multi propeller boat

what are advantages/disadvantages of multi propeller boat?

Can boat have 4 propellers?

I ask because work on electrical boat, but one single electrical machine have not lot HP's. I think put 4 electrical engines in line with 4 propellers. But not know will this be enough good at all?

what if I put 6 propellers in line as example?

 

you can have as many as you like !! Need to know more about the actual boat size length etc etc and what is it to be used for . with multipal props you may not even need rudders at all .Have to be a bit more specific about what you are trying to do and make !!
Theres a wealth of knowledge and exsperiance here and theres nothing new under the sun !!

 

Your problem is not the power of one electric motor. There are enough motors up to 50 Kw available on the market. Your problem will be to get enough energy stored in the batteries to make it worthwile to have such a lot of electric motors on your boat.

Are you thinking of a special effect, like a turbine effect, if you put 6 screws in series?? Interesting whether somebody can answer that question. I personnaly would not go to more than 2 motors with 2 screws and two sets of batteries, should you wish to travel on the Adriatic or the Mediteranian sea. In case one system fails. But you can have a hunderd motors with propellors if you wish, but how are you going to power it?.

 

Your problem is not the power of one electric motor. There are enough motors up to 50 Kw available on the market.
RE: I know.. and think I put 6 x 50Kw! (and still not enough) if sailing yacht is 100 feets


Your problem will be to get enough energy stored in the batteries to make it worthwile to have such a lot of electric motors on your boat.
RE: in these days not so problem at all only cost of batteries...
imagine 1 ton of fuel and 1 ton of batteries if I have enough place for batteries, this will have less weight than few tons of fuel


Are you thinking of a special effect, like a turbine effect, if you put 6 screws in series?? Interesting whether somebody can answer that question.
RE: yes, i was think about that exactly!! and this is main question here. Anyone can explain about that something more maybe?

 

Hi there,
You better think it over very carefull. 6 x 50 Kw motors. I do not recommend to go over the 48 Volt DC on the sea. i.e at 50 KW consumption, it means 1000 Ampere per motor and that times 6 . There are no electrical components on the market which does that in an easy way. Also your cabling will be massive and the losses and electrical field created in the cabling will be massive. Anything which can be lifted by a magnetic field will fly towards this cabling.

Lets assume you do go ahead and convert the 48Volt into 500 Volt AC. Still the current at the battery side is 7000 Ampere. Fuses??? Switches??? O.K. Now you decide to go for higher DC voltage. One touch with your barefeet on a wet floor and a tiny touch with hour finger to a bare electrical point and you will be jumping like a dead crayfish.

Not a good idea. but ....... maybe you can make it work. Who knows

Bert

 

You better think it over very carefull. 6 x 50 Kw motors. I do not recommend to go over the 48 Volt DC on the sea.
RE: Voltage: 150 V

see http://www.piktronik.com/index.php?...category&layout=blog&id=20&Itemid=115&lang=en

60kW AM - Water cooled


i.e at 50 KW consumption, it means 1000 Ampere per motor
RE: 329 A per motor


and that times 6 . There are no electrical components on the market which does that in an easy way.
RE: 329 A per motor exist! and every motor is independent.. this mean you must not have on big cable for all 6 motors! you have 6 smaller independent cables


Also your cabling will be massive and the losses and electrical field created in the cabling will be massive. Anything which can be lifted by a magnetic field will fly towards this cabling.
RE: see above answer... this is bigger yacht.. this all is in engine room... not on open place...


Lets assume you do go ahead and convert the 48Volt into 500 Volt AC. Still the current at the battery side is 7000 Ampere. Fuses??? Switches??? O.K. Now you decide to go for higher DC voltage. One touch with your barefeet on a wet floor and a tiny touch with hour finger to a bare electrical point and you will be jumping like a dead crayfish.
RE: what 'bare' electrical points you talk? these points no exist at all.... and all is inside engine room... you imagine electric motor on open deck

Not a good idea. but ....... maybe you can make it work. Who knows
RE: electric yachts exist... sure you cant know, when 90% of people is not try it...

but my main question is not answered only (as usual)

I ask: will 6 propellers in line create some turbine effect where will be loosed power (or any other bad effect)? this is my main question, all other electrical questions that you have 'fair' are are easy to solve by experienced electric person

 

Look, it is a nice dream to have 6 electric motors put in line at 60Kw each.
First at all, it is 101,5 Hz Alternating current thus 329 x 6 = nearly 2000 Ampere at 150 Volt AC. Lets assume you have the knowledge to make the converter from DC batteries to 150 Volt 101,5 Hz AC. Are you planning to have a higher Voltage then 48Volt DC batteries on board?.

Good luck to you. I will order your white flowers already.

But, lets assume you know what you are doing and make a converter at 85% efficiency to push out 400 Ampere with a 48 Volt battery (you need some extra, you cannot make it for 300 or 329 Ampere) It means up to 1200 Ampere from the batteries. You need to have the converter protected with a fuse. You need to screen the converter from radiating, otherwise your harmonics will really give you some pleasure on your electronic equipment like, Radar, sonar your PC etc.

I also assume that your are clever enough to make it 6 seperate battery banks of 48 Volt, each with their own charger and each with their own battery monitoring system. Or are you planning to make one converter of 7200 Ampere at 48 Volt at 101,5 Hz ??? What are you planning to do? Make your boat try to fly? 360 Kw electric motors can be compared with at least 700 Hp diesel engine, if I can believe the reports written on this subject. This just for only a 30 meter cruising yacht?

But I like to thank you for the website, I have been searching for some time for a 6 Kw motor. They have 4,5 KVA (6,5 Kw) 30 Volt 120 Hz 150 Ampere submersable motors. Absolute the one's I was looking for. It is not too difficult to make a 30 Volt , 120 Hz chopper to drive the motor. I will run the motor at half the power in anyway and only for max 30 minutes allowed at full power. Rick and Jeremy, maybe you like to look at those motors from Austria/Jugoslavia for your own projects. I have no idee what they cost.

But sadly, I haven't heard how you are going to charge the batteries, nor what kind of batteries you will be using. Nor how you will fuse, control and charge . But I had an Italian friend and I must say, Ferrari, Lambourghini comes from Italy, so maybe you will make it all work. Looking forward to your idee. Tell us more on how you are planning to make it work !!!
Bert

 

Sorry, my answer crossed your reply.

Like I said in a previous thread, I cannot comment on having 6 screws in series, whether they start performing as a turbine booster. I don't have the equipment nor space to test it. I assume there must be some turbine effect, which should be to the benefit of the yacht.

Also I noticed that the motors are 3 phase.

 

I hate to talk to a number, thus I am going to give you a name.
Guiseppo.

Maybe Guiseppo, you and me can figure this out. I do not think anybody will or can give you an answer.

First at all, you like to see 6 screws, in line, under the hull, forming one unit ,which somehow gives some extra whooom to your yacht. Or maybe 2 x 3 screws in line.

Is the 60 Kw motor the correct choice?(by the way only for 30 minutes, otherwise only 45 Kw) The motor is not submersable. Thus you need a methode to transfer the 45 Kw through the hull to your screw. You are correct. It is not possible in that case to have the six screws properly in line.

But if you suggest the 10,5 Kw motor, yes in that case, it is possible. Model no UWM10
thus we both agree, we select the 10,5 Kw for our experiment.

Do we need a certain distance between each motor?. What do you think?

Does the screws have to be synchronised, to create a turbine effect?. Or can they spin at different speeds? What do you think?.

Do we need a "pipe" in which all six motors and screws are being mounted. What do you think?

I think , yes we probably need it, to create some contained area to ensure some turbine effect.

Will there be an advantage, when there is a turbine effect?. I don't know.
Lets hope some other forum members join in and help us out.

Bert

 

Look, it is a nice dream to have 6 electric motors put in line at 60Kw each.
First at all, it is 101,5 Hz Alternating current thus 329 x 6 = nearly 2000 Ampere at 150 Volt AC. Lets assume you have the knowledge to make the converter from DC batteries to 150 Volt 101,5 Hz AC. Are you planning to have a higher Voltage then 48Volt DC batteries on board?.
RE: yes, the have all in kit!
http://www.piktronik.com/index.php?...atid=23:complete-solutions&Itemid=126&lang=en

KOP96300

The DC-DC converter from Piktronik

http://www.piktronik.com/index.php?option=com_content&task=view&id=23&Itemid=62&lang=en





But, lets assume you know what you are doing and make a converter at 85% efficiency to push out 400 Ampere with a 48 Volt battery (you need some extra, you cannot make it for 300 or 329 Ampere) It means up to 1200 Ampere from the batteries. You need to have the converter protected with a fuse. You need to screen the converter from radiating, otherwise your harmonics will really give you some pleasure on your electronic equipment like, Radar, sonar your PC etc.
RE: Piktronik have whole system...


I also assume that your are clever enough to make it 6 seperate battery banks of 48 Volt, each with their own charger and each with their own battery monitoring system. Or are you planning to make one converter of 7200 Ampere at 48 Volt at 101,5 Hz ??? What are you planning to do? Make your boat try to fly? 360 Kw electric motors can be compared with at least 700 Hp diesel engine, if I can believe the reports written on this subject. This just for only a 30 meter cruising yacht?
RE: Display, control and battery monitoring unit
http://www.piktronik.com/index.php?option=com_content&task=view&id=24&Itemid=63&lang=en

 

I hate to talk to a number, thus I am going to give you a name.
Guiseppo.
RE: you mean this person is here at forum? that we post him personal message?


Maybe Guiseppo, you and me can figure this out. I do not think anybody will or can give you an answer.

First at all, you like to see 6 screws, in line, under the hull, forming one unit ,which somehow gives some extra whooom to your yacht. Or maybe 2 x 3 screws in line.
RE: this is what I ask.. on any way you see that I am 'cover' all your electrical questions.. but I alone ask this.. good question or maybe one line 3 motors and other line 2 motors (in holes between)


Is the 60 Kw motor the correct choice?(by the way only for 30 minutes, otherwise only 45 Kw) The motor is not submersible.
RE: heh but all diesel engines are not submersible ) if my shipyard team can build whole ship, be sure the can build metal shaft/axis for motor


Thus you need a methode to transfer the 45 Kw through the hull to your screw. You are correct. It is not possible in that case to have the six screws properly in line.
RE: yes, I think this.. I alone ask have enough space at all.. pls. maybe if to tight will be some negative effect


But if you suggest the 10,5 Kw motor, yes in that case, it is possible. Model no UWM10
thus we both agree, we select the 10,5 Kw for our experiment.

Do we need a certain distance between each motor?. What do you think?
"RE: yes, I think this.. I alone ask have enough space at all.. pls. maybe if to tight will be some negative effect"


Does the screws have to be synchronised, to create a turbine effect?. Or can they spin at different speeds? What do you think?.
RE: this is all I ask.. you think more, and these are real questions... I ask if someone know as advice, before I talk with shipyard engineer

Do we need a "pipe" in which all six motors and screws are being mounted. What do you think?

I think , yes we probably need it, to create some contained area to ensure some turbine effect.

Will there be an advantage, when there is a turbine effect?. I don't know.
Lets hope some other forum members join in and help us out.
RE. yeh...

 

Guiseppo, I doubt it, that we will find on this forum anybody who has the knowledge to answer your question with accuracy. I cannot, I don't have the experience. All what I can do is to phylosophy.

Your problem with the 60 Kw motors, is the problem to create a methode to put the six screws in line and have it encapsulated with a "tunnel" casing to create the turbine effect.

Each of the six screws need to be driven by a belt, or gearbox, like the one from Jeremy Harris in the efficient electric boat.
To enable to create a turbine effect, we need a metal tunnel. In this tunnel we have 6 screws mounted. As soon the tunnel has an hole in it, it will not create the full turbine effect. Probably no turbine effect at all, because the "pressure" will escape. While if you look at the 10,5 Kw motors, it would be easier to mount them in line and ensure that the "tunnel" has no leaks in them or make easy coverplates to seal the "tunnel".

My gut feeling is that you need half a distance of the diameter of a screw between the screws. The best is to go to the airport or aircraft museum and see whether you can look how a turbine creates its escalating force. This, you will have to design in your mind and convert this methode to something placed in water.

That is all I am able to help you with.

You will never disclose your name, thus I like to say to you. Good Bay Guiseppo good luck with your project.
Bert