New 8.5 rib - engine choice

CaptainGb · 25 September 2010, 09:00

Good morning all ... my first post on this forum. I'm planning to order a new rib, between 8 and 9 m, for west country cruising and just having fun. Regarding engine setup, what do you think my litres/miles would be for twin 250hp? Is there anything equivalent in term of power using diesel fuel?
The usage will be purely private, maybe 50 hours per year. so do you think petrol O/B will be more cost effective over few years (taking into account purchase cost, maintenance and fuel use)? If O/B, E-Tec or 4 stroke?
Also, can diesel ribs be easily beached? I'm thinking about the drive protection.

Thanks in advance.

spartacus · 25 September 2010, 09:36

Give it 5 mins...

Welcome to the forum by the way.

Pikey Dave · 25 September 2010, 09:41

2x250 E-TECs with Icon controls, excellent power:weight, great fuel economy, quiet, low oil consumption & no smell/smoke when set to XD100, 300 hours/3 years to first service & the sheer low down grunt of 2 stroke, you'd struggle to match that with a 4 st & no chance with diesel

Cypman · 25 September 2010, 12:13

Welcome, I am sure you will get lots of advice !!! For my "pennie's worth" I would stick to petrol outboard(s) 2 or 4 stroke as you choose. I consider that diesel installations are less appropriate when your annual usage is low (circa 50hrs) as you will not amortise the considerable additional initial cost.
Moreover, most inboard engine legs will not lift clear of the keel line making them unsuitable for beaching. The main disadvantages of petrol outboards are the poor availability of fuel afloat and the greater fuel burn. The choice is yours, god luck and enjoy your ribbing.

RRIBS · 25 September 2010, 15:36

If you are looking for an outboard/s, look no further than the new V6 Yamahas. I have the new 300HP BETX on the back of my RIB, with a 19" Saltwater S/S propellor and it just flies. The new Yamahas work well as pairs too. Lighter than their older equivalent and in some cases the same price. The engine sound is superb, performance brilliant, and first class fuel economy. Give Yamaha a call and don't discount them. These new engines are the best for price and power to weight ratio. Best of luck. Let us know what you choose. Regards. Welcome to Ribnet!

Poly · 25 September 2010, 19:32

Quote:

Originally Posted by RRIBS

Give Yamaha a call and don't discount them. These new engines are the best for price and power to weight ratio.

Ehm, actually the equivalent sized etec is about 15 kg lighter per engine (and in the right shaft size etc could be over 20 kg lighter). I also thought the Etec's were cheaper (list price) than Yamahas but I don't have price list or know who offers the biggest "discount".

And that CaptainGb is the problem with advice on which engine threads - most people have an opinion - but its unlikely that many have actually tried all of the competition on your particular type of boat and even less likely that they've lived with it.

In terms of fuel ecconomy with twin 250s I suspect this will have a lot to do with how much self control you have with the throttle. At full throttle I'd expect them to be burning something like 150 L/hr

. However when cruising at "sensible speeds" most people here seem to claim something like 1 L/nautical mile (almost regardless of boat/engine) +/- 20%.

For 50 hours a year, then almost certainly petrol ob's work out more affordable than diesel inboards - and the only obvious reason for speccing diesel in a new lightly used leisure boat then becomes availability of dockside fuel.

Bigmuz7 · 25 September 2010, 20:59

Single OB too

for those hours.... Verado 350 sci .. my biggest was the 275 .. so dont have the data for the 350 ... but with the DT&S boy did I like that engine

.... it really hums like a peach .. now my english teacher would have put me in detention for that phrase

( have I given my age away ?

)

willk · 25 September 2010, 21:03

Quote:

Originally Posted by Bigmuz7

now my english teacher

They taught you English?

Bigmuz7 · 25 September 2010, 21:15

Quote:

Originally Posted by willk

They taught you English?

Fae an Irishman talkin too a SCOTSman .. the answer ofcourse is no!

but lets not let that piffeling quibble get in the way of a thread .. those morris dancers can fight it out amongst themselves

And someone had to be able to tell me how to communicate with them

GJ0KYZ · 25 September 2010, 21:18

With a boat that size you have to be prepared for big fuel bills. Someone I know recently bought a Scorpion 8m+ with a single 300hp Verado that burns in excess of 2 litres per mile at fast cruise. My boat (6.8m / 225 ETec) burns 1.5 litres per mile at 35-40kts. I don't know too much about diesels except they weigh a tonne and rust up quick, and the smell of diesel makes me sick.

Steve_B · 25 September 2010, 21:22

Hi and welcome.

I have a 9m Parker (commercial spec, so heavy and well equipped) and run 2x250 Verado's.
I was a 2 stroke addict and reluctant to change to 4 stroke. I have no regrets at all.
The difference in full consumption between engines of a simular size will be insignificant compared to how heavy you are with your right hand! And for 50 hours/year, other costs will have more impact on your pocket.
I can only give you my figures which are when loaded with 10/14 persons and 440ltrs of fuel;-
20kts - 45ltrs/hour ish
25kts - 55-60/hour ish
30kts - 73/hour ish
45kts+ -200/hour!

As for the selection of your boat, go try as many engines as you can and find what you like, we all have attachments to our own preferances.
Steve

CaptainGb · 25 September 2010, 21:26

Thanks to all of you for taking the time to post.
Engine leg seems to be out as it seems they wouldn't allow problem free beaching.
Bigmuz recommend 350hp for a rib designed to handle 600hp. Would that prevent the rib to achieve it's designed performance or require the single to be pushed very hard?

Bigmuz7 · 25 September 2010, 21:57

Quote:

Originally Posted by CaptainGb

Bigmuz recommend 350hp for a rib designed to handle 600hp. Would that prevent the rib to achieve it's designed performance or require the single to be pushed very hard?

Just telling it like I see it .. a single 275 Verado pushed my 8.5 like it wasnt there .. you get two of them if you want

with all the outboard costs and all the petrol they will drink.. if you have the petrol money in the budget .. stroll on

but for all the hours you will be doing .. i think you would be wasting cash .. but ofcourse it depends where you sail ?

Chris · 25 September 2010, 22:01

Quote:

Originally Posted by CaptainGb

Good morning all ... my first post on this forum. I'm planning to order a new rib, between 8 and 9 m, for west country cruising and just having fun. Regarding engine setup, what do you think my litres/miles would be for twin 250hp? Is there anything equivalent in term of power using diesel fuel?
The usage will be purely private, maybe 50 hours per year. so do you think petrol O/B will be more cost effective over few years (taking into account purchase cost, maintenance and fuel use)? If O/B, E-Tec or 4 stroke?
Also, can diesel ribs be easily beached? I'm thinking about the drive protection.

Thanks in advance.

Hi there with regards to your questions on fuel consumption that's going depend on a lot of factors not least which hull you are chosing however your probably looking at about 80-100 litres per hour for each engine for the E-tec 250's at full chat and about 40-50 litres each at cruising speed.

50 hours a year is not that much and you will only need to do a few of longer day trips at 8 hours per day and you will soon find yourself clocking up 100 hours.

So if you are looking at average fuel consumption of say 100 litres per hour (assuming time spent at idle etc) then you would use 10000 litres per year so annual fuel costs at current rates will be £12,000

Which Rib are you thinking of getting?

Chris

Poly · 25 September 2010, 22:11

Quote:

Originally Posted by CaptainGb

Thanks to all of you for taking the time to post.
Engine leg seems to be out as it seems they wouldn't allow problem free beaching.
Bigmuz recommend 350hp for a rib designed to handle 600hp. Would that prevent the rib to achieve it's designed performance or require the single to be pushed very hard?

What are you planning to use it for? Most people here are quite enthusiastic about power/speed - but I doubt many would feel the need for 500 HP on the back of an 8m boat if its just for general leisure / family use. Also twin engines are generally considered inefficient, so e.g. 2x250 HP is possibly equivalent to 1x350 (30% loss?).

Pikey Dave · 25 September 2010, 22:12

Ah now ! that's another kettle of worms, the old big single or medium twins question. IMO (don't forget opinions are like ar***es, everybodies got one) depending on how deep your pockets are I'd go down the twin route & put at least 500hp on the back. If its rated at 600hp, then it will probably need 450 to perform. There's NOTHING worse than an underpowered boat, hp is like money & sex, you can't have too much of either. Flogging an underpowered boat will use more fuel, than running a comfortably powered one at it's most efficient rpm. Remember when it comes to engines 1+1 doesn't =2, more like 1.5

CaptainGb · 25 September 2010, 22:25

Well, the one rib I find interesting is the ribcraft 850 cruiser. To be based in the Falmouth area and used for local fun days out and longer ones to the scillies.

Pikey Dave · 25 September 2010, 22:36

Quote:

Originally Posted by CaptainGb

Well, the one rib I find interesting is the ribcraft 850 cruiser. To be based in the Falmouth area and used for local fun days out and longer ones to the scillies.

& what is pushing it?

boristhebold · 26 September 2010, 07:04

I have a yamaha 200 2 stroke pushing a 7.5m cobra rib, top speed about 46knots, don't know about litres per hour but a full day out cruising along coast stopping for lunch andnhaving a few bursts of speed I probably get through about 70 quids worth.

Poly · 26 September 2010, 09:51

Quote:

Originally Posted by CaptainGb

Well, the one rib I find interesting is the ribcraft 850 cruiser. To be based in the Falmouth area and used for local fun days out and longer ones to the scillies.

Why have you narrowed your choice down to that boat? Do you really need 8.5m for what you suggest? especially if you are only using it 50 hrs a year which suggests "nice weather" rather than must go out every week regardless.

On the 2009 IoM trip (which didn't go because of the weather) I had the pleasure to be a passenger on a 7.8m Ribcraft with single 250 HP (Yam) - in some rather lively conditions. The boat was more than capable (hardy soles with smaller boats ventured out too and survived). I'm quite sure the boat would have made it to the IoM too with the very capable Mr Kennet at the helm - but it wouldn't have been fun - but even an extra 70cm wouldn't have sorted that.

I wouldn't have said it was undepowered either - unless you have a hidden desire to get into racing - it was still getting air borne.

Mollers cruises in the sort of area you are in and likes his trips to the Sillies - which he seems to manage in an Osprey about 2m shorter than you are looking at.

So unless you've got money burning a hole in your pocket, a desire to pay more for fuel, pay more to store it, a bigger status symbol, or a massive family etc... then I'd suggest you try some of the shorter boats - you might be pleasantly surprised.

EDIT: Oh, and I'm not sure I'd be wanting to beach an 8.5m, £60000+ rib regularly either