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Old 19 April 2004, 02:30   #1
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Country: Hong Kong
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Boat name: The Fish
Make: Fountain / the other one is a Rib
Length: 9
Engine: Inboard Diesel 230Hp
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Backup Outboard Diesel

After looking through the various forums, the consensus on powering a long distance rib is a single inboard diesel.

- Petrolís donít provide the range and it costs more to buy (twice here).
- Twin motors mean a lot more cost/maintenance/weight for equivalent power.

The problem is not having any backup if the engine or drive fails.
A 10Hp backup motor should push the boat along at around 6 knots in Ďdisplacementí Ė enough to get me back from anywhere.

A light petrol outboard fits the task, but I donít want to carry petrol as well as diesel.
A light kerosene outboard will do the job; there are light kerosene outboards available.
There arenít any light diesel outboards available. Iíve not been able to find a light 10Hp diesel outboard (<50Kg) anywhere.

Two questions:

1. Will kerosene work in a diesel engine? [What is the diff. kerosene/diesel?]
(At least the backup fuel could be used foe the main engine too)

2. Does anyone know of a light diesel outboard?

If it is too heavy (like the shoddy Chinese things available [100Kg]), it wonít be easy enough to chuck on the back in an emergency.

Hereís what Iíve found so far:

4Hp 93Kg Chinese ($1000) http://www.chinadiesel.com/mrn/diesel_outboard.htm
6Hp 60Kg Chinese ($900) http://www.morganequipment.net/page13.html
10Hp 75Kg Chinese ($1300) http://www.morganequipment.net/page13.html
25Hp 115Kg Coventry Climax
http://www.dieselmarine.net/
27Hp 94Kg Yanmar http://www.yanmar.co.jp/english/index-m-under.htm
36Hp 115Kg Yanmar http://www.yanmar.co.jp/english/index-m-under.htm


Also,

I recently bought a 7.5Hp air-cooled Yanmar diesel (industrial motor) that weighs 33Kg, but I need to go through all the hassle of putting a drive unit and prop on it . At least it is a good quality Japanese made aluminium block engine.

Thinking of putting a Thailand style prop shaft on the end of it, with a 4:1 chain drive for good thrust. I recon the whole thing should weigh about 45Kg and be able to use the main engineís spare prop.

Any ideas?
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Old 19 April 2004, 08:23   #2
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You can use Kerosene in a diesel but it will destroy the fuel injection system very quickly - no lubricating qualities. I've been told if you mix 30% lube oil with kerosene it'll be ok in an emergency - diesel's cheaper!
Incidentally what we know of as 'diesel' is actually gas oil, real marine diesel is MUCH lower quality.
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Old 19 April 2004, 13:25   #3
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I think there may be a misunderstanding here?
You want to know if diesel will work in a kerosene engine?? personally I have never heard of kerosene engines apart from jets and as an alternative fuel for petrol engines once they have warmed up, as in the second world war when petrol was in short supply.
I have thought about an electric motor for trolling and manouvering, but that would need either a large battery payload, or smaller batteries and a generator to top them up. So if you want a diesel boat you need a diesel generator (do they make them that small)? or you are back to petrol.
Personally I like the idea of an electric auxhilary engine, but I cant see a way to make it viable.
Nick.
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Old 19 April 2004, 13:51   #4
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Thai style long-tail sounds favourite to me, but it would take up a lot of room!

I don't know of any new diesel outboards although one was made a long time ago - 15 - 20 years? It can't have been very good as they weren't around for long!

Those Chinese things certainly arn't exactly 20th let alone 21st century, the reliabilty and usefullness are anyones guess though!
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When a boat looks that good who needs tubes!!!
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Old 19 April 2004, 15:27   #5
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Quote:
Originally Posted by robarro
I recently bought a 7.5Hp air-cooled Yanmar diesel (industrial motor) that weighs 33Kg, but I need to go through all the hassle of putting a drive unit and prop on it . At least it is a good quality Japanese made aluminium block engine.
What about mounting it on top of a seagull silver century shaft? You'd need to look into drive ratios and rpm, but may be possible by changing the prop. A Seagull driveshaft (on the smaller ones anyway) is just a steel box section so should be easy. Let us know how you get on as I was thinking the same way as you.
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Old 19 April 2004, 15:44   #6
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Ruggerini (italian) make a 15hp outboard and it weighs about 80ish kgs. They appear to be reliable. Allan Priddy will be able to give you good info, I think. I have a Yanmar 27hp as a backup. It weighs about 90kgs.
Gas oil and red diesel are the same product. Gas oil has a higher calorific value than kerosene.
As Cookee says, kero lacks the lubrication for the mechanical parts. Use your nous as to how you could oil it......as a clue, some marine petrol engines are lubricated this way.
I would imagine diesel would be ok in a kerosene engine. It is a bit thicker though. This might be ok because it would run a bit rich because of it's higher calorific value but this might be compensated, to some extent, at the jet by it being a bit thick. I'm just guessing here.
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Old 19 April 2004, 20:16   #7
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Have just received a reply from a dealer about Yanmar 27Hp outboards, quoting £10k+ and long delivery. I found someone else selling 4 for £6k each, will search for who if anyone wants me to.
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Old 19 April 2004, 22:05   #8
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Kerosene and diesel ARE very similar - in fact winter diesel in many countries IS kerosene!

Jet fuel is also almost identical - it is true that under heavy load conditions in hot climates kerosene can cause problems due to reduced lubricity but the addittion of say 5% oil will restore matters.

The military have been trying a single fuel policy - using jet fuel in planes and trucks etc - only had problems when used without additives in desert type conditions after extended running periods.
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Old 20 April 2004, 00:04   #9
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From VW/Audi manual for 1.9TDI engine supplied to military - in low temps when arctic diesel starts to wax, it is permissable to add petrol up to 25% volume!! Also says that this will invalidate the waranty....
So if anyone can finad anything other than Polish Vodka still liquid enough to float a rib at these temperatures you know how to fuel it!

Think we've left the thread here, sorry...
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Old 20 September 2004, 17:42   #10
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Does anyone know anything about the ruggerini small diesel o/b's ???http://boatdiesel.com/Engines/Ruggerini/Ruggerini.cfm
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