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More hovercraft stuff - the Clyde this time

Posted: Tue Mar 11, 2008 2:56 am
by Telo
Two trips a day, with up to 130 npassengers at 40kts, between the SECC pontoon in Glasgow, Braehead, East India Harbour in Greenock and Dunoon.

More at BBC

Re: More hovercraft stuff - the Clyde this time

Posted: Tue Mar 11, 2008 11:34 am
by Superstrath
[quote="Shard"]Two trips a day, with up to 130 npassengers at 40kts, between the SECC pontoon in Glasgow, Braehead, East India Harbour in Greenock and Dunoon.
quote]

That should read 12 passengers, I think.
I don't fancy the notion of "Another bonus in using the hovercraft would be its ability to navigate through bridges which do not open, according to Mr Macleod"
That sounds like a recipe for disaster to me, these beasts appear to handle worse than my Snowgoose.

Posted: Tue Mar 11, 2008 11:37 am
by jim.r
Do you recall the Hovercraft that ran from Largs to Millport? quite a while ago..

Re: More hovercraft stuff - the Clyde this time

Posted: Tue Mar 11, 2008 9:44 pm
by DaveS
Superstrath wrote:I don't fancy the notion of "Another bonus in using the hovercraft would be its ability to navigate through bridges which do not open, according to Mr Macleod"
That sounds like a recipe for disaster to me, these beasts appear to handle worse than my Snowgoose.
A good few years ago I crossed the channel on one of the SRN4s working near its operational limit (F7?). The motion was incredible: the normal 3 degrees of freedom of a boat plus sliding bodily sideways, tipping up on diagonally opposite corners, and occasionally coming to a shuddering halt when the wave height was enough to let the air escape from the skirt. The amount of yaw was particularly worrying. Crossing a tanker, we swerved back and forward between "easily missing" and "on collision course". We eventually missed his stern by about 100m. It was obvious that the driver had a fight on his hands.

Posted: Wed Mar 12, 2008 12:30 am
by Silkie
I thought it was six degrees of freedom; the three translations of surge, sway and heave and their corresponding rotations; roll, pitch and yaw?

Feeling increasingly uncomfortable, as I type, with the dawning realisation that I'm speaking to a proper engineer. :shock:

Degrees of freedom

Posted: Wed Mar 12, 2008 5:40 pm
by DaveS
You are, of course, absolutely right.

The motion of any object can be completely defined at any point in time by a combination of all applicable differentiations of distance wrt time (i.e. velocity (ds/dt), acceleration (d2s/dt2), jerk (d3s/dt3), etc.) applied to each of the three degrees of translational freedom, and differentiations of angle wrt time (i.e. angular velocity (dw/dt), angular acceleration (d2w/dt2), etc.) applied to each of the three degrees of rotational freedom. *

I suppose what I was really trying to say is that some of these combinations seem to happen with hovercraft but not with boats. And if you're only used to the combinations which happen with boats, finding yourself subject to others is likely to be surprising! :o

* the numbers should really be superscripts, and the w should really be a lower case omega, but a couldna see how tae dae that...

Re: Degrees of freedom

Posted: Wed Mar 12, 2008 6:11 pm
by jim.r
DaveS wrote:You are, of course, absolutely right.

The motion of any object can be completely defined at any point in time by a combination of all applicable differentiations of distance wrt time (i.e. velocity (ds/dt), acceleration (d2s/dt2), jerk (d3s/dt3), etc.) applied to each of the three degrees of translational freedom, and differentiations of angle wrt time (i.e. angular velocity (dw/dt), angular acceleration (d2w/dt2), etc.) applied to each of the three degrees of rotational freedom. *

I suppose what I was really trying to say is that some of these combinations seem to happen with hovercraft but not with boats. And if you're only used to the combinations which happen with boats, finding yourself subject to others is likely to be surprising! :o

* the numbers should really be superscripts, and the w should really be a lower case omega, but a couldna see how tae dae that...

erm are'nt you overcomplicating motion sickness?

Posted: Thu Mar 13, 2008 10:29 pm
by Silkie
Seems simple enough to me.