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Author Topic: ABOUT THE TUG PROPULTION...  (Read 4169 times)

rathikrishna

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ABOUT THE TUG PROPULTION...
« on: December 11, 2010, 06:55:36 AM »

Good morning Friends...last night i as watching a rare programme in History channel. it was about some extra ordinary crafts, basically used at port side. because of the nature of the programme i started my own research in the subject of TUGs. actually i have started work for a TUG, with some samples, along with my imagination.as i tried to explore things, i got even more exciting things from old Popular Mechanics, elder than me,and in that article writer says the word TUG means a VIOLENT PULL...yes i saw it in video. my doubt is this...ho engineers produce great amount of violent thrust within minimum RPM..?  if i can explore it, it may much helpfull to me, while making my TUG, all with limited stuffs with ,me...  will some one advice me..?
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pugwash

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Re: ABOUT THE TUG PROPULTION...
« Reply #1 on: December 11, 2010, 07:45:39 AM »

Hi Rathi Sorry I don't know much about tugs but in the "tugs and towing" section there are many discussions about
props and motors and knowing how you have to improvise this may give you some ideas.

Geoff

 http://www.modelboatmayhem.co.uk/forum/index.php?topic=26835.0
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boater12

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Re: ABOUT THE TUG PROPULTION...
« Reply #2 on: December 11, 2010, 08:39:03 PM »

You have a pm RATHIKRISHNA  :-))

Jim.
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farrow

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Re: ABOUT THE TUG PROPULTION...
« Reply #3 on: December 11, 2010, 10:18:09 PM »

Tugs are basically are fitted with very large screws for hull size with a coarse pitch which revolve at a slow revolution, driven by a powerful engine working through a reduction gearbox. That is why they have large bollard pull but have a slow speed through the water in relation to horsepower to vessels length. I hope that gives you a basic idea of how they work.
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rathikrishna

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Re: ABOUT THE TUG PROPULTION...
« Reply #4 on: December 12, 2010, 08:09:28 AM »

Thank you all respected Members...i got some idea now..so i have started working on its hull..and by tonight i will find a big motor and will rework for a great torque with less RPM. i still remember in that TV programme , the narrator says that the 6000 HP Diesel Engine transmits its raw power through a powerfull gearbox, and its final rpm goes in to 500... so amazing...i hope i can record this programme by this day as it may repeats..but now i am looking for a good prop design for it...thank you again...
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Pirate

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Re: ABOUT THE TUG PROPULTION...
« Reply #5 on: December 12, 2010, 08:18:23 AM »

Don't forget Rathi,
 that most tugs use a shrouded prop (Kort nozzle) as that as has previously been discussed.This makes the propulsion units power used more efficiently.Thus more torque/bollard pull per rev/hp.
Looking forward to your interesting interpretation and clever solutions as ever.

Regards
Pirate
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rathikrishna

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Re: ABOUT THE TUG PROPULTION...
« Reply #6 on: December 12, 2010, 08:25:53 AM »

Hai Pirate...now i am adding the Kort nozzles to all of my crafts..its a revolution..and may i ask one thing again..actually what is meant by the word bollard pulling..?  as my subject is aeronautics marine science is no much known subject...thats why..please...
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Shipmate60

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Re: ABOUT THE TUG PROPULTION...
« Reply #7 on: December 12, 2010, 10:24:09 AM »

Rathi,
A bollard pull is the amount of pulling force that a tug can generate with the tow rope secured around a bollard.
This is the stationary force generated by the tug.
It is measured in tons.
Some Ocean Going Salvage tugs can generate up to 2000 plus tons, harbour tugs up to about 100 tons max.
A line is secured to the tug and a secure bollard with  a meter incorporated in the line.
The tug goes full ahead and the force generated in the tow line is measured.

Bob
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rathikrishna

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Re: ABOUT THE TUG PROPULTION...
« Reply #8 on: December 13, 2010, 07:54:54 AM »

Hai Shipmate...thanks for the valuable information...i am studying a lots about marine engineering....so your explanations will help me a lots...and yes many other members who willing to study more...thank you again...
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rathikrishna

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Re: ABOUT THE TUG PROPULTION...
« Reply #9 on: December 14, 2010, 07:24:14 AM »

Good after noon Friends..by last days i found a motor and collected a prop from an aluminium sheet...some photographs here...
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rathikrishna

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Re: ABOUT THE TUG PROPULTION...
« Reply #10 on: December 14, 2010, 07:24:57 AM »

close ups..
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rathikrishna

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Re: ABOUT THE TUG PROPULTION...
« Reply #11 on: December 14, 2010, 07:26:02 AM »

here..
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rathikrishna

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Re: ABOUT THE TUG PROPULTION...
« Reply #12 on: December 14, 2010, 07:31:58 AM »

Respected Veterans..i am posting these photo graphs here not to boast or to show anything big..but its a humble request again, that i am looking for a great guidance from you all...actually this motor is from an old VHS HQ VCR..its brushless as we can see, and runs on pulse width modulation.all you can see the needed wave form at the base of the motor. its a square wave signal.i can make this signal from simple IC circuits. its not the matter here!!..  it can only revs up to 400 to 500 Rpm max..but it can deliver a high torque..up to 3/4 Hp at 9 volts. and can brake , reverse instantaneously as needed, as we can see in a VCR. and the prop is in 3 inches..and i hope i can simply increase the pitch of the blades as i need ...will this combination work nicely..?  please any guidance..?  so i can avoid my time loss and useless effort..its  a request again...Rachu
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Shipmate60

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Re: ABOUT THE TUG PROPULTION...
« Reply #13 on: December 14, 2010, 08:38:37 AM »

Rathi,
There are 2 ways to power your tug.
A very coarse pitch prop spinning slowly or a finer pitch prop spinning faster.
With a motor of that power you could use a step up gearbox to deliver about 3000 rpm at the prop.
It might be a better idea to try it first and see just how course the prop can be set.

Bob
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nick_75au

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Re: ABOUT THE TUG PROPULTION...
« Reply #14 on: December 14, 2010, 09:02:25 AM »

Hello Rathi,

I think 3/4 HP is a little optimistic, that would mean a 500 watt motor and at 9 volts would be 62 amps!

In saying that the motor would , at 500 rpm probably have no problem spinning a 3-4 inch prop as at low RPM power required is very low, in the order of 10's of watts.

Cheers
Nick
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kiwi

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Re: ABOUT THE TUG PROPULTION...
« Reply #15 on: December 14, 2010, 10:28:59 AM »

Hi,
Love your tug. I have a couple of similar motors, but have no idea how to make them go. Your skills continue to amaze me.
Keep up the good work
cheers
kiwi
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roycv

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Re: ABOUT THE TUG PROPULTION...
« Reply #16 on: December 14, 2010, 04:40:11 PM »

Hi Rathi, I would be interested to know which batteries you are going to use and charging arrangements you have for your tug boat.
Looks like you have to use what ever you can find!
I wish you every success, keep up the postings.
regards Roy
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rathikrishna

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Re: ABOUT THE TUG PROPULTION...
« Reply #17 on: December 17, 2010, 08:58:59 AM »

Oh Friends..at back ground its not my TUG..its my new fishing trawler..the Kingfisher..i compleated my speed controller for the motor..but it is much disappointing..its immensely powerfull...without flaw..but eating my battery pack instantly..so its not feasible..so now i am trying for a new motor..i got some motors from old scooters and autorickshwas, as wiper and starter motors..i have to rework them...hope it work...Shipmate will you tell me how can make a high coarse prop for me..? any idea to share..? and ROY, i do not have any modern battery packs and equipments..still i am based on NiMh battery packs..but recently i got some highly powerful battery packs from palmtop DVD players, as people gave me to service, but its too hard to get lens assy here..so they abandon it..so its a joyfull thing to me...most of them are based on 9 volts..and in to Li Poly..hoooy....it gives me more than hour with most of my crafts...i will post all of my goodies here step by step..from battery charger to motor differential controll, through engine sound generator...its all proved by years...here i can make a full radio system for a Dollar...(Rs 50/-)..so i hope all it may help some people at least...so i need only a little time to post it all...sure...but with one request..please dont make fun on me..especially , as i am a girl.. its a kind request...have a nice day all...god may bless you all...
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farrow

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Re: ABOUT THE TUG PROPULTION...
« Reply #18 on: December 17, 2010, 10:23:08 PM »

Hi Rathi,
I do not think anyone on this site thinks any less of you for being a girl, in fact I am totally fascinated that you can make your own motors etc, as I have no idea to. Your screw/propeller is very much like the first original ship propellers and should work, the efficiency will not be as great as a moulded brass one, but then most proprietary brass propellers have flat brass sheet cutouts soldiered into a brass boss nut.
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Shipmate60

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Re: ABOUT THE TUG PROPULTION...
« Reply #19 on: December 17, 2010, 10:41:38 PM »

Rathi,
Just bend the blades at a courser angle of attack (trying to use your aeronautical terminology)
Or
Just bend the blades more.

Bob
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gregk9

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Re: ABOUT THE TUG PROPULTION...
« Reply #20 on: December 17, 2010, 11:39:55 PM »

Another type of motor you could try would be a car heater/ventilation motor, they have good torque for model tugs and you should fine many in car scrap yards, you will just need a couple of screwdrivers and need to take a bit of trim off rom underneath the dash to find them. it would not take as much current to power either, so less battery drain for you to make useable.
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rathikrishna

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Re: ABOUT THE TUG PROPULTION...
« Reply #21 on: December 18, 2010, 09:56:55 AM »

Hai Shipmate..an aeronautical prop is simply an aerofoil we know..will this work on water..? most of my props are flat bladed as i cuts all from aluminium sheets..i will try to angle it more and will try by today night...thank you..
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rathikrishna

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Re: ABOUT THE TUG PROPULTION...
« Reply #22 on: December 18, 2010, 10:00:23 AM »

Greg..i will collect some motors from junkyard by tomorrow..and will try with it..today i cant , because its too late here 3:30 eve and i have to drive more than 120 kms to my nearest junkyard.so by tomorrow i will leave home early morning, and also planned to collect some scraped toys from scrapyards. so i will be back with some motors...thank you for the advice..Rachu
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