The Offshore Voyaging Reference Site

Get-Home Backup For Offshore Motorboats—Part 3, The Winner

In Part 1 of this series I concluded that yes, we really do need a get-home option for an offshore motorboat, and in Part 2 I took a deep dive into the benefits and disadvantages of each option.

Now I’m going to stick my neck way, way out and pick a winner.

Not Confirmation Bias

But first, one interesting thing in all of this is that if you had asked me to pick my preferred get-home two years ago, before I put all this time and analysis into this decision, the solution that is my winner today would have been at the bottom of my list then—once again reminds me of the importance of making these decisions using research and thoughtful analysis, not gut feel or crowd “wisdom”.

Enough said. Can I have the envelope please…cue the thumping bass music…

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OK, two motors and two drive chains. Deals directly with the problem of one motor failing and or one drive chain failing.

What are the chances of one drive chain fouling and not the other? I think you are being overly optimistic to expect only one drive chain to be at risk.

This might be another solution.

One main engine and drive chain with a standby engine or generator which can be geared at will to a hydraulic system driving a hydraulically retractable sterndrive (which can be retracted into a stern compartment if desired).

It would be sized to permit a boat to beat off a lee shore under severe conditions.

I have no idea how expensive this would be relative to other solutions however it would constitute a near fail safe rarely used solution, which is what you are looking for.

If you want to get home, you have to pay for the ticket.


One of the big risks with any kind of complex “only for emergencies” drive system is that it won’t work when you need it.
Such systems, almost invariably, end up seeing less thorough and less frequent maintenance than the main engine does. They tend not to be tested at full capacity very often.
They can, in principle, protect you against the situation where mechanical damage (from grounding or fouling) takes out both main engines of a twin-engine installation but not the retracted wing / backup engine of a single-screw vessel. That, however, seems to be a relatively rare scenario.



Your comments are very apt and sensible. However, the point of a backup system is that it can pull you out of any situation that might come up, no matter how rare the possibility, particularly something like having to beat off a lee shore in periculous circumstances when, for some reason, all normal systems have failed. Having to deal with two different systems may just be one of the costs of such an insurance system. And of course, the insurance system has to be routinely tested.

In any event, is the system suggested by me that complex?

Scott A

Hi John,

As a layman reader who like many others has the dream of one day cruising and living aboard, I’ve eagerly read your (and the AAC community’s) analysis and discussion on this topic.

For backup propulsion of an offshore cruiser, it’s clear that finding tradeoffs that result in “maintainable complexity” is the sweet spot, and your argument for a twin engine system is convincing.

Having two identical engines adds propulsion redundancy without adding new technology, and most importantly IMO, allows the boat owner to become more practiced in a single maintenance routine. Far better for an owner to focus scarce time on the art of diesel maintenance, and do so on a single model of engine, than to split that time between multiple types of prop propulsion, each with different parts, maintenance schedules, and modes of failure.

For a diligent owner, I believe such economies of time, parts, and expertise will contribute greatly to the reliability of this system. The discipline would seem to be in the importance of keeping both engines in fighting trim at all times, and to never leave the marina with one of the engines operating below spec. Perhaps to think of the vessel more like a twin engine airplane in this regard…

The twin configuration has the bonus of being applicable to both mono and multihull designs. In addition to any more news on Artnautica and Boréal developments, I look forward to any future articles discussing stability and hull shape in this AAC powerboat vein.

Gerben Van Duyl

Hi John, very good article, great research. Just a quick thought/question: you will already be bringing a substantial outboard for your tender. Could that be given a transom mount on the mothership so it can bring you home, as a third option. You could even bring an ultra low-pitch prop for this purpose, easy to swap out. In fact, you could take it one step further: Two outboards! One in active duty for the tender, one in spare, and together they are a capable Get-Home team. Also circumvents the problems of twin-engine fouling, catastrophic diesel fuel contamination and even rudder failure. Think the new 2017 Yamaha F25, great for a substantial tender, 2 x 25 = 50HP, but you need a crane to lift it as it still weighs 60Kg.

Marc Dacey

Well, I certainly agree with your point about the coupler; that was part of our reasoning for an AquaDrive installation. The twin Beta 50s are also reasonable, but allow an interesting calculation of what you don’t like: increased complexity. I’m thinking that two engines allow two PTOs, with the option of belting in either spare or additional alternators or to run compressors or watermakers as desired. The rationale being that this sort of load is “parasitic” over two drivetrains, not one.

On the other hand, I’ve done precisely what Gerben suggests: put a RIB Zodiac on the hip of an ailing Atomic 4-driven sailboat, fired up the Honda 100 and trucked an hour or so back to our dock on a dead-calm day. I think his suggestion is reasonable and in some ways more flexible, save for the need to carry sufficient gasoline, which is annoying and problematic offshore. Which leads to my last observation: is there a market for a diesel outboard and could it be made light enough to be used on a typical tender?

Gerben Van Duyl

Yanmar is about to release diesel outboards again?

Marc Dacey

Yes, I get that, and they can be used together. So far, I’m having good results with a hydraulic transmission and the AquaDrive, but it would not be difficult to throw a Drivesaver in that line.


A sailboat engine room containing two Deutz V-8s, each with a hydraulic PTO of about 80hp, driving anchoring gear, forward and aft thrusters and retractable stabilizers and Hundestadt variable pitch props. In addition, two giant alternators per engine. Every motor in the vessel sized to accommodate 50 or 60 cycle. Three 220v generators with a total capacity of 190kw. Twenty communications devices and radars on board. A 24/7 satellite link continually monitoring and broadcasting 100 vessel functions to the main control office in New York.

The perfect expression of a sailboat that will never be used by it’s owner.



As I’ve suggested, choices always start from intended use. For a ULDB powerboat planning to go to remote places the KISS principle still leads to twin engines being the best choice. And a pair of little BETA’s or Yanmars are a far cry from an engine room crammed with two V-12’s and two or three generators.

One thing I learned from trying to nurse one of those monsters 900 miles down the Baha where no fuel is available is that widely spaced big props don’t allow low speed operation on a single engine. At idle speed (8knots) you will simply drive in circles, and full rudder is barely sufficient to maintain course. With two small inline 4 cylinder engines one would have the option of keeping the props close together. I’d study very carefully the trade offs between maneuverability, interference flow, and single engine utility.


As a coastal cruiser, I may not have much credibility here perhaps, but I have been thinking about this topic a bit lately. My heavy duty Twin Disc transmission is being rebuilt right now as it was showing subtle signs of trouble. What if I had a transmission failure in some remote location up the coast thinks I?

I have a Nordic Tug 37 with a single 380 HP Cummins Diesel. I really like the fuel economy and security of a heavy keel and single prop in our log strewn waters of Coastal BC. I do not fancy the extra cost and maintenance of a dual engine setup.

We have two 275W Solar panels on the pilot house roof that does a great job of topping up our house bank three seasons a year but in the winter time, despite all LED lighting, we do not have enough sunlight to spend days at anchor without running our generator. The ~13KW generator works very well and quite reliably. It doesn’t take up much space in the engine room and it’s there.

I’ve been thinking that a great get home option would be to have an electric motor that could be deployed when needed running this off the house bank and generator. This would not impact the normal running configuration and despite some cost, would be an elegant solution to this problem. I note that Torqeedo makes a pod that might fit the bill…

Would it not make sense to consider a generator and some form of electric thruster?



Yes, After I posted, it hit me that you did discuss this earlier. Sorry.



Hello John
Thank you for your great article. In a twin engine configuration would you go for twin rudders or would it be possible to have a single rudder. A twin engine/single rudder configuration would also make the engine room shorter, giving a bit more living space.
I am eagerly awaiting your articles covering the roll stabilization issue.


Twin screw / single rudder can be made to work. It reduces the handling and redundancy advantages of a twin engine installation, and doesn’t bring much (if any) improvement in cost or fuel consumption, so it’s pretty rare.

Stein Varjord

Hi John.

As you’d expect from my comments on previous posts, I totally agree with you on this. My experiences indicate that all your points make sense.

Since I’m a multihull guy, I have much experience with twins. Also with motor twins…. 😀 Always on sailing cats, but as you point out, they’re also motor boats. My present 40 foot cat has two Yanmar 27 hp diesels on sail drives with rather big fixed props. That’s unacceptable, of course, and will be changed, but I’ve tested it some.

When we picked it up last autumn, we went through the centre of Amsterdam and more with just one engine working. That includes many bridges and locks with about one foot of clearance on each side. Also it includes having to stop, wait in position and start moving again in very tight spots. This cat was easily able to. Of course a lot more clumsily than with both running, but still no stress. Some other cats can’t even go straight at speed unless the props fold.

I don’t know if I’m right, but I think it’s important to have counter rotating propellers and position the correct one on the correct side to benefit from the propeller “walk”. The distance between the props on this boat is almost 6 meters, 19 feet, so in a mono, I don’t think it’s possible to put them too far apart.

About damage or fouling of both drives: Cats are maybe​ not entirely comparable, due to the big distance between the drives. Still it’s worth noticing that this almost never happens.

Many cats have outboards. It’s generally accepted that if they are on the stern, they can only be used in calm seas. Many put them in pods further forwards, under each side of the bridge deck. This works much better, if the outboards have a very long extension to get the prop deep, thus making them not suitable for a dinghy. The solution saves weight and money on boats that sail well enough to do that most of the time. Diesel inboards are way better in everything else.

As a get home solution on a monohull, I’d say outboards need to stay on the dinghy. In rough seas, that means towing is the option. The ability to move upwind will anyway be very limited.

If I was on a lee shore in significant wind with a non operational main engine and no sailing option, no outboard engine setup would make me feel less stressed. I’ve seen a big rib with twin 150 hp outboards trying to tow a 45 foot monohull sailboat away from a lee shore in France. Rental boat where crew couldn’t sail in strong wind and got rope in the propeller. The RIB failed. Plenty of power, but not enough grip on the water and no control in the very rough seas. The boat hit the shore…. Outboards are great, but propellers need to be deep down.


Hi Stein
The difference between single engine operation on a sailing cat and the difficulties of trying to run single-engined with a 1800hp sport fisherman that I mentioned in an earlier post are two-fold. The sailing cat has real rudders, hopefully large enough to maintain control at all speeds while the windward hull is being partially lifted. The power boat has tiny rudders designed to work in the high speed flow coming off it’s large propellers. The props themselves are large and draggy when not turning and the flat planing underbody offers little directional stability, thus accentuating the turning effect of a stationary propeller. So, apples & oranges!

Stein Varjord

Hi Richard.

A agree that it’s quite a different situation, especially if comparing to the semi planing types of boat. However, such boat types are quite unsuitable for long distance motor cruising. The rotten efficiency being the most important reason. An efficient long distance motor boat needs to have a hull shape much closer to a sailboat, as John has described. Real displacement hull. This is mostly true even for a catamaran version of this.

I also agree that the main difference is the rudder size. That does indeed matter a lot. I plan to never fly hulls with this boat, though! 🙂 I have done a lot of hull flying, but most cruising cats are not even able to lift a hull. Ours is able, due to half the weight of the typical cruisers, but for approaching the limits that close with our home, I’d like twice as deep rudders. These are a bit short of two feet, 55 cm.

The type of boat discussed here will need to behave well even at low power. Some may even want a small sailing rig on it, for stability, economy and added backup safety. That means it needs significantly bigger and better shaped rudders than the typical semi planer.

With twin engines, I assume twin rudders is the only option? Talking about redundant systems, rudders are high on the list of useful backup items. 🙂 In which case, the prop wash will also hit at least one of these rudders. On my boat, this is an essential reason why it behaves acceptably on one engine.


Thanks John and all participants for some interesting comments.
Agree with your twin engine lay-out, but for ” near home” cruising just a single one, with both hydraulic
thrusters powered from the genset. However, the other extreme case always comes to mind, Idlewild, a 53 ft alloy, 11 ft beam, with a single 55HP Kubota, no thrusters, goes from Alaska to Greenland, South Africa and around the world. KISS to the extreme !!
Most commercials are single power, and with proper maintenance, you will get a long way. I prefer large rudders, round bilge, and opposing props, 3 or 4 large diesel tanks, so that a case of bad fuel will have limited effect, and at least try out your last bought fuel first so that you know if it is good or bad. That’s what we have now, with two old-time under-powered diesels, and absolutely no computers involved. In our small marina, 3 different boats with new large diesels for some reason blew up, lucky that no one was in the ER, all were computer related.
I can easily run on one engine if the set speed limit is low and the large rudders no doubt play an important part, and are essential for low speed maneuvering.
Some of you brought up the ( diesel) outboards and I think they will become very popular, being very compact, easy to replace, but need to be placed in some kind of pot. Yes, there will be a computer hiding somewhere 🙁


“all (failures) were computer related.” Its important to not forget that many “modern” diesel engines with electronic fuel management will not run if the voltage falls below a critical level. In my case that was 23V. Not only will the engine not start, but it will immediately shut down as the solenoid in the fuel system fails to hold the delivery valve open! With a twin engine installation if you manage to get one engine running, the starter load from the attempt to start the second engine will kill both of them! So if you choose to power a single engine boat with one of these engines, you darn well better have a generator on board, and isolated battery systems that can be called into play!

Marc Dacey

I don’t know enough about this to know why the old “compression lever” setup has fallen out of favour on diesels; it strikes me that one could, with some ingenuity, start on one cylinder by applying sufficient rotational force to the flywheel, as I believe Michel Desjoyeaux did in the 2001 Vendee Globe via a crash gybe. A solution may be a mechanical starter of this type. I’ve been thinking that instead of a spare electric starter, one of these would cover both “busted starter” and “compromised batteries”.

Stedem Wood

I cruise with a single and robust wing with its own skeg, shaft and feathering prop.

If diesels weren’t reliable, we wouldn’t be cruising. The manufacturer’s reps are never going to say that their products aren’t reliable when asked about twins. But, if engines, or at least the peripheral components on which they rely, didn’t fail, we wouldn’t be having this conversation. I’ve previously mentioned a failed impeller and can think of other occasions where the get-home could simply be a get-out-of-jail card that affords some back up until something can be rectified. Dead in the water leaves no options other than the anchor in suitable waters.

Twin skegs have a lot going for them and afford protection from big floating debris like logs better than a single skeg. Large displacement-sized twin rudders, benefiting from prop wash for maneuverability will be better protected than twin rudders on sailboats.

My experience with debris has been very fine and poorly marked nets in Southeast Asia and 200 meters of floating 14mm line, likely cast off a tuna seiner in the western tropical South Pacific. On four separate events, (this stuff is really hard to see, net floats are the size of a used bar of soap; the floating line was blue and visible only after snagging it) the material was hung up on a forward hull zinc, which is mounted on posts or the hydraulic stabilizers. Only once did fine gill net wind into a big ball on the prop. I have to note the success of the prop-shaft line cutters in two other operator-error events.

Dead in the water meant diving my running gear; or stabilizers in the case of the floating line, (in the water over an hour) in the open ocean, on a rolling boat and is a lasting memory.

I’m lucky for daylight each time, I’ve since purchased an underwater light that will attach to a mask strap.

I never thought that twins would get the nod but I’m convinced after your unshakable analysis and conclusion, that twins are the reliable choice. The benefit of maneuverability is just a bonus. Using all your equipment all the time will bring better reliability than my current practice of running the wing monthly under full load for at least an hour. That exercise, with shaft locks, inadequate electrical generation and disabled stabilizers needs to be planned in advance and is a nagging pain. Maintaining a Gori prop requires getting in the water every two weeks to run the shells of the critters out of the exposed gears.

You’ve won me over. A strong wing isn’t Cheap but it’s the next best solution if you want a sturdy, reliable second choice that is immediately available.

There’s one additional, sometimes difficult step to using the wing. Getting the purpose-built spanner on the shaft’s notches to keep it from spinning is not possible if the prop is free-wheeling. Getting the shaft stopped where the notches are accessible also takes some effort.

Thanks for bringing the topic and starting the conversation.


Comment to RDE reply: re stop solenoids. Have had a few problems with stop solenoids on motorhome and truck, both Cummins where they closed the fuel supply somewhat, not all the way Remedy was to remove solenoids and went back to the old system, by pulling a cable to stop engine. As to the computer related problems on the other boats, on one the engine “bolted” and con-rod broke. I just prefer the proven and tested older style diesels, the combination of electronics with a moist salty environment….. ????


Same experience here, only it was a $170,000 V-12 that ran away. I wasn’t there to observe, but I was told the Captain and CAT factory mechanic clawed each other up pretty badly when they both tried to get out of the engine room at the same time as pistons and flying bits started hitting the ceiling.

Jurjen Hoekstra

Hi John, reading your articles on the ‘get home’ discussion, I follow your logic for twin engines. I do not agree or disagree, but had different arguments when I had my 55 foot single engine motoryacht build. In discussion with a very knowledgeable friend who owned several motoryachts and is engineer by profession, we came to the conclusion that based upon research it appears that approx. 90 % of diesel engine problems are related to either cooling or fuel problems. Also if a cooling or fuel problem occurs, it is not said that only one engine will have the problem, high chance both engines will suffer. Furthermore engines of a reputable brand nowadays are very reliable. I therefore decided to build in a heavy duty version of a Doosan L086TIH (intended for workboats), that delivers it’s max torque at lower RPM, has a better fuel efficiency than the light duty version (for yachts) and basically can run at 80 % of it’s load the rest of it’s life. I further invested in a reliable cooling and fuel system instead of a twin engine. The cooling system has double big water inlet filters and the cooling system is not weakened by using the cooling water to heat a boiler. Also a water inlet alarm and exhaust alarm were added. The fuel system has a double Racor filter and a separate fuel reconditioning system was installed to always maintain clean fuel. I have not yet many hours on the engine, but with the mentioned precautions I hope to have created a very reliable ‘single engine system’. Jurjen Hoekstra


Thank you Jurjen, very interessant:)
Am not surprised by your research where a very large percentage of diesel problems are caused by cooling and /or fuel related and your observation in the case of a twin engine set-up both engines likely to be effected.
Never heard of Doosan diesels, but thought Scania Vabis to be one of the best on the market. Am surprised, noting reliability, you didnt go with keel cooling, which to me it is a more reliable system , unless you operate in warm waters, but remember a case many years ago, the ship I worked on had to reduce RPM as the cooling became a problem. Dont know if too many tubes in the heat exchanger had been plugged off. For maneuvering, two engines are helpful, but an expensive way to solve that problem. I have a 15kw electric bow thruster, but find it a cheap way to do it and cuts out when it overheats when you need it most, not forgetting the need for a large battery capacity. Am seriously thinking of replacing the electric motor with a 25hp outboard where the prop etc will fit in the 15¨ tube, but not sure if there is a wireless operating system for outboards on the market. The anchor hold is sealed of from the rest and has a large hatch to provide ventilation. Would have preferred an hydraulic system powered by the genset, but too expensive to do install now. Enjoy your new boat.

Jurjen Hoekstra

Hi Rene, thanks for your comment. As for manoeuvrability in close quarters, I know twin engines seem to be the solution (I once operated a twin engine 55 foot yacht for several days), but I invested in the bow thrusther and stern thruster. Electric, as I had no knowledge of hydraulics and it seemed a lot of messing about having to add the hydraulic pump and all the hydraulic pipes, electrics is more my thing and I thought easier to repair in case of a malfunction. Doosan is the former Daewoo from Korea and they are huge in producing marine engines, generators, road construction equipment, heavy duty equipment. Recommendations I received were very positive and they are known for their reliability. As a fan of V8 engines, I initially wanted to install the VW marine V8 that had just come out, but convinced by my friend that this engine was very sophisticated and would require a qualified engineer for every little hick up, I choose the ‘simple’ Doosan L068TIH which I can service and when necessary repair myself.


Came across this one today

Stein Varjord

Hi Doug

I tried the link and it doesn’t lead anywhere. Maybe complete it?

Also, I’d like it if you say something about what the link leads to. At least what it’s about and why it’s interesting. That way one can choose if it’s worth looking more into before using potentially limited data capasity.


Sorry for the broken link, google MY SILA INUA.

Modern origami aluminum construction. This is Sila Inua, designed by Joubert-Nivelt and built in France. She’s a long-range powerboat intended to support small scientific expeditions in the Arctic. About 16 x 5m (52.5′ x 16.4′) and 70,000 pounds displacement ready for sea with 11,080 L (2930 usg) of fuel aboard.


Thanks Doug for the note, a very interesting KISS boat.

Mickey Elam

I’m curious what about status on writing in re stabilization for such a motor boat. I’ve read pretty much everything Steve Dashew has written on SetSail about stabilization but I’d like to know more from John’s perspective as well as the views of other designers on the subject.

I’ll be the first to admit that I’m coming from a place of very limited experience in that I’ve spent no time offshore on a small boat. The engineer in me rebels at paravanes and the efficiency impact they impart, but the complexity of dynamic stabilization schemes (vane stabilizers, gyroscopes,…) don’t thrill me either. Is such stabilization required or just desirable?

Matt Marsh

Stabilization is a hotly debated topic with no one clear, correct answer. Some designers and some skippers believe active stabilization is essential for an offshore motorboat; others are content with paravanes or to just let the hull do its own thing.

Active-fin stabilizers are a very well established technology. If they are properly built and properly installed, they’ve proven to be quite reliable, long-term. (You can of course do a shoddy job of installing crappy ones, with the expected results.) There’s some evidence that, at least for some hull types, stabilization improves fuel efficiency by enough of a margin to overcome the drag of the fins and partly justify the extra cost. The main problem is that they’re a big capital expense up front.

Gyroscopic stabilizers are in a less mature stage of development. I would need to see warranty certificates on the order of 10,000+ hours before I could comfortably recommend going down this road. I’m not convinced any gyro manufacturers have reached that quality standard yet.

Mickey Elam

Thanks for the comments. I’d like to take the discussion a bit further if I may, and discuss active stabilization in the context of the powerboat covered in this book, the Artnautica LRC 58. From what I’ve read, it seems at least one owner (are there more owners yet?) feels pretty strongly that stabilization of some sort may be needed.

So, for that boat as an example, just how big a capital cost (ballpark) are we talking to add fin stabilization? While at-anchor stabilization would be nice, and I’ve read about some systems that claim to do at-rest stabilization, it seems to me that flopper stoppers should do most of that for “free” in terms of ongoing energy use and, certainly, ease of maintenance.

Mickey Elam


Thanks for the response and please forgive my ramblings and returning to the same topic as, while I’m trained as an engineer, I’ve never really used that training on the job, so I get sucked down whatever interesting rabbit hole I may run across on the web!

With that said, this topic has prompted me to delve into stabilization techniques.One of the techniques I’ve run across is the use of anti-roll tanks. Most of the installations I’ve seen, especially on small boats, has involved installation of such tanks fairly high up in the boat; I’d think such installations would have a serious negative effect on stability. Do you have any ideas around integrating such a tank into the hull structure of the boat? In particular, I’m curious if such a tank could be integrated into the boat without negatively affecting displacement or stability by rearranging the existing fresh water tank(s) to serve the same purpose? From what I’ve read, the weight of the liquid in the anti-roll tank should be about 1.5%-2.5% of the displacement of the boat; on the Artnautica LRC 58 for example, I’m thinking that works out to about 600 kg (600 liters) of fresh water. That is certainly not too much fresh water for such a vessel to carry given its mission.


Active -fin stabies should be seen as an investment and it could save your marriage.
Its design is pretty simple, but maintenance is often neglected due to its location and often hard to get to. They should be used regularly to prevent rams pitting and causing seals to leak and the grease-gun should be a regular visitor. The unit should be tested, but make sure your speed is low enough not to cause any damage by flying stuff through the saloon, galley etc. Too bad they are of no use at anchor, that’s where the gyro stabies come in handy. Have no experience with paravanes.



Cost to have fin stabies installed ? I have no idea. They were part of the boat when we bought it. Sorry, I cant help you.



Hello Everyone,

Albeit late in this stabilization discussion, I believe it will be interesting to note that the LRC58 that crossed to the Bahamas was sold by its first owner almost right after arriving at destination. I contacted him at the time, but the boat was already sold, and I am not aware what was the main reason.

Anyhow, a boat being sold almost new, after a major (and impressive crossing must be said), by its very first owner, may add to the fact that the LRC58 would become an even better boat if equipped with some form of stabilization.

Stedem Wood

Easy way to check stabilizer’s efficacy is to ride on an equipped boat and turn them off and on.

On my very round-bottomed power boat, the difference is forgetting where you put your coffee cup down or having everything from the starboard side on the port side and vice-versa.

Maintenance on Naiad stabilizers has included greasing one zerc fitting each side, once or twice each year for four years. 4,000 hours and over 33,000 miles

Designer expects paravanes (included in the design of the boat) to reduce boat speed one knot from the 9ish knot speed with fins.

Fins will work best if the boat is designed from the beginning to use them. Coffer dams (most easily accomplished on a metal boat) for the fin mechanism is a good idea. Even though the fins are meant to depart on a hard impact, the fin shaft has been folded back to the hull on a sister-ship. Structural metal bent but nearby tanks remained intact and there was no water ingress. Don’t know if there was water in the coffer dam. Short answer is that the shaft sticking through the hull is vulnerable in a hard grounding.

I’m on the hard next to a boat that obviously added fins as an after thought. The geometry of the installation will impart more of a sideways moment to the whole boat than a roll-righting moment because the shaft points nearly straight down on a hard-chined flat-bottomed vessel.

Gyro stabilizers use a lot of electricity, work while anchored, take 30 Minutes to spool up and have been described to me as less effective under-way.

Gyros have a strange characteristic of imparting a torque 90 degrees to the direction they’re being deflected on the plane of rotation.

That will impart a pitching moment to a roll and and rolling moment when pitching.

Lots more on the topic, of course but I’m hopeful this adds some helpful personal experience and observations to the thread.

Andy Nemier

Just found this thread by following the information bread crumb trail on the internet, in search of anything –LRC58–. I’m a member here at AAC – why didn’t I check here first!

I have been following the LRC58 since it’s introduction a few years ago, and have loved it from the moment I first laid eyes on it. I spoke to Dennis a couple of times to schedule a visit while we were in New Zealand, but sadly that meeting never materialized. And of course, I have read every word written about the FPB’s. A fellow cruiser we met owned an FPB64 and I was able to kick the tires for a week long period in Tahiti. My point here, is that I’m a huge fan of the long skinny aluminum boats for transoceanic passage-making.

And my Vote: Yes, I too believe that a twin engine installation is definitely the way to go. I was personally thinking that a twin engined Beta 43 would do fine. Stabilization is definitely something to be considered. I currently have an active fin system, made by ABT which works perfectly and has turned out to be bullet proof – but in my imaginary LRC58 – I would want to explore an ART (Anti Roll Tank). I have experience with these too, and they work great. The reason I would want to go with a passive system is because it mentally takes away any stress. Whenever we cross an ocean, I’m always stressed that the big girl is gonna stop, or the stabilization is somehow going to fail. LESS = MORE. The less equipment I have, the less stress I have to deal with.

Which brings me to the generator. I was also thinking that with a twin engine set-up, you would have multiple alternator charging options, which could also be augmented with Solar and Wind. I personally have to run my 20KW genny like 6 hours a day on anchor, and many sailboaters I meet never have power issues. Obviously their demands are less, but their passive charging systems tend to meet their power demands. I am constantly exercising Power Management when at anchor. A lot of guys I hang with just forget it all together and the genie is “always-on”, but that’s not the way I want to roll.

What would be great for me, is to take the simplicity of systems in a sailboat and transfer that over to a KISS principled motorboat. (with ART) ?

Stein Varjord

Hi Andy.
I’m a fanatic sailor, so if a boat has no sails, for me it’s not a boat. I do, however, realize that not the whole planet agrees with me, and I like exploring ideas, so a couple of thoughts:

Of sail boat power consumption you say “obviously their demands are less”. I can’t see any reason for that. A 20 KW generator for 6 hours a day indicates that you have a big boat and run AC and a lot more all the time. I think you might find options to reduce your consumption a lot, without serious comfort issues, which is what most sailors have done. Then there is system efficiency. A big topic, but some of the most important issues:

Move over from AC to DC where possible. The inverter etc will eat 10 – 20% of your power. More for some appliances like laptops. The AC generators that are now the norm, combined with AC chargers, are extremely inefficient and overly ripe for replacement with better systems. A good DC generator is rare, but exists and will have vastly better efficiency. With twin engines you can have even better with the system Nigel Calder helped develop with Triskel. In a narrow motorboat I would definitely go for twin engines, no generator and this system. Video and explanations here:
Sawafuji, which is the company behind the high quality Engel fridges etc, have a simpler system based on similar thoughts as Triskel.

When it comes to stabilisation, I’m not going to convince you, but just for the record, a cat doesn’t need stabilisation, it has way better maneuvrability since the engines are far apart. It has more space for a given length, and ditto with speed. Load capacity is the same. For a motor cat, there’s no need to go to the extreme in long narrow hulls. A 1:9 ratio would be easily good enough to give the cat advantages and have plenty load capacity.

Stein Varjord

Hi John
I forgot to answer this one. Sorry. Better late than never. 🙂
There are a lot of cruiser motor catamarans, but I don’t know of any good ones. I really don’t know the marketplace , though, since I’m such a fanatic on the sailing bit. 🙂 I do however suspect that every production version is aimed at a very different public than the one living through AAC. Perhaps it could be possible to cooperate with the maker and just strip off most of the bullshit and make something nice, but I’d guess it would be a major project. To make it comparable with the boats discussed at AAC, I assume it needs to be designed from a fresh start. Not very available….

At METS the two last years I’ve talked with the boss of tech development at Fisher Panda, a renowned German maker of generators and some other products. They are quite ambitious with expanding their product lines in logical directions connected to their expertise, which is electric generators. Almost the same as electric motors. They have released a full series of (“battery charging”) DC generators.

I have no experience with those products, but the company seems to have a great track record for reliability, is very focussed on quality and gives an excellent impression. Nice people. Quite nerdy guys. If something should not work as expected, this is a big enough and serious enough company to be able to stand behind it and fix whatever needs it, in the right way.

They now also make electric motors for boats, by the way. When I asked how soon they would need service, they said that the ball bearings and simmer rings at the axle were the only items that could possibly get worn. They were meant to be serviced by the owner. Simmerring should go first. About 5 000 hours or 5 years…. A new one costs about 20 Euros retail and is standard type. I like their attitude… I assume there are more companies looking at the AC generator options, since the market is rapidly changing on this area, but I don’t know of any.

The Triskel system I only know from the videos and a bit of reading, so my ability to judge it is limited, but it seems to make sense. If you can give better understanding I’d be very interested. I’m not going to buy anything from them anytime soon, but I love to understand things.

Felix Madrid

Is there any news on the twin engine Artnautica LRC 58, Mk 2?

Kit Laughlin

A note on anti-roll tanks: I understand these work better with rounder hulls and slower roll periods. I was investigating one for Seabiscuit, 40′ wood Sharpie-design, 14’6″ beam, 4′ draft, 12T, with flat aft sections and high initial stability, but with very quick longitudinal rolling movements in confused seas. I decided against the tank. My new boat, 48′, also 14.6″ beam, but 6’6″ draft and 30T, a round hull and ballast in the bilge has a significantly slower roll period. I built paravane stabilisers (following the Beebe formula for location and length) for her and they work very well. I do worry about snagging fishing gear off shore at night, though.

I mention this because I think a roll tank would work better on Anika J, the new boat, because of the hull shape and ballast. I have not seen the underwater drawings for the Artnautica 58, but she has a shallow draft so I assume she has flatter aft sections like my first boat, so perhaps stabilising this shape using roll tanks will be more difficult.