Fuel consumption: sail/motor. are you serious?!

[Johan Leopard51]

Whether it is ‘which 4x4 is best’ or sail vs power, there are always ten angles to consider.

For us, that tend to be 8 or sometimes 10 people, mostly seeking comfortable seas in tropics, the ideal would be a 50-ish foot sail cat that has a proper flybridge and proper motors.

The flybridge is crucial for us in our weather and number onboard. I’d give up some sail area for a flybridge and make up for that with a lighter yacht.

We don’t use our 740Hp to race around, maybe once in a while do 14 knots for 2-3 hours to make a weather window or safe anchorage.

Most sail cats imho have motors that are too small, so their fuel consumption at around 7 knots without sail is horrific compared to a same weight power cat with two 300’s doing same crossings. We’ve done trips where sail cat same trip is 50% more on a 6-7 knot speed 400nm round trip!

But I do love sailing as it keeps you engaged and they’re beautiful.

And yes the best 4x4 is an old LandCruiser …

[Dockhead]

Originally Posted by HankOnthewater

. . .My 16 mt 22 ton boat uses 4.3 lt per hour, doing 5.5 knots. That is in fairly flat seas, clean bottom. That is for me the most economical.

Very similar here. My boat is 16.4m, catalogue displacement 20mt, actual weighed displacement full of cruising gear and spare parts 25mt.


I budget 1 liter per mile with a reasonably clean bottom and reasonably good conditions. In dead calms motoring very slowly 5.5-6k it's 0.4 to 0.5l/mile. Relaxed cruising at 7 knots will be about 0.8l/mile. Any kind of sea state or headwind and it goes up from there.


I can motor at 9 knots using about 3000 RPM in calm weather, but then fuel consumption is completely different.

[StephenF]

Just for info,

I rented a bareboat in Croatia for a week in July. The boat is a Cobra Future 40ft with Fly Bridge. During the week (actually 6 days) I cruised at around 7 knots (not a fast boat) and used Euro 720 of diesel over a distance of 239 NM (Zadar - Frapa - Hvar - Vis - Split - Sukosan).

Boat specs:
Make: Cobra
Model: Futura 40 with fly bridge
Type: Motor yacht
Motor: Yanmar 150hp single diesel engine
Cruising speed: 7knots

Looking at the internet, I budgeted for my consumption to be around 10 to 12 litres per hour, which was spot on. My stats were:
Fuel Spend: 720 Euro
Fuel Consumed: 450 Liters
Distance: 239 NM
Duration: 42 h

Therefore:
Litres/h: 10.7
Average trip speed: 5.7 Knots
Litres/NM: 1.9
Cost/NM: Euro 3

[Johan Leopard51]

Interesting that your numbers (mono hull I deduct?) are not that dissimilar from 51 cat

Chilled cruise good water we do about 650 liters on outer islands say 350nm return trip ten days with the 120nm crossings sticking to around 7 knots so as to depart early light and arrive before bad light. (Do not rely on blue charts below 10m in Seychelles - must do visual)