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Author Topic: Model narrowboat which won't steer  (Read 15914 times)

WCW

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Re: Model narrowboat which won't steer
« Reply #25 on: October 13, 2006, 09:52:54 AM »

To counteract any effects of the extra weight from the internal strengthening, I have taken the lead-acid battery out (1300g) and replaced it with 2 7.2V nicad packs (800g).  This makes the boat weigh the same as your one without internal reinforcement.  When sailing it at the lake on a day with no wind or chop on the water, it still steered just as badly.  From this I don't think the weight is the problem.  The servo is fixed by a wire clip, it was attached to the servo when I posted the boat to you. 

I hope to get to the Warwick boat show, if I do I will bring the narrowboat and demonstrate the problem to you. 

Regards,

WCW
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George Turner Models

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Re: Model narrowboat which won't steer
« Reply #26 on: October 13, 2006, 11:46:06 AM »

Look forward to meeting you.

Sharon
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tigertiger

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Re: Model narrowboat which won't steer
« Reply #27 on: October 14, 2006, 03:24:43 AM »

Look forward to meeting you.

Sharon

Sharon, WCW,

Please let us know the outcome.
From this forim I can see that may people go the 'non-standard' route. There may be a useful lesson, even if it is a simple one.
Even if there is no clear resolution, I would be interested to hear.
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malcolmfrary

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Re: Model narrowboat which won't steer
« Reply #28 on: October 14, 2006, 10:41:43 PM »

It might be a silly question after all this time, but I've just had another look at the picture at the start of the thread - how fast is it going?  In the picture the water looks very busy, and I would assume that a canal boat would proceed at a fairly leisurely pace. 
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WCW

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Re: Model narrowboat which won't steer
« Reply #29 on: October 15, 2006, 10:04:49 PM »

The narrowboat is sailing quite fast in the photo, it was another club member sailing it while I took photos.  When I've sailed it it's mostly been at a slow speed, slightly faster than a scale 4mph. 

Regards,

WCW
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George Turner Models

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Re: Model narrowboat which won't steer
« Reply #30 on: October 17, 2006, 01:26:37 PM »

In the circumstances George and I have decided to give WCW a full refund for the price of his kit as he is obviously not happy with the handling of his boat. I can only re-emphasise that this has been the only complaint with all the kits sold & we have done our utmost to rectify the situation.

Look forward to seeing you all at Blackpool, please don't spend all your money on John's stand but share it with us. ;D ;D

Sharon.
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Martin [Admin]

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Re: Model narrowboat which won't steer
« Reply #31 on: October 17, 2006, 05:56:29 PM »

Just to prove the point, this is Georges model I tested at the Ellesmere show.....
http://www.modelboatmayhem.co.uk/wwwpics/PICT1396.MOV
( Quick time 10.2 Meg -  )

Martin
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WCW

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Re: Model narrowboat which won't steer
« Reply #32 on: October 18, 2006, 04:36:48 PM »

Dear Sharon,

Thank you very much for the offer of a refund for my narrowboat kit.  Your help with the steering problem has been useful, many thanks.  The video Martin posted shows one steering a lot better than mine does. 

Regards,

WCW
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Stavros

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Re: Model narrowboat which won't steer
« Reply #33 on: October 18, 2006, 11:40:51 PM »

WCW this might be a silly question but have you considered changing the rudder servo as I have had a similar probelm with a tug,it was nicknamed the drunken sailor by the lads at the club!!!!bloomin comedians.Try it as mine was allright on the bench,rudder was allways straight when it came back from sailing but would it go in a straight line no way it had a mind of it's own,try it,it could be the problem,if it is please throw it as far as you can or alternatively frame it and present it to Sharon with a bouquet of flower ;) :D
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WCW

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Re: Model narrowboat which won't steer
« Reply #34 on: October 30, 2006, 01:58:30 PM »

Changing the servo had no effect unfortunately.  Thanks for the suggestion though. 

WCW
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Stavros

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Re: Model narrowboat which won't steer
« Reply #35 on: November 07, 2006, 11:34:16 PM »

Paul good tip that one just set up yaucht with one set up changed at the lake due to other probs sent yaucht out could not understand for a second whyu it did not want to sail in st line,brought it back to see thta rudder throw was different wiht the new set,felt a right plonker(Welsh druid need not reply!!!!!!!!!!!!)
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tobyker

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Re: Model narrowboat which won't steer
« Reply #36 on: November 09, 2006, 11:59:36 PM »

Strange. Have you checked the fore and aft trim of the boat? With a long flat bottom she won't steer if she is at all down by the bows, and this could cause her to swing either way. I'd even try a bit of ballast to get her down by the stern a bit, to see what effect that has.
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Daryl

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Re: Model narrowboat which won't steer
« Reply #37 on: November 10, 2006, 08:51:27 AM »

This is of no help but last weekend in the first round of our winter sereis steering competition one of our members had a GT Narrow boat and had nearly a clear round (10 obstacles). It steered very well, daft question but did you deveate from the instructions?
As with the above post my colleagues boat was trimmed level, I did mention to him about this post and he was mystified.

Daryl
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WCW

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Re: Model narrowboat which won't steer
« Reply #38 on: November 12, 2006, 10:05:13 AM »

Thanks for the fore-and-aft trim idea tobyker.  My boat floats level but digs the bows in when going along.  I'll trim it bow up and test it to see if it improves the steering.  It may be a while before I can test this though as the lake I sail on has been drained to be cleared out. 

psships, I'm afraid I can't afford a computer radio, I'm just using a Hitec 27MHz Ranger 2 set. 

Daryl, I added a plasticard framing to support the battery but otherwise it is as instructions.  The extra weight of the framing is compensated by using a smaller battery. 

Martin, I sadly won't be at the International Model Boat Show as it's a bit far to travel. 

WCW
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EXBoat

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Re: Model narrowboat which won't steer
« Reply #39 on: November 12, 2006, 10:24:44 AM »

It's all down to the torque of the motor, the boat will turn in the opposite direction to the rotation of the motor, you adjust the rudder on it's shaft until you get the boat running straight.
the trim control on the radio control system may be enough to cure the problem.

EXBoat
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tobyker

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Re: Model narrowboat which won't steer
« Reply #40 on: November 12, 2006, 11:59:57 PM »

WCW, your description of the bows digging in confirms my view. Although I've not seen the prop shaft angle, I reckon this may be pushing the bows down, and making the boat unsteerable. Most long keel boats are designed with a bit of stern drag. I know that if i put my heavy bro-in-law in the bows of my canadian canoe I can't steer it at all - get him to sit a bit further back and she goes fine. You may have to opt for a more scale ie slower speed, involving less upwards thrust - but by all means try a bit of weight in the stern first. Good luck.
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Abuelo3

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Re: Model narrowboat which won't steer
« Reply #41 on: November 13, 2006, 10:41:20 PM »

Hello from Veracruz, México
Did you put some Resistances at the motor in order to not have "electric noise"  :oat the radio receiver, It is the diameter of the propeller larger than the length of the ruder.

best regards.
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wombat

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Re: Model narrowboat which won't steer
« Reply #42 on: November 15, 2006, 11:13:03 PM »

Hi WCW,

Watching "Narrowboat Afloat" on Real-Time, all the narrowboats seem to be running stern down - the bows seem to be 6" to 9" higher than the stern

Tim the Wombat
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Malc Reade

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Re: Model narrowboat which won't steer
« Reply #43 on: November 15, 2006, 11:34:19 PM »


Tim

Funny you should mention that..

We saw a narrowboat on a low-loader in transit on the way down to the Warwick show last week, and it had certainly been floating aft-down by the amount that you mention in your post judging by the very obvious water line.

It might be a solution to this long running problem?

Regards, Malc


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andywright

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Re: Model narrowboat which won't steer
« Reply #44 on: November 16, 2006, 08:07:08 AM »

All boats steer better slightly bow up, bow down and they are like a round log. Water depth also has a bearing on this matter, though I don't think at model size we have to worry about it. Heavy weights ie batteries need to be as low as possible otherwise when turning the vessel will tend to heel to the outside of the turn, especially a displacement type craft, this does not apply to fast boats.
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Scottie

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Re: Model narrowboat which won't steer
« Reply #45 on: November 18, 2006, 07:59:36 PM »

I had exactly the same problem with my ro/ro ferry although my set up was different. I have twin motors. props and rudders. At first I made rudders to 'scale' according to the plans and she wandered all over the lake just as WCW's narrowboat is doing.

So, I hear you all say, what was my solution?

BIGGER RUDDERS!!!!

I made two new rudders at twice the area of the originals - longer front to back and only slightly deeper than the first ones. She now sails in a straight line without any messing.

This may or may not cure your problem but it did for me.

Scottie
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wombat

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Re: Model narrowboat which won't steer
« Reply #46 on: December 12, 2006, 09:49:00 PM »

Working on my narrowboat design, another though occurred to me.

If you have the weight concentrated at the stern and the bow, the whole thing is effectively a dumbell. With a long, narrow hull, this is more acute. The whole thing will be unstable and will tend to oscillate under steering

Tim the Wombat
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HS93 (RIP)

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Re: Model narrowboat which won't steer
« Reply #47 on: December 12, 2006, 10:05:53 PM »

Has anybody seen the program on discovery home with Alan Herd ,his boat has a permanent list to one side ,once you notice it you cannot keep noticing it  Peter
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tobyker

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Re: Model narrowboat which won't steer
« Reply #48 on: December 12, 2006, 10:06:33 PM »

I think the mass centralisation thing applies more to bikes and cars which rely on friction grip at the ends for roadholding. In boats which sit in rather than on their operating medium, the shape of the immersed portion, rocker and drag probably have more influence. If you were dealing with a very fast fin keel sailing boat, you might get a bit more speed in coming about if you kept the ends lighter, and this may also be desirable to reduce pitch in a fine ended craft. For narrow boat steering at scale speeds, I would venture that some keel drag and keeping the weight low are probably the essentials.
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Colin Bishop

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Re: Model narrowboat which won't steer
« Reply #49 on: December 12, 2006, 10:39:07 PM »

A shallow lake and wheels would probably cure the problem....

Seriously, the distribution of ballast will affect the steering characteristics although, as has been pointed out, it is by no means the only, or even the most predominant influence, depending on the type of hull and the position of the power source. No keel means that a boat is likely to "skid" in the turn. A long keel boat will tend to steer a straight line ahead but be a pig to steer in reverse. A central keel will make the boat more sensitive, possibly excessively so, so you have to apply constant helm corrections. As far as weight is concerned it's best to either concentrate it amidships or more or less equally along the length of the hull. If it's at the ends, which would be pretty unusual, then it would adversely affect steering. A balanced or semi balanced rudder is usually better than the pintle hung variety and of course, if it is directly in the propwash then steering will be much more positive. My previous full size yacht had the outboard slung on the transom alongside the rudder which meant that you had no control until the boat was making appreciable headway either forward or astern which could make things difficult at times. My present boat has the outboard in a well just forward of the rudder which makes it much more responsive. You do however have to watch for the stern coming out as the boat turns as she pivots around two thirds of her length from the bow. It's all too easy to be watching what the front end is doing without realising that the stern is about to clout the boat in the adjacent berth!

All this presupposes a flat calm. Introduce the effect of windage and it all gets even more complicated!
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