Post Number: 1
|Posted on Friday, January 21, 2005 - 09:01 pm: ||
My wife and I are in the process of restoring the first hull of the "Large Yacht Series" built by Stephens Brothers of Stockton, California. With the exception of modern navigation and safety gear, we want to restore her to as near original as practical/possible. She is a 47 foot, 1926, 35,000 lb combination raised deck cruiser. Her original engine was a Hall Scott 100 hp which drove a 30 inch pitch by 28 inch diameter wheel through an offset reduction gear of about 3:1. Although seeping oil and providing significant free play, the original reduction gear is still in place requiring a left hand engine to drive the right hand wheel of original specification.
Her current engine is totally inappropriate. It is an early Crusader, 300 hp, V-8 that does not fit completely into the engine compartment. It is backed by a 1.52:1 Velvet drive giving a total reduction of about 4.6:1. The engine's torque curve is such that 1000 RPM is absolute minimum clutch speed without killing the engine. Hull speed is reached at 2000 RPM while maintaining about 17 inches of vacuum. By 2600 RPM the vacuum is down to about 11 to 12 inches with little increase in speed and much increase in wake.
We are thinking that a Gray Marine (military version with low end torque)would be an appropriate engine replacement. We believe that the combined reduction is about right to be able to maintain appropriately slow speeds at clutch speed.
We are open to a single reduction unit if such may be available (and changing engine rotation if necessary) or, possibly, rebuilding the existing reduction gear and replacing the Velvet drive with a small reduction gear and clutch. If rebuilding the original reduction gear, can we have new gears cut for a different ratio? Are there other options? This should be resolved before we are able to select an appropriate engine.
Any suggestions on which model Gray Marine might be appropriate for our use with continued reliability and availability of parts? Any other suggestions on how the problem might be approached? Any input on this topic would be welcomed.
|Posted on Monday, March 06, 2006 - 01:33 pm: ||
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