Single Prop with Optional Tandem/Paired Diesel using Wing Engine

[Bahama]

I want to take the time here to thank everyone for all the smart information that I do find and for the very knowledgeable suggestions that I've received.

I want the ability to eventually circumnavigate and so I want to design for maximum distance with the propulsion; and so that means keeping the diesel engine size down to a moderate size. I'm fine with that unless, for emergency reasons I want to go fast.

What are good design choices that allow me to have a moderate main engine, and optionally join my wing engine that I use for generating electricity use as a get-home engine as an emergency backup, and to offer go-fast reserve power for emergencies?

For example, I'm going to build a cutter cruiser that has a LOA 48’; Beam: 14’ 2-5/8” LWL 41’; Draft 6’2”; Displacement 21 Tons. I ordered the Orca plans from Ted Brewer and plan to stretch her 3 feet and add 4 inches to her beam (http://www.tedbrewer.com/sail_steel/orca.htm).

I'd like to get your opinions as to sizing the main and wing engines; I want a modest sized diesel motor that will work well for me and yet give me maximum range, and enough electricity to run the AC if I want and all the toys; I do plan to have a decent sized array of batteries. So any suggestions regarding the size for the wing engine and how to tie best tie them together is greatly appreciated. Thanks.

One suggestion that I read somewhere else was to use both motors to generate electricity and then power the single prop using an electric motor.

I also read that 3 to 4 Braking Horse Power per Ton is adequite, 5 is ample, and 6 is a bit too much. Given that, what if I had a 3 B.H.P./Ton size and a 5 B.H.P./Ton? The 3x size would be used for blue water and the 5x for all else. Either could be used to generate the batteries, although the 3x would be the best for that. For emergencies this provides near 8x to get moving if you really needed to.

Thanks for any recommendations.

[apex1]

Why for goodness sake are you trying to complicate EVERY single aspect on your project?

You are (as too many others here) on a perfect way to end up with no boat at all. Or worst with a never ending catastrophe.

What you have in mind is just not sensible, it is a "Oviparouswoolmilkpig".

Do NOT go for a small Diesel and run another one (or two) systems for emergency or El. requirements.

Install a beefy, proven, derated Diesel in the upper ballpark of your maximum demand and run a CPP.

Have a 150 or even 250 amps alternator coupled, and a proper sized batterybank / inverter- charger- power management.
That will take you round the world as long as you live and at the lowest (lifetime) cost possible.

Look here and download the whitepaper: "achieving the impossible"
http://www.victronenergy.com/support-and-downloads/white-papers/

If in doubt, book a flight to Tahiti and have a look at the real circumnavigators setups! No wing engines, no wind generators (there is no wind where you anchor at night), no additional gimmicks. And usually ONE PV panel to keep the starter battery up on level.

The fear of being out at sea with a broken engine is unreal. (as is the idea of the unsinkable boat)
Choose the right one and be fine.

Richard

[Easy Rider]

Consider diesel-electric. Two engines but either one can drive both props independently or both engines for full power. This is an over the counter thing using bus components but I don't know if anything is available for smaller units.
With an efficient hull like you plan one can actually go at very slow speeds and there are many other advantages.

Easy Rider

[mark775]

Please listen to Richard's advice. He comes off gruff (probably a tad impatient because this comes up often) but he knows what he is talking about.
IMO, diesel-electric doesn't work here. "With an efficient hull like you plan one can actually go at very slow speeds and there are many other advantages" Keep it simple. You don't need too much power to attain hull speed.

[Bahama]

Please listen to Richard's advice. He comes off gruff (probably a tad impatient because this comes up often) but he knows what he is talking about.
IMO, diesel-electric doesn't work here. "With an efficient hull like you plan one can actually go at very slow speeds and there are many other advantages" Keep it simple. You don't need too much power to attain hull speed.

What I'm curious about is how to decide on the proper power. As I've been reading I see many different formulas; and I need power for the generation of electricity, because I will have AC on this, and if I choose to turn it on at night, I want the option.

Also, what the best CPP power inverter setup (as Richard suggests).

What motors should I consider? I was looking at a Detroit Diesel 4-71, which seems very hardy and would last forever for me. From what I read it had the benefits of the legendary 6-71, but toned down for less power while still maintaining the hardy construction. I also looked at the Volvo’s, but they are certainly more pricey than the DD’s. I hear that the Detroit Diesels will cost less to maintain and more mechanics know the DD than a Volvo. I want a beefy block that will last forever and I want to run her at far less than what she’s capable of, again, so that she’s not strained and will last a long, long time. Perhaps toning down the 6-71? I just need some help determineing the right engine.

[Easy Rider]

Mark,
Most boats at slow speed need to go in and out of gear constantly to go 1 or 2 knots as most boats go several knots at idle. No problem w DE. Go as slow as you like.

Easy

[mark775]

I was just thinking of efficiency losses and expense, Easy. I get yelled at in the harbor until the Harbor Master gets sick of yelling - I could slip to whatever RPM I want but I don't tell him! (I just throw a perceived wake at three knots!)
Bahama, there are certainly better people than I to say what horsepower. This I do know - there is always talk of glazing cylinder walls and carboning up and such from running too cool/ not enuf load. It is my experience that as long as you are not at idle, and under some load, that is not a factor - so go with a bit more HP. In the US and probably EU, there is no such thing as carbon (to speak of) any more. As much as I respect the old diesels, parts are going to be harder to find and the new stuff is wonderful! I know that the good Detroit mechanics are going to be dying as time goes on and there will be fewer that can make a Jimmy run well. Richard's knowledgable about CPP and can get you pointed to a good dealer. It is a trade-off in cost in the short-term. No reduction/reverse gear but add the cost of CP.

[apex1]

No Easy, sorry.

DE is not the way to go (except you don´t mind cost and expenses).

The house load is much too low on a yacht to make that sensible. (cruiseships are a bit different)

In a yacht of the mentioned size and use, I would go for the smaller 6cyl. engines in the 6 liter ballpark. Deere or Deutz for example. They come in M1 ratings around 120 hp @1800 rpm (or can be derated to that figure).
Coupled with a Hundested, Westmekan, or Helseth CPP you have a fuel sipping setup which does not bother you under sail and under motor.
Though some 40hp are sure enough to get up to hull speed in dead calm water (it should need less), you are in need of another 40hp pretty often. The last 40 you should wish to never being in need, but it is more likely than not that there comes a day when they get you out of the way of a weather front. (when you are really on passages)

The El. requirement should be handled by a large alternator (or two) of high quality (Zena), a good quality battery bank (Surette, Trojan), and a highest quality inverter / charger / batt. manager. (Victronenergy)

One does not need a AC generator on a boat of that size, as long as there is no air cond. running. But if air cond. is a must, install a DC genny instead (you will have the extra money for a DC genset, when you are able and willing to install aircond.!). The controller unit you have already on board, the Victron!

Go through the whitepapers as I recommended, and have a look at the CPP thread here (although the latter was much spoilt by some stubborn jackasses, it is worth reading).
http://www.boatdesign.net/forums/props/controllable-pitch-propeller-summary-30695.html

Regards
Richard

[Bahama]

No Easy, sorry.

...In a yacht of the mentioned size and use, I would go for the smaller 6cyl. engines in the 6 liter ballpark. Deere or Deutz for example. They come in M1 ratings around 120 hp @1800 rpm (or can be derated to that figure).
Coupled with a Hundested, Westmekan, or Helseth CPP you have a fuel sipping setup which does not bother you under sail and under motor.

...The El. requirement should be handled by a large alternator (or two) of high quality (Zena), a good quality battery bank (Surette, Trojan), and a highest quality inverter / charger / batt. manager. (Victronenergy)

...Go through the whitepapers as I recommended, and have a look at the CPP thread here (although the latter was much spoilt by some stubborn jackasses, it is worth reading).
http://www.boatdesign.net/forums/props/controllable-pitch-propeller-summary-30695.html

>>The fear of being out at sea with a broken engine is unreal. (as is the idea of the unsinkable boat)<<

I wanted to comment on this from a previous post; I'm just trying to examine all angles of a problem and come up with what is a good idea. Although I ask out of the box questions, it's typically to examine all avenues to see if there is any merit to the idea. I don't just go with complex for fun, it's merely that I'm willing to look at simple and complex to see what is best. Simple is alway preferred if possible (less things to go wrong), but it's good to look at a wide view of things... and to learn. I don't have a fear of a broken boat (although it's always a remote possibility), I was really trying to come up with an economy engine that would sip fuel, yet also have some extra ponies on reserve to haul butt away from a storm if needed-a wing engine seemed like a nice possiblity.

I'll look at the papers (links) that you mention, thanks for the recommend.

[Marco1]

Install a beefy, proven, derated Diesel in the upper ballpark of your maximum demand and run a CPP.

Have a 150 or even 250 amps alternator coupled, and a proper sized batterybank / inverter- charger- power management.
That will take you round the world as long as you live and at the lowest (lifetime) cost possible. .......
Richard

Agreed 100%.
My choice of engine
If money for new engine: John Deere
If you are after a second hand: A factory rebuilt Gardner all polished and chromed.

If you want to exercise your inventive juices, I would use them into developing a good filtering and polishing fuel system.
For example. Two holing tanks with a centrifuge between them to eliminate water and rubbish you are bound to pick up when refueling. Plus. A day tank hooked up to a polishing system to keep a small amount for the day (or the week) perfectly clean and with no sediments at all.

[apex1]

I'm just trying to examine all angles of a problem and come up with what is a good idea.

That is your right! And no one here has a problem with that.

Although I ask out of the box questions, it's typically to examine all avenues to see if there is any merit to the idea.

"out of the box" means more often than not, that just the one who asked the question is "out of the box", the Industry has usually coped with that question already some twenty years ago, and did not stop to watch any further development!


I don't just go with complex for fun, Thats the right approach. Whats not there does not break.

it's merely that I'm willing to look at simple and complex to see what is best.

Oh, we understood that in general, before you came up with scaling vessels, adding complex and unproven systems, and asking for advice how that might go together.

Simple is alway preferred if possible

Well, you are miles away from that thinking, do you realize that?

(less things to go wrong), but it's good to look at a wide view of things... and to learn. I don't have a fear of a broken boat (although it's always a remote possibility), I was really trying to come up with an economy engine that would sip fuel, yet also have some extra ponies on reserve to haul butt away from a storm if needed-a wing engine seemed like a nice possiblity.

Yes, it seems to be. But at the second glimpse (or after 200.000 miles at sea), one can change his opinion due to better understanding. And we all have changed our opinions a several times during life, thats how it goes.

I'll look at the papers (links) that you mention, thanks for the recommend.

Do not get me wrong,

I am not hammering on your (a bit stubborn) attempt, to reinvent the wheel, I just want to tell you, that is ALL already handled here on the Forum, and we came always to the same conclusion:

Proven systems, simple systems, all the beef you can find in any item, and the ability to say: "I do not really need that", makes happy years on a passage.
Any MUST is probably as deadly as a fixed schedule on the open ocean.

Go ahead, and do not mind when we kick your ass sometimes, I do never mean it insulting, just to get your feet back on the ground.
You only have one life, why wasting it in inventing new methods, systems, rules or scantlings?
We know how we bring our industry further, we are aware of all the possibilities to take advantage over a competitor. Unfortunately they are as well aware.
Read:
If you do not find it at least in some noticeable figures, you can be sure it has no merits. (do not make the mistake to count the other way round! 80% of the boats in any marina worldwide are crap)

So, go ahead with your ideas, and be prepared to find no assistance, no applause, no advice on them. It is not meant to belittle you, but might save you some time, much money, and maybe, one day.... your ass.

Regards
richard

[Bahama]

If you want to exercise your inventive juices, I would use them into developing a good filtering and polishing fuel system.
For example. Two holing tanks with a centrifuge between them to eliminate water and rubbish you are bound to pick up when refueling. Plus. A day tank hooked up to a polishing system to keep a small amount for the day (or the week) perfectly clean and with no sediments at all.

I laughed when I saw your note because I was logging on to ask this very question! I just got done reading about all the bio bugs in fuel and how they are caused from water that may be in the fuel as it's pumped in and from condensation in the tanks as the lay around mostly empty.

When I read that it made sense to me that you'd want some kind of a small filling tank to act like a huge glass bulb and then provide a filtration system on the output; then this would feed into the main tanks.

Then to keep the water out of the tanks, just have an fuel intake placed at the end of a floatation device and skim the top layer of fuel into a filter and water separator device; the pump is turned on automatically for awhile every morning when the sun first rises and then 12-hours later (this is an easy clock device to make). So twice a day it runs for a few minutes to clean the fuel and remove any water, simply from skimming.

I read these micro organisms need air at first to get started... why not flood the tank with Nitrogen? That's what is done to preserve wine in a wine bottle after it's been corked. The Nitrogen is heavy and lays on the surface of the wine (or fuel in this case).

Also, related to fuel, I was wondering if anyone has ever channeled a water pipe into the fuel to heat it up when the water becomes cold. I would have the input and output of the pipe run from the top of the tank and then just run the pipe around the inside a bit to provide good heat exchange. Then I would pump clean water through this pipe and a heat exchanger that was hooked up to the output water cooler from my engine. The heat from the engine would heat up the fuel, but not heat it up too much. A temperature sensor could determine the temperature of the fuel and determine if the pump should start to flow, if so, then it would simply pump when the engine is running until the fuel temperature rose above the minimum temperature threshold. This type of system would use less electricity to heat up the fuel; pumping hot water is certainly less energy than what it would take to heat up the fuel using some form of electric coil.

And lastly on this subject, I've searched around and not found anything so far where magnetic fields are used to determine fuel level. It's not hard to create your own device that measures fuel level safely 100% outside the tank--no holes to drill, no electricity in the fuel (very nice for gas because it's spark free). It can work through any material, even steel. You're just measuring the change in magnetic field between the top and bottom of the tank--the presence of fuel changes the magnetic field because it has different magnetic efficiencies than the dead air space.

Ok, the last last thing... reserve fuel tank... any great ideas for this? The best I can think of is make sure that it's continually fed fresh clean fuel; and so I imagine it being a small separate tank where the cleaned filtered fuel is fed into (from my auto filter comment) and the top part of the tank feeds into the other tanks-so it acts like a reserve that is constantly fed and can only be drained dry by opening a separate fuel line into it.

[apex1]

Bahama,

you have a really impressive addiction to make even the simplest systems overly complicated.



When I read that it made sense to me that you'd want some kind of a small filling tank to act like a huge glass bulb and then provide a filtration system on the output; then this would feed into the main tanks.

That would make bunkering a whole weekends chore.

....... to clean the fuel and remove any water, simply from skimming.

No, does not function.

I read these micro organisms need air at first to get started... why not flood the tank with Nitrogen?

Think again!

Also, related to fuel, I was wondering if anyone has ever channeled a water pipe into the fuel to heat it up when the water becomes cold.

Why would you heat your fuel? Even in Arctic waters it is not needed. As long as your Sampan floats on water you are above the temp level where Diesel flocks paraffin out. Your day tank btw. is heated automatically by the return pipe.


Ok, the last last thing... reserve fuel tank... any great ideas for this?

Your day tank is the reserve tank. The fuel in there is the cleanest you can get because much of it ran through the engine already.

A proper fuel polishing system is mandatory on every passagemaking vessel which relies on Diesel propulsion.
When you can afford it, have a centrifugal separator prior to the filters (plural) polishing the fuel before it enters the day tank. If these 5000 to 10000$ are too much, have at least two static separator filters installed.

The optimal setup would look like:

Main tanks- separator- filters- day tank- fine filters- engine intake- return pipe- day tank.

With such a setup you don´t have bio growth or water in your fuel.

It is not only the water and oxygen you could see with your eyes what you have to address, there is as much or more in solution in the fuel. That you have to get rid of.
On larger motoryachts we run dry one of the tanks (usually there are 5 or more), then use that one as a reservoir to polish the fuel from one tank into the other. Quite often you can hear the separator running even in port for exactly that reason.

Regards
Richard

[apex1]

Bahama,

you have a really impressive addiction to make even the simplest systems overly complicated.



When I read that it made sense to me that you'd want some kind of a small filling tank to act like a huge glass bulb and then provide a filtration system on the output; then this would feed into the main tanks.

That would make bunkering a whole weekends chore.

....... to clean the fuel and remove any water, simply from skimming.

No, does not function.

I read these micro organisms need air at first to get started... why not flood the tank with Nitrogen?

Think again!

Also, related to fuel, I was wondering if anyone has ever channeled a water pipe into the fuel to heat it up when the water becomes cold.

Why would you heat your fuel? Even in Arctic waters it is not needed. As long as your Sampan floats on water you are above the temp level where Diesel flocks paraffin out. Your day tank btw. is heated automatically by the return pipe.


Ok, the last last thing... reserve fuel tank... any great ideas for this?

Your day tank is the reserve tank. The fuel in there is the cleanest you can get because much of it ran through the engine already.

A proper fuel polishing system is mandatory on every passagemaking vessel which relies on Diesel propulsion.
When you can afford it, have a centrifugal separator prior to the filters (plural) polishing the fuel before it enters the day tank. If these 5000 to 10000$ are too much, have at least two static separator filters installed.

The optimal setup would look like:

Main tanks- separator- filters- day tank- fine filters- engine intake- return pipe- day tank.

With such a setup you don´t have bio growth or water in your fuel.

It is not only the water and oxygen you could see with your eyes what you have to address, there is as much or more in solution in the fuel. That you have to get rid of.
On larger motoryachts we run dry one of the tanks (usually there are 5 or more), then use that one as a reservoir to polish the fuel from one tank into the other. Quite often you can hear the separator running even in port for exactly that reason.

Regards
Richard

[FAST FRED]

I would build such a vessel (desire for two propulsion engines and a need for an efficient generator) very differently.

2 ways,

The prime engine would be your favorite engine that can produce 50 -60 hp at 1500 , or the lowest rpm the mfg will allow. The prop would be a oversize cruising prop that was efficient at 1500 and would allow 1800 with out overload,.The main engine would have a hyd pump, probably a hyd start too.

The genset would be a hyd package .

The house loads for electric would be a hyd power pack ($1800 6KW) that could run off either main or genset power.

The shaft would have a chained Hyd motor to use sometime either when the main fails or if you get really hungry for range and prefer to go slower and simply run on the genset.Both together should allow the main to reach 2100 on the oversized prop if FLANK speed is needed to escape Krackatoa, or the Tax Man.

Advantage is that the vessel will either be at anchor (95%) or in a slip 5%.

The genset at high speed would make enough power for a hyd windlass or a bow thruster , while the ideling main would get your slow motion under control.

Depending on the size of the freezer eutetic plates , and weather a huge $$$ Universal AC converter is aboard would decide if the fridge/ freezer ran on Hyd or AC voltages. Ditto for air cond.

Second way is an LST tranny , two engines on a BIG common shaft , either or both can be run together.

A 2-71 for genset and or long range efficiency and the trusty old 6-71 for throwing 7 ft wakes (or the 4-71 for 5 ft wakes).

All use SAE #1 sized bell housings so whatever you decide is bolt on.

"A proper fuel polishing system is mandatory on every passage making vessel which relies on Diesel propulsion.
When you can afford it, have a centrifugal separator prior to the filters (plural) polishing the fuel before it enters the day tank. If these 5000 to 10000$ are too much, have at least two static separator filters installed."

Quite true for most stock boat tanks , but a proper (bailing sump) tank has little need for anything but the std twin primaries and one engine secondary.

Even if you get 10% water in the "fuel", its free and simple to cure , just some time and effort.


FF

[Bahama]

Thanks for all of the details; I've never seen a diesel setup (obviously from my writing). I just read about them for the first time last night and what was described as the problem was air and water giving what the organism need to start growing, so I just figured skimming would work. I read what you wrote and it seems very practical. I'd be very interested to see how the water gets removed and also this centrifugal force strainer... My first mental picture of it would be a cylinder strainer spins (possibly with some small fins to create a current, like a blender) and the good fuel get sucked out of the center where it would be cleanest; but I'll try to find a picture.

As I read all that I can about boating in pursuit of my dream, my head gets filled with thoughts about the design; especially since I tend to read late at night.

Last night I imagined an automatic stabilizer with ballast tanks at each end of the boat fore and aft, and a long pipe connecting them; the water was only allowed to transfer downhill when the peak angle was reached and it started moving the other way; and then it was locked when the water stopped flowing in the downward direction.

I also pictured a series of water turbines being used in the pipe to collect the energy from the flow back and forth.

I'm not sure if it would work or not, but it popped into my head.

[Bahama]

...Install a beefy, proven, derated Diesel in the upper ballpark of your maximum demand and run a CPP.


I calculated 84 HP as ideal and 126 HP as my targeted high end rating.

I want to get a larger engine and depower it. Would it be reasonable to look at engines that are around 140 to 168 (2x84) HP and depower it to my target 126 HP?

Continuous Duty NEW engines that I found in this HP range are:

MITSUBISHI
6D16-NA (129HP)
6D24-NA (169HP)
6D16-T 165HP)

DEUTZ
BF6L913 (131HP)
TD914L6M (131HP)
BF6L914 (151HP)
BF4M1013MC (156HP)
BF6L913C (156HP)
TCD914L6M (156HP)
BF6M1013M (163HP)
BF6L914C (166HP)

VOLVO
D5A-T (119HP)
D7A-TA (174HP)

JOHN DEERE
6068TFM75 (158HP)

LUGGER
L1066T (135HP)
L1066A (185HP)

BAUDOUIN
4-S108-S (128HP)
6-S108 (128HP)
4-S108-SR (148HP)

I'll keep reading about them. I'm not familiar with Lugger and
Baudouin, but certainly know the others.

[apex1]

The Luggers are based on Deere, the Baudouin´s and Volvo´s I would not install, the rest is ok.
As I said, 6cyl. 6 liter displ. and about 120 horses @ 1800 rpm, thats my recommendation for such boat.
Leave the old DD animals where they belong........in Freds boat.

I refuse to comment on your trim tank idea.........

Fred,

what has your tank system to do with a fuel polishing system?
Right, nothing.

When you next time bunker half and half* in Mexico or Spain you will understand me immediately.

Regards
Richard
* half water, half fuel.

[FAST FRED]

"I want to get a larger engine and depower it."

Poor idea , the higher loaded engine (diesel) will live longer with better fuel efficiency than a de rated lightly loaded diesel. Great idea for a car gas engine tho.

At 24/7 cruising "full" speed 80% of an industrial engines rated power at 90% rated load seems best.

Try for a prop that will load the engine at Least 60% at Long range cruise rpm..

The fuel consumption at full speed will be at least double the LRC fuel consumption , but you may be 1 1 1/2K faster.

Dual engines on one shaft will change the "ideal"prop dimensions.

"what has your tank system to do with a fuel polishing system?
Right, nothing."


The question to me is how do we keep ALL the water + crud out of a tank , and feed clean diesel to the engine.

Crud growing in a tank with some water in it can be cleaned with piles of big of big bucks of filters , polishing and transfer pumps and pails of chemical$.

Sure it works

, but for a cruiser the gear necessary , the power required and of course the pipeing and valving ,spares , pumps , filters that must be changed and discarded (properly?) and a book of valve settings and procedures just are silly ,

when a better tank design , that costs maybe $100 more to build (one time) solves ALL the problem , CLEAN FUEL,with only some expense of labor .

Everyone chooses to cruse in the way they feel most comfortable with , a small ,on board refinery just doesn't thrill me.

Removing a deck plate , pulling a custom fill pipe setup and dumping any water found is less effort and has no power or spares requirements.

FF

[Easy Rider]

Try for a prop that will load the engine at Least 60% at Long range cruise rpm.

Yes and that means you'll be burning 60% of MAX fuel burn.

Easy Rider

[apex1]

"I want to get a larger engine and depower it."

Poor idea , the higher loaded engine (diesel) will live longer with better fuel efficiency than a de rated lightly loaded diesel. Great idea for a car gas engine tho.

That is just not right!
Always, the beefy, derated engine will live longer. That is even better (and highly recommended) when the engine runs under sufficient load, of course.
And here we are again at the CPP.

Try for a prop that will load the engine at Least 60% at Long range cruise rpm..

Yes:
http://www.boatdesign.net/forums/props/controllable-pitch-propeller-summary-30695.html


.............

The question to me is how do we keep ALL the water + crud out of a tank , and feed clean diesel to the engine.

Crud growing in a tank with some water in it can be cleaned with piles of big of big bucks of filters , polishing and transfer pumps and pails of chemical$.

Sure it works

, but for a cruiser the gear necessary , the power required and of course the pipeing and valving ,spares , pumps , filters that must be changed and discarded (properly?) and a book of valve settings and procedures just are silly ,

when a better tank design , that costs maybe $100 more to build (one time) solves ALL the problem , CLEAN FUEL,with only some expense of labor .

Everyone chooses to cruse in the way they feel most comfortable with , a small ,on board refinery just doesn't thrill me.

Removing a deck plate , pulling a custom fill pipe setup and dumping any water found is less effort and has no power or spares requirements.

FF

I understand what you have in mind when you are talking tank setup.
Unfortunately life is not so.
You just don´t manage to bunker clean fuel in every port on a passage. And there is no way to get the water, biogrowth, rustflakes and mud out of your tanks by just running a additional filter. (I am referring to the sh!t you got in by the bunker station)

Sufficient separator / filter size and surface are mandatory. That must not be a centrifugal sep. of course (and I did not say it must), but it must be much more than the average filter installation.

Regards
Richard

[david@boatsmith]

Just for grins, I have worked in the past on landing crafts that had 4 671s mated up to 2 transmisions. For what it's worth my work involved putting in new stern tubes and foundations for 2 new single diesels.

[BTPost]

There seems to be some confusion over how 4 Stroke Diesel Fueled Engines react to differing Loads. Once the Engine comes up to Operating Temp, it really doesn't matter to the engine, how much higher loading, is applied, up until Max Rated Load is achieved. Operating Temp should be maintained by a correctly designed Thermostat & Cooling System, that will allow the engine to operate from some minimal load (5-10%) clear up to 100% of Rated Load, without having any effects on the engines operation. If the engine operates below Operating Temp, then yes there are consequences, but once Operating Temp is obtained, then it is the Cooling Systems job to maintain that Operating Temp no matter what load is placed on the engine, right up to Max Rated Load. Many boat designers do not really look at this area when deciding on a Engine Package for a specific vessel installation, and this, clearly,a Design Function that needs to be accounted for.

[apex1]

There seems to be some confusion over how 4 Stroke Diesel Fueled Engines react to differing Loads. .......

Unfortunately that is not the entire truth.

Loading a Diesel to at least 60% is a must for a service life according (or exceeding) designed hrs. BTO. A CPP does provide that.

Fuel in oil, carbon build up (yes, even on common rail and fully electronic controlled trains), not free burned valves, set bearings! (who did assume that?), and so on and on.

The theories are looking so nice........

Live a year out at sea on a fishing trawler in the northern Hemisphere.

Reality is so darn ruthless........

... and when you would whish to have the salesman right besides you, most probably he will enjoy a nice day while you fear for your life.

Designed engine displacement X 2, designed hp X 1.5, designed rpm X 0.6 and you may get close to a reliable passagemaker propulsion.

A real engine for circumnavigating starts at 25 liter displacement (better 60), is always a straight six, and can run on one single cyl. for years without probs.

Unfortunately that is not a setup our friend could accommodate, so leave it as it is. His choices have been right.

Regards
Richard

ahh, when you are back from next circumnav, let us know your renovated opinions.....

[FAST FRED]

Unfortuniatly a diesel engine requires sufficient combustion pressure while operating to survive.

Simply getting the engine to normal operating temperature does ZERO to get the fuel performance or service life the engine is capible of.

The firing gas pressure goes behind the compression ring causing a good seal. Lower the compression pressure (load) looses this seal, causing the cylinders to be burnished , loosing the hone scratches that hold the lube oil for the piston.

Blowby , oil dilution requiring more oil changes

slobbering , oil burning , and high fuel use for little power.

Nigel Calder had a series of articles in PBB that showed with lower loads gensets ( constant speed diesels) used 200% to 300% More fuel per hp produced at light loads.

Not much fun for a cruising boat,attempting LRC.

National Fisherman had a great series on Underloading a few years back.A very expensive hassle for the fish guys
600hp trawling, 55hp running hyd stuff retrieving , costs a bunch of engine life.

Ditto for gen sets , they MUST use a day and a far smaller night loads unit.

FF

[Bahama]

I was reading more about the CPP and it seems like it works quite nicely with making any system efficient. I did find an interesting article that also touted it's efficiency with an diesel-electric setup that you may find interesting... the author obviously favors the Diesel-Electric with the CPP over a direct-drive Diesel-CPP system.

http://nauticpal.com/content/diesel-electric-propulsion-how-efficient-it-compared-conventional-direct-driven-propulsion-s

I talked to the NA about engine size and he recommend going down lower to save on weight; he felt that going beyond 90 HP is not going to do much of anything beyond costing fuel, which I think we were all in agreement with--I don't think I agree with his assessment that it won't go "any faster"... I think more accurately you'd say that the costs in fuel per extra knot goes up astronomically beyond 90. I could double my HP and maybe only get 1 or 2 more knots (or whatever the calculations end up being). So, where this is heading based on the info from him I think is that going beyond 90 offers very little extra for me, so I have to decide is my target HP engine going to be: 90, or a range between 90-100, or 90 to 110 or 120? Anything beyond 90 seems to be a decision of how much "emergency" room do I want to escape a storm at 9 or 10 knots rather than 8 knots.

Litterally hundreds of tiny little decisions in boat building... fun and mind boggling at the same time.

[Bahama]

I refuse to comment on your trim tank idea.......

You're a good man Richard, you crack me up with your threads sometimes. I did get this idea to noticably work while testing it out in a canoe, but I don't think that the water would scale well because I'd rather have the space for something else useful--this was only pondered while thinking of how to smooth out rough seas, not for everyday travel.

I did consider the idea of temporary bags mounted on deck for the same purpose, which would work, but it's above the waterline and that's not desirable in rough seas.

So that led me to the idea of sea anchors on each end with heavy ballast placed at the bottom of each one to keep them pointed down in rough seas. The sea anchors would be designed to open up like a parachute on the upswing, but glide effortlessly on the down swing. Lead ballast weight in the bottom of the sea anchors would keep it pointed downward. The lines of a 50' boat would probably need to be 25' (tangle free) to maybe 30 to 35' (low risk of tangle). Now that's a lot more simple and safer... but I got there to that idea while thinking of water bags on a deck... just part of the creative process.

So, take a swing or two at that idea. I think what is key is keeping the sea anchor pointed down, and so that would mean FAR more weight than a traditional sea anchor that is normally horizontal, not vertical.

What this idea has going for it is simplicity and leverage. Because it's placed on each end of the boat you have huge leverage on your side and that reduces the diameter required for the anchor.

A design like this would need some kind of a safety release hitch mechanism that would release the entire anchor from pulling hard on a line that leads to it, that way, if it's causing problems during a real crazy storm (I don't think that it would), then the captain can just release it from the Pilot House or helm with the hard pull on the hitch release line.

I like this idea as well because it's not heavy, it's just using drag friction to our advantage when we want it.

Even having one of these devices would smooth things out a bit--I think the bow would have the most impact if you installed just one.

[FAST FRED]

If you really want efficiency you need to set the boat up for Long Range Cruise LRC.

Take the square rt of the LWL and multiply it be between .9 and 1.15 . the higher number if the boat is at the slimmer lighter end of "normal", the slower if its a fat heavy boat.

That will give your LRC cruise speed , there you should only need about 2 hp for each ton (2240lbs) of boat in the water.

IF whatever that HP required number is is over 60% of the engines realistic rated output , GREAT.

Hopefully its at a nice low RPM to load the engine better and reduce on board noise.

Next question is prop efficiency , almost always its impossible to go too large a prop diameter , as a large 2 blade is even better , nore efficient than a 3 blade at putting HP (now called thrust) into the water.

Dave Gerr Prop book will give all the rules to get started.

FF

[Bahama]

If you really want efficiency you need to set the boat up for Long Range Cruise LRC.

Take the square rt of the LWL and multiply it be between .9 and 1.15 . the higher number if the boat is at the slimmer lighter end of "normal", the slower if its a fat heavy boat.

That will give your LRC cruise speed , there you should only need about 2 hp for each ton (2240lbs) of boat in the water.

IF whatever that HP required number is is over 60% of the engines realistic rated output , GREAT.

Hopefully its at a nice low RPM to load the engine better and reduce on board noise.

Next question is prop efficiency , almost always its impossible to go too large a prop diameter , as a large 2 blade is even better , nore efficient than a 3 blade at putting HP (now called thrust) into the water.

Dave Gerr Prop book will give all the rules to get started.

FF

Thanks Fred--

The LWL will be 41' 10-3/4" (41.89583333')
Square Root of that is: 6.472699076
x0.9 = 5.825429169
x1.15 =7.443603938

42000 Lbs. / 2240 x 2 = 37.4 HP

37.4 / 0.6 = 62.5 HP

So if I'm understanding what you wrote correctly; the most fuel efficient HP would be 37.4 HP; however, we have wind and currents to fight at times, and so giving myself the 40% extra for that will give me an optimal engine for fuel economy at 62.5 HP.

Correct?

So going beyond 62.5 HP is costing me extra fuel because I'm no longer at optimum.

If I were to compare apples to apples from the many rules of thumb that I'm reading, I'd break them down to this:

1 HP / 1120 Lbs. is optimal fuel efficiency in calm weather

1 HP / 672 Lbs. is 60% of optimal, giving the diesel motor some extra power for harder weather conditions

1 HP / 550 Lbs. seems to be the minimum power needed for what is deemed to be a "seaworthy" vessel capable of getting you off a lee shore in a gale.

1 HP / 500 Lbs. is another common rule of thumb used as a minimum HP size to use (I assume giving up some more fuel economy for safety in running from storms)

1 HP / 450 Lbs. seem to be the final reasonable limit; anything beyond this number (e.g. 449 or lower) will really cause the fuel economy to rapidly decline--until by the time that you reach numbers in the 1HP per 400 to 350 Lbs. area some would say at that point you are just wasting fuel unless your hull will fully plane above the water.

1 HP / 400 Lbs. seems to be a common limit for many high-end American coastal cruisers

1 HP / 350 Lbs. is the final limit given by people who are willing to have an upper end of power left to run from a storm--but it will dramatically cost you in fuel.

From everything that I've read and heard, this seems to be the best recap where I'm comparing apples to apples by converting to 1 HP per various weight ranges.

Anyone wanting to critique it please do.

Fred, I really appreciate what you wrote because I do want to get some decent fuel range and that forces me to keep my HP down because I DO want the range and I DON'T want to be the typical American with too much engine.

I made a list of what I could find so far and sorted it by RPM; I've limited my RPM to 2300 or less; and I'm staying with HP between 84 and 97:
Manufact/Model Curr/Old HP RPM Duty Rating
--------------------- -------- -------- -------- ---------------
Deutz/TD229-6 Old 89HP 1500RPM Continuous Duty
Deutz/D229-6 Old 83HP 1800RPM Continuous Duty
Deutz/F6L913 Old 84HP 1800RPM Continuous Duty
Daytona/DME-4 Old 90HP 1800RPM Heavy Duty
Volvo/D5A-T Old 97HP 1900RPM Heavy Duty
CAT/3304B-NA Old 85HP 2000RPM Continuous Duty
Deutz/D229-6 Old 91HP 2000RPM Continuous Duty
Deutz/BF4L913 Old 86HP 2150RPM Continuous Duty
Deutz/F6L913 Old 97HP 2150RPM Continuous Duty
Sisu/320 DSM Old 83HP 2200RPM Heavy Duty
Sisu/420-DM Old 84HP 2200RPM Heavy Duty
Lugger/L439T Old 86HP 2200RPM Continuous Duty
Lugger/L4239T Old 86HP 2200RPM Continuous Duty
Deutz/TD229-4 Old 87HP 2300RPM Continuous Duty
Deutz/BF4L914 Current 93HP 2300RPM Continuous Duty
Deutz/F6L912 Current 93HP 2300RPM Continuous Duty

Thank you to everyone for your insight and help.

[mark775]

Always, I have advocated for a simple fuel system with good, large vents, a sump from which the fuel is taken and multi-stage filtration. My vision has been biased by a pretty clean, dry supply. When in Mexico, I use these: http://www.westmarine.com/1/1/19738-large-funnel-5gpm-10-h-x-8-1-2-dia-100-micron.html . They are slow, cumbersome, and one more thing to clean/store but work amazingly well at removing contaminants and water. Knowing how Richard feels about this (You just don´t manage to bunker clean fuel in every port on a passage. And there is no way to get the water, biogrowth, rustflakes and mud out of your tanks by just running a additional filter. (I am referring to the sh!t you got in by the bunker station)), tho there are some places in BC and Alaska where the fuel is not perfect, my filtration system deals with it nicely but I believe that if I were more of a world-traveler, I wud do it his way. The main thing about these West filters is that they are excruciatingly slow (most people have slow fills/small vents anyway- so it wudn't matter but I am accustomed to 100 gallons, coffee and signing in under five minutes) and do allow a little water thru. One last note - fuel shud always come from the lowest part of your tank - a sump is even better. Do you want to find the dregs/slag/water right after you fill...or just when it gets ruff out?
As far as wing motors and inventive ideas, if one keeps it simple and robust, it is reliable by its nature. The more stuff you have to deal with, the more thru-hulls, shafts, plumbing, etc., the more there is to fail. Problem is, depending on the failure, the very idea that was supposed to lend redundancy or "get home" ability can cause catastrophy. I don't mean to be a wet blanket but all one needs to do is look at how the commercial fleet does it (bigger, simpler, slower, stronger). Forget the "what-ifs" of things like a broken shaft (You're going to have a safety factor of five or better and cannot break the sucker), dirty fuel (you previously dealt with it, one way or another), or mechanical malfunction (you are running slow and doing maintenance? Dang near anything is good for a lifetime). In short, I feel that you are over-thinking the thing...

[Marco1]

On the topic of fuel cleaning, the system we had in place for a large generator was like this.
Two 5000 litre tank and one 1000 litre day tank.
The fuel tanker would dump the bunker fuel into the first 5000 litre tank and we would run an Alfa Laval centrifuge from the bottom of the tank to the top for a few hours and eliminate most of the rubbish, (water, tar and general dirt). When we were satisfied the fuel was ok, we woul let it stay for a day and the next day pump it to the second tank with the same centrifuge.
THe first tank was free to take another load of fuel any time.
The second tank would get the same treatment and from there it was pumped to the day tank.
The 'day' tank had a slow filtering system that would run continuously of the sort called toilet paper by pass filtration, but a bigger version of it.

We were able to run an Ingersoll Rand 7 cylinder generator on bunker fuel that was designed for normal light diesel only because of the centrifuge eliminating all the particles mainly tar that those injectors were not designed to take. Never had a brake down due to fuel.

[FAST FRED]

"You just don´t manage to bunker clean fuel in every port on a passage. And there is no way to get the water, biogrowth, rustflakes and mud out of your tanks by just running a additional filter".

This is correct , but my recommendation was not simply for a 2 element switchable filter , it was for a proper built tank and USING the tank to clean the fuel as part of the normal PM of the boat.

The fuel going into the tank would normally be pre filtered.

IF its a modest boat (under 400 or 500G)the extra time of running a few hundred gallons thru a "Baha filter" doesn't take much longer.

For a larger boat we use a seperiate filter (Fram) that has a hose that clamps over the delivery nozzle and then empties into the fuel tank.

This gets everything that wont go thru a really fine screen OUT of the tank.

The tank it self is not just a box of fuel.

The fill system is a removable tube (tubing with 1/4 --1/2 inch holes) that has a secondary tube of screening that can be pulled to clean it (as needed)from the outside tube.

Below the fill tube is a well that the fill tube sits in ,and the fill tube had at its bottom a cup that fits tight in the well and is below the bottom of the tank when installed.

With the usual 2 or 3 fill pipe inch setup the cup only holds a cup or so , but even a cup at a time the water can be removed with ease.

The complete tubing and inner tubing is used to "bail" the water out of the tank.

On most boats condensation is mild so a regime can be established that pulls the cup regularly when its half full.

No water in the tank? no bugs either.

This is system found on many US Navy Utility boats .

Big hassle if you have a 10,000 gal tank, the centrifugal is the choice , but for use 100 to 1000 gal boats it does work.

Sparkman and Stephens has a fine drawing shown in Skeens "Eliments of Yacht Design " , at your local library.

The big pain is when the best position to install the fill is inside the boats woodwork. Proper clean fuel servicing HAS to be part of the initial design.

FF

[FAST FRED]

So going beyond 62.5 HP is costing me extra fuel because I'm no longer at optimum.

Higher HP rating may work IF the boat has other gear that cont power.

An engine driven generator (fig 2hp per 1 KW), or a large hys system to operate stabelizers .

Engines vary tremendously in where the efficiency actually IS , in terma of load and RPM.

No rule of thumb is perfect for each engine.

What is perfect is a "Fuel Map' but there are harder to get from most engine folks than plans for a Suitcase Nuke weapon.

ASK and see what you get ,
usually just a HP curve and computer generated prop graph ,
which is totally useless for figuring efficiency.

FF

[Bubblehead]

I really like this thread, being a newbie. I've been thinking about 2 questions:
1. How to get rid of the genset and still have nice AC/refrigeration in port. Thinking is to have big (2-3kAh) battery for energy storage, run PTO via clutch to compressor and BLDC motor/alternator. So when engine runs, it powers compressor and charges battery. When engine off, battery runs compressor via same motor/alternator.
2. How to get the dink in the game for emergency propulsion. With a small (Lister AC1) aircooled diesel as the dink engine, perhaps it could be pulled in an emergency and relo'd to a designed mount in the ER to turn a sprocket on the shaft?
Thoughts?

[FAST FRED]

The simplest in port setup is to put two freon circuits in a eutetic plate.

One set has 5/8 or whatever the plate can handle from a big belted engine drive compressor.Usually a cast iron York.

A smaller tubing in the plate allows a std refrigeration "can" condenser 1/8 to 1/4 hp to pull the box down , with hours of running.

As most boxes are well insulated the dockside unit will not run much, after the box is cooled.

Works very well!! For a live aboard.

One contemplation is to Only hook the dockside unit to the freezer section , and "steal" cold to keep the fridge side cool in port.

Offshore both fridge eutetic plate and freezer eutetic plate are on the engine circuit, so the entire system becomes one big freezer.

Since there are no stores offshore, after a week its either frozen or its gone.

WE chose this setup and use a small cooler box . Offshore the frozen stuff is pulled the night before , and stuck in the small box with the next days drinks .

The beer gets cold free , from the steaks defrosting.

Biggest hassle is along shore , where the fridge contents must be placed in the small box ,(to operate the engine compressor) or frozen vegis and containers of milk will result.

FF