Yamaha 420sti fuel burn

beamishken · 09 April 2017, 16:46

Finally got my 7.4 delta up and running and trying to work out range.
Has anybody got a rough idea on mpg for something similar roughly 2tonnes all up & fast cruise about 30kts @3100rpm
420 yamaha sti with hydra drive

Brian · 09 April 2017, 19:54

Yes, you can almost bet on 1ltr per nmile.

Tim M · 09 April 2017, 21:36

I've got the 370sti and I get slightly better than a litre a mile with a 7.4m Redbay so around 1/nm should be pretty accurate.

beamishken · 09 April 2017, 22:04

OK that sounds nice and easy to work out range thanks for the info

willk · 10 April 2017, 07:42

Quote:

Originally Posted by beamishken

OK that sounds nice and easy to work out range thanks for the info

What fuel capacity does she have?

beamishken · 10 April 2017, 07:56

Quote:

Originally Posted by willk

What fuel capacity does she have?

300ltrs was what she was advertised as having but I thought (hoped) it would be more. I emptied the tank last night and going to fill up and measure how much I put back in

I was thinking of heading to easdale from Largs by water but if it's only 300 ltrs that's going to leave me needing fuel up there which might be a pain
Still got a few jobs to do so it might be we trailer up
Obviously very weather dependant too

paulbrown22 · 10 April 2017, 10:03

As with Brian, my Ribtec running a single similar Yanmar 6LP gives pretty much 1 litre per NM, maybe a bit better in optimum conditions. I plan on 1l/NM.

willk · 10 April 2017, 13:35

Quote:

Originally Posted by beamishken

300ltrs was what she was advertised as having but I thought (hoped) it would be more. I emptied the tank last night and going to fill up and measure how much I put back in

I was thinking of heading to easdale from Largs by water but if it's only 300 ltrs that's going to leave me needing fuel up there which might be a pain

Good plan - the man who knows what his tank REALLY holds is a rare thing!

I've filled at Crinan boatyard (which you almost pass) and they are easy to deal with - not sure about opening times though. A couple of spare cans should get you through Day 1 and 2, so a refill for the return leg would be the question. IIRC they have fuel at Craobh Haven nearby? Their hours might be more flexible. If RTB via the west of Jura then there is road diesel in Port Askaig.

Mr RIB · 10 April 2017, 16:30

Quote:

Originally Posted by beamishken

Finally got my 7.4 delta up and running and trying to work out range.
Has anybody got a rough idea on mpg for something similar roughly 2tonnes all up & fast cruise about 30kts @3100rpm
420 yamaha sti with hydra drive

I have run Yamaha 420STI and 360's for many years and still currently have a 420 in my 9m RIB, which weighs 2500kgs fully fueled. From my experiences they burn about 30litres an hour at 3000rpm and 25litres an hour at 2600rpm.

A recommended safe fast cruise rating is 3300rpm and they seem to like anything from 2500 to 3300 but obviously the higher the RPM the more they burn!

Brian · 10 April 2017, 16:39

Quote:

Originally Posted by willk

IIRC they have fuel at Craobh Haven nearby? .

Yup, you IIRC correctly.

beamishken · 10 April 2017, 18:18

I've found the best place to fill up is at the tanker guy in oban byvtge ferry pier but given its only likely to be 200ltrs and a holiday weekend I doubt that would work.Craobh is probably the best bet as they be 200ltrs and a holiday weekend I doubt that would work. Craobh is probably the best bet as they have someone in the office at least during the day
It's roughly 100nm from Largs so I'd be happy to do another 100nm but think much further is pushing our luck especially with a new to us boat

How far are the planned trips? I'd rather not be trying to find fuel on the Saturday evening so maybe a couple of 25ltr drums would be the way to go

Of course this planning could all be academic depending on the weather

willk · 10 April 2017, 18:37

Quote:

Originally Posted by beamishken

I'd rather not be trying to find fuel on the Saturday evening so maybe a couple of 25ltr drums would be the way to go

25l drums are how I roll. Four on deck take up very little space and will do(you at least) 100Nm. The Sunday trip is usually a handy one before people load up and head home - don't expect to burn much gas on it, if you even bother. You'll have big enough cruises done and ahead of you without it!

Mr RIB · 10 April 2017, 20:51

I have run Yamaha 420STI and 360's for many years and still currently have a 420 in my 9m RIB, which weighs 2500kgs fully fueled. From my experiences they burn about 30litres an hour at 3000rpm and 25litres an hour at 2600rpm.

A recommended safe fast cruise rating is 3300rpm and they seem to like anything from 2500 to 3300 but obviously the higher the RPM the more they burn!