An actual hybrid application

Since I don't know what you intend by "short run", you choose the length of the trip and then calculate the payback time, in the manner seen before. Only then you'll be able to affirm that such a system is viable.

 

There is already technology to cover those short trips over water Questor.
Engineers like to call it a "bridge".

Maybe I’m a little harder than usual but I have had a bad day with some eco muppets that have managed to study at all the best schools but can’t still do some 1'th grade math...

I know you don’t like numbers Questor but if you just assume that daiquiri is a little little right in his numbers you would se that in order to recover energy in any usable numbers, the trip would have to be shorter than the ship itself.

The WW2 subs (as well as every other modern sub) extended range submerged is not a result of their diesel/electric drive system but just a simple matter of hydrodynamics. Subs are many times more efficient operating under water than at the surface. No green hybrid electric mumbo jumbo magic. Just sweet tiny water molecules sweeping along some steel plates.

 

The more I learn about submarines the ore I want one.

 

If I rephrase the overpowered part to "usually have more power than they need", would that clarify things?

 

I'm not sure what you're attempting to do, prove or disclose, but I do question your ability to gather reasonable data. No, your rephrase does nothing to relieve the gross misunderstanding of the subject. In fact, I'm curious as to where you've gotten this "diesel sailboats are over powered" stuff. Since clearly you are not capable of sizing an engine/drive package for any specific hull form, let alone a diesel, the remaining premise is moot.

Are alternative drive and propulsion systems possible? Sure, many in use, but all of these systems diesel included, have to make some compromises across several issues, most of which I feel you haven't much of a grasp of, though you do seem to have an interest.

I'd recommend you continue your studies and self education about the subjects you are interested. You appear to have gotten off on the wrong foot on a discussion forum by attempting to over state what you know or understand. This arena is a good place to ask questions and develop ideas, but stick within your area of expertise and subjects of understanding. If you make announcements with erroneous facts or questionable data, you will be challenged. If you do this repeatedly, then you will be ignored by all but the novices, which will do you no good at all.

 

Well, I started this discussion because I did not know the answer for some parameters. I clearly stated my assumptions in the beginning, which could of course be wrong. This assumption has nothing to do with how to "properly size an engine/drive package". It is simply concerning how people use their boats, and there is no clear answer for that. My observation, which could of course be wrong, is that many people don't run their engines in their sailboats at maximum power, but at a lower power rating. Therefore, engine downsizing COULD be possible. To move a specific boat at a specific speed under specific weather conditions, you need a certain power power output. It does not matter where this power comes from.

Further, I have not assumed anything about the propeller or transmission. So these parameters are up to discussion. A standard propeller and/or transmission might not cut it.

If you explain how I am misunderstanding this, perhaps I could learn something. You are just repeating that I am incorrect. Maybe you could care to enlighten me?

 

There was your mistake. (one of many)

Though your observation was not wrong, the conclusion was.

Sailboats need reserve power to handle drag induced by the bare rig, in adverse conditions as cruising free from leeshore.
On a sunny afternoon they don´t need that much power, sure.
But replacing a proper sized propulsion just because it is rarely used at full power is not a wise decision.

All clear on that?

I could go on and on, but it is not worth. You simply could use the search function here to find out it was all said and all discussed `til death.
Just yesterday another snakeoil salesman opened a thread here to tell us he has the solution (and he claims to be the market leader, so we must trust him).

Phantasies..........

 

It is not clear. That is why I started this thread. Remember that I am proposing to replace an engine with a hybrid having the same total power. A 40 kW diesel is replaced by a 30 kW diesel + 10 kW electric. So the propulsion is "proper sized". So you are saying that the minimum "extra power range" is approximately the same as the diesel in your tank will give you? I am not so sure about that.

 

No, I am not saying that, don´t read what you want to read!

And I am not willing to go in detail here for the 3677th time.

Do some legwork and use the search function if you really want information instead of a confirmation of your wild guesses.

 

The question then remains:

Where do you get the power for the 10kW electric motor?

If you say "batteries", what happens if you need all 40kW to head into some weather in a life or death situation and the batteries run down?

Marine systems are about safety and redundancy because any failure can kill you.

I'm sure the manufacturers do not put in larger engines than are required because that would cost a lot of money. They put the right size engine in.

Reduce that size and add the electric (30kW Diesel and 10kW electric) and you end up with not enough power being able to be sustained when you need it in an emergency.

Just add a 10kW electric to an existing 40kW diesel and you accomplish nothing.

 

The electric motor is powered from batteries. Of course the batteries run down. That is the issue. These batteries are not used, except when necessary. Therefore, the batteries are charged. I'll put it this way, the proposed setup is a 30 kW diesel (which you could call underpowered) and a 10 kW "boost" motor (which could work as an alternator as well). I'll restate the question differently:

What is the minimum acceptable time period for running the "hybrid engine" at 40 kW (40 kW is considered "properly sized" for the specific boat) if you only have 30 kW available after this time period has elapsed?

I am not expecting any numbers, but some opinions from seasoned sailors/boat designers. Whether the hybrid setup is cost effective/feasible is a totally different matter.

 

Ok, we are talking the same language here. Cool.

I think this has to be looked at from the other end of the question. The question should be (and you can answer this easily):

How amp-hours do you need to run a 10kW engine for 12 hours?

I see your strategy: Run a diesel at its peak efficiency curve, getting the most power per liter of diesel, even when going into the dock. Take the extra energy and put it in the battery bank. Later, draw on this energy when you need full power.

Only problem is you may have to motor for 12 hours at full output sometimes. What size bank do you need to run the 10kW electric motor for 12 hours?

Answer: 10kW = 10,000 Watts, running 12 hours = 120,000 Watts. By Ohm's Law: Watts = Volts x Amps, 120,000 = 12 x Amps

Solving... Amps = 10,000 Amp*Hours for a 12 hour run. Seems pretty difficult to keep that many batteries on board.

As a benefit, I like that you have a 2nd engine, which would, for the first time, make a redundant system in a monohull sailboat that could give it a "limp home" capability under the 10kW motor alone, if the batteries hold out.

 

Here we go again. Yes, there are clear figures for pleasure and commercial craft usage. This is formation is available in a number of locations and will tell you "how people use their boats".

Now, why would a skipper run his engine at less then WOT. Maybe conservatism, maybe they're still paying for it, maybe they realize the engine has a "groove" for maximum fuel efficiency, maybe a combination of all of the above. Now, lets reduce their available power so they have to run their engines at WOT just to get the same level of punch. Would this be a reasonable economic decision?

The simple fact is most sailboats, except those marketed as motor sailors are under powered, particularly if diesel equipped. Every single boat, that's more then a trailer sailor, will have engine upgrade options, with power ratings in excess of twice that of the base engine. There are several reasons for this, a large one is weight, again particularly with diesels.

You don't get something for nothing and you again point out your lack of understanding. You're second guessing the designer and arbitrarily lowering the engine output. Then you justify this decision by calling it "properly sized". So, how do you come to these grand conclusions? Is there a formula that you employ, some math to suggest the 40 KW drive was 25% too big?

What good is a 10 KW electric motor? What will a 10 KW motor bring to the table? More convolution, complexity, more maintenance, additional cost and for what goal? What boat that needs a 50 HP diesel can be pushed though anything but a dead calm and helpful following current, with 12 HP? What owner would tolerate having to run his main engine out of it's efficiency "groove", making it scream, because it's weak kneed, just to have the option of crawling along at row boat speed under the electric option? How many tons of batteries are you going to burden this yacht with, just to offer a half a day's range on a motor that is 1/4 the size it needs to be to push the yacht at a reasonable pace?

 

Please post the figures that you mention.

I don't think you understand the parallel hybrid concept, and therefore you do not understand my question. The main gain is not electric only drive, but instead potential for fuel savings. Depending on implementation, electric only drive might not be possible for a parallel hybrid.

I haven't said the concept is good, but in order to evaluate it, you need to determine the value of certain parameters. Before you know these parameters, you cannot dismiss it. I said 40 kW is "properly sized". The hybrid could have 30 kW + 10 kW = 40 kW power and therefore I am not second guessing the designer. Although, you would have different "ranges" for the two engine types. Running the diesel engine at full throttle (meant as an expression) might be a good economic decision. Diesels thrive at high power outputs. Since you like to post harsh comments, but no numbers to back it up, we will never know.


The math was a guess based on observations. I am not saying 25 % is the correct number. That is up to dispute. Maybe it's 10 %. If you have some information regarding this, please post it.


The result of all this, will probably be that the parallel hybrid is too expensive to implement / cannot provide enough range on max power output. But that is not what I asked. I asked what the "range" on max power output should be.

 

Haha, that was a good one!

YOU do not understand, and stubborn as you are, you do not and will never follow the hint given.

You are NOT here to learn! You are here to make a senseless idea working.