50: Fuel consumption, range

[Mayeus]

Hi all,

I'm delivering a 2019 Lagoon 50 to Tahiti from Tortola (BVI) and the owner has no information on fuel consumption, range, etc. The boat holds 1020 Litres in 2 tanks.

Any help appreciated

May

[Galumay]

Really totally dependent on what engines it has in it.

Regardless 1020L fuel in a sailing cat is a lot of fuel!

Had a quick look, standard engines were 57HP Yanmars, fuel consumption curve here

https://www.dieselpartsdirect.com/do...jh57-specs.pdf

[Mayeus]

Yeah 2x57Hp. Thanks for the consumption curves but I really need to know nm/ltr.

[mvweebles]

Ex powerboat (including power cats) delivery skipper based out of San Francisco here. Pacific coast is notorious for long legs so range was a constant issue.

Owners are amazingly optimistic about fuel burn. It's like asking a parent who's the most talented kid in a kindergarten class. If I listened to owners, I'd still be floating in the middle of the Pacific.

I'd figure that boat would do around 10 l/h at 8-kts giving you a range of around 800 nm to dry. Reduce to 7-kts and you'd like extend your range 15%-20%. Somewhere on the tanks there should be a plaque stating their actual volume - sales literature isn't always accurate to to changes in configuration along the way.

Also in catamarans due to different configuration in each hull, the tanks aren't always the same. I've seen where one tank is vertical and was difficult to balance the two tanks which further reduces your usable capacity.

By the time you get to Colon, you'll know.

Good luck

Peter

[more]

Originally Posted by Mayeus

Hi all,

I'm delivering a 2019 Lagoon 50 to Tahiti from Tortola (BVI) and the owner has no information on fuel consumption, range, etc. The boat holds 1020 Litres in 2 tanks.

Any help appreciated

May

live data
lagoon 52 fuel consumption: 22 l/h average
but this is a charter boat and VOLVO 2 X 75 HP
Max. speed: 10 kts
Cruising speed: 8 kts
charter usually 9,5-10 kts and 22 l/h

[Galumay]

Originally Posted by Mayeus

Yeah 2x57Hp. Thanks for the consumption curves but I really need to know nm/ltr.

Thats why I posted the link with the consumption curves in it!!

[mvweebles]

Originally Posted by more

live data
lagoon 52 fuel consumption: 22 l/h average
but this is a charter boat and VOLVO 2 X 75 HP
Max. speed:10 kts
Cruising speed:8 kts
charter usually 9,5-10 kts and 22 l/h

Max fuel burn at max speed. Throttle back to 7.5 - 8.0-kts and fuel burn will halve.

[NBs]

Hi,

hi, here's a little direction on consumption. Note that speed, wind front, waves and flow will increase fuel consumption at all times. So no one can give you the right answer just for your trip.

I think 15-20 litres 8kn/hours and 6-7kn 10-13litres/hours

https://www.catamaranfreedom.com/sailing-catamaran-fuel-consumption-with-10-fuel-saving-tips/

NBs

[mvweebles]

Originally Posted by Mayeus

Yeah 2x57Hp. Thanks for the consumption curves but I really need to know nm/ltr.

The curves show 5-6 lph at 2200-2400 RPM. Factors affecting speed are LWL, load, conditions, etc. 8.0 kts is around 1.1 SWL for a 50-ft cat. Assuming a clean bottom and decent props.

With all due respect, are you sure you're the right person to deliver this boat from the Caribbean to Tahiti?

Peter

[boatman61]

If I may suggest, use one engine at a time, say 6hrs/engine then switch.. this keeps your tanks balanced and doubles your range. Delivered a Lagoon 45 from Florida to Gibraltar on mainly the 57hp engines.
Due to mainly very light headwinds only managed 3 days sailing when the wind kicked up to 25+kts.. from the ESE..
Don't try for maximum/cruising speeds, aim instead for most efficient rev's which for me was around 5.5kts.
Made the Azores with maybe 6hrs left in each tank, the Lagoon 45 carries 1020litres.. better to get further a tad slower than get nowhere faster..
Work your route out from refill to refill..
You'll make the Galapagos from Panama (900nm very light winds) with plenty of fuel to spare then its an easy downwind run under sail to Nuku Hiva where you can refill (no potable water).. one bad thing about Nuku Hiva, when there's a swell the concrete pier fuel dock can be a boat wrecker.

[GordMay]

Greetings and belated welcome aboard the CF, May.

[mvweebles]

Originally Posted by boatman61

If I may suggest, use one engine at a time, say 6hrs/engine then switch.. this keeps your tanks balanced and doubles your range. .

I wish this were true. By running one engine you might increase your range 15%, maybe a bit more in very flat seas. There is no getting around the laws of physics. It takes a certain amount of horsepower to move a mass. Whether that power comes from one or two engines makes little difference. There are some benefits from reduced friction and such from the power train. But also some losses from asymmetric push made worse by the wide spread of a catamaran.

Peter

[MBWhite]

I just did a web search on "Lagoon 50 charters" and it brought up quite a few sites. I'd suggest sending some questions to one of those places and they can give you a much more accurate answer since they have probably had to answer it before.

[Captain Bill]

I almost agree with Boaty. I don't get quite twice the range using one engine. The extra drag from the rudder offset required to hold course, and a little higher power setting on one engine probably reduces the range to 1.6 or 1.7 times the two engine range.

[mvweebles]

Originally Posted by Captain Bill

I almost agree with Boaty. I don't get quite twice the range using one engine. The extra drag from the rudder offset required to hold course, and a little higher power setting on one engine probably reduces the range to 1.6 or 1.7 times the two engine range.

20 years ago a guy took a Grand Banks 42 trawler from California to Hawaii. These boats carry about 500 gallons and have a range of maybe 1500 nms at slow 6-kts leaving you about 700nms short of Hawaii. To extend range, in addition to m to carrying fuel in barrels, he decided to run on one engine at a time. To reduce drag, he removed one prop. To balance hours on the engines, in the middle of the pacific, he removed his installed prop and reinstalled the other prop, then ran on that engine. He speculated he extended his range by about 20%. It was a crazy feat. BTW - he was single-handed and swapped props alone.

There is a fair amount of information on this as many powerboats have twin engines. In my delivery career, I probably moved 40-50 powerboats - singles and twins - non-stop from Southern California to the PNW area (roughly 1000 nms) , and a few dozen to Cabo San Lucas (900 nms). Folks in this sphere of offshore cruising take fuel consumption extremely seriously. If you could extend range by 50%-60 just by running on one engine, a LOT more power boaters would do it.

Feel free to give it a try though.

Peter