Model Boat Mayhem
Mess Deck: General Section => Beginners start here...! => Topic started by: sean Half-pint works on February 14, 2013, 03:02:08 pm
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Hi all, hear is a daft question for you,
which is the best type of prop for a tug boat, brass or the plastic/nylon ones?
I don't want her to go especailly fast, but I do want something I can put as much of the availible power as down with, I have yet to decide on motor, but I am looking at a medium/slow revving thing that provides excelent torque, and a decent prop shaft of course!
Next point.
Is it possible to connect more than one motor to a prop shaft? if so what is the best way of doing this? linier (one behind the other) or side by side with a gear box arangement?
Thanks in advance!
Sean
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May I recommend a 900 series motor with a 65m Brass prop. You should want for nothing else.
See Stavros our resident power merchant. :}
regards
ken
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I don't think a 65MM prop would fit in the excisting steering thingy (I cant remember the techical term for the rudder with the prop inside the tube) on the Dickie tug, although it cant be that hard to replace surely?
Thanks Ken, I will look at the 900 series as well...
Sean
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Its a Kort nozzle - available from numerous suppliers - I use Marks Model Bits and or Steve at www.modelboatbits.com (http://www.modelboatbits.com).
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Thats the one! :embarrassed:
Sorry Im still getting my head around the nautical terminology! if i dont know I describe it and add thingy, and usually people know what I am on about HAHA :embarrassed:
Thanks for the link!
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You won't get anything bigger than a 50mm prop in the Dickie Kort Nozzel as fitted.
A 540 motor is probably as big as you need to go.
Ned
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Awesome, It did look something like that, but i havent taken the ruler to it yet {-)
Are brass or plastic props best for towing and such like? also how do the number of blades affect things?
Sorry for the newbie questions, but better ask than Guess?
Sean
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A three bladed Brass prop would be the best for a Kort nozzle.
Ken
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Awesome, Thanks, Im still a little confused as to what difference the number of blades makes.
Also for a 50MM 3 blade brass prop, what sort of price should I be looking to pay (Not wanting to get ripped off now)
As always sorry for the questions!
Sean
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Here you go Sean,
http://www.cornwallmodelboats.co.uk/cgi-bin/sh000001.pl?REFPAGE=http%3a%2f%2fwww.cornwallmodelboats.co.uk%2findex.html&WD=prop%2050mm&PN=3bladem4.html%23a534051#a534051
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if you have a small apture due to the hull design ( top side of the keel to under side of the hull ) and you want more bollard pull (towing power ) then the 3 blade will give, go to a 5 blade prop
with a bigger reduction ,or a bigger engine ,or both
that's what we do in the real world on our trawlers to keep up with the times
in the 70 ties 60 footers had 250 hp with 3 x 1 red and 45" prop , and towed 2 nets now the same boat has a 60 " nozzel with a 5 blade prop on 6.1 red with 500 hp engine
and tows 5 nets and has 3 times the bollard pull
its all about BLADE AREA , keep in mind that 5 blades don't like high rpm :-))
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When buying a new prop, remember that a Kort Nozzle uses flat-tip blades in contrast to an ordinary commercial prop that has rounded tips. You can fit the latter in a nozzle but the arrangement always looks odd.
A four-blade, 2" Kort Nozzle prop from George Sitek will set you back £19.06. http://www.gsitek-props.co.uk/ (http://www.gsitek-props.co.uk/) and from Prop Shop http://www.prop-shop.co.uk/ (http://www.prop-shop.co.uk/) about £24.
I think the prop recommended by Kenny is a conventional prop, i.e. not a Kort.
Regards,
Barry M
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I think the prop recommended by Kenny is a conventional prop, i.e. not a Kort.
Regards,
Barry M
You are, of course right. You would not need a Kort with these.
Cheers
Ken
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the big 5 blade LH scew plane prop in the middle of the pic would be great in a nozzel (we view or props from the stern looking forward out here )
look just like a real veem or (Mercado prop from japan )
http://www.gsitek-props.co.uk/photogallery/Specials%20015.jpg
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OK lads and lasses, SO lets see if I have my head around this yet,
More blades= bigger surface area= more thrust BUT are not keen on high RPM's?
Brass seems to cut smoother through the water at low revalutions and be stronger, but heavier, and 500 and 600 size motors seem to come in both high RMP and high Torque variations?
If I have got that wrong let me know please lads and lasses!
Sean
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You have it about right.
Why change the motor and prop though.
Why not leave the drivetrain as original.
Bob
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Bob,
When I was running my tug last (about 4 years back) she was sluggish, and very underpowered, >>:-( <*< so for the moment I am looking and getting ideas, there is a lot of flex in the original prop blades, which can't be a good thing can it? also there is about 4MM clearance between the edge of the prop blades and Kort nozzle... which cant help things along... so I want to increase the power she puts out, and the obvious answer is a bigger prop and more potent power plant... %)
unless there are any other ideas I can try?
Sean
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That is unusual as most of these are too fast.
The 540 motor is a high speed motor giving in excess of 10,000 rpm on 7.2 volts.
Bob
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the first run she went like a cork out a bottle, ran the battery down, second run she was like a sloth on sedatives... even with a full battery... I am sure the prop has something to do with that?
Sean
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If you are doing this as a start to tug towing, forget it. The Dickie adapts nicely with mods to the toy
that make it a nice running model.
It will not have the maneuverability to make a decent tug towing vessel
Ned
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its more for something to get my head around the concepts of Tx/Rx motors and basic concepts of model boating...
I know the manuverablity of the dickie is on a par with large tankers...
thanks for the heads up Ned!
Sean
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the first run she went like a cork out a bottle, ran the battery down, second run she was like a sloth on sedatives... even with a full battery... I am sure the prop has something to do with that?
Sean
If she went well the first time but not the second then I do not follow your logic that the prop is at fault. I suggeat that you look elsewhere and my bet would be the battery - even if it appears fully charged.
Barry M
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It could be... Im stabbing in the dark, as I have no idea what would cause it on a boat... the logic was the flex in the blades caused drag reducing the speed.. I have ordered in a new Battery anywho, so I will have a play and see how she goes O0
Sean
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Sean,
Plastic blades will flex and thus a switch to a metal blade can only improve matters as will fitting a prop that is a good fit in the nozzle rather than the 4mm quoted. However, if nothing has changed mechanically between 1st and 2nd runs then look to the electrics.
Incidentally, if nothing from the Sitek range provides a good fit to the internal diameter of your Kort, give George Sitek a ring. As he makes his own props, modifying one to suit your Kort will not be a big job.
Regards,
Barry M
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Thanks Barry,
I will order in a prop to suit the Kort, and a nice brass prop, coupled with the new Battery, before I prat about on the motor side O0 Is there a given amount of clearance needed for a prop in a Kort? or is a tight fit best?
Thanks again...
Sean
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If you go for a brass prop its more than the tug is worth.
Ned
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Fair point indeed Ned... hmmm a cununderum now... I think the thing to do now is get her battery and see how she goes... I do admit I have fallen in love with my little tug...
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Sean,
Ned may well be right. It depends on how much you want to develop your model. Try your new battery first and then work from there.
In respect of prop/nozzle clearance, full-size practice relies on a gap of a few millimetres. Model practice should give a running clearance and no more if you want the best Kort effect.
Barry M
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Thanks Barry and Ned, I will let you know how things get along... O0
As always thanks for the advice lads, and sorry if I seem a little dim.. Im still finding my sea legs... ;D
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Sean,
Why I asked is if you search the other conversions most keep the motor and prop as this gives more than adequate performance.
If you start putting larger props on a 540 motor you will certainly improve the performance to that of a speedboat and increase the current draw from the motor.
To check the battery put a voltmeter across the battery when running in the bath.
Bob
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Hi Bob,
I just popped the hull and contents in the bath and the battery voltage is way down on its stated 6.5 volt... I charged it till the charger light turned green, left it ti stabilize for a little while (about an hour or so) popped it into its connector any my voltmeter was ticking (i call it ticking) at 4 volts... then mum shouted at me for my tug being in her newly cleaned bath... {-) {-) :police: >>:-(
sean...
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If you start putting larger props on a 540 motor you will certainly improve the performance to that of a speedboat
Tug racing anyone??? (jokes) thanks for the heads up though!
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if you increase the blade surface or size and put a bigger redaction on the current motor it will improve the towing ability , but not effect the free running speed a lot
IN THE REAL WORLD hull design only lets the boat go so fast then it starts to push water and bury its self , like most tugs witch are over powered for there water line length
BUT hook them up to a dead pull and they will move the earth ( love um )
and it should reduce the batterie drain (less load on the motor ) you can always free run at half throttle if you have to much POWER {-) like i will have to do 60mm 4blade brass prop on 6 .1 red with mfa 540 on 12 v if you hold yer hand at the bow and not let it go forward at full noise it will bury the stern
(http://i1266.photobucket.com/albums/jj529/atomicmaloo/MODEL%20BOAT%20PIC/DSC00942_zps662312b0.jpg)
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if you increase the blade surface or size and put a bigger redaction on the current motor it will improve the towing ability , but not effect the free running speed a lot
I like that statement, although she lacks the manuverablitiy for true tug towing events, but still I can have fun with her!
IN THE REAL WORLD hull design only lets the boat go so fast then it starts to push water and bury its self , like most tugs witch are over powered for there water line length
I believe this is why tugs have the high bow, almost like the atlantic bows on some naval vesels?
BUT hook them up to a dead pull and they will move the earth ( love um )
Thats the best bit! Nowt wrong with pulling 4 barges at a time!
and it should reduce the batterie drain (less load on the motor ) you can always free run at half throttle if you have to much POWER {-) like i will have to do 60mm 4blade brass prop on 6 .1 red with mfa 540 on 12 v if you hold yer hand at the bow and not let it go forward at full noise it will bury the stern
Is there such a thing as too much power on a Tug? from what I have seen the Dickie is fairly robust, and a couple of well handled examples should easilly cope with even 1:76 scale warships of the biggest proportions... Do you have any photos of the reduction set up please? Eventually I want to build a warship of some kind (probably a battle cruiser type) when I have gained alot more experiance in things model boat... I don't think I will try and bury the stern...
however I still think tug racing could be amusing! {-) O0
(http://i1266.photobucket.com/albums/jj529/atomicmaloo/MODEL%20BOAT%20PIC/DSC00942_zps662312b0.jpg)
Finally, Shiny parts ;D
Sean
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HERE IS A PDF of all the motors they make
http://www.mfacomodrills.com/pdfs/gearbox_colour_brochure.pdf
and a pic of mine is on page 9
sorrey about the size of the page (dont know how to enlarge it) theres more spec lower down on the page to
(http://i1266.photobucket.com/albums/jj529/atomicmaloo/MODEL%20BOAT%20PIC/mfa.jpg)
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you my or my not have seen this
http://www.modelboatmayhem.co.uk/My_models/31%20Dickie.htm
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Guys....this one had me scratching for the grey cells :(( until I saw that the FWD motors were actually for the reversable pitch propellers
This electrics/motors are a real credit to the builder :-)) ...... http://www.youtube.com/watch?v=JXMtpmDD06I (http://www.youtube.com/watch?v=JXMtpmDD06I)
Here is another link to the bow thruster setup....http://www.youtube.com/watch?v=xjCFhQzdWhI (http://www.youtube.com/watch?v=xjCFhQzdWhI). ........Derek
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WOW it amassing what is out there
great stuff
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here is a bit of info i found about sizing motors /props etc
http://www.building-model-boats.com/model-boat-motor.html
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Thanks all of you for the bits and bobs of advice, guidence and putting up with me and my curiosity!
All the best
Sean