Starting a small diesel, manually...just how hard can it be?
- Thread starter Greenheart
- Start date
Triassic
Well-Known Member
Something like this.
http://www.autoelectricalpartsuk.co...rgency_Jump_Pack_JP1_Guardian_Automotive.html
http://www.autoelectricalpartsuk.co...rgency_Jump_Pack_JP1_Guardian_Automotive.html
Greenheart
Well-Known Member
That's very good sense, of course...but to be honest I had been looking at the smallest diesels, as alternatives to petrol outboards in very small yachts...
...so I was thinking of the weight-saving that might be gained by dispensing with the starting battery altogether.
The weight of a dedicated starting battery seems to be regarded as inescapable in most yachts...despite the fact that small diesels are often lightweight themselves.
I'm not trying to persuade anybody that this is a wise alternative to existing practice - just wondering how overladen small yachts might sail better without unnecessary weight.
That puts paid to a nice idea, then!
Triassic
Well-Known Member
Someone did try and explain to me once that there are two kinds of batteries on yachts, those that are designed to provide high amps for starting purposes, and those that are designed to run all the low amp equipment for a long time..... (I'm not that clever so he kept it simple....). He also told me that the engine ones don't tend to last as long as they should because they are rarely discharged very far (unless you have a dodgy engine that doesn't start easily) and this lack of cycling isn't good for them? Either way I decided not to have an engine battery on my boat, I just have the one large leisure battery which is maintained via a solar panel and isn't even connected to the engine charging circuit.
The reason I was looking into those emergency jump packs is because I thought it might be useful to have a second independent power supply on the boat.
micha571
Well-Known Member
My Bukh DV10LSME has a cord with a handle, which is supposed to be wrapped around a little rim on the flywheel and pulled for hand starting. Never tried it though...
pvb
Well-Known Member
A starter battery for a small diesel weighs next to nothing - even less if you go for the expensive Red Flash option! As long as you keep the weight low, it shouldn't make any difference to the performance of a small yacht.
pvb
Well-Known Member
That's the opposite of the truth! It's cycling which ultimately kills boat batteries. Car batteries, which never really get discharged, last for years and years.
drakes drum
Well-Known Member
It can be very hard. Diesels are much higher compression engines than petrol so even though the small marine ones are small capacity you wont turn one over without a decompressor or the room to use a scaffold pole as a lever.
NormanS
Well-Known Member
The only time that I couldn't start the engine on my present boat, was because the starter motor had died. The fact that I have a huge bank of batteries, was of no benefit.
C
catalac08
Guest
15HP twin cylinder Yanmar, not much in the way of a flywheel on those engines-no chance even when very young and very fit despite having decompressors on and dropping just one cylinder. Stops immediately, even when engine hot! Now my 20HP outboard main donk-no problem at all.
Triassic
Well-Known Member
Oops, maybe that was me that got it the wrong way round then. Told you I'm not an electrical genius! Either way I manage very nicely with just the one battery.
Greenheart
Well-Known Member
I believe it. I'd given serious thought to bigger and bigger petrol/LPG outboards as nice compact, non-obstructive, manually-started lightweight engines with plenty of power...but the gear ratios, short shaft-depth and choice of little propellers, just doesn't seem to suit non-planing hulls, despite their use by small commercial fishing boats.
Don't you get the feeling all that horsepower would deliver power better, if the ratio turned a bigger prop, more slowly?
I'm pretty well sold on the lightweight diesel as the ideal auxiliary for any boat whose hull form can accommodate it. Knowing that the 1GM10 weighs less than me, helps...
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Seajet
...
Dan,
I get the idea you're thinking of stored kinetic energy, rather than a battery to start an engine; there have been so many ideas re starters, from ground auxillary battery units ( ' trolley acc' ) on RAF Spitfires to the incredibly noisy Houchin ground starter units for fast jets, to Auxiliary Power Units - A.P.U.'s - small turbines, to spool up main jet engines;
the characteristic whine then burrr when a Harrier starts up is the APU running then the main Pegasus engine coming to life.
APU's are used on every airliner & most fast jet fighters, - also as main engine on some cruise missiles.
On boats they tried things like the ' Dynastart ', essentially a coiled spring about to release its power to turn over & start the engine, but for now as far as yotties are concerned the electric starter seems best.
However if I was specifying a design involving an inboard diesel I'd specify a Plan B starting system with some sort of decompressor so one could get the thing spinning then drop it so the engine fired, I'd reckon this good for up to say 30 hp engines then the compression when trying to fire might be too great.
I get the idea you're thinking of stored kinetic energy, rather than a battery to start an engine; there have been so many ideas re starters, from ground auxillary battery units ( ' trolley acc' ) on RAF Spitfires to the incredibly noisy Houchin ground starter units for fast jets, to Auxiliary Power Units - A.P.U.'s - small turbines, to spool up main jet engines;
the characteristic whine then burrr when a Harrier starts up is the APU running then the main Pegasus engine coming to life.
APU's are used on every airliner & most fast jet fighters, - also as main engine on some cruise missiles.
On boats they tried things like the ' Dynastart ', essentially a coiled spring about to release its power to turn over & start the engine, but for now as far as yotties are concerned the electric starter seems best.
However if I was specifying a design involving an inboard diesel I'd specify a Plan B starting system with some sort of decompressor so one could get the thing spinning then drop it so the engine fired, I'd reckon this good for up to say 30 hp engines then the compression when trying to fire might be too great.
AngusMcDoon
Well-Known Member
My former X99 had the same engine. It was possible when hot with 2 people (1 to twiddle the decompressor). Never managed it from cold.
pvb
Well-Known Member
The Dynastart wasn't a coiled spring, it was a combined dynamo and electrical starter motor.
Avocet
Well-Known Member
I used to have to hand-start a dumper truck with a very old twin cylinder Lister. This was back when I was a teenager - all testosterone and surplus energy though. The trick was having a stick of just the right length. You'd set both decompressors and wind the handle LIKE MAD. Then, when it was going as fast as possible, You'd have to push the stick with your shoulder BUT KEEP WINDING. The other end of the stick would be wedged against the decompressor for the back cylinder. If you were lucky, it would cough into life and you'd feel it getting easier to turn the starting handle. At this point you knew you could throw the front decompressor and it would be away. Quite a palaver though.
Our BMW D12 has quite a clever arrangement. The starting handle goes in the CAMshaft, rather than the crank, and the cam turns at 1/4 of engine speed, so you get a 4 : 1 speed increase when cranking via the camshaft. The other clever feature is a mechanical timing gear on the decompressor that lets you turn it half a dozen or so times to get the flywheel spinning quickly and then disconnects itself to bring the valves into play automatically. I'm sure it's a system that works very well when it's mounted in a dumper truck or on a cement mixer, but as I can't swing the handle even one revolution in the space of our engine compartment, it's a bit pointless!
Our BMW D12 has quite a clever arrangement. The starting handle goes in the CAMshaft, rather than the crank, and the cam turns at 1/4 of engine speed, so you get a 4 : 1 speed increase when cranking via the camshaft. The other clever feature is a mechanical timing gear on the decompressor that lets you turn it half a dozen or so times to get the flywheel spinning quickly and then disconnects itself to bring the valves into play automatically. I'm sure it's a system that works very well when it's mounted in a dumper truck or on a cement mixer, but as I can't swing the handle even one revolution in the space of our engine compartment, it's a bit pointless!
AngusMcDoon
Well-Known Member
An advantage of outboards is we don't have to worry about this problem. Even my electric start 10hp requires only the cover to be removed and the emergency start cord wrapped round the flywheel. Starts 1st or 2nd pull from cold with little effort. Simples.
AngusMcDoon
Well-Known Member
Camshaft half engine speed surely? It must put some strain on the cam belt/chain/gears as well.
Greenheart
Well-Known Member
Think I remember that, from the scene in The One That Got Away where Hardy gets into a plane and nearly escapes.
Actually I really was only thinking of the weight of the diesel unit as a reason for looking at alternative ways to start one...but the video above showed me how jolly compact they can be, and I believe what PVB said about the smallness of starter-batteries.
I think the awful frequency of questions on this forum which relate to problems with marine diesels, combined with their shocking new price, is a much greater discouragement.
Bit of a thread-drift, but does anybody here have anything to contribute, to banish my trepidation about the unknown? I'll only ever be able to afford an old yacht, most probably with an old diesel. Is their record pretty good compared to outboards (with which I'm more familiar) or are they like pre-1980s British cars...pray as you turn the key?
Egbod
Well-Known Member
A friend has now modified his electrics after we couldn't start the diesel by starter motor (weak battey) or by hand.
We cheated by me turning the engine with decompression, then he operated the starter motor and flipped the decompression levers to get it going.
He has now put an extra switch on the starter motor circuit so that he can start the diesel on his own with a weak battery.
We cheated by me turning the engine with decompression, then he operated the starter motor and flipped the decompression levers to get it going.
He has now put an extra switch on the starter motor circuit so that he can start the diesel on his own with a weak battery.