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”

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…

Why Blu Emu?

The naming of a child – or boat or pet or anything that becomes a part of the family (yes, I know this is purposely provocative!) is a momentous decision for the owner, the thing and is part of a long-standing tradition in many cultures. Re-naming is variously seen as something that shouldn’t ever occur, to being ok if done “correctly”, through to not mattering at all.

While naming/re-naming is fraught with cultural differences (if you care about them), the name itself is an important tradition in many cultures. A warship called “Invincible” is viewed differently to one called “Cheerful” or “Dainty“! Amazingly “Cockchafer” has been attached to four warships, perhaps indicating a change in the use of language over time…

While talking names, it’s important to note the use of a female pronoun (“she”) for boats. There is lots of information about this, but a nice summary is:

Since the beginning of recorded history, man has used water crafts to travel and explore the world. Each civilization has its own traditions regarding naming boats, but they are most often feminine names. While it is not known exactly why ships are named after female figures, there are two prominent theories. One hypothesizes that boats were named after goddesses and other mythical figures, and later shifted to popular feminine names as recognition of gods and goddesses faded. The second major theory focuses on the basis of European languages. A number of languages, such as German and French, have a complex system of gender involving grammatical terms in which objects are assigned specific masculine or feminine tones. Olde English also used this system of naming, with many inanimate objects such as boats referred to in the feminine form. As the English language changed and evolved, the tradition of using this feminine form for ship names continued and is still present today.

Interestingly, Lloyds of London while young at “only” a few hundred years old, decided in 2002 to use “it” for ships rather than she. Media of the time noted though:

[Lloyds said] “However, I don’t think there is anything wrong with calling ships ‘she’ in conversation. It’s a respectable maritime tradition.”…

A spokesman for the Royal Navy said it would continue to refer to ships as female. It traditionally chooses masculine or geographical names, such as Iron Duke or Lancaster, for its vessels – although Andromeda, Penelope and Minerva all served in the Falklands War.

“Lloyd’s List can do what it wants. The Royal Navy will continue to call its ships ‘she’ as we always have done. It’s historic and traditional,” he said.

“Ships have a soul. If I remember my history, they are female because originally the ship was the only woman allowed at sea and was treated with deference and respect – and because they are expensive.”

I could not find much about other cultures’ naming, but one report on Chinese ship naming history shows historical names like “Pure Harmony”, “Bestowing Peace”, “Clear Distance”, “Galloping Horse” and even “Big Ship”. Apparently the ship names were not as important – at least for chroniclers – as in parts of Europe.

Blu Emu

Anyway… after quite some time thinking about it, we chose the name Blu Emu for our boat. We chose it because:


  • Has two legs, and is one of only two birds in the world which has two feathers of the same length from the same quill (a catamaran has two hulls)
  • Is fast (our catamaran has high L:B ratio 12.3:1 and semi-displacement hulls)
  • Can travel great distances (we want to go around the world including cold areas)
  • It is said that there are up to 12 different color layers in an emu egg making it very unique. There are three primary layers in the shell of an emu egg. The outside is dark green. The middle layer is teal, and the inside layer is nearly white. Occasionally there is a fourth layer, which is thin and rather gray, between the outside layer and the teal layer. The teal and blue are actually as many as seven subtle layers of color, each about the thickness of a sheet of paper. (teal/blue = ocean)
  • Is quintessentially Australian – it even appears on the Australian coat of arms [did you know that there are two animals on the Australian coat of arms – the emu and the kangaroo, and that these were chosen as being endemic to Australia and are also the only two animals that cannot go backwards! An even more interesting note is that the Kangaroo is supposed to be demonstrably male – which the logo below does not show…]


  • Shortening of Blue, referring to blue water/ocean capable
  • Quintessentially Australian slang (meaning red or reddish, esp of hair; but the important part is Australian)

We also like to think “Blu Emu” can be written as “Blue mu”, which leads to:

  • Mu was derived from the Egyptian hieroglyphic symbol for water, which had been simplified by the Phoenicians and named after their word for water
  • Mu means a reduced mass (light catamaran) in the Two-Body System (a catamaran has two hulls)
  • Mu means a magnetic dipole moment (a dipole has 2 pole, like a catamaran’s two hulls)
  • Mu is the prefix given in IUPAC nomenclature for a bridging ligand (which is a ligand that connects two or more atoms, usually metal ions – which sounds remarkably like an aluminium catamaran!)