old heavy"lugger" vs high reving & more hp

[globaldude]

Hi guys, I read various post and just hope that some of you very talented & experienced people can give your opinion as to which way you/they would go .
I have in my posesion [ sp?] a JP4 Lister 40 hp with a hyd- box, it weighs in at 1.5 ton .I brought it because it was cheap, $750, and has one hour on it's meter [ seems lijit given it's history]
I had intended to fit a diesel / electric drive system [ and may still ] but when this engine came up I thought ;
1;It has a great name for reliability

2; even though it's heavy, I could then use less balast - my 50' yacht is designed to have 4.5 ton of lead, so why not less lead [ @ 750 it's cheaper than lead ! ]

3; it would be down low and fairly central .

4; I can forget the more complex issues of the hybrid , therefore getting on the water faster . [ my boat is only a hull & decks at this stage ]

5; I can only spin a 24" prop and the enormous torque of this engine would would seem to be ok , direct drive . [ as would an electric drive ]

BUT BUT BUT, it takes up a lot of room, it's heavy [ can't get the weight as low as lead ] wouldn't be running at peak efficiancy - as would a [ quieter ]gen set to power [ at "cruise"] the electric drive and or charge the batterys/balast.

Thoughts and opinoins please.

[antonfourie]

I would go for a lighter engine and have the weight in the keel where you want it.

[globaldude]

Ah, sorry, I should've made it clear re my boats design.
She only draws 850mm with her centre board up !, and the 4.5 ton lead balast is/was to go in her shallow bilge. The engine would be well down in said bilge [ yes I'm a bit concerned about any water sloshing about in such a shoal bilge, but there shouldn't be any !!]

If it were a deep-ish keel, yes the balast should be as low as possible.
She is flush decked [ lots of boyancy - & room] and I'm going away from the original design in that I'm taking out the centre board [ takes up huge amount of room & makes big boat lots of small rooms ] and fitting twin asemetrical lee boards.

Hey I see you're a pom, what's your opinion about this engine ?
I've had two opinions re the Lister from two pommy mates [ both whom have done extensive sailing and are experienced nautical types ] as to it's reliability !
One says they're the best , the other says they had a problem with leaking injectors [ if they weren't used often - otherwise they're good] and he's personally seen a cylinder head blown off by dribbling injector allowing too much fuel into the combustion chamber .

[longliner45]

fuel in diesle engines explode under pressure about 17lbs per square inch. what fuel that is not burned is returned to the tank. dont see how too much fuel in a cylinder can blow off a head. ,,,would question my source, remember only so much air and fuel will burn,the rest goes back. also are you 100 %sure of the wieght of you engine and tranny? placing a large weight above the keel will defeat the purpose of the keel,remember I am not a designer,,,good luck longliner,

[bilgeboy]

Longliner,

I think Globaldude is more correct on this one. Excess fuel in the cylinder can do alot of expensive damage. You can put pyrometers on the exhaust gas to try to detect overfueling before its a problem, and thats a pretty inexpensive way to avoid this problem.

The returned fuel is a neat little built-in lubrication system for the injector, and never enters the cylinder. Once that happens, there is no going back.


G-dude,

I always say, "a diesel in the hand is worth two in the yacht of dreams". You are going to have so many other problems to occupy your mind, go with the easy solution to this one. Its natural to dream about the best case scenario. In a way, thats what boatdesign.net is all about. But then you've got to build it! I think you should move on to the next step. If it is at all a real issue, your next boat will correct for this and the other 50 things you could have done differently. Think about it while you cruise around in this boat.

Any engine can blow up if neglected. Diesel shops around here test injectors for free, you pay for the work on the bad ones. Pop them out and get them checked out. I think it is far more common to have a black smoke condition WAYYY before you will blow the head up. That's an unrealistic outcome for a neglected engine, and an impossibility for the maintenance hungry do-it-yourselfer that you are.

Mike

[longliner45]

yes you are correct I was wrong,,,,anything can happen to anyone at anytime,anywhere,,,,or is it just me?

[Guillermo]

G-dude
I find it an acceptable option for an internal ballasted boat, probably allowing you to save some hundreds of kilos from the lead ballast (A proper calculation will be needed). If the engine is in good condition, the Lister solution will help you to keep things in a KISS way.
Check the 24" propeller limit before.

[FAST FRED]

These engines are of quite odd design so would not be as efficent as a modern one.

You may get 15hp for each gallon of diesel it eats ,
while a modern aftercooled ,"lectric injection turboed lightweight may get 24hp.

But your Lister will work AFTER the lightning strike , the modern one ?? perhaps not.

FAST FRED

[globaldude]

thanks fred, for making me feel better that is.
I brought the engine from a "mate" of mine and found out a few days ago he'd gone and sold the bloody thing AGAIN to someone else. [ I didn't pick it up strait away - 1.5 ton of it - so he figured I didn't want it !!.
At least he has a concience and when needled he pid me the $1000 extra he got for selling MY engine .
So looks like he's done me a favour . Back to the diesel / electric thinking , love the regeneration aspect - "free" / parasidic energy.

[FAST FRED]

"love the regeneration aspect - "free" / parasidic energy."


You're dreaming of course,

if you use the shaft and prop to run an alternator the prop works as a VERY efficent Speed Brake.


To contemplate the speed reduction, tow a heavy duty pail astern the same diameter as your propellor , and remember the filled pail is "stalled" the turning prop is far more efficent at pulling out power , slowing you down , even in half a gale.

There aint no free lunches, unless your a buro rat feasting at the public troff.

How much does your boat displace in long tonnes?

About 3X that amount makes for a fine cont HP number to look for.

5x the tones disp and you have to be a Yank , and love really big stern waves and big fuel bills.

Why not get a truck engine & marinize it? Or look for a boat running takeout with low time?

FAST FRED

[Guillermo]

...How much does your boat displace in long tonnes?
About 3X that amount makes for a fine cont HP number to look for...
I think 2*Disp is quite enough to run a 'normal' displacement hull even over Fn=1.34 ; betwen 2 and 3 is a trend nowadays, certainly, but not really justified in my opinion for an efficient globetrotter, if that's what we are talking about; and over 3 we have a clear excess of power unless for semi-displacement and planning boats.
By the way, I'm not used to imperial units. I understood we should talk about 'long tons' and not 'long tonnes', as 'tonnes' is metric. Am I right? :confused:

Globaldude:
About the propshaft alternator you may be interested in reading this:
http://www.sailnet.com/collections/gearandmaintenance/index.cfm?articleid=ouread0028
Cheers.

[FAST FRED]

The rule of thumb is broad and any weight chosen (for a ton) between 2000lbs and 2400 lbs will give the same (broad) result.

The modern boat has far higher demands for service than the old sail auxileries, so needs hotel power while the main is on.

Engine driven air cond ,or refrigeration , hyd systems for roll stability , electric cooking & hot water heaters and de salination gear , are just a START! Dont forget the hot tub!

Sure would be an embarasement to loose a Knot every time cookie turns on the range.

FAST FRED

[Guillermo]

..The modern boat has far higher demands for service than the old sail auxileries, so needs hotel power while the main is on...
Well, I may accept an HP/D ratio between 2 and 3 to allow for some hotel power. But if you have to run a big engine when sailing under sail alone, or at anchor, only for hotel reasons, that's not very efficient. To that end is better, in my opinion, the use of an auxiliary.

[FAST FRED]

"To that end is better, in my opinion, the use of an auxiliary."

Even better is a design that does not require a noisemaker (auxilary generator) for anchored service.

Not hard to do , depending on the number of days between main engine operation , for those that can forgoe the Jaccuzi and electric range.


FAST FRED

[globaldude]

thanks Guillermo for the link, I copyied a bit to get a responce from Fast Fred;

Using the instrumentation on Calypso V (boat speed measurable to 1/100 knot) we have never been able to detect any difference in boat speed between having the propshaft alternator “On” or “Off." Remember, however, that the fixed three-blade propeller (22-inch diameter x 19-inch pitch) is freewheeling in any event. Why not capture all that available power?

I was going to ask you Fred, why , and I've heard it said before, do you say that a free wheeling prop induces far more drag ??.
surley the rotating prop is, to more or less degree, corkscrewing through the water and therefore offering less resistance !?.
In other words, the resistance is pushing / rotating the prop and the prop is yeilding to the preasure, thereby offering less resistance -- yes no !?.
If the prop were to turn in time with the water speed, there could be no argument that it was causing resistance [ apart from it's wetted surface ].
So dosen't it follow that the more it turns , the less the drag ?.
I don't know if that's right , it just seems logical to me .

[FAST FRED]

"it just seems logical to me ."
When what seems "logical" is wrong its called counterintuitive.

Any prop freewheeling is presenting the blade surfaces in an unstalled condition for the full diameter of the prop. EG a speedbrake of propellor diameter.

This will absorb far more HP than the stalled prop .

Even with a large 4 blade prop with BIG BAR 71 (Blade Area Ratio of 71%) the stopped & stalled prop willl have less drag as the stalled blades will not absorb the HP .

A fine experiment would be to lock the prop with a pipe wrench and sail at speed in moderate wind conditions (under hull speed), then luff up & knock off the wrench and get back on course. The results may suprise you.

There will be little difference in higher winds where the boat is at hull speed as usually you are producing more power than the hull can stand.

Freewheeling MUST be aproved by the transmission MFG , as many will overheat from lack of pumped oil.

FAST FRED

[globaldude]

Ok fred, so I'm " counterintuative "as well as thick :p [ I like it - LOL ] you quote a 4 blade prop with a blade area of 71% having less drag stalled than freewheeling because ---- what ?, the remaining 29% is "Gaps" the water can freely [ relatively ] flow through !?, as opposed to a turning prop presenting a 360 degree [ 100% ] barrier - reads resistance to the water.
to quote you below, the stalled pail, doesn't it present a 360 degree resistance to the water also ?

"To contemplate the speed reduction, tow a heavy duty pail astern the same diameter as your propellor , and remember the filled pail is "stalled" the turning prop is far more efficent at pulling out power , slowing you down , even in half a gale."

There must be some other dynamic going on here I can't see.:confused:
"absorbing HP" ?,
Prehaps it would help if you explained what a " speed brake" is & how it works .

Give me an argument that explains why the " stalled " 360 degree, pail has less resistance than the yeilding turning prop .
Isn't this all about resistance, and isn't the turning prop yeilding to that same resistance thereby offering less or obsorbing less resistance !?

I also ask myself why the chap, who's log, he claims, is acurate to 1/100th of a knot, would have his prop freewheeling if it induced MORE drag !?.
I 'll try to email him and ask him to test/ confirm our -- opps, my speculations

[marshmat]

The same effect is noticed on twin-engine aircraft that have the engines mounted at opposite ends of the fuselage, rather than on opposite wings.
When one prop is not in use, it must be feathered and braked. If it is left to freewheel, it is operating in an unstalled condition and so is extracting power from the flow over it, creating drag and causing wear to its transmission and mechanicals. If it is braked, it stalls- but at a high stall, it will create less drag than if it's spinning and extracting power. The same principle should apply to boats.

[Guillermo]

...Any prop freewheeling is presenting the blade surfaces in an unstalled condition for the full diameter of the prop....
...This will absorb far more HP than the stalled prop ..FAST FRED

Not so easy, I'm afraid. Let's remember a Larry Zeitling post, I think in these forums:

"To freewheel or not to freewheel has been debated in the sailing community since Ericsson invented the screw propeller. As you say, a two bladed prop that can be locked behind the deadwood offers less drag than one allowed to freewheel but not as low drag as a folding or feathering blade prop. The British journal Yachting World published a series of tests about 20 years ago that compared the drag of freewheeling and fixed three blade props. The experiment was quite ingenious. A boat with a three bladed prop was anchored in a tideway. A spring scale was inserted in the rode. As the tidal flow reached a speed of six knots, the prop was allowed to freewheel and the scale force measured. Then the prop was locked and the force measured again. The process was repeated with several props and several degrees of resistance to rotation as might be provided by a shaft in a stuffing box and turning a transmission. The conclusion was that a freewheeling prop with NO RESISTANCE offered the least drag, followed by a FIXED PROP. The most drag was offered by a SEMI-FREEWHEELING prop rotating about 1/2 to 2/3 the speed of a free spinning prop."

[FAST FRED]

The conclusion was that a freewheeling prop with NO RESISTANCE offered the least drag, followed by a FIXED PROP. The most drag was offered by a SEMI-FREEWHEELING prop rotating about 1/2 to 2/3 the speed of a free spinning prop."

The above is quite correct.
Any boat with a stuffing box will be far from "freewheeling", and the added drag of a shaft alternator places the most drag on the boat.

So ,
"love the regeneration aspect - "free" / parasidic energy."


Is ONLY true at gale conditions where the huge drag of a working prop wont slow the boat at all.

Otherwise DRAG costs SPEED.

But a loss of speed for a box of cold beer might be a worthy trade?

FAST FRED

[Guillermo]

Well, we have the gearbox, shaft bearing and stern gland to induce resistance. If those elements are well conceived, a relatively big propeller may be not so far away from freewheeling. And if the coupled alternator is not a big one, (The idea isn't run a lot of high consume electrical appliances at the same time), just to keep your batteries up, maybe the thing is not so dramatical, as the owner of Calypso V states, and you call allow yourself a couple of 'luxuries' like cold beers when in a long passage. :)

[globaldude]

I'm so glad those Pomme buggers did that test, It was bugging me so much I thought I was going to have to go and do the exact same test. :mad:

The results are conclusive and I'm sure the test boat had a stuffing box [ or a big water pump :eek: ] & most likely a G/B attached to the prop shaft !

We all know for every resistance [ in this case] there is an equal and opposite reststance , the yeilding prop must have less resistance .
The stalled prop allows some "clear" flow through the blades --- very much so on the thin bladed aircraft prop , and the " parasidic " power sapping ,interfering , arse dragging, semi freewheeling prop will give me cold beer, nice music, lots of fresh water and an extended - slower - cruising range .
Of course this is all just dreaming - if I listen to the scoffers who abound - but I take heart in the likes of you lot, who are , or who has " been there & done that" .
I have been a member of an "Inventors trust " for about 6 years here in NZ and like this Forum, find like minded people don't scoff [much] at " different " thinking.
That's not to say we agree with all we hear, and there are many a lively debate as to the pro's & con's of a thingy bob .
I do think Brian Eiland is having a hard time convincing the sailing bods the merits of his " aft mast " , but I like his thinking , albeit unproven .
Pete.

[globaldude]

Update, I got the old lister going today, the original starter motor she came with was stuffed and a new one was quoted at $700, virtually what I paid for the engine Nah !!. I had a similar sized starter so adapted and mounted it on the other side of the engine.
Problem is without the decompresion buttons pulled [ engaged ] the starter "bounces" on the compresion and can't turn her over.
I suspect the same would happen to th original starter also.
By engaging the decom buttons, spining her up & dropping one - two - three etc buttons she fires.
All good !?. Not really, I don't want / expect to be button pushing in the engine room when I'd rather be at the bridge.
So maybe this engine is not suitable -- what say you all ? .

[FAST FRED]

Probably the starter is weak.

Plan B a solenoid to push the button as needed.

FAST FRED

[ron17571]

I really like the lister,the ones i read about with the big flywheels were cranked over by hand,i imagine with the compression release thrown on to make it catch and start.Seems like a fuel sipping diesel,as an auxilary it sounds great,im not sure how to use it as a main engine,unless hooked up to a gen.to make electric for some sorta hybrid setup.try a search engine for info.

[globaldude]

Having started and run the lister - well - I know it would " see me out" the bloody thing is built like a tank !!. Annd welllll , that's part of my problem with it actually.
She does run well, but it's not what you call a balanced engine - to be fair, there's a lot of weight spinning around in her guts and well like I said, having heard her running ---- I've decided to sell her !

I have two Kubota 3 cyl 667cc diesel engines that I couldn't resist buying while on a trip to Japan years ago.I'd never started them.
I dragged them out from under a bench, put oil in them, hooked up an IV [diesel] and threw 24v at the 12v starter to give it a good spin ------ splutter varoom , instant start !!. But oh so smooth !!! , and quiet .and all at probably 1 - 1.5 liters per hour.
So, back to the electric motor / alternator main engine, with the twin Kubota's either side running 15kva alternators.
I will have , in effect, 4 propultion means. Sail , electric, & two small diesel emergency engines that can be coupled to the drive shaft if needs be.
I have a controlable pitch prop so would be able to dial up a fine pitch to enable the small diesel/s to get me "home".
I'll try to post a pic of the electric engine. The vert axis tower is one my friend builds and the alternator [ reads soon to become my engine ] is driven from this beast. Oh and it just glides silently - the turbine - unlike the noisey wind mill types.

[globaldude]

I forgot to say, we're planning to have two 48v banks [ coupled to 96v for engine] with around 3000ah of reserve. They will be AGM batterys set low as possible in the bilge - around 2.5 ton . All house power will be 240v, std here in NZ = cheap fittings and tools appliances same as [ real ] house.

Hey BILGE BOY, thinking about the "excess fuel" in the combustion chamber [ old post] I think it's entirely possible with the Lister because it's possible to crank it over at full throttle [ puting lots of fuel in the chambers] with the decompresion buttons engaged [ without realising ] and therefore no compression to fire.
when disengaged there's a lot of fuel to go bang !!. --- No, I didn't, but I could imagine it being done !!