Who's In Control?

[Thistle]

Who\'s In Control?

A question from this week's New Scientist (26 Feb 2005) (The Last Word, p93)
"Wheeled vehicles steer from the front. So why do boats and most planes steer from the rear, even boats that have no propellers?"

Answers, please, to lastword@newscientist.com - and, of course, published here first!

 

[webcraft]

Re: Who\'s In Control?

The raggie answer to Volvo's front-facing IPS drives . . . who is going to be the first with a bow rudder?

- Nick

 

[longjohnsadler]

Re: Who\'s In Control?

All motion is relative (Einstein)
And my sister (who's got a GCSE in physics) thinks you're talking bollox.

 

[Colin_S]

Re: Who\'s In Control?

Fork lift trucks???

 

[longjohnsadler]

Re: Who\'s In Control?

Ausa dumpers?

 

[No1_Moose]

Re: Who\'s In Control?

Wouldn't it be best to have a bow and stern rudder?
I would think that a boat would be difficult to control with just a forward rudder because you will be turning the relativly light bow against the heavier stern. A forward rudder will be more susceptible to damage in the case of powered vessels you will lose the prop wash over the rudder and hence manouverability under power, unless of course a sail drive was mounted back to front in the bow /forums/images/graemlins/grin.gif. I would imagine that a forward rudder will have less braking effect than a stern rudder.
Does the speed of the water increase around a hull (i am thinking that the stern is a bit like the top of a wing) as it leaves the stern? If it does then this advantage would be lost.

I don't actually have a clue!

 

[Aries]

Re: Who\'s In Control?

Think about when you are motoring backwards. If you have a tiller the forces on the rudder are very different to going forwards. Its all down to fluid dynamics.

 

[Greenwichman]

Re: Who\'s In Control?

"Miss Britain" - first boat to do a ton (1930s) - has her rudder in the bow. She is on display in National Maritime Museum Greenwich.

 

[eyehavit]

Re: Who\'s In Control?

Its about traction, steering is affected in particular by traction and the lack of it, especially radial to the direction of travel. Traction and steering depend on the friction between the tyres of a vehicle and the road just the same as between a boat and water. However, boats just don't have the same radial traction as a car or truck and will quickly slew out of control with only a fwd rudder. Aft rudders evolved because they make it much easier to correct the tendency to slew. The turning of the rudder also produces a braking force and because it is applied to the aft of the boat tends to straighten rather than compound the problem if mounted fwd. On the other hand, icy wet greasy roads don't do much for front wheel steering.................

 

[Guest]

Re: Who\'s In Control?

Rear wheel steering on road vehicles is fundamentally unstable, due to reversal of slip angles between initiating and maintaining the turn; this would be seriously dangerous on anything other than low speed vehicles.

I am inclined to think that a front rudder would work ok, but if you really want to know why small boats have a rudder at the rear, ask a Viking, next time they raid.