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Old 26 March 2016, 15:16   #1
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Diesel ribs?

So, to ask a "how long is a piece of string" question of people's experience.....

Apart from the particular personalities of petrol v diesel I'm curious as to the general view on diesel inboards in ribs?

If a man was looking at buying a second hand daysil boat (eventually) that he might hope to travel a few hundred miles from home in a week diesel seems to be much more widely available if you aim for fishing harbours.
The three spots you can get petrol on E coast of Ireland are all within the Dublin bay area, so tankering petrol would be v necessary.

What's the max engine hours you'd accept? Are diesel engines assumed to have a finite service life? Assuming a reasonable level of service history.
Do rebuilt engines make you nervous or is that generally a good sign?
How do outdrives survive the non-judgemental love they get from weed and barnacles?

Are they noisy, smelly, slow, hateable beasts? Or smooth, economical, reliable and desirable?
Are they generally the preserve of commercial boats?

I was thinking something of at least 150 hp upwards in 6.5-7.5m.
And this is a longer term planning question rather than money burning a hole in my pocket tonight question.
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Old 26 March 2016, 15:40   #2
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Much the same as "any" inboard, go for closed cooling not direct sea water cooled if you can, or its regular rebuilds imho. 6 Pots are rather nice & smooth, probably not that much choice out there in all honesty.

Yanmar 6's or Ford Mermaids are all you'll find in reality I suspect
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Old 26 March 2016, 16:30   #3
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Yup too many questions.
Diesels are bigger and heavier, but more economical. Mine, 315hp does 1ltr per mm at 30nmph.
They are not noisy or smelly but much more reliable. My diesel ribs have only failed to start when the battery was run down too low. And that is in 16years of owning diesel.
They are "safer" in that you are not sitting on a floating bomb.
They take the sea better, but are not as fast and prone to very slow take up on the throttle.
How any of your questions have I answered?

Loads more opinions along in a minute.
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Old 26 March 2016, 16:49   #4
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A lot depends on your intended use if your just bay hopping and running around local & or doing waters ports I'd say go petrol if your going to do long runs without refuelling go diesel
Diesel ribs are significantly more expensive to maintain & legs can suffer corrosion if left in the water lots more to go wrong
I've got both but for different purposes
Yes they are cheaper to run but you could outweigh that saving in maintenance/ repairs
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Old 26 March 2016, 18:06   #5
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I know of a very well priced, large scorpion over your way with an inboard diesel

I was so tempted to buy it myself and blast it back to southampton and put a cabin on it

If you want the info I'll put you in touch with the guy
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Old 27 March 2016, 06:44   #6
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Diesel

On my second diesel rib and I will never go back to petrol.
First one was a Humber 8.5 with a Volvo KAD44 super engine but quite complicated and not suited to life in an open boat , lots of belts and pulleys to change and fairly complicated electronics which suffered from salt water . The engine was 16 years old when she left me after a life of whale watching and then private use by me. 1l a mile consumption ,amazing performance from the supercharger/turbo charge combination . Top speed around 35kn.
Second one is a Yanmar 6lp much simpler engine ,currently on 1100 hours and I expect it to keep going for several thousand more , new leg fitted due to hitting something before I got her.
Scorpion 8.5 runs at 42kn top speed again 1l a mile at 32kn cruise. Very quite and smooth .Fairly slow until 2000 rpm when turbo comes on then a lively surge up to top speed.
Red diesel currently .92 on pontoon in Portsmouth but other sources are available at much less.
300 mile range not sitting on a bomb as in previous post .
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Old 27 March 2016, 11:06   #7
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Thanks guys,

That's given me a good idea of how you find living with them.

I'm leaning towards one as a long term plan (I suppose otherwise I wouldn't have asked the question) but will see how my needs evolve.
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Old 27 March 2016, 11:19   #8
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Yup too many questions.
Diesels are bigger and heavier, but more economical. Mine, 315hp does 1ltr per mm at 30nmph.
They are not noisy or smelly but much more reliable. My diesel ribs have only failed to start when the battery was run down too low. And that is in 16years of owning diesel.
They are "safer" in that you are not sitting on a floating bomb.
They take the sea better, but are not as fast and prone to very slow take up on the throttle.
How any of your questions have I answered?

Loads more opinions along in a minute.
Much more reliable than what? Petrol? I've never experienced a breakdown with a properly maintained outboard.
'Floating bomb' is a little ridiculous , when did anything petrol powered including
Boats you know of explode?? FYI although more diffcult to ignite diesel has more energy content
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Old 27 March 2016, 12:01   #9
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Much more reliable than what? Petrol? I've never experienced a breakdown with a properly maintained outboard.
I've had breakdowns with both outboards and diesels. I'm not convinced that diesels are necessarily more reliable than outboards, but I don't think they're any worse.

Quote:
'Floating bomb' is a little ridiculous , when did anything petrol powered including
Boats you know of explode??

It's not exactly unheard of. Try googling petrol boat explosion and see what you find. To be fair though it's less of a problem with open boats.

As others have said though it's availability of fuel at the quayside that is the big advantage of diesel, especially if you're going anywhere off the beaten track.
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Old 27 March 2016, 13:59   #10
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I've had breakdowns with both outboards and diesels. I'm not convinced that diesels are necessarily more reliable than outboards, but I don't think they're any worse.




It's not exactly unheard of. Try googling petrol boat explosion and see what you find. To be fair though it's less of a problem with open boats.

As others have said though it's availability of fuel at the quayside that is the big advantage of diesel, especially if you're going anywhere off the beaten track.
Can't seem to remember the last time a motor boat / rib floating around the uk coast explodes in a fire storm of glass fibre and body parts.......................i'm sure we've also all owned petrol Cars in the past - oh and funny that none blew up and we're all still alive, amazing
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Old 27 March 2016, 14:26   #11
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I have a bit of experience of both. Which is best for someone very much depends on a number of factors.

Cost: Diesels are expensive to buy - new and used. Maintenance can be expensive too - but then, green diesel is cheap. The balance will be a personal thing. Old diesel RIBs seem to be very pricey - given that they are going to stick an arm into you financially!

Condition: Old diesels are a minefield. If a leisure boat has been lying about afloat or stored, a whole world of pain can await the new owner. A working boat might be different. I'd prefer to buy a diesel that did 300 hours a year than 30. Outdrives are another matter entirely. They seem to be the weak link in the whole diesel story. Diesels deliver a large amount torque at low revs, and if a diesel boat is driven like a petrol - with sharp and choppy throttle action - then the drive train can receive a lot of stress.

Fuelling: I don't entirely "get" small trailerable (6-7m) open diesel RIBs. Half the boat is engine and they aren't ideal for long distance cruising. They are getting filled at the pumps - might as well be petrol, IMO. It's with the bigger RIB that fuelling becomes important. If they are not being trailered, then the fuel has to be transferred or purchased at a dockside pump. Petrol is rare enough on the water everywhere. TBH, there's not a huge availability of diesel either. It means that you end up fuelling from cans. I've driven around with 400L of diesel or petrol in my van - I know which I felt more comfortable with!

Available boats: Avoid all the Quicksilver engines. You'll see Volvos, VWs, Yamahas, Yanmars and Cummins. Avoid the exotics like Steyr. You'll find quite a lot of heavyish boats running 315hp Yanmar 6LPs. They're fine in most ways, but I find the turbo lag soul destroying (on a heavier boat).

Maybe by the time you're ready - the Yanmar 8LVs will be entering the secondhand market...
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Old 27 March 2016, 14:39   #12
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Interesting comments there willk.
I've not owned an oil burner, but one maybe invited into the stable at some point.

I have 1200ltrs of cherryade on tap in the shed.
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Old 27 March 2016, 14:57   #13
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Maybe by the time you're ready - the Yanmar 8LVs will be entering the secondhand market...
I'd settle for a better exchange rate!

Thanks for all the info.
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Old 27 March 2016, 17:56   #14
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I think willk has pretty much hit the nails on the heads. I'd agree with most of what he says although I've never had a problem finding diesel waterside anywhere usually someone serving the local fishing community who will fill you up if you mention cash
I avoid marinas for fueling as the fuel is usually overpriced
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Old 28 March 2016, 11:38   #15
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By definition a diesel rib with equivalent power will be substantially heavier than an outboard powered boat. This makes driving each a very different experience. Along with that, as willk mentions, is the lack of low rev power and you can find yourself in a big(ish) sea where you can't overhaul a wave so you can only move at wave speed. Sometimes this is very little above planing speed but on larger waves it can be 30kts. This might seam fast enough but you'll not be able to climb the hill in front of you and you'll be stuck in the trough until the following wave lifts you and provides a hill to run down, this for you to repeat over and over on a long journey can be hard work. It's more a power to weight issue than a diesel petrol issue.

However, I do feel much safer sitting on top of 500lts of diesel than 500lts of petrol.

I've not had a problem finding diesel fuel and I've found a number of oil supply companies run a large van containing a diesel tank and pump and they'll meet you at a harbour. Payment is usually through the telephone with the parent company and your credit/debit card.

It's kinda one of those things you need to try for a while so you weigh the pros and cons for yourself.
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Old 28 March 2016, 11:59   #16
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However, I do feel much safer sitting on top of 500lts of diesel than 500lts of petrol.

.
I find this whole petrol 'bomb' thing a little daft. If it were the case, we'd have 1000s of potential explosions permanently trundling around our roads.

A fire on any boat is a serious situation, gas cylinders then become potentially more dangerous.
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Old 28 March 2016, 12:19   #17
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The flash point of petrol is -42degs (ish) diesel is over 50 degs so in relative terms petrol is much more likely to go boom.

I think petrol cars are a different proposition. Both in terms of basic design requirements and subsequent diy electrics.

That said I havea petrol boat and I'm not expecting any big bangs.

Google Opel Zafira fires
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Old 28 March 2016, 12:50   #18
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I find this whole petrol 'bomb' thing a little daft.......
I know what you mean but a boat engine is a whole lot more vulnerable than a car engine, especially so since it's effectively in a container surrounded by air and therefore only a minor electrical spark would be required for ignition if petrol became free in the engine compartment. Just the day to day maintenance of the engine ensures some fuel or fuel vapour in the engine campartment and sparks will be freely available at the alternator slip rings!
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Old 28 March 2016, 13:56   #19
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I know what you mean but a boat engine is a whole lot more vulnerable than a car engine, especially so since it's effectively in a container surrounded by air and therefore only a minor electrical spark would be required for ignition if petrol became free in the engine compartment.!
I've lived in a high volume leisure boating area for all of my life, it's NEVER happened.
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Old 28 March 2016, 14:22   #20
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I've lived in a high volume leisure boating area for all of my life, it's NEVER happened.
Hehe, that's lucky! It will, there's always a first.
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