C lectric
Guru
Scary,
I think what you have was done most likely by Hatteras. Indicated by the fact that two others you found were setup the same.
Also that your book says rated rpm is 2800 so, to me, there has been some customizing.
Your boat is a full displacement hull or nearly so built to be an economical seakindly boat at hull speed, not planing or semiplaning.
Hatteras used the DD because they were good strong engines capable of operating many thousands of hours with decent service and servicing.
However, Hatteras realized the engines were capable of producing much more power than the hull could use so there is a limiter somewhere to prevent engine abuse and wasting large amount of fuel.
Hatteras could have asked DD to modify the injection pump and reduced the rating but I think, can't say for sure, that if done by DD, DD would have left a RATED and a HIGH IDLE that were different. The fact that your APPARENT rated and high idles are the same tells me the throttle is limited somewhere by a stop.
You can check if you wish but since your hull likely cannot use any more power there is no point other than just to know. They apparently left you with somewhat more power than the minimum to move the boat at hull speed to account for head seas or winds. Good and I'd be surprised if that were not so.
With this setup Eric has a point that you could be overpropped and not know it. If the engine had been derated by DD and a new rated and high idle left then you could use those differences to determine propping suitability. With a stop the governor could feed more fuel than the engine can use at that max rpm if the load is too high. The best way to monitor is the use of a pyrometer and watch for high EGT in your case.
I think what you have was done most likely by Hatteras. Indicated by the fact that two others you found were setup the same.
Also that your book says rated rpm is 2800 so, to me, there has been some customizing.
Your boat is a full displacement hull or nearly so built to be an economical seakindly boat at hull speed, not planing or semiplaning.
Hatteras used the DD because they were good strong engines capable of operating many thousands of hours with decent service and servicing.
However, Hatteras realized the engines were capable of producing much more power than the hull could use so there is a limiter somewhere to prevent engine abuse and wasting large amount of fuel.
Hatteras could have asked DD to modify the injection pump and reduced the rating but I think, can't say for sure, that if done by DD, DD would have left a RATED and a HIGH IDLE that were different. The fact that your APPARENT rated and high idles are the same tells me the throttle is limited somewhere by a stop.
You can check if you wish but since your hull likely cannot use any more power there is no point other than just to know. They apparently left you with somewhat more power than the minimum to move the boat at hull speed to account for head seas or winds. Good and I'd be surprised if that were not so.
With this setup Eric has a point that you could be overpropped and not know it. If the engine had been derated by DD and a new rated and high idle left then you could use those differences to determine propping suitability. With a stop the governor could feed more fuel than the engine can use at that max rpm if the load is too high. The best way to monitor is the use of a pyrometer and watch for high EGT in your case.
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