# Steam Turbines with CPP



## blueprint2002 (Sep 7, 2011)

Happened to come across a 1969 “Maritime Reporter” with two pages devoted to three “Vanguard class” ore/oil carriers built in Japan for San Juan Carriers, with the then common geared steam turbine propulsion, uncommonly combined with a controllable pitch propeller. Naturally enough, there was no astern turbine, the CPP making it redundant.
As is well known to all, the marine steam turbine disappeared soon after that, even from the biggest tankers and the fastest container ships. However, I have been wondering what was the experience with the “Vanguards”, and whether there were any similar machinery installations on any other ships. Anyone have any personal experience of those ships, or knowledge of them? Thanks for your time and trouble.


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## Tim Gibbs (Apr 4, 2012)

blueprint2002 said:


> Happened to come across a 1969 “Maritime Reporter” with two pages devoted to three “Vanguard class” ore/oil carriers built in Japan for San Juan Carriers, with the then common geared steam turbine propulsion, uncommonly combined with a controllable pitch propeller. Naturally enough, there was no astern turbine, the CPP making it redundant.
> As is well known to all, the marine steam turbine disappeared soon after that, even from the biggest tankers and the fastest container ships. However, I have been wondering what was the experience with the “Vanguards”, and whether there were any similar machinery installations on any other ships. Anyone have any personal experience of those ships, or knowledge of them? Thanks for your time and trouble.


Sorry, no experience but a few thoughts;
- Simpler turbine construction & improved turbine efficiency
- Improved manoeuvrability & astern power
-Less demanding on combustion controls when manoeuvring
-Possibility of constant speed PTO to drive alternator
-Increased propeller maintenance & damage risk 
-Reduced propeller efficiency


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## blueprint2002 (Sep 7, 2011)

Tim Gibbs said:


> Sorry, no experience but a few thoughts;
> - Simpler turbine construction & improved turbine efficiency
> - Improved manoeuvrability & astern power
> -Less demanding on combustion controls when manoeuvring
> ...


Thanks, TG, that seems to sum up the pros and cons. The ships were fitted with a shaft-driven alternator & MFP for use at the higher of two possible shaft speed settings.


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## Tim Gibbs (Apr 4, 2012)

blueprint2002 said:


> Thanks, TG, that seems to sum up the pros and cons. The ships were fitted with a shaft-driven alternator & MFP for use at the higher of two possible shaft speed settings.


One of many ideas to improve steam plant efficiency I'm sure. I have often wondered whether they delivered. We've has multi-stage steam bleeds, complicated back pressure systems and reheat boilers which I'm sure were shown to the bean-counters to be cost effective, which they probably were at the design point . However, when trading conditions cause the ship to operate off the design point it started to go t*ts-up


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