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Author Topic: How to tow?  (Read 9926 times)

Martin (Admin)

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How to tow?
« on: September 15, 2006, 12:32:47 pm »



Discussion point....

How much harder a discipline is towing with a single screw tug that the latest twin screw , bow thruster & Voith Schneider type type tugs?

How do the basic principles differ?

( OK I know I know nothing about model boats! so please keep it simple!  ) ::)

Martin.
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Shipmate60

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Re: How to tow?
« Reply #1 on: September 20, 2006, 11:28:02 pm »

Martin,
It depends what you are towing.
Large objects can be easily towed by single screw tugs as the tow acts like a large sea-anchor.
Twin screw, Voith etc are more manouverable and more useful in pushing on, to position easier.
The more manouveral tugs are more useful in confined waters.

Bob
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cbr900

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Re: How to tow?
« Reply #2 on: September 21, 2006, 04:30:33 am »

Towing of any sort is not that difficult single, twin or extra multi shafted, but for being able to maneuver the towed object twin minimum and preferrably bow thruster will make the job much simpler..


Roy
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towboatjoe

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Re: How to tow?
« Reply #3 on: September 21, 2006, 01:38:06 pm »

I would have to say a pilot of a single screw would know the quirks of his vessel very well. Everyone knows that a single screw tends to pull to one side due to the rotational thrust of the wheel. It's even more evident when backing.

I believe a pilot would steer his tow to take advantage of the wheel thrust and avoid the weakest manuvers as much as possible.
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Beachcomber

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Re: How to tow?
« Reply #4 on: September 21, 2006, 02:01:24 pm »

If you are using 2 tugs, use the most powerful tug as the stern ( steering ) tug
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Red_Hamish

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Re: How to tow?
« Reply #5 on: September 21, 2006, 04:58:46 pm »

Hello all, another point is when using a pair of tugs if the one with a larger bollard pull only has a single screw it will still be the lead tug, as the twin screw is always the rear tug  :o . Similarly if the pair of tugs have twin props then the weaker one will be the lead tug  ::) Best part of finding out is do it in company whether there are encouraging comments or derisive comments, it is all good fun  ;D

cheers

Jim  ;D
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Re: How to tow?
« Reply #6 on: September 24, 2006, 10:26:58 pm »

above all, DO NOT GET INTO A BROADSIDE ON POSITION TO THE TOW, otherwise the tow will flip your model over, and you may loose it

this is exactly what caused my Southampton to roll over.  Luckily for me, she has a lock down hatch in the front and rear, making the hull air tight, if it had not got such feature, Southampton would have gone under.

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meechingman

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Re: How to tow?
« Reply #7 on: September 25, 2006, 09:18:03 am »

Use a 'gob rope'. That's a simple loop of rope fastened near the stern of the tug through which the main towline passes. You set the length of this loop to suit and, as the towing angle gets too big, the weight of the tow gets transferred away from the main line's hook or bitts to the gob rope's anchor point. Result, no upturned, or 'girted', to use the correct term, tug!   ;D

The pic shows the gob rope on my tug 'Heighton' [ex 'Southampton']



Andy G
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cbr900

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Re: How to tow?
« Reply #8 on: September 25, 2006, 01:25:15 pm »

ANDY,

Would it not work just as well to pass the tow line through the arch that you have the gob line wrapped around, would this not keep the tug from going belly up....


Roy
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andywright

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Re: How to tow?
« Reply #9 on: September 25, 2006, 08:36:21 pm »

Not in real life, the gob needs to slackened or tightened depending on where you want to put the tug, you have trouble exerting side force if the gob is tight.
I find on model tugs a steerable kort is the next best thing to twin korts.
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DavieTait

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Re: How to tow?
« Reply #10 on: September 25, 2006, 09:16:31 pm »

As with real life tugs the main thing to consider is motor power ( modern Tugs are very powerfull ) and the depth the propellor(s) are. The best fishing boats are the ones that have the prop as low as possible so that all the motive force gets used , too close to the surface means greatly reduced propellor efficiency. For a tug i'd consider fitting it with internal ballast tanks that can be filled once the tugs on the water , this would let you have a nice heavy tug for towing stability when on the water and in use but not too heavy for transportation , etc.

I've had to tow several fishing boats ( with another fishing boat ) over the years and with a longer tow rope we always put a car tire in the middle with the tow rope attached so that there was a loop of spare cable below. This acts as a shock absorber and makes the tow easier to handle. I'd doubt that this would be nescessary when towing with models but if you have to use longer tow ropes then its something to consider.

Davie
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Re: How to tow?
« Reply #11 on: September 26, 2006, 03:20:49 am »

I have no idea what I am talking about, but meechingmans pic shows the tow point moving, if it were a fixed tow point, would it not be better, and the gob rope pulling off centre would this not cause the tug to slide sideways instead of pulling straight.
I don't know that is why I am asking...


Roy
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Dave_Sohlstrom

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Re: How to tow?
« Reply #12 on: September 26, 2006, 05:38:17 am »

Hello All

I spent 4 years oystering on Willapa bay Washington State USA. During those 4 years we towed our 70' oyster dredge and 50' oyster barges with a 36' tow boat with a single 6-71 diesel engine for power. Tow post was well fwd of the prop and rudder. We made up to the tow with  variable lenght of tow line depending on weather conditions and space to manover. Tow line was tied to the tow post in such a way that it passed thought center of the tow post and could be cast off without fouling the tow post. We NEVER made any manover that put the tow line at a greater than about 30 degree angle to the center line of the tow boat.
It was suggested to pass the tow line thought the arch to control the angle of the tow line to the vessel. This will not work if the arch is even with or aft of the prop and rudder because you would lose all manovering control. the tow vessels stern has to be able to swing as she turns.

I hope that this may help some and I am sure that I may be preaching to the choir

Later

Dave
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meechingman

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Re: How to tow?
« Reply #13 on: September 26, 2006, 10:02:47 am »

Firstly, running the towline through the arch would be too restrictive, although if you look on this site....
http://www.xsbb.nl/phpbb/index.php?id=TUGSPOTTERS&sid=1b4ca0c558daae73982df913656c69f1
you will find a thread on 'Towing Pod', which does just what you suggest! I like a bit more slack on the gob rope.

Secondly, the hook on this tug is a little weak for my liking. The weight is all on the bitts, the line goes loosely through the hook just for show. It doesn't move much.

Andy

PS: I second Andy's comment about single steerable korts. I was brought up on a real twin screw tug, great to handle. Heighton has twin screws but only[for the moment] just one ESC and is outperformed by my other tug which has a steerable kort. When I get the second ESC in Heighton for independent motor control she'll perform more like she should!
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andywright

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Re: How to tow?
« Reply #14 on: September 26, 2006, 03:04:49 pm »

In answer to cbr's point, if the gob rope is tight, the tug will hardly manouvre side ways at all, the secret with model tugs is to have enough slack to manoevre, with out 'girting', but not to much. Unless you are a wiz kid modeller and can build a gob capstan which works, theres food for thought, got to build a working winch first.
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BlazingPenguin

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Re: How to tow?
« Reply #15 on: October 17, 2006, 12:53:11 pm »

In relation to model tug boats........VERY SLOWLY!  ;D

John Hughes was my partner at last years Featherstone 'Tug In', having never done it before, that was his advice to me, which I followed....and we came 1st! couldnt get my head in the car!
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norry

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Re: How to tow?
« Reply #16 on: October 18, 2006, 10:55:52 pm »

The Experts at Work...

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Channel

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Re: How to tow?
« Reply #17 on: November 18, 2006, 10:44:45 am »

Hi Chaps,

If you're interested in knowing more about towing why not keep a look out for a book called 'Tug Use In Port' . . . its a technical manual for tugmasters and used heavily in training.

One thing that really winds me up at model tug towing events is seeing a single or twin screw tug towing over the bow whilst acting as stern tug. I've worked as a AB and Mate onboard tugs for a number of years (mainly single and twin screw) and have only ever done this twice (both times on barges) - unless of course we were pushing up with the bow on the ships side. Be brave sling the towiline on the hook and gog down - but not too mch give yourself a bit of slack to be able to keep steerage . . .

Graupner's Southampton makes a good stern tug if you increase the size of the props or make her independant screw. I find as bought she can't manouvere very well.

I've been on a tug that got girted whilst docking a ship  . . . interesting experiance but she went to an angle approx 60 degrees (!!!!) then held there and once she'd slowed the ship down popped back up. It was caused by the gog slipping - we later managed to get it back down and continue . . . . . . (only damage done was to our underpants!!!!!)

If you want to see some good pictures of tugs in action keep a eye on www.tugspotters.com

Cheers
Chris


Cheers
Chris
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Roger in France

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Re: How to tow?
« Reply #18 on: November 19, 2006, 07:34:35 am »

"Tug use in pot" ! Would that be a pint pot?

Please what is "...girted..."? And, "...went to an angle of 60 degrees...." tipped which way? Sounds terrifying no wonder you behaved a tad childishly in the pants dept.

Roger in France.
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bosun

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Re: How to tow?
« Reply #19 on: November 19, 2006, 09:49:51 am »

As a lad working on the tugs out of Newport, we used what we called a KANT rope,  basically the same thing as a GOB rope already described.This rope was the only rope that we carried for towing, as we always used the ships ropes, the kant rope was a massive nylon rope made up of three  sometimes  four strands, each strand a big as a man,s forearm, we would have to splice these ourselves, when I say we, that would be two deckie,s aged 15/16, and a mate who was usually about 18, sometimes it would take all day, and was always booked in as overtme, The rope would have a great big shackle attached to the eye, and that would be shackled over the tow rope. Depending on what the skipper wanted , it would then be either made fast to the stern bollards, or run through the bollards, to a massive steam capstan, the kant rope was allowed to stay slack untill the tug turned and then the winch would  be used bellowing great clouds of steam and pull the tow rope closer to the bollards, thus changing the angle of the tow from midships to the stern . On one occasion the kant rope was to made fast to the stern bollards, and the stain was so much that the bollards were torn out of the deck killing one of the young deckies. I also remember there was a tug at the time working out of Liverpool and she was turned over with the loss of 4 men when she girted.
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Channel

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Re: How to tow?
« Reply #20 on: November 19, 2006, 09:42:56 pm »

Roger,

Being girted is when the tug goes 90 degrees to the tow and gets pulled over . . .

The tug went 60 degrees over to starboard (docking into Swansea at the time) - I did have my camera with me but was too busy looking for a escape route if needed !! The tug was quite big for the ship - thats probably helped us survive!

Chris

"Tug use in pot" ! Would that be a pint pot?

Please what is "...girted..."? And, "...went to an angle of 60 degrees...." tipped which way? Sounds terrifying no wonder you behaved a tad childishly in the pants dept.

Roger in France.
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norry

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Re: How to tow?
« Reply #21 on: November 19, 2006, 10:12:35 pm »

                  ...Hi guys...

Only had one experience where we were almost girted by a certain popular Clyde Puddler whilst towing her stern first out of Irvine...The Puddler overtook us as her engines were put astern whilst we were still connected to her...we tripped the tow hook & let them have their rope back at a fair rate of knots...
There were some choice words from our Skipper to her Skipper as he was told not to touch his engines until we had towed his vessel clear of the harbour...

...Regards...Norry...
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Shipmate60

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Re: How to tow?
« Reply #22 on: November 20, 2006, 12:24:32 am »

Many years ago a TID tug was girded in Chatham 2 basin, Engineer killed and took nearly a week to find her as she was turned turtle and moving.

Bob
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