What brands build efficient long range (ocean crossing) motor cruisers

[Morgali]

I know about Kady Krogen and Nordhavn, what other manufacturers are making yachts which get close to 3k miles on 800-1200 gallons of fuel? (Preferably in the 40-55 foot length)

[Eder]

This one will cross any ocean while motoring...



https://ipy.com/42-motor-sailor/

[Morgali]

Originally Posted by Eder

This one will cross any ocean while motoring...



https://ipy.com/42-motor-sailor/

Doubtful when only tanking 320 gallons of fuel...

[Eder]

That's about 3000k NM's at 1500 rpm not counting using the sails...what am I missing?

[Morgali]

Originally Posted by Eder

That's about 3000k NM's at 1500 rpm not counting using the sails...what am I missing?

That would be an incredible eye-popping 10 nautical miles per gallon of fuel carried. I would be extremely surprised if it was capable of this. Not saying it doesn't do it, but I haven't seen a spec sheet that says it does.

[Morgali]

Originally Posted by Eder

That's about 3000k NM's at 1500 rpm not counting using the sails...what am I missing?

That would be an incredible eye-popping 10 nautical miles per gallon of fuel carried. I would be extremely surprised if it was capable of this. Not saying it doesn't do it, but I haven't seen a spec sheet that says it does.

[Eder]

I have a IP460
otw to the Marquesas I crossed the doldrums averaging 1/2 gal/hour at 5 knots.
Of course this can vary by current or wind direction but my range with 190 US gallons (6 jerry cans in the anchor locker)was about 1700 nm's motoring at 1500 prm.


Add in sails and the IP motorsailor will be in range of anywhere in the planet.

[Morgali]

Originally Posted by Eder

I have a IP460
otw to the Marquesas I crossed the doldrums averaging 1/2 gal/hour at 5 knots.
Of course this can vary by current or wind direction but my range with 190 US gallons (6 jerry cans in the anchor locker)was about 1700 nm's motoring at 1500 prm.


Add in sails and the IP motorsailor will be in range of anywhere in the planet.

I have to say that is impressive. Someone on my dock has an ip38 and said they burn .8g/hr @ 6kts

[Eder]

https://www.yanmar.com/media/global/...4JH4-TE-LR.pdf


Theres a fuel consumption graph on page 2



Just under 2 litres/hour @ 1500


Your friend most likely would be over 2000 rpm to burn that fast.

[Morgali]

Originally Posted by Eder

https://www.yanmar.com/media/global/...4JH4-TE-LR.pdf


Theres a fuel consumption graph on page 2



Just under 2 litres/hour @ 1500


Your friend most likely would be over 2000 rpm to burn that fast.

This is also going to depend on the size of the vessel. Installed in, prop size pitch and multiple other factors. That's all before you get to see state and everything else like that. The manufacturer is fuel. Economy ratings don't necessarily equate to the installed and functioning fuel economy of the engine in a vessel. But it is interesting

[ItDepends]

Lot's of back and forth, while missing the key point:

Range is a HUGE function of speed for any given boat. The first, very rough, theoretical calculation is the power required at the prop increases as the cube of the speed for a boat in simple displacement operation. Based on that, you'd expect the fuel burn at 5 knots to be (5^3/6^3) about 60% of the fuel burn at 6 knots. So a range of 500 NM @6 kts becomes 830NM @ 5 kts.

Run at 3 knots and a lot of boats become ocean crossing capable (according to a spec sheet anyway...)

Another real world data point, my 52 foot sailboat (38,000 lbs/70HP) uses almost exactly 1 Gal/Hr at 6 knots, so 6NM/gallon. It comes close to 10 NM/gallon at 5 knots (in calm seas and no wind)

That's a huge difference in fuel usage from something like a Nordhavn 50 which weighs more than twice as much, and uses an engine three times the horsepower.

[Pizzazz]

Efficiency is a relative term. Fuel consumption per nautical mile depends on many factors but basically for a decent size 50 ft boat (you need to waterline length for comfort) in typical ocean swell, it goes approximately like this:

Boat with a 40-45 waterline
~5.0 nmpg: monohull sailboat, motoring at 7 knots, weight matters little
~3.0 nmpg: catamaran, motoring at 7 knots, weight matters a lot
~2.0 nmpg: planing boat at 7-8 knots, lower comfort
~1.3 nmpg: displacement cruiser @ 7 knots (aka Nordhavn, Krogen, Hatteras)
~1.0 nmpg: planing boat at 10-11 knots, weight matters (aka Swift 47)
~0.8 nmpg: planing boat, shallow degree, at 20 knots, weight matters very, very much
~0.5 nmpg: planing boat, deep vee, at 25 knots, weight matters very, very much

Let's assume the above a approximately correct (I would be happy to get more data but real world data not test results in flat water). What would be your options:

1) Sail (mono's and cats) are perfect for crossing oceans, especially downwind, quiet, romantic but note that you cannot cross on ocean under power, i.e. cannot fit enough fuel in a power catamaran.

2) The displacement cruisers can carry nearly as much fuel as you want but you are speed limited. It could get boring very quickly, i.e. it takes 2800/7 = 400 hours under continuous engine noise to do the shortest crossing. Also, these ocean capable cruisers are extremely heavy, some ballasted, i.e. they rely on static stability for comfort.

3) You can try a planing boat but it is unrealistic to fit the required fuel. It is possible to do it (say fit 1,500 gallons on 50 ft cruiser and still make 7 knots), it is risky, you will be limited to displacement speeds for at least the first third of the journey (until the boat gets light enough to get on a plane) and it is just not a good idea to do so. You want a planing boat to plane because they have dynamic stability and it can get very uncomfortable if you are so overloaded that you cannot ride with the waves for example. So it will be risky, uncomfortable and boring at the same time.

If you want to cross an ocean at planing speeds, lookup wikipedia on the record attempts, the boats and how they were refueled in mid ocean.

An interesting alternative are semi-displacement hulls where you sacrifice a little bit of fuel efficiency on the top end vs. better comfort in the transitionary region (10-15 knots, which by the way is the typical max speed you can maintain in medium seas). The more fuel efficient semi-displacement boats, such as the Beneteau Swift range achieve this efficiency by keeping the boat very light which could be a problem long-term. You should definitely give them a chance.

My view is that power boats are on way of extinction due to the high fuel prices. So, I would get an older boat (my preference is planing) and use it as much as I can in the next 4-5 years until they are banned or usage is severely restricted due to environmental considerations.

[Morgali]

Originally Posted by Pizzazz

Efficiency is a relative term. Fuel consumption per nautical mile depends on many factors but basically for a decent size 50 ft boat (you need to waterline length for comfort) in typical ocean swell, it goes approximately like this:

Boat with a 40-45 waterline
~5.0 nmpg: monohull sailboat, motoring at 7 knots, weight matters little
~3.0 nmpg: catamaran, motoring at 7 knots, weight matters a lot
~2.0 nmpg: planing boat at 7-8 knots, lower comfort
~1.3 nmpg: displacement cruiser @ 7 knots (aka Nordhavn, Krogen, Hatteras)
~1.0 nmpg: planing boat at 10-11 knots, weight matters (aka Swift 47)
~0.8 nmpg: planing boat, shallow degree, at 20 knots, weight matters very, very much
~0.5 nmpg: planing boat, deep vee, at 25 knots, weight matters very, very much

Let's assume the above a approximately correct (I would be happy to get more data but real world data not test results in flat water). What would be your options:

1) Sail (mono's and cats) are perfect for crossing oceans, especially downwind, quiet, romantic but note that you cannot cross on ocean under power, i.e. cannot fit enough fuel in a power catamaran.

2) The displacement cruisers can carry nearly as much fuel as you want but you are speed limited. It could get boring very quickly, i.e. it takes 2800/7 = 400 hours under continuous engine noise to do the shortest crossing. Also, these ocean capable cruisers are extremely heavy, some ballasted, i.e. they rely on static stability for comfort.

3) You can try a planing boat but it is unrealistic to fit the required fuel. It is possible to do it (say fit 1,500 gallons on 50 ft cruiser and still make 7 knots), it is risky, you will be limited to displacement speeds for at least the first third of the journey (until the boat gets light enough to get on a plane) and it is just not a good idea to do so. You want a planing boat to plane because they have dynamic stability and it can get very uncomfortable if you are so overloaded that you cannot ride with the waves for example. So it will be risky, uncomfortable and boring at the same time.

If you want to cross an ocean at planing speeds, lookup wikipedia on the record attempts, the boats and how they were refueled in mid ocean.

An interesting alternative are semi-displacement hulls where you sacrifice a little bit of fuel efficiency on the top end vs. better comfort in the transitionary region (10-15 knots, which by the way is the typical max speed you can maintain in medium seas). The more fuel efficient semi-displacement boats, such as the Beneteau Swift range achieve this efficiency by keeping the boat very light which could be a problem long-term. You should definitely give them a chance.

My view is that power boats are on way of extinction due to the high fuel prices. So, I would get an older boat (my preference is planing) and use it as much as I can in the next 4-5 years until they are banned or usage is severely restricted due to environmental considerations.

Holy cow, thank you for the detailed answer.

I am thinking of going to an island packet sailboat. They seem to be pretty fuel efficient from the owners I've spoken to, and can motor great distances if for some reason sailing became impractical offshore.

[mvweebles]

Originally Posted by Morgali

Doubtful when only tanking 320 gallons of fuel...

I have moderated the Willard Boat Owners group for 23 years. Willards are a clsssic displacement trawler that have made some very long cruises. Early owners in the 1960s took them from California down Baja fishing, through the Panama Canal, even to the Galapogas Islands.

With some minor sail assist, I do not doubt this IPY motorsailor could make it from California to Hawaii, the longest leg of a common circumnavigation. In 1987, a Willard 36 did the same journey and burned 330 gals of diesel averaging about 6 kts, or 0.9 gph.

I've also gone from Long Beach to La Paz MX, over 1000 nms on a Willard 40 and burned about 175 gals diesel at 7.2 kts. The boat carried 600 gals and could easily make Hawaii. Add a slight sail assist and slow down to 6.25 kts and this 42 foot IPY could make a 2400 nm crossing without too much concern.

Peter

Picture of a Willard 36, a William Garden design produced by Willard Marine, Costa Mesa CA, from 1961-1970. A sistership went from CA to HI in 1987 burning about 330 gals diesel. She returned a year later to Seattle (consumption unknown) Attachment 263946

[NPCampbell]

Originally Posted by Morgali

I know about Kady Krogen and Nordhavn, what other manufacturers are making yachts which get close to 3k miles on 800-1200 gallons of fuel? (Preferably in the 40-55 foot length)

The biggest factor affecting range for displacement hulls is speed. The type of boat is almost immaterial because even planing hulls abide by this relation at displacement speeds.

When traveling under hull speed, horsepower required goes up roughly with the cube of speed. i.e. it takes 8 times the HP to double your speed. Obviously, your engines fuel efficiency vs HP is non-linear and this plays a part but it is trivial compared to the cubed component. As you approach hull speed, the ratio gets worse unless your hull has a planing design.

For instance, if you look at the specs of the Leopard 53 PC, it only gets .8 nmpg at "cruising speeds" of 17 knots with a range of 450+ nm. However, at 7 knots it get 3.5 nmpg with a range close to 2000 nm.

With some of the trawler style boats mentioned in this thread, if the fuel efficiency is poor at 8 kn it will be "roughly" quadrupled at 5 kn, ignoring all other factors. (8/5)^3 = 4x range.