Novice rib owner: A question about range

[boogaloo]

Hello

I've just joined this evening, and posted in the 'new members forums with a brief into. Despite buying a RIB a couple of years ago I've had very little experience, as I bought just before lockdown, was unable to use for a few years, then had some reliability issues that meant I got little use from my 5.8m Tornado. However I've just bitten the bullet and got her a new lease of life - hull restored to new, new tubes, new 140 4 stroke and all new instrumentation.

I have a question about RIB range, as I'll need to do my engine break in. I have, I think, an 80l tank in the console. I honestly have no idea what to expect in terms of range for the 140 4 stroke and that kind of tank, but will need to run for about 10 or so hours for the break in, though I'll probably do that over several days.

Does anyone have a very rough estimate of how far I am likely to be able to get driving relatively conservatively while the engine breaks in? I'm seeing some wildly different litres per km figures for my engine.

Any advice appreciated!

[cdbxyz]

Our Ribcraft 585 / Suzuki 140 combination uses around 0.8-1l/nm when cruising in calm/light seas around 20-25knts. Going faster increases consumption significantly.

Conditions can further increase consumption - if out in bigger seas with a lot of throttle adaptation for example.

Do you have a digital gauge connected to the 140?

Best way to get a true read is to top off the tank, go out and drive around /make trips as you would, fill it back up noting the fuel amount then compare to gps distance tracked.

80l seems on the small side for this combo, we have a 180l

[boogaloo]

Thank you for the advice! Your setup sounds very comparable. I believe it's a 90l tank on paper in the console, but real world people seem to report more like 80 usable.

When the boat was made in 2020 I guess it was intended to have something more modest as a motor.

Yes - I have the digital gauge and will use my break in period to get some good stats on how it performs. I'd just rather head off for a long jaunt around the coast rather than doing laps of a smaller area

Sounds like I'll need to take a couple of 20l extra canisers if I'm planning a longer jaunt.

Thank you again

[Easedalenovice]

It is better to buy 10 ltr (actually hold about 11 ltrs) cans as these are far easier to store and lift on a boat. Get yourself a jiggle syphon also. I agree on the 0.8 ltr per mile also

[Pikey Dave]

My 5.45 does around 1nm/litre with the same engine. Depending on tide /conditions, it varies between 1.2 & 0.8 nm/L. I use 0.8 for passage planning purposes.
Re. running in. We ran ours in up at Oban, iirc, it was something like 15mins at tickover, 2 hrs sub 4000rpm & then 7hrs or so, at varying RPMs using the full rev range & no more than a few seconds at WOT. It's a while ago, so I may be a little hazy on the exact numbers. We just pootled around the Oban area until the hours were up, the conditions were lively at times, so we got to use the full rev range of the engine, which was good. Don't keep it at a constant RPM for long periods during the run in. If you're doing it over a couple of days, you'll be fine with 80L for the first day, fill up after day one, note how much you've used & you'll have a better idea how much you'll need to finish the job.

[ptm]

I know you have probably completed your run-in now, but as a reference, we did the loop around Anglesey yesterday in my Destroyer with a year old Suz 140. We averaged about 18-20 knots and consumed 46 litres of fuel, which I am more than happy with. Depending on who you listen to, and how many corners you cut, it is roughly a 70-80 mile round trip. That’s around the 1.5 mile per litre mark at least. So your 80 or 90 litre tank will give you reasonable range. It’s a great engine.