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Author Topic: Director Paddle Tug  (Read 3618 times)

Buccaneer

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Director Paddle Tug
« on: October 24, 2013, 07:40:09 PM »

I have just been given a nicely made Director Class Paddle Tug, made on the 39 inch Kingston Mouldings Hull, by a fellow club member. He finds it a bit awkward now to lug up and down stairs to his flat. It has no motors as he tried a couple of options, not sure what, but just could not get it to go at any reasonable speed. It has well made 120mm diameter paddle wheels directly from the plans. I tried the 2 Clyde Models 300rpm motors from my own paddle tug but on a flat calm day and at full power the tug barely made walking pace. Any wind or waves and it just would not have coped.
 
Does anybody have suggestions for a motor fit? I would ideally like two independently driven motors with a belt drive. Has anybody out there built one and got it running nicely? All inputs gratefully received!
 
John
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mickyrubble

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Re: Director Paddle Tug
« Reply #1 on: October 24, 2013, 08:25:11 PM »

hi ,
 i have the Glasgow paddle tug and was told that the original paddlers had fixed paddles (not independent).Mine came with a MFA 540 geared 6:1 O0 O0 O0
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Channel

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Re: Director Paddle Tug
« Reply #2 on: October 24, 2013, 09:33:00 PM »

Director class were built with independent paddles, the same was true for many paddle tugs (the steam ones especially).


I built a Director class model and sold it - always regretted it. Enjoy her!



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derekwarner

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Re: Director Paddle Tug
« Reply #3 on: October 24, 2013, 10:09:15 PM »

Buccaneer ......you will find oodles of postings on Director Class paddle tugs  on the Paddleducks.uk website......would be well worth reading up rather than reinvent the drive experiment's....Derek
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Derek Warner

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john44

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Re: Director Paddle Tug
« Reply #4 on: October 25, 2013, 02:45:22 PM »

I got my Geared units for my Glasgow from Kim Clyde Model Boats
who was of great help sorting out the correct ones for my boat.

john
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BarryM

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Re: Director Paddle Tug
« Reply #5 on: October 25, 2013, 04:36:57 PM »

John,
I used two Como Drills 919D - 501 Series geared motors running on 6 Volts, driving through 1:1 toothed pullies to feathering paddle wheels. The latter were constructed using the 'Model Maker' plans.  (I have scans of the original MM magazine articles on the Class if you are interested.)
The motor's output at 50:1 reduction is 158 rpm which is about 60 rpm more than you will ever need and some tweeking of the ESC is advisable to limit the revs.
Regards,
Barry M
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NFMike

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Re: Director Paddle Tug
« Reply #6 on: October 25, 2013, 11:27:25 PM »

Ooh! Grinder :)
She was working Gibraltar when we lived there ... about 50 years ago. I never actually went on her but did get out on Confident, the other 'big' naval tug there at the time (a more normal screw boat), once while the two of them were parking a carrier (no idea which one  :embarrassed:  ). Had a good view of Grinder frothing the water up.

Buccaneer

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Re: Director Paddle Tug
« Reply #7 on: October 26, 2013, 05:09:30 PM »

Many Thanks to you all for your suggestions. I had ben thinking along the lines of the Como geared motors so the figures are useful. I'll give Paddleducks a good search as well. Thanks again to you all.
John
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big bill

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Re: Director Paddle Tug
« Reply #8 on: October 29, 2013, 01:45:19 AM »

gday , just a word of warning , your set -up sounds OK, so why the low speed/thrust ??
please check the depth if the paddle floats, as my paddler (aussie side wheeler ) did a similar thing ,so i lowered  the paddle shaft ,so as the top of the floats was approx. 5/10 mm below the water surface , to fully submerge the floats on rotation
as the floats rotate , they scope out the water , w the floats submerged by 5/10 mm , you maximize thrust.
i could be sending you on a wild goose chase , but its worth looking at , food for thought
regards bill s 
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BarryM

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Re: Director Paddle Tug
« Reply #9 on: October 29, 2013, 08:41:14 AM »

John,
In your original post you did not mention whether your 'Director' had fixed or feathering wheels. I use the latter fitted at scale height and these operate fully immersed at the bottom of their rotation. The feathering action minimises any tendency to scoop water.
There is anecdotal evidence that this model benefits significantly from the feathering wheels but, even without them, I have never heard of the need to change the drive shaft height. When afloat, what is the proximity of the paddles on your model in respect of the waterline?
Barry M
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Buccaneer

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Re: Director Paddle Tug
« Reply #10 on: October 29, 2013, 12:53:31 PM »

Hello Barry and Bill,
I too am now thinking that Paddle height may be a possible cause. I have fixed blades, 22 mm wide, which are between 33-55 mm out from the centre. I have had the drawing instruments out and a quick full size drawing would suggest that if the blades are 10 mm below the water at the bottom of the stroke then they would be fully immersed for about 90 degrees of travel and enter/exit the water over an angle of 120 degrees.


I ballasted the model to the waterline painted on it and suspect, now, that it may have been too deep. There are support brackets under the paddle housing sponsons that may well be getting into the water and creating extra drag as well. My quick trial confirmed Derek's problems and with all your kind inputs I have a few areas to work on. Does 10 mm immersed at the bottom of the stroke sound about right?


Thank you again for your help, although I know that at the end of the day that is what we are all her for!!


John
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BarryM

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Re: Director Paddle Tug
« Reply #11 on: October 29, 2013, 05:00:57 PM »

John,
The sponson supports on Grinder are fitted such that their bases are just on the waterline and no more. If yours are fitted as per the Kingston drawing, then they should be similar.  Have a look here.
Barry M
 
 
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big bill

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Re: Director Paddle Tug
« Reply #12 on: October 29, 2013, 10:34:44 PM »

g'day john , be guided by barry  , who has built the model ,very nice too !!
looking at the photos, you can see what i was trying to say to you ,the floats look to be at least 10/15mm+BELOW the w/line , this allows the floats to push water at 100% , rather than as low as 30%-we have to allow the water to rush back into the space scooped out by the spinning floats , this does take time , if this doesnt happen , the float looses drive
this is also why i suspect , a larger diam. +more floats per wheel , may be more efficient , this seems to be the case w aussie side wheelers .
i also suspect that feathering p wheels do little to help in model size , but this is only my suspicions , i have to build a lot more models to find out .
 good luck
bill s 
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Buccaneer

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Re: Director Paddle Tug
« Reply #13 on: October 30, 2013, 07:23:22 PM »

Hello Barry and Bill,
I've had my model up on the bench where I can look at it directly from the side. The Paddle Wheels look right relative to the sponsons and supports. The waterline is marked with an 8mm wide red band and curves up slightly at bow and stern, which doesn't help things. I've ordered two Como Drills 1:50 motors and by looking carefully at paddle depth when ballasting I will hopefully end up with a better performance.
Thank's again for your inputs.
John
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big bill

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Re: Director Paddle Tug
« Reply #14 on: October 31, 2013, 04:52:40 AM »

gday john ,
always hard w a paddler ,performance is altered by hull shape ,paddle efficiency,and i suspect diameter.i use monerperm piles +3:1 reduction via t/belts , giving a paddle shaft speed , no load ,of approx. 300/350rpm,i can slow it down w the s/control on the water , but on a windy day , i use all the revs , but on better days , i can slow down the shaft revs , and the hull actually goes faster , i think this is the designed speed for the hull , i call it "walking the hull " i cant explain this any better .
by increasing the paddle shaft revs , i get more thrust , but create a lot more bubbles .
 the hull shape of the aussie paddler doesn't help , blunt bow
the tug hull should be easier to drive  .
my personal view , is that you need at least good thrust for a model , and wind doesn't help , so i now aim all my paddlers at 300/350 rpm , we can always slow it down w speed controls .
 i would like to have a go at a UK paddler ,but the building card is a bit full,and the file is growing every week !! it keeps me sane , to dream a lot +2 ither Aussie paddlers in the shed , under construction ,plans for no. 4 LOL
good luck , bill
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BarryM

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Re: Director Paddle Tug
« Reply #15 on: October 31, 2013, 08:34:09 AM »

Bill,
If you are getting more speed when you cut back the revs and create fewer bubbles then it's because your paddles are cavitating at the higher revs. All you are doing at the higher revs is introducing more air and the floats lose 'grip'; slowing down gives the paddles a chance to bite on the water and effective propulsion is regained.
Regards,
Barry
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big bill

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Re: Director Paddle Tug
« Reply #16 on: October 31, 2013, 09:46:43 AM »

hello barry ,
 you are right about the cavitation , but ,even w that going on , the extra revs does increase thrust ,as w full power , i have steerage way , but on the reduced revs ,as the wind came up ,i was loosing control of the model .to be fair to the model , the wind was a bit excessive , but it did blow harder ,as the day moved on .
with-out the extra revs +tank steering , i would have being blown across the pond , and in need of a tug !! as it was , i was able to retrieve the model , under its own power .the model wheels are only approx. 125mm in diam.,and i want to try the adelaide paddler ,in the same scale , which has much bigger p wheels ,177mm and 14 floats .
i have had a 1/18 adelaide pull up beside mine , and then pull away , w less revs on than my-self , thats why im suspicious of the relation ship between p wheel diam.+number of floats per wheel .
adelaide paddler has very large diam. paddle wheels , due to it being used as a towboat/tug , much bigger than most aussie paddlers
bill
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big bill

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Re: Director Paddle Tug
« Reply #17 on: November 01, 2013, 01:47:17 AM »

i was just wondering , if any-one had a view/opinion/experience w the different diam. paddle wheels/no. of floats on there models ??
it may make a difference w the choice of a new project .
im wary of small diam paddle wheel models now,and tend to choose larger diam. paddle wheel for projects , both adelaide and pevensey Aussie paddlers are larger in diam.+im using pev paddle wheel kits on ps rodney , due to lack of good info on vessel , she was burnt about 1875?? or later .
i know some feel that too many floats make a difference , but my paddler has only 8 per float ,and i was left behind by a slower revving , larger , adelaide .
also my hull shape is a blunt bow , adelaide tends to taper from the bow ,back to the front of the paddle box , both hulls are reasonably broad .
unlike a prop driven vessel , we cant just add revs to increase thrust , paddle wheels have a max. rev range
food for though??
bill s
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