Topic: Props/Multiple motor single shaft drive (Read 7379 times)

sean Half-pint works · « **on:** February 14, 2013, 03:02:08 pm »

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

Tug-Kenny RIP · « **Reply #1 on:** February 14, 2013, 03:07:46 pm »

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

sean Half-pint works · « **Reply #2 on:** February 14, 2013, 03:23:35 pm »

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

sailorboy61 · « **Reply #3 on:** February 14, 2013, 03:28:27 pm »

Its a Kort nozzle - available from numerous suppliers - I use Marks Model Bits and or Steve at www.modelboatbits.com.

sean Half-pint works · « **Reply #4 on:** February 14, 2013, 03:30:38 pm »

Thats the one!

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

Thanks for the link!

Netleyned · « **Reply #5 on:** February 14, 2013, 03:36:01 pm »

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

sean Half-pint works · « **Reply #6 on:** February 14, 2013, 04:04:12 pm »

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

Tug-Kenny RIP · « **Reply #7 on:** February 14, 2013, 04:32:50 pm »

A three bladed Brass prop would be the best for a Kort nozzle.

Ken

sean Half-pint works · « **Reply #8 on:** February 14, 2013, 04:39:00 pm »

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

Tug-Kenny RIP · « **Reply #9 on:** February 15, 2013, 12:31:22 pm »

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

old shrimper · « **Reply #10 on:** February 16, 2013, 02:17:17 am »

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

BarryM · « **Reply #11 on:** February 16, 2013, 09:02:14 am »

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/ and from Prop Shop 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

Tug-Kenny RIP · « **Reply #12 on:** February 16, 2013, 10:18:20 am »

Quote

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

old shrimper · « **Reply #13 on:** February 16, 2013, 10:29:24 am »

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

sean Half-pint works · « **Reply #14 on:** February 17, 2013, 02:16:26 pm »

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

Shipmate60 · « **Reply #15 on:** February 17, 2013, 02:34:07 pm »

You have it about right.
Why change the motor and prop though.
Why not leave the drivetrain as original.

Bob

sean Half-pint works · « **Reply #16 on:** February 17, 2013, 02:45:11 pm »

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

Shipmate60 · « **Reply #17 on:** February 17, 2013, 02:49:20 pm »

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

sean Half-pint works · « **Reply #18 on:** February 17, 2013, 02:52:56 pm »

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

Netleyned · « **Reply #19 on:** February 17, 2013, 03:03:16 pm »

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

sean Half-pint works · « **Reply #20 on:** February 17, 2013, 03:10:38 pm »

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

BarryM · « **Reply #21 on:** February 17, 2013, 04:12:21 pm »

Quote from: sean Half-pint works on February 17, 2013, 02:52:56 pm

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

sean Half-pint works · « **Reply #22 on:** February 17, 2013, 04:18:10 pm »

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

Sean

BarryM · « **Reply #23 on:** February 17, 2013, 04:40:57 pm »

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

sean Half-pint works · « **Reply #24 on:** February 17, 2013, 04:48:54 pm »

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

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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Author Topic: Props/Multiple motor single shaft drive (Read 7379 times)