Ribcraft 585 / 680 fuel economy cruise/WOT

[RickW]

Hi Everyone,

In the process of finally finalising an order - well sort of

Many thanks to those of you on here who have given advice over PM and email / phone it is very much appreciated

Looking at the Ribcraft website and various threads here it looks like these are typical

585 with 140/150hp c. 0.8-1 l/nm throughout the rev range max 35-40 knots

680 with 200-250hp c.1.2-1.8 l/nm depending very much on revs speed up to just shy of 50 knots

Now I have heard and seen various reports some 680 owners are getting 0.8-1 l/nm but I am trying to get an idea at what cruise and if this is an absolute ideal and if generally its more

Basically trying to get some more info to inform which way ultimately I go

Hope to get to see a couple more 585/680 to get my eye into the overall jump in size as can see the advantages of the bigger size (as mentioned on the other thread going) and the advantages of the smaller size in terms of beaching / towing etc

Nightmare decisions

[nocando]

My son has a 6.8 with v6 df200 and at a cruise of about 22-27 mph he gets 0.9l per statute mile.

It will do just over 50mph with his normal loading.

He tows the 6.8 with a grand Cherokee as the 6.8 is the wrong side of 2k for a normal car. He also had to sit the towing test, not sure if a 585 would be any different.

He left the forum quite a while ago but if you need specific info I can ask him?

[RickW]

Yes it was your son x59d who posted about just sub 1l/nm for a cruise which is amazing given the extra weight i guess unlike the 585 the fuel consumption goes north exponentially when you hit the loud button. Just trying to get a range of responses

[pow2gran]

I had a 585 with a 140 Suzuki and it replicated the fuel use on the Suzuki website. Whilst I didn’t trade up to a ribcraft I have a 6.8 Shearwater Cutter which I rigged with a new 200hp Yamaha. The Shearwater is a heavy build. 585 topped 40knts whilst the 6.8 tops 42knts. Steady cruising in 585 was 20 to 25knts at 0.8 l/m. The 6.8 cruises 25 to 30knts at 1.1l/m. 585 will tow on single axle 6.8 you will probably need twin. Weight of trailer 585 was around 1800kg and 6.8 around 2300kg.

[nocando]

Well it stands to reason the louder you push the loud button the more you burn.

The easiest way to look at it is 1 litre per MPH upto about 35mph them it gets up there.

[Bigplumbs]

Over a season the actual amount you spend on fuel is not that high and differences between boats and engines quite small in total real terms

My advise would buy what suits you and ignore economy as it makes little difference. If you use it 20 times a year you will do well and that will most likely only between £100 and £200 difference in fuel one over the other is that really worth worrying about

[RickW]

The difference between 585 and 680 is very real in real terms it’s a chunky jump in terms of cash. Do you have either or have bought either from new? Granted on the fuel is they moderately slightly more thirsty on the bigger boat but that is why I am asking for real owners opinions both at cruise and full chat

[nocando]

So I've asked him for you and basically cruise is 22-35lph depending on how fast he wants to cruise. If you open it right up you will be close to 70lph with his setup.

Last year a 585 and his 6.8 were side by side and the difference in size is substantial and he priced both so knows the cost difference too.

[RickW]

Thanks nocando your posts were helpful as was this was above - my previous post was referring to the gentleman who said there was very little between the boats costs wise obviously there is for build costs I guess at full chat basis 70 lph we are looking at 1.6 - 1.7 l/nm vs 0.9/1 l/nm at cruise. Just need to get some more ideas from other other 585 / 680 owners

[lakelandterrier]

Hi Rick,

Really don't think you'll get anything like 0.8l/NM for a decent cruising speed in a 6.8. i'd estimate nothing better than 1l/NM - 25%increase in fuel consumption.

my 585 with a 140 $Stroke gives me 0.78l /NM at a comfortable 25kts cruising speed

That's a comfortable speed for size. Can go faster, but burn more fuel for no real benefit, and with harder ride unless flat calm.

A longer hull will enable comfortable cruising a higher speed but at higher fuel burn, and is it just speed you want - what's the benefit of the extra 5kts on a day out?

[scrambler]

Originally Posted by lakelandterrier

my 585 with a 140 $Stroke gives me 0.78l /NM at a comfortable 25kts cruising speed

I also have a RC585/Suz140 and even at 25 knots I never see as much as 0.70. Mine was new last year so I wonder if it's the newer Suzuki being more economical? Here I'm getting 0.60 at 21.8 knots. Probably some tide helping but you can see I'm not in the main channel so not a lot of tide.

[RickW]

Thanks all can i ask where the 585 would be l/nm at full chat also? As always many thanks to the owners LLT and Scrambler for the input it is genuinely helpful

[Mick Balch]

I’ve a 2008 Ribcraft 6.4 with DF Suzuki 150 which although a great boat is cramped with 6 seats. Suggest you go for the boat which suits your practical needs and forget the fuel economy as at that size and HP they are are very similar unless you blast around everywhere. Cheers.

[RickW]

Hi LLT, The reason I was asking is once I see one in a leisure set up rather than dive rack will have a better idea of space and comfort - genuinely torn as to which way to go. Likewise need to come and have a peek again at the 585. I would occasionally like to dive off either one but not have it set up as a dive rib (prefer hardboats with a lift for diving when the purpose of the trip is diving)

[nocando]

He sent me this to post for you, it is between 5-10% under reading in reality.

It is only usually him and wife that use this so the fuel burn is probably only those 2 for reference.

As you can see it is a leisure setup but leave the back seats off there will be lots of room for dive kit.

Enjoy the search, whatever boat you pick will serve you well.

[Pipster100]

Hi RickW, I bought a 585 at the end of last year with a Yam150F on the back, I absolutely love it. I was also looking at the 6.8 which is a great boat but in the end decided that the 585 suited my needs better. I wanted the option of being able to tow it comfortably behind may Transporter T5 camper without having to use my Discovery so could head off for weekends camping and take the RIB. 90% of the time I'll be using the boat around Falmouth where I live, being that little bit smaller/lighter it's easier to beach for BBQs and can usually squeeze onto the harbour masters pontoon in St Mawes which is generally only for tenders. The layout is 4 jockey seats, most of the time it's just 2 of us + the dog. I'm currently having a removable bench seat custom made (don't ask the price in case my wife reads this!!), occasionally I'll have more friends with us so this will then give me 7 seats, I can take the bench out whilst fishing or diving. The seat is designed that it sits almost all the way to the back of the boat so there's still room in front, granted, this will never be as much as a 6.8 but suits my needs, the back rest hinges forward and sits flat on the seat so you can still fully raise the outboard. I haven't done enough trips yet to see just how accurate the fuel flow/trip gauge is so wouldn't like to give you false info.

[RickW]

Hi Pipster - yours was the last 585/680 thread so I remember the discussions. Glad you are having fun with yours

[lakelandterrier]

Originally Posted by Bigplumbs

Over a season the actual amount you spend on fuel is not that high and differences between boats and engines quite small in total real terms

My advise would buy what suits you and ignore economy as it makes little difference. If you use it 20 times a year you will do well and that will most likely only between £100 and £200 difference in fuel one over the other is that really worth worrying about

Not sure I fully agree with first point. In a good season I'll do 700+NM so use c. 560l of fuel. That's £700. Put that up to larger heavy boat and engine @ 1.1L/NM you're at 770l. At fuel barge prices that's well over £350 difference (+45%) plus all the other on costs of larger boat & engine. That would influence my decision at any rate(but I did live in Yorkshire for several years).

I agree with your second point - buy what suits you - but also what suits your capital / running budget, else you'll end up with a boat you don't use because of the bills. All I'm saying is don't ignore the costs, just understand them as part of the overall decision.

[Phil M]

Originally Posted by RickW

I would occasionally like to dive off either one but not have it set up as a dive rib

I'm in the same position so had removable rear jockey seat pods fitted. It I want more space for diving, they are 4 bolts each to remove. If I start to dive more again, I could come up with a dive rack that fits the same bolt holes.

For what it's worth I have a heavy Destroyer 5.8 with a merc 115 and cruise at about 0.7 l/nm on a good day.

Phil M

[mhb100]

Rick W,

Don't take this wrong, but I think your asking the wrong question. Fuel costs are not likely to be the key variable. What are you going to do with the boat?

The 585 is a big little rib. A good compromise in terms of running costs, low storage costs, can be towed by many larger family cars, and can be launched by yourself if required. Single axle trailer so much easier to manouvre. Pretty much fits in a standard drive/ car park space.

When you step up your cost will increase for fuel, storage/ marina, insurance, maintenance, depreciation, etc. If your towing you will really be in 4x4 and loose flexibility in parking and storing.

I'd work out all the other costs and not worry too much about fuel. As some one said to me if your asking that type of question a larger rib is not for you.

If you know what you plan to do with a rib then I'd suggest you try a few out, or see if you can join a few ribnetters.

If your going brand new then your going to probably miss this summer although you may be able to get a deal on a demo boat for a boat show from September

I have a 7m rib, upgraded from 5m its capable and does 50 knots, and better if you Carry more than 4, but truth is I'd have been better of with a 585 with a 150 and saved a lot.

Good luck with what you choose I'm sure whichever will put a smile on your face.