5kn. We think we will be happy with 5kn, as the place where the curve starts getting worse quicker. At 5kn, draw from the battery is about 7.7kW, 160amps.

The maximum we could imagine, for a short time as it would deplete the battery very quickly, is probably 7kn, or 25kW of power. However, this could be delivered through two motors, one in each hull. So each motor would draw 12.5kW or about 250amps from the battery pack. This wouldn’t be good, or even possible, with a single battery pack at nearly 2C discharge, so a separate second battery pack would be needed. The motor itself could be rated larger, continuously, than 12.5kW as running electric motors at their maximum for long periods of time can effect the cooling and efficiency. Something like a 20kW motor would probably be fine, one in each hull with a second battery pack.

Now, although 5kn only draws 7kW from the battery pack, there is loss in efficiency: between the battery and the motor, in the motor, and from the motor to the prop shaft itself. It is likely to be around 85% (at lower speed) to 90% efficient (5kn+). So while 7.7kW is drawn from the battery, only 6.9kW makes it to the prop shaft which is where a form of comparison to a power of a diesel engine can be made – at the prop shaft. Note that the propeller itself is anything from 55-65% efficient, but since for a parallel hybrid the same propeller is used for both diesel and electric, I haven’t bothered taking that into account!

So after all that – if you’re still with me! – we want an electric motor of about 10kW continuous for each engine. This would give us a total of 20kW of propulsion making 6.2kn and draw about 22kW from the battery(s) at 225amp per pack. It would also allow us to run on one side of the boat only at 5kn, freewheeling the other propeller.

Make it all work

A key part of the change that needs to occur is to redo the electrical system. Blu Emu is over 20 years old and the electrical system has clearly been put together over a period of time without much care – there are wires hanging in the engine room that are open at one end, and no labelling!

The first thing is to have a plan! The following is our current (Feb 2021) plan.

Blu Emu future electrical plan for parallel hybrid (version 3)

The key parts of the plan, from the diagram, are:

  • Inputs are on the left:
    • Solar – as much as possible at 48V, coming through MPPTs, and connected to the +ve and -ve bus bar with fuses. 2-3kW is easy, and upto 9kW is possible on Blu Emu. As a powercat, there should be little problem with shading and therefore panels can be in series to increase the voltage which, for MPPTs, should make them generate power earlier in the day.
    • Alternator per engine – upto 6kW each at 48V, coming through regulator (Wakespeed, Balmar or CANbus digital). Our Perkins 135hp diesels allow upto 6kW/8hp power takeoff
    • Shore power – 240V AC coming through an isolating transformer as we are an aluminium boat, and directly into the charger
    • A 48V DC diesel generator is something we don’t want: another expensive diesel, but should not be needed.
    • Each electric motor can also function as an electrical generator while the diesel is running. It isn’t clear this is a good idea while the diesel is also running large alternators, but may just happen unless we can work in a clutch on the electric motors.
  • Storage is in the middle
    • A 48V battery bank, LiFEPO4. As large as practical and cost effective given the rapid change in battery technology. We may start with a group of 16x 280Ah cells from China, which would give a bank of 13.4kwh bank with 10.7kwh usable (at 80% discharge).
    • Shown is also a starter battery, 12V. We don’t think that this will be needed though and does complicate the system quite a bit because of the need for charging.
    • For simplicity, there is only one battery bank. It is 48V as this is the largest voltage that is commonly seen as electrically safe (the EU apparently has much more stringent rules for >50V as it can kill). There are also many products for 48V, including anchor winches. Finally 48V is a bit of a sweet spot for electric motors – there are many available at this voltage and it provides a decent continuous output potential without enormous amperages making wiring hard/impossible.
  • Voltage change is in light grey
    • The charger-inverter needs to convert from 240V to 48V to allow shore power to charge the batteries. It is difficult to find a better option than a Victron Multiplus II (the 48V version of course).
    • The 12V systems need conversion from 48V to 12V (which could be a buck boost, like the Scotty from Safiery, or the named Victron Orion).
  • Green shows systems that consume power
    • 12V always on – direct from the battery, stepped down, these are for systems that should not be off the standard 12V panel
    • 12V – all the usual 12V systems on a boat, caravan, etc.
    • 12V NMEA – this is only for the NMEA2000 systems on the boat, separate to the other 12V to keep those requirements separate
    • 48V – any systems that are 48V, the primary is the electric motors themselves. This could include other major systems too such as anchor winch (perhaps in the future) and dinghy battery charger.
    • 240V No Break – for 240V systems that may be needed even if shore power is not available.
    • 240V switched – for 240V systems that can only be used if shore power is available. This is a function of the Victron Multiplus II that we will use as a combination charger-inverter.
  • The underlying colours show the voltage of the different areas: light green for 12V, light yellow for 48V and light blue for 240V.
  • A few further comments:
    • RCDs (residual current device) are not shown
    • We haven’t worked through sizing for wires, fuses or switches
    • Some of the systems have question marks (?) – we aren’t sure whether we’ll have them, or if we do what voltage will be used. For example, the windlass is 12V currently but 48V versions are available; we have a 12V watermaker now, but 240V are available.
    • ACR is an automatic charge relay, and isn’t shown. These are used to combine two batteries so when charging they appear as one battery, yet when using them they are separate. As we hope not to install the starting battery for the diesel engines, we hope not to need the ACR.

Check it works

Who knows! At this stage, we only have plans. But it isn’t any use if the plan is not returned to afterwards and it can be evaluated and lessons learnt, so this is a placeholder for the return time.

What I have done is a spreadsheet to play with options of amount of solar, battery size, speed desired and other options. The output is a table of when diesel is needed and when electric propulsion is to be used, over the entire 24hr day. So a certain solar input, alternator input, speed under electricity, speed under diesel, battery size, will show that electric propulsion is possible for 12 out of 24 hours, and total distance is 158nm at 1.8lpnm (for example). If people are interested (hint – leave a comment, or send me email!), I’ll clean it up and make it available on the blog.

Random links to others

A Norwegian tourism company who built their own hybrid electric power cats. 800kW of batteries, 10 hour run time, 1.5m propellers! The Brim Explorer. BUT – you have to be careful with batteries, especially lithium!

Good information sources:

  • SV Lynx – hybrid. Detailed long article on why hybrid, scenarios, and their own uptake
  • SV Entropy. Good long article of the system design of a LiFePO4 battery system.
  • Fischer Panda Easybox hybrid. Manufacturer of generators, but a good overview of hybrids with easy to understand diagrams.
  • SV Pleione’s story. Good article (PDF) on an electric conversion with lots of pictures, speed facts and learnings.
  • Maine sail has good information on planning and especially design diagrams of electrical systems in general, such as here, and the site
  • Plus all the others referenced already in the text above!

Please let us know what you think, and maybe whether you are thinking of the same!

Hybrid electric power for Blu Emu

This post will be controversial for some readers, but we like the idea of electric power for our Blu Emu. This post is an introduction to why we want to use it, what we would use it for, and how we intend to actually implement it. At the moment, this is all based on research and ideas, and not one electron has been harmed during the making of these ideas!

In the future, maybe we will become the Electric Blu Emu

Continue reading “Hybrid electric power for Blu Emu”

An Itty-Bitty Grub Screw Nearly Sank Blu Emu!

G’day there, well, here is my long awaited first blog post.  I’m not going to bore you with the many reasons why it’s taken 12 months to write this after the fact, but it’s done. Yes, it’s true what the title states, a misaligned 10mm grub screw nearly  sank the boat and why it happened will be examined below.  To set the scene….

Continue reading “An Itty-Bitty Grub Screw Nearly Sank Blu Emu!”

On the capsizing of multihulls…

There has been scuttlebutt about the inability of multihulls (catamarans and trimarans) to self-right after capsize for many decades. There’s also sometimes a belief that it’s very easy for them to turn turtle (as capsize can be called). The general gist of one side of the fanatics is:

  • once a multihulls gets turned over, you can’t get it back whereas a monohull can (not is) be designed, built, sailed and crewed to allow (semi-)automatic re-righting. So it’s far better to be on a monohull.

The “other” side generally responds with:

  • sure, once a multihull turns over she can’t be re-righted, but she almost always floats and provides a (uncomfortable!) platform to survive in until rescue. It’s also not easy at all to capsize a multihull, and the majority you see are racers and thus not generalisable.
    Also, almost all monohulls won’t re-right either as they aren’t designed, built, sailed AND crewed to do so and when turned usually go straight to the bottom of the ocean… and even if they do re-right, they have often lost their mast and ability to provide a stable platform for their crew to survive.

Do you think Ford or Holden is best? Cats or dogs? Catholicism or Hinduism?

Decisions have usually been made and sides taken: we have decided on a catamaran and are happy. But we can all still learn, and there have been quite a few scientific studies on the ability of multihulls to not turn over. I’ve quoted and copied what I find interesting pieces from a some publications here, and I’ll add more over time if you know of others (send me an email). We are obviously interested in respect of our vessel, so there’s some comments below for her.

TLDR: multihulls won’t capsize from non-breaking waves, and can probably handle breaking waves up to their beam.

Continue reading “On the capsizing of multihulls…”

An aluminium powercat

Our Blu Emu is made from aluminium. However, aluminium wasn’t on our must-have list when we were looking. But as we now have such a boat, I got interested in the material and found out why it is such a great thing to build boats out of: I have made a page about aluminium boats, and noted the StrongAll® method that ours is built using. this different method means for a 50’/15m boat, she in incredibly strong with 12mm thick hulls and 6mm thick deck and superstructure. Did you know most shark cages are made from aluminium? The US F16 fighter is 80% aluminium? Armour plating is often made from aluminium…

There are very few aluminium boats compared to being built from other materials. There are even fewer aluminium catamarans, and even fewer aluminium power catamarans! One of them is our sistership, the Santorini 65 (for sale recently), which was reviewed by Multihulls World (pay for full article).


Most of the other aluminium power catamarans you will find are those larger ones built for passengers, as 50’/15m is about the cutoff where the extra weight of aluminium is worth it for the strength and other properties: you probably won’t see many 30′ or 40′ aluminium power cats ever, unless they are very specialised.

Our Blu Emu is unique in that she is an aluminium power catamaran narrow enough to go through the French canals. Can’t wait!!

Long range power catamarans

Peter Brady provided a brief history (Multihull World Magazine, #142) of how he saw the development of long distance power catamarans:

Arthur Defever 1960’s (“long range cruising” monohulls) –>
Robert Beebe 1974 (“passage maker” monohulls) –>
Malcolm Tennant 1990’s (catamarans) &  Roger Hill 1990’s & Peter Brady 1990’s in Australia (catamarans).

To this, the production capability for power catamarans really took off when the French company, Fountaine Pajot, started their prolific line of “trawler” yachts in the last 1990’s, continuing to this day.

The qualities of the “passagemaker” were defined by Beebe as 2,400nm range at 7.5kn, self-sufficient for at least two weeks.

Brady opines that 2,000nm at displacement speed is a “reasonable bench mark”, with 55-65′ boats making 8kn at “displacement speed”.

This “displacement speed” indication is perhaps a better metric and allows calculation of the standard “hull speed” calculation of 1.34 x sqrt(LWL), with a “displacement speed” changing the multiplier from 1.34x to 1x or 1.1x (so a 49′ boat would average 7-7.7kn, a 64′ boat would average 8-8.8kn).

It is worth saying now that many trimarans and catamarans are acknowledged as NOT being limited by this theoretical hull speed as the formula is based on the hydrodynamic (wavemaking) properties, but hulls that are very narrow for their length (some say 8:1 or more on LWL:BWL) may instead be more limited by the interaction properties of the waves off each hull. There is not

So as a working definition, a passage maker or long range cruiser can be classified as being able to go at least 2,000nm on standard tanks at a speed of 6-8kn (depending on length, but 36-64′ covers most cruising size boats).

I have collected fuel consumption, displacement and size for quite a collection of power catamarans that I consider cruising boats. By this I mean they have considerable range and autonomy, have a displacement or semi-displacement hull shape, and can sleep at least two couples. This precludes the larger and smaller fast fishing boats (hull shape; range), patrol boats (comfort; sleeping), and all the smaller aluminium cats.

Based on the data I have collected, for production boats, these are long range passage makers:

  • Sunreef 70 – range 3200
  • Africat 420 – range 2800
  • Fountaine Pajot 46 Cumberland – range 2100

and for non-production boats, these are those I can find enough data to support as long range:

  • Tennant 66 Domino – range 7000nm+
  • Tennant 60 Catbyrd – range 6000nm+
  • Tennant 54 PH8 – range 3000nm
  • Tennant 44 St John – range 2000nm
  • Roger Hill 66 Tenacity – range 2500nm
  • Roger Hill 66 Lola – range 3200nm
  • Brady 17.5 Passagemaker – range 3200nm

By definition, these power catamarans (a mix of one-off and production boats) are not long-range:

  • Fountaine Pajot 37 Maryland (with 75hp engines, not 150hp) – range 1500
  • PDQ 41 – range 1500
  • Pachoud 49 Solitaire – range 1250
  • Fountaine Pajot 37 MY – range 1200
  • Lagoon 43 – range 1200
  • Horizon 52 – range 1150
  • Fountaine Pajot 35 Highland – range 1100
  • Fountaine Pajot 44 MY44 – range 1100
  • Ligure 50 – range 1100
  • Aquilla 48 – range 1050
  • Fountaine Pajot 40 Summerland – range 1000
  • Fountaine Pajot 44 Cumberland – range 1000
  • Leopard 51 – range 1000
  • Leopard 43 – range 1000

and those with less than 1000nm range at the requisite speed:

  • Aquilla 45 – range 950
  • Leopard 37 – range 900
  • Fountaine Pajot 34 Greenland – range 900
  • Aspen 120 – range 750
  • PDQ 34 – range 680

So it’s rather obvious that if you want a long range passage making power catamaran, you have three choices in production boats. I believe the Sunreef 70 is still in production. Africat had at least 31 hulls (as at 2010!), the Cumberland certainly has a few around, and at the upper end of length there would be a few secondhand Sunreef’s coming through the charter fleets. This means there is a reasonable list of production boats – even if only three designs – to choose from.

Going non-production, you are generally into one-off builds. Even though the big-name designers may have sold multiple hulls of the same initial design, these are often modified over the build so that they may only partly resemble each other once finished.

However…It is rather small-minded to ignore the fact that today there are more options to do passage making. For example the Silent 55 is a solar-assisted, pure electric or hybrid diesel-electric power catamaran that can passage make at 100nm per day on solar alone – essentially forever (at only 4kn though). Or it can go at 6-8kn combining both solar and diesel (range is uncertain, but with 600L diesel for the genset combined with daylight solar, it should be over 1000nm). So here is a passage maker that can go faster for short distances, or essentially has an infinite solar-powered range at lower speed. This tradeoff is something that DeFever, Beebe and maybe even Tennant probably couldn’t have imagined.

Lastly, the technical list of non-long range power catamarans ignores the fact that all of those referenced have an excellent range of at least 900nm. There are few times in a passage maker’s travels where more range is needed – the Pacific (Panama-Marquesas) and Atlantic (Bermuda-Azores, Cape Verde-Barbados, Cape Town-St Helena) are such, but these are an extremely small part of the time on water a passage maker spends compared to being close to land and places where diesel – quality or not – is available.

The options available are borne out by the travels of the Leopard 37, which are delivered to the Caribbean on their own hulls from South Africa even though they have a nominal range of 900nm only. They did passages of over 2500nm at 7kn in the most efficient fuel zone, a single engine at a time, and using extra tankage which make such long passages quite feasible for the few times they are needed. Some may argue that the fuel consumption figures are for calm flat water with no tide and thus theoretical and impractical as far as passage making in concerned: the delivery of the Leopard 37 should put that to rest as they encountered a variety of conditions in the Southern Atlantic including 35kn winds. Also, while it is true that careful choice of route and conditions are sought to cope with the fuel and boat size, this would be true of most any boat, monohull or multihull. Perhaps only Domino, Catbyrd, and Dashew’s FPB’s would consider conditions and routes others would not dare – but they are in a breed by themselves, perhaps a “super passage maker”.

As a final warning, almost all of the above it theoretical waffle. It doesn’t take into account some vital points of decision: is the boat designed and built to handle the conditions of a long passage? Are the people aboard capable and ready for such voyages?

If you know of other long range power catamarans and can provide at least three data points of speed-consumption, please let me know and I can add them.

Other interesting articles about power catamarans are:

and for some first hand information, Domino and SnoDog are fantastic.

RYA Day Skipper – crawling before we run (part the two)

In part zero and one I explained why you would find us in the UK in May-June. The UK, in this case, means the Cornish town of Falmouth. Falmouth has the third deepest natural harbour in the world and the deepest in Western Europe. It’s name is also derived from the river Fal. It is claimed that an earlier Celtic name for the place was Peny-cwm-cuic (which translates as ‘head of the creek’) which is anglicised as “Pennycomequick”. Isn’t language fun!
While we didn’t get to see it, there is lots to see that is more than 50 years old which is the average age of most things in Australia. For example, at the entrance to the Carrick Roads, Pendennis Castle was strengthened to resist the Spanish Armada and was the second to last fort to surrender to the Parliamentary Army in the English civil war. Hmm….
Cornish Cruising do numerous RYA courses and, run by Nick, we had two fantastic teachers in Phil and Bob, and were joined by local lad Jack who already knew the area better than most since he was on the water since he was four years old and his father ran a local boat charter and fishing business!
Here are a set of photos from the four days of course. We didn’t get any chance to look around on land much as the course often went until 7 or 8 at night.

RYA Day Skipper – crawling before we run (part the one)

Blu Emu was resting on her laurels, or at least her hulls, in Saint Martin (abbreviated incidentally as SXM for some reason) in the Caribbean. Peters and May, who happen to be an international shipping company and not, as it appears, a Sydney clothing store or firm of slightly dodgy lawyers, needed the boat in Antigua. Antigua (with a much more boring abbreviation of ANT, although somewhat sort after as an Internet location by the Providers Internationale Soft Suede), was only about 100 nautical miles away as the pirates fly but that was a long long way when you are sitting in Australia wondering how your boat is going to get there!

Fortunately, we made contact with a Captain – yes, the capitalised honorific was appropriate – Greg who had skippered our new boat in previous times for the likes of the National Geographic while whale filming, and the Death In Paradise crew for episode 1, series 5. I’m not sure how the boat felt about being the “millionaire’s yacht” but she carried out her role with quiet aplomb worthy of aluminium. Stoic perhaps, or even Metallic.

Captain Greg agreed to pilot her on her last (for now!) Caribbean escapade to Antigua, righting all the wrongs that could be fixed and providing a manual simple enough for even idiots (that’s us folks, although it is less idiocy that lack of experience). He even said that he was going to buy her if we had not already done so, such was his love of her. Our trust and hope built high, bedded even more when we found that his family happened to own an entire island in Guadeloupe and was thus less than likely to “do a runner”.

Prepared, victualled (look it up… did you find it means buying food and water for a voyage?) and with a zarpe she was ready. I’m pretty sure you had to lookup “zarpe” too. Google fortunately provides us with a clear explanation:

Zarpe: first person singular (Eu) present subjunctive of zarpar.

Zarpe: third person singular (Elle and Ella, also used with voice and other) present subjunctive of zarpar.


Such is the wonder of information on the Internet… A zarpe is a customs clearance for vessels. You clear out of one country and receive a zarpe, and you must provide it to the next country you enter as proof of where you have just been and that you cleared out correctly, rather than clearing out quickly such as when being chased by irate husbands (wives are never irate of course… remember the honeymoon!).

After some tribulations, like a leaking shaft seal and 30kn and 3m swells, she arrived in Antigua and joined the Peters and May hired Zea Bremen. Modern ships have something called AIS, or Automatic Identification System, which allows anyone to track larger vessels throughout the world. You can see where Zea Bremen is right now if you want.

Lifted aboard, they kindly gave her the entire hold to herself, while the other 15 boats had to endure the “outside” above her.

RYA Day Skipper – crawling before we run (part 0)

There is nothing like a normal, relaxing and fun honeymoon. Concentrating on each other to the exclusiveness of anyone and anything else… which is why we decided not to do that, and instead our honeymoon consists of firstly, getting our RYA Day Skipper and ICC; secondly to look around what and where we will do with and leave our boat; and thirdly to spend time aboard our boat – which I have never seen with my own eyes! It is likely to be anything but relaxing, only a little time to concentrate on each other, and…well… it hopefully is fun.

Let me explain a little.

In case it isn’t obvious, Eraine and I bought a boat in 2018. To summarise, it’s the right boat for us, just at not the best time (years before we retire) and not in the right place (the Caribbean). But the price was good (in case you thought about that question). The blog gives some points along that purchase path.

We also were married in December 2018, but what with everything else happening we decided to postpone the nuptials until a more appropriate date. With some bloody mindedness worthy of a Darwin Award winner, we decided to incorporate the honeymoon and driving our new boat across the Atlantic on her way to the antipodes. After some snags, including some odd doubting of our own abilities to make the trip given our years in boats of 10-20 feet on placid lakes being preparation for our new boat of 50 feet across one of the most treacherous and long ocean passages on the planet. We instead found a willing shipping company and bravely paid them.

This ruined the quiet honeymoon Transat (sailor talk for trans-Atlantic crossing) plans, so we were forced to make things harder in other ways. Fortunately, this presented itself in the problem of, once our new baby arrived in Europe we didn’t actually have the requisite accreditation to touch her. In the same manner as sitting behind the wheel of a car while over the limit can get one in trouble, we couldn’t actually take ownership until we completed some training that wasn’t need in Australia. Strangely, in Australia one can go on a 2 day boating course to qualify for any boat upto, say, 20m (60 feet) long and then head off around the world in the sure knowledge that the Australian accreditation will, while absolute rubbish, allow one to transit through every country in the maritime world (I’m unsure whether it would work in Mongolia or Nepal, but no doubt some intrepid unmarried twit has got the Guinness record for trying it).

So in Australia we couldn’t find anyone who could appropriately train us in the manner that Europe has become accustomed. That is the International Certificate of Competency, or ICC. Oddly, the title manages to suggest ability without saying in what – basket weaving? Nose hair dying? Hmm…. Anyway, the French put great store on the ICC, as do the Dutch and sometimes the other EU member states. To get an ICC, you just have to complete the training in the country you want to visit, in their language only, get a local licence and pay money to turn it into an ICC.

Our French, Dutch, Belgium and German are shiite. Fortunately, most of the United Kingdom are also shiite at that, so the Royal Yachting Association has kindly agreed to give you an ICC if you complete one of their Day Skipper courses. Four fun-filled days on a motor yacht (in our case; you can choose the sheet/rope-twiddling version if you are a sailor).

Hence our plans morphed into: do our RYA Day Skipper in the sunny windless and tideless UK (you can tell where this is going, can’t you…), do some research across France about just how high their bridges are (to the nearest centimetre please – we need it!), and collect our baby from the clutches of the shipping company and drink champagne in, well, Champagne. Vive la France!

Oh, and we’ll be on our honeymoon so it will just be a normal, relaxing and fun time like everyone has…