"Jim Wilkins" writes:

"Richard Smith" wrote in message ...

"Jim Wilkins" writes:

"DoN. Nichols" wrote in message
...

On 2020-03-22, Richard Smith wrote:
Hello all




==========================

Is this a work boat?
https://www.zf.com/products/en/marin...cts_29102.html

Link goes to webpage showing a thruster for boats. ZF suggests you
install at least one of these on your boat and you will benefit. This
propeller can retract. So the vessel motoring normally on a voyage
doesn't have to drag it through the water.

A thruster propels a boat in the direction the thruster is pointed.
"Bow thrusters" are in a tube through the bow and only propel the bow
around "sideways". They are very useful.
This will propel the boat in any direction. Notably useful.
But...

There's a balance to reckon - is it more advantageous to have than the
disadvantages.

A work boat might have one.
If it were judged worth installing one.
Given - negative side
* capital cost of the "as supplied" equipment
* the installation cost
* the running cost
* the risk to the boat if the equipment malfunctions
* the risk to the boat if the installation malfunctions
Explaining the latter - without proper compartments, a leaking
bow-thruster tube can be the reason a boat sinks.

To the benefit:
* the boat might be more capable of doing manouvring operations,
perhaps pushing barges into awkward locations - and customers might
preferentially seek its services over other boats.

As best as I can say.

Ask an expert if it matters to you.

Rich S
============================

Actually I was thinking of a work boat that uses GPS and Azipods to
hold its position while working on a bridge etc in a tidal estuary. I
considered that sort of problem when I was at Segway. It might be a
good field for someone who understands both fabrication and higher
math, such as complex numbers and servo loop stability. If the arc
interferes with satellite reception you could use pseudolites on
shore.

Sorry Jim - many apologies - I realised after initial reply that you
were likely to mean this - that a boat could hold position with an
"autopilot" using GPS signals.
The GPS signal is processed and commands are sent to thrusters.
Holding position - "position over ground" - is very very commercially
useful.
eg. for a lot of marine civils installation.
Some pipelay vessels now hold just on engines / thrusters and GPS. I
once calculated you'd burn something like 4 tonnes of fuel an hour
laying a pipeline - nothing in the current scheme of things - cost in
billions of $ overall.
Anyone correct / give a more accurate figure on that?
Rich Smith