Global cruiser concept - 25m stabilised monohull

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pbury

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Location
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I am a yacht designer for 30 years and have travelled many thousands of miles at sea in sailing/power catamarans and monohulls in the Tasman/Coral Sea, Bass strait, Pacific and Atlantic oceans. I understand the compromises of these types of hull forms and found them all to be lacking in varying ways.

I live in Australia and am at the stage of designing and building my own ‘retirement’ boat for world cruising/live aboard with me and my wife - I have come up with a criteria list:

  • Power, not sail – sails, masts and keels are not cheap, you still need a diesel engine, and I am getting too old for drama, and the compromises on space of a sailing boat are too much
  • Fast, efficient hull configuration capable of sustained 250 nm/day speeds and much higher sprint speeds, all whilst burning small amounts of fuel. The world is far too big for boats that go distances at 5 knots. Real world range of 4000nm plus at these speeds – the Pacific Ocean is a large place
  • Comfortable at sea and anchor without mechanical or rigged stabiliser systems. Motion of cats not great in a seaway, nor unstabilised monohulls
  • Ability to go upwind, to punch into a sea. Cats suck at this as do wide monohulls and the sea seems to be rarely flat, and often going the wrong way
  • Ability to go downwind/down seas at pace with ease and control. Big rudders and good steering moment generation. Good quartering seas ability
  • Onboard spaces suitable for a couple and friends, with a split of casual and sleeping areas in line with a modern apartment. Indoor/outdoor spaces with excellent ventilation, including forced ventilation for all cabin – deck/topside hatches useless at sea
  • Large amount of deck space for outside living and flexibility of entertaining. Vessel suitable for casual commercial use (day charter)
  • Seriously serviceable equipment with full access to all important equipment.
  • Full headroom engine room, separate workshop
  • Direct crane access for generator/main engine install/removal
  • Oil change system for main, gearbox and generator
  • Full size intake/discharge sea chests
  • Fuel day tank with polishing system, fuel transfer between all tanks
  • No inaccessible serviceable items, removable panels as needed
  • Significant solar installed and an independent in-port/get home electric propulsion system
  • Dry out ability, protected drive lines
  • A kick arse tender and anchoring system as I don’t want (or will be able to afford) to be in a marina at all
  • Built to Australian commercial vessel standards for open ocean use, Lloyds SSC structures, IMO standards for damaged/intact stability
I have come up with a stabilised monohull design to meet these requirments (like a trimaran but with very small volumes in outer hulls).


Paul
 

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Ok, so my first observation is to put real numbers to your speed and cruising range.

If we assume 240 miles per day, that would be 10 knots. 25 meters is roughly 80 feet. Square root of the length of the waterline is about 9. So 10 knots is reasonable.

I don't see an estimate for displacement, but am assuming a fairly significant draft for the weight of essentially a mono hull.

So then the question is how many Horse Power to push an 80' hull at 10 knots? The next logical question is how much fuel is required to cruise 4,000 miles? Assuming a simple 1 MPG, that would be 4,000 gallons or 32,000 pounds of fuel. Was that what you were calculating?

Ted
 
1736306580452.png
So a variation of a Craig Loomes design?
View attachment 161065
I suppose you could say that, in that there are three hulls with the centre containing the most displacement. But the Loomes design is high speed planing, my concept is high displacement speeds only. Same configuration as the US littoral class ships is a better comparison.
 
Ok, so my first observation is to put real numbers to your speed and cruising range.

If we assume 240 miles per day, that would be 10 knots. 25 meters is roughly 80 feet. Square root of the length of the waterline is about 9. So 10 knots is reasonable.

I don't see an estimate for displacement, but am assuming a fairly significant draft for the weight of essentially a mono hull.

So then the question is how many Horse Power to push an 80' hull at 10 knots? The next logical question is how much fuel is required to cruise 4,000 miles? Assuming a simple 1 MPG, that would be 4,000 gallons or 32,000 pounds of fuel. Was that what you were calculating?

Ted
The stabilised monohull configuration allows for narrow centre hull configuration compared to a monohull. This reduces the drag fundamentally and improves potential hull speed. If the outer hulls are configured correctly, they will add very little to no extra drag. My fuel consumption figures are around 1.1litre/nm at 10knots still water/air with a lightship displacement of around 26T lightship, 38T loaded. More specs below, apologies in advance for metric units:

LOA: 25.0 m

BMax: 8.3 m

Draft: 1.6 m full load

Construction: Advanced composites

Class: Structure to Lloyds SSC

Maximum speed: 19 knots

Cruise speed: 10 knots

Range at cruise: 4050 nm with 10% reserve

Main engine: 1 x CAT 3406e/C15 3:1 reduction gear driving controllable pitch propeller

Arma drive motors: 2 x 20kW variable frequency electric motors driving folding propellers

Generator: 1 x 40kW

Bow thruster: Optional electric tunnel thruster, 40hp

Climate control: Airconditioned throughout, hydronic heating

Solar PV : 50m2, 10kW

Fuel: 5200 litres, integral, 4 tanks

Water: 3000 litres, integral, 3 tanks

Watermaker: 800 litres/Day

Ride control system: Optional aft foil active ride control (roll/pitch)
 
Yes some of Loome's plane, most don't.
Nice concept. I like the auxiliary propulsion system.
That's a lot of boat to shift at 10kn at 1.1l/nm
1000012241.jpg


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Yes, still water/air is key in that figure, but narrow hull, lower wind drag and single high efficiency diesel/prop combination key.

Some external renders attached...
 

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Interesting concept. I don't know much about this type of design but I wonder does it really achieve the best of both worlds mono/cat? Or does it compromise both? That would be my concern.

Other observations:
-It looks like pretty limited interior lounge space for a vessel that sleeps 8
-How well does the tender store above the day lounge? It appears forward visibility might be limited as it is.
-Overall the accommodations seem large for your program. A couple (primarily?) plus friends. Is your desire for hull speed driving the length?
-If the hull is that easily driven I think you should do a hybrid diesel electric drive. Then you could put the prime gen (or a couple paralleled for redundancy) further aft. Or in the amas? Really develop something new!

Are you thinking aluminum?
 
thanks for the comments Diep, regarding your points
- lounge space could be more for sure, but we think that is all we need, even with 8 onboard. We will be in warm climates mostly so outside will be used often
- tender fits low on the foredeck, sightlines are compliant with commercial standards, so I think ok
- yes accommodation is generous, but trying for something more like apartment size spaces, for extended periods onboard
- there is nothing more efficient than a diesel engine on a shaft driving a big controllable pitch propeller, we have electric drives in the armas for redundancy, in-port use
 
This type of project is right up my ally and thinking so I will follow this thread with interest. The costs to build it would take everything I have and my age would preclude a long use of the boat.. I can appreciate and live vicariously through you.
I might be making an assumption but my guess is if you can afford the build and operation of this vessel then you had to be pretty successful at this game already.
 
The stabilised monohull configuration allows for narrow centre hull configuration compared to a monohull. This reduces the drag fundamentally and improves potential hull speed. If the outer hulls are configured correctly, they will add very little to no extra drag. My fuel consumption figures are around 1.1litre/nm at 10knots still water/air with a lightship displacement of around 26T lightship, 38T loaded. More specs below, apologies in advance for metric units:

LOA: 25.0 m

BMax: 8.3 m

Draft: 1.6 m full load

Construction: Advanced composites

Class: Structure to Lloyds SSC

Maximum speed: 19 knots

Cruise speed: 10 knots

Range at cruise: 4050 nm with 10% reserve

Main engine: 1 x CAT 3406e/C15 3:1 reduction gear driving controllable pitch propeller

Arma drive motors: 2 x 20kW variable frequency electric motors driving folding propellers

Generator: 1 x 40kW

Bow thruster: Optional electric tunnel thruster, 40hp

Climate control: Airconditioned throughout, hydronic heating

Solar PV : 50m2, 10kW

Fuel: 5200 litres, integral, 4 tanks

Water: 3000 litres, integral, 3 tanks

Watermaker: 800 litres/Day

Ride control system: Optional aft foil active ride control (roll/pitch)
Based on fuel economy (LPM) and doing conversions to gallons and HP, your projection is to push a 25 meter 38 ton vessel at 10 knots with 60 HP. That seems very optimistic.

Looking at the Cat 3406e, I'm curious what HP you plan to use? The internet shows a range from 375 to 465 HP. Seems like quite a large motor for a projected cruise requirement of 60 HP.

Assuming this is a passagemaker, what's your alternative form of propulsion?

Ted
 
thanks for the comments Diep, regarding your points
- lounge space could be more for sure, but we think that is all we need, even with 8 onboard. We will be in warm climates mostly so outside will be used often
- tender fits low on the foredeck, sightlines are compliant with commercial standards, so I think ok
- yes accommodation is generous, but trying for something more like apartment size spaces, for extended periods onboard
- there is nothing more efficient than a diesel engine on a shaft driving a big controllable pitch propeller, we have electric drives in the armas for redundancy, in-port use
I agree 100% on the efficiency of the diesel shaft as prime mover. I just imagine the potential positive tradeoffs of removing the geometrical constraints of the shaft/driveline and engine. Like what happens if you put a genset in both amas and eliminated the main in the center hull? Size one of the gensets for normal consumption/cruise and both for max/fast cruise.

You appear to have a lot of space for solar. Obviously couldn't passage on solar but maybe short hops without firing up.

If you had an electric drive could you eliminate the CPP? You wouldn't need to manage engine loading/rpm as much.

Sorry if this is diverting too much off the chosen track of the project.
 
Based on fuel economy (LPM) and doing conversions to gallons and HP, your projection is to push a 25 meter 38 ton vessel at 10 knots with 60 HP. That seems very optimistic.

Looking at the Cat 3406e, I'm curious what HP you plan to use? The internet shows a range from 375 to 465 HP. Seems like quite a large motor for a projected cruise requirement of 60 HP.

Assuming this is a passagemaker, what's your alternative form of propulsion?

Ted
Hi Ted, here are the resistance/power calcs. Probably need to reduce propulsive efficiency a little and you are right in saying it is optimistic. But I believe I am within 25% of real figures with these numbers, my real-life experience with these calcs has shown them to be quite accurate.

The CPP will allow constant engine speed in usual operation, at max engine torque and lowest SFC, with the pitch of the propeller varying power drawn from the engine. The 3406e may be too big for the low hp used at cruise but my plan is to run at higher hp regularly (every 12hrs) and have a good sprint/high speed cruise capacity.

A lot of my professional experience is in commercial fishing vessels operating in the not so friendly seas near me. Most of them run single engines, with no back up propulsion system. My opinion is that a single diesel on a CL screw, if feed with clean fuel and well maintained is extremely reliable and unlikely to let you down. In this vessel, electric drives in each outer hull powered by the onboard generator will give a completely separate, get home or in-port propulsion system.
 

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For a while I have been following a Youtube channel featuring a boat that is a monohull, but it has been built to be comfortable, fuel efficiënt and perhaps it may give you some ideas.

They do .88 gallon per nm at 10 kts, have 4700 gallons of diesel onboard and can actually do 7500 nm on the usable fuel.

I read some of your other specs, but don't see a realistic way of going electric at that speed. The only way to go electric would be at a speed of about 5 kts and you would need about 30 Kwp of solar plus about 300 - 400 Kwh of Lithium ion. If there is one thing I don't want onboard it is lithium ion, especially not if you want to go blue water.
A lot of the specs are relatively easy to arrange. Fuel polishing is basically standard, day tank the same, reverso oil change system is easy to install, solar panels as well, stabilizing a monohull while at anchor and underway while not using a lot of electricity is no problem. I have it onboard, works like a charm, don't need a generator for that.
The kick arse tender I would forget, no need for it. It is nice to go around at 40 kts, but why would you ? We have a 3.10 mtr dinghy with a Mercury electric outboard (can charge it via solar, but best of all......no gasoline onboard) and that brings us everywhere. It is lightweight, easy to handle, can get anywhere.
As for the anchor..........make sure you oversize, have about 150 mtrs of heavy chain onboard and you will be able to anchor anywhere. Just make sure the chain locker has good drainage and that you can close off the chain locker door into the bow cabin. There is a nice video on Youtube of a 150' yacht that got flooded because the chain locker door to the inside did not close off well. Ship was going against the waves, lots of water entered the chain locker via the opening in the deck, drain could not get it out fast enough, water came in the boat.
 
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Hi Ted, here are the resistance/power calcs. Probably need to reduce propulsive efficiency a little and you are right in saying it is optimistic. But I believe I am within 25% of real figures with these numbers, my real-life experience with these calcs has shown them to be quite accurate.

The CPP will allow constant engine speed in usual operation, at max engine torque and lowest SFC, with the pitch of the propeller varying power drawn from the engine. The 3406e may be too big for the low hp used at cruise but my plan is to run at higher hp regularly (every 12hrs) and have a good sprint/high speed cruise capacity.

A lot of my professional experience is in commercial fishing vessels operating in the not so friendly seas near me. Most of them run single engines, with no back up propulsion system. My opinion is that a single diesel on a CL screw, if feed with clean fuel and well maintained is extremely reliable and unlikely to let you down. In this vessel, electric drives in each outer hull powered by the onboard generator will give a completely separate, get home or in-port propulsion system.
I'm curious if you know what the fuel consumption is of the drive train without propulsion? This would be the fuel burn for the engine transmission and shaft without the the propeller at projected operating RPM. The reason I bring this up is based on a larger engine operated at a power consumption of less than 20%, where fuel consumption before propulsion becomes significant. As an example, my John Deere 4045 pushing the boat at 6 knots consumed 1.2 GPH. Of that fuel consumption, .3 to .4 GPH was non propulsion consumption of the engine and transmission in neutral.

Regarding your backup propulsion (generator to electric drive), what is the sustainable speed for days on end and the life expectancy in continuous use? As an example, an electric bow thruster can work quite well in its intermittent designed parameter for many years, but the propulsion system isn't designed to push the boat continuously for a thousand miles.

Regarding single engine passage making, I repowered my Cherubini 45 with the above JD engine and traveled 39,000 miles in 8 years with 6,000 engine hours. My maintenance schedule could be described as OCD (obsessive compulsive disorder). The only failure I had was from an ECU (Electronic Control Unit) that became temperature compromised. So things fail that aren't maintenance time based. Thankfully, my cruising was near coastal and inland. So the tow was maybe an hour. As a percentage of time, I felt that less than 5% of my cruise would put my boat and or my self at great risk, should the engine fail.

Based on your cruising expectations, it would seem your risk percentage is significantly higher for potentially being stranded days from rescue. As it appears that your design parameter is to out run storms, it seems a faster speed for backup propulsion would be required than your in port electric positioning drives.

Charles Lindbergh flew across the Atlantic Ocean in a fairly simple single engine airplane. His odds of success were good as the airplane engine only needed to run for 34 hours, and he only did it once! Increased time and increased repetition increase risk of a component failure as opposed to deferred preventative maintenance failure.

Ted
 
I like the design a lot but I am afraid there would be no market for it. It is interesting to target a 3,000 nm range but very people would need that on a regular basis. The entire generator/panels/electrical propulsion is redundant since you cannot beat the efficiency of a well designed straight shaft drive, even taking into account low speed and losses in the machinery. Here is one way to calculate it:

A high rpm diesel needs around 220g of fuel per kWh at optimum rpms. At low rpm's this goes up to around 250-270g. The friction power to turn a diesel engine is not that much. The power in the alternator can be managed (i.e. alternators are only 60% efficient, so you might as well cut field to the alternator not to waste fuel on that but recharge batteries from solar). The rest of the power is lost in generating heat and this can also be managed by installing hotter thermostats, to keep the overall cooling fluid volume low. This will also help the diesel engine keep warmer at low rpms.

A good, efficient generator uses around 300g of diesel per kWh, say 250g mechanical power and 50g in the synchronous alternator generation. So, it is always higher than a straight diesel to propeller connection.

Most planing motor yachts have a range of 300-400 nm. You can easily design a long-range cruiser with double that range which would be sufficient for most cruising grounds. Ocean crossing range at higher than displacement speed is needed for very, very few motorboaters and hence the market is very small.
 
It always seems to come down to what you want to compromise in order to optimize for something else. If you want faster and more efficient, you need to be skinny. But if you are skinny, you compromise interior volume and living space. You pontoons will limit roll under some circumstances, but also force to boat to follow the sea surface contour in other cases which will make the boat feel less stable. And it will be more tender like a cat vs wallowy like a round hull. Your outrigger design picks up decade for solar etc like a cat, but it also makes for a dimensionally much larger boat vs a traditional monohull with equivalent living volume. It’s all tradeoffs, which you surely know better than any of us.

My own preference is to optimize for how the boat is used most often, while making sure it’s fully capable of running in the corner cases. Everyone i know who as done a lot of ocean crossing says they still spend no more than 5% of their time doing crossings, and 95%+ is coastal cruising. So to me, that’s what you want to optimize for, NOT for crossings. You want to be fully capable of highly safe crossings, but the boat doesn’t have to be optimized for that, just fully capable of it.

This is where I think the whole FPB style of boat has it all exactly backwards. They are optimized for the 5%, and capable of the 95%. It’s backwards.

What does this mean? I think it means a displacement monohull. It will be a bit slower on passages - think 8kts rather than 10kts - and burn more fuel. But you will start and end in the same place, still be comfortable, and be MUCH more comfortable all the rest of the time.

My two cents, worth what you paid for it which is even less that two cents.
 
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That Dashew FPB that Mambo linked above is pretty much the gold standard for ocean-crossing recreational boat design at the moment. So if you are trying to develop a new concept, it will have to significantly outperform that on most measures.
 
I am a yacht designer for 30 years and have travelled many thousands of miles at sea in sailing/power catamarans and monohulls in the Tasman/Coral Sea, Bass strait, Pacific and Atlantic oceans. I understand the compromises of these types of hull forms and found them all to be lacking in varying ways.

I live in Australia and am at the stage of designing and building my own ‘retirement’ boat for world cruising/live aboard with me and my wife - I have come up with a criteria list:

  • Power, not sail – sails, masts and keels are not cheap, you still need a diesel engine, and I am getting too old for drama, and the compromises on space of a sailing boat are too much
  • Fast, efficient hull configuration capable of sustained 250 nm/day speeds and much higher sprint speeds, all whilst burning small amounts of fuel. The world is far too big for boats that go distances at 5 knots. Real world range of 4000nm plus at these speeds – the Pacific Ocean is a large place
  • Comfortable at sea and anchor without mechanical or rigged stabiliser systems. Motion of cats not great in a seaway, nor unstabilised monohulls
  • Ability to go upwind, to punch into a sea. Cats suck at this as do wide monohulls and the sea seems to be rarely flat, and often going the wrong way
  • Ability to go downwind/down seas at pace with ease and control. Big rudders and good steering moment generation. Good quartering seas ability
  • Onboard spaces suitable for a couple and friends, with a split of casual and sleeping areas in line with a modern apartment. Indoor/outdoor spaces with excellent ventilation, including forced ventilation for all cabin – deck/topside hatches useless at sea
  • Large amount of deck space for outside living and flexibility of entertaining. Vessel suitable for casual commercial use (day charter)
  • Seriously serviceable equipment with full access to all important equipment.
  • Full headroom engine room, separate workshop
  • Direct crane access for generator/main engine install/removal
  • Oil change system for main, gearbox and generator
  • Full size intake/discharge sea chests
  • Fuel day tank with polishing system, fuel transfer between all tanks
  • No inaccessible serviceable items, removable panels as needed
  • Significant solar installed and an independent in-port/get home electric propulsion system
  • Dry out ability, protected drive lines
  • A kick arse tender and anchoring system as I don’t want (or will be able to afford) to be in a marina at all
  • Built to Australian commercial vessel standards for open ocean use, Lloyds SSC structures, IMO standards for damaged/intact stability
I have come up with a stabilised monohull design to meet these requirments (like a trimaran but with very small volumes in outer hulls).


Paul
Nice if you can afford it. A couple of points I would contend with based on my experience. Don't bother catering for visitors, we've travelled hundreds of sea miles to meet visitors because 'it didn't look far on the map', give them temporary accomodation, much better to use the space onboard for your own comfort. Go on a diesel maintenence course and treat you engines like your first girlfriend, lots of caresses and TLC and you won't need a crane to change them.
The worlds a massive place to explore and when the good lord made time he made plenty of it and you won't use it all, If you want to dash around the world and empty your bank account go ahead. My advice is to put the boat in gear and your mind in nuetral.
Slow down, chill out, learn to live with nature.
 
That Dashew FPB that Mambo linked above is pretty much the gold standard for ocean-crossing recreational boat design at the moment. So if you are trying to develop a new concept, it will have to significantly outperform that on most measures.
Gold standard?
Are they currently over 1% per year, of the boats manufactured in their size for ocean crossing?

There are other boats equally safe or safer for crossing that don't require you to live in a submarine below deck.

Ted
 
Gold standard?
Are they currently over 1% per year, of the boats manufactured in their size for ocean crossing?

There are other boats equally safe or safer for crossing that don't require you to live in a submarine below deck.

Ted
I'm talking about overall performance.
 
I've admired the Shuttleworth tri designs for a long time. I remember reading about Adastra and the skinny design of the amas that cut through the waves rather than ride over. Similar to the Roger Hill cat designs I guess. Here is the 32: Trimaran-32m

I think to get decent living space with the tri design you need to be north of 70'. Compare the Leen 56 to the 72 for example.
 
and dont go over 24 m due to red tape problems in many countries and stay below 20 m if you want to stay in ports sometimes. i am on the same idea , i have some money and a lot of time but you not only traveling but mostly at anchor but if you want to explore the country which is the reason for travelling you want to leave the boat in a safe place like a marina and there the length is important.....whereas diesel consumption and pricing is not that important seeing the overall costs......so a reasonable compromise of speed, costs, length , marina berth avalability etc has to be found. not easy if you see all the new dashew influenced boats like artnautica arksen circa looking for buyer's. the only ones who are sold are the tall and clunky nordhavns......far away from a skinny fast boat
 
great, to get everyones opinions. I am aware of Dashews designs, he really did set the bar high for high efficiency ocean cruising.

Just as an aside, the main hull of this boat will be built from a solid 8mm carbon fibre female hull ocean racing yacht mould, modified to suit this application. Picture attached. External ply frames will be cutoff, internal structural and coring added (mostly for insulation) and the external shell faired
 

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sounds like a real project. regarding engine pls consider are clean engine so that the boat can be registered worldwide, so Ocean A RCD CE mark will be helpfull. there is a wonderfull xpm 78 built in turkey and now in the US with a beautiful gardner engine but it is very difficult to sell her due to the fact you can not easily register her in europe or america..... due to the old style engine without emission cert
 
.......... You want to be fully capable of highly safe crossings, but the boat doesn’t have to be optimized for that, just fully capable of it.

This is where I think the whole FPB style of boat has it all exactly backwards. They are optimized for the 5%, and capable of the 95%. It’s backwards.

Excellent post with a very useful yardstick for perspective: optimized vs capable. Buyers almost always do a plus/minus chart for selection, of must-haves/wants. An overlay dimension of capable/optimized would be a useful perspective.

Peter
 
Gold standard?
Are they currently over 1% per year, of the boats manufactured in their size for ocean crossing?

There are other boats equally safe or safer for crossing that don't require you to live in a submarine below deck.

Ted

While I understand your point, I agree with @Ertyqway that the FPB is the gold standard for ocean crossing powerboats. Yes, they are a tiny fraction of the market compared to Nordhavn. But you might be surprised to learn a large percentage of transocean treks by Nordhavns have additional fuel in a bladder. Using the yardstick TwistedTree laid out, the Nordhavn is capable but not optimized. Dashew optimized the FPB for transocean passages to comfortably compete with cruising sailing yachts. The speed and distances FPBs have covered are remarkable to say the least. The relative comfort in >Force 7 conditions cannot be ignored.

Money aside, if I wanted a boat capable of circumnavigating at pace, no question an FPB would be my top choice. If my circumnavigation were a typical multi-year affair with stops along the way (some lengthy while I return home), a Nordhavn (or similar) would be my choice.

Returning to the OP, the FPB is not only fast and incredibly long range, but it's very fine bow allows comfortable running in very difficult conditions - it pierces waves vs rides over them (Santa Cruz yacht designer Bill Lee's "Merlin" was infamous for speed and wet ride - Lee coined the term "fast is fun"). How would a multi-hull compare? What problem is being solved?

Peter
 
While I understand your point, I agree with @Ertyqway that the FPB is the gold standard for ocean crossing powerboats. Yes, they are a tiny fraction of the market compared to Nordhavn. But you might be surprised to learn a large percentage of transocean treks by Nordhavns have additional fuel in a bladder. Using the yardstick TwistedTree laid out, the Nordhavn is capable but not optimized. Dashew optimized the FPB for transocean passages to comfortably compete with cruising sailing yachts. The speed and distances FPBs have covered are remarkable to say the least. The relative comfort in >Force 7 conditions cannot be ignored.

Money aside, if I wanted a boat capable of circumnavigating at pace, no question an FPB would be my top choice. If my circumnavigation were a typical multi-year affair with stops along the way (some lengthy while I return home), a Nordhavn (or similar) would be my choice.

Returning to the OP, the FPB is not only fast and incredibly long range, but it's very fine bow allows comfortable running in very difficult conditions - it pierces waves vs rides over them (Santa Cruz yacht designer Bill Lee's "Merlin" was infamous for speed and wet ride - Lee coined the term "fast is fun"). How would a multi-hull compare? What problem is being solved?

Peter
In my mind the FPBs, whilst good are not the final evolution. I dont want a boat that relies on mechanical stabilisers - they are expensive, maintenance intensive and take significant power. I also think the outside space of FPBs is woeful - adequate if you spend your time in cold climates but not for where I want to go.

The trimaran configuration allows for a much, much finer hull than the FPBs and, in theory, even better seakeeping and speed ability at sea. I suppose we will have to wait until this thing is real to really know...
 

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