Post Number: 2
|Posted on Saturday, January 22, 2005 - 12:29 pm: ||
This is a near duplicate of a message I posted under Gray Marine. However, given the high percentage of new members (like myself) and visitors to this BB and the fact that my post deals with multiple possible areas for discussion, perhaps I will be forgiven for the duplication.
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 (she was built for an in-line). 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. In the marina we need to shift in and out of gear to keep the speed down. Hull speed is reached at 2000 RPM while maintaining about 17 inches of vacuum (about 20 at no load idle). 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? I expect it will need new gears anyway. Are there other options? This should be resolved before we are able to select an appropriate engine.
Any suggestions on which model Gray Marine (or other engine) 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 Saturday, January 22, 2005 - 05:01 pm: ||
I can't be of a lot of help with your project other than to relay my own. I have a 1929, 78' boat built of steel powered by her original direct reversing (no gear, the engine runs backward)140Hp, Atlas Imperial engine. Running 325rpm full tilt turning a 54" x 38" screw. Would be interested in chatting about restoration tips and proceedures with you.