Author Topic: Arctic/Offshore Patrol Ship AOPS  (Read 454603 times)

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Offline Colin P

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Offline Not a Sig Op

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Re: Arctic/Offshore Patrol Ship AOPS
« Reply #1651 on: December 21, 2018, 16:29:57 »
Wouldn't the back-EMF drop to zero and resistance drop to only the actually value across the coils, therefore causing the current to spike up, possibly limiting the ability of the generator to maintain the voltage, causing a brown out?

Pedantic, I know...

No, an ice chunk jamming in the props is taken into account when designing the system.

Worst case, your protection trips and shuts off the motor.

As an example, one vessel I worked on had a "boost" module for her generator exciter for exactly the scenario you described.

If the exciters couldn't handle the load, the boost module kicked in for a up to a preset time.

The timing on the motor protection would be set a bit shorter, so either the ice chunk came out and the motor began to spin normally, or the motor tripped off before the boost module shut off.

That was an older vessel, other vessels will probably handle it differently, probably just current limitation in the propulsion drives/trip off the drives, but ice jamming will be considered in the design if it's classed as an ice breaker.

Conventional propulsion vessels classed as ice breakers will have some sort of design consideration to deal with it as well, probably either a clutch designed to slip at high torque or sacrificial "shear pins" like a snow blower.
« Last Edit: December 21, 2018, 16:33:46 by Not a Sig Op »

Offline Swampbuggy

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Re: Arctic/Offshore Patrol Ship AOPS
« Reply #1652 on: December 21, 2018, 19:12:34 »
Interesting graphic

https://scontent.fyvr3-1.fna.fbcdn.net/v/t1.0-9/48406357_10157013346644533_5452765319359627264_o.jpg?_nc_cat=102&_nc_ht=scontent.fyvr3-1.fna&oh=c6c2cd137783e68833b4c1ebd69ee428&oe=5C99D284

I find it interesting to see that #6 is still being referred to as ROBERT HAMPTON GRAY. Has there ever been anything official from the RCN confirming that name?

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Re: Arctic/Offshore Patrol Ship AOPS
« Reply #1653 on: December 21, 2018, 19:53:18 »
I find it interesting to see that #6 is still being referred to as ROBERT HAMPTON GRAY. Has there ever been anything official from the RCN confirming that name?

Yes its official.
"When your draught exceeds your depth, you are most assuredly aground"

All opinions stated are not official policy of the CF and of a private individual

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Offline Uzlu

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Re: Arctic/Offshore Patrol Ship AOPS
« Reply #1654 on: December 26, 2018, 07:27:24 »
Quote
“The gap is not fully solved, we still have about an 18-month gap to address, but (there’s) a good commitment from the government to continue to work with us on that in the new year, ”McCoy said.

To eliminate the gap and avoid layoffs entirely, McCoy said, the shipyard would need a contract for eight AOPS and continuous Halifax-class work.
https://www.thechronicleherald.ca/news/the-year-in-shipbuilding-271085/

Offline suffolkowner

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Re: Arctic/Offshore Patrol Ship AOPS
« Reply #1655 on: December 26, 2018, 08:39:18 »

Offline Rifleman62

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Re: Arctic/Offshore Patrol Ship AOPS
« Reply #1656 on: December 26, 2018, 09:04:36 »
Quote
On the labour side of things, over the summer Irving and the shipyard union reached a new, four-year collective agreement, following months of challenging negotiations, narrowly avoiding a strike.

Interesting, with all the projects, years of work, and Irving attempting to close the "gap" there is the Union flexing. Bet 4 years from now there will be a slow down, threats of a strike.
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Offline MilEME09

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Re: Arctic/Offshore Patrol Ship AOPS
« Reply #1657 on: December 26, 2018, 11:01:22 »
And why is it the schedule for tge CSC cant be pushed up?
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Offline Uzlu

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Re: Arctic/Offshore Patrol Ship AOPS
« Reply #1658 on: December 26, 2018, 11:31:50 »
And why is it the schedule for tge CSC cant be pushed up?
It takes a lot of time to prepare the design.

Offline Underway

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Re: Arctic/Offshore Patrol Ship AOPS
« Reply #1659 on: December 26, 2018, 18:14:19 »
And why is it the schedule for tge CSC cant be pushed up?

No rushing the CSC.  Need to do a really good job on the prep work before you even cut the steel.  Time spent on the front end will save millions of dollars, time and headaches down the road.