Hi, Roger, and List/Group,
This really has more to do with a spacer than drive saver, though I like the
flexibility of it in case the alignment isn't perfect.
Those of you who have been around a couple of years know how we jacked the
tranny out of the mounting plate (now replaced, no harm done other than
inconvenience in making up a keeper to stay moving with the engine, and the
packing gland needing redoing cuz of the weight of the tranny on the shaft
when it came out, also redone). Recent readers also know of my search for
line cutters, which would have prevented that (which shouldn't have
happened, but stupid sailor tricks happen all the time, anyway, so a mooring
line overboard isn't guaranteed against for all time on our boat, as much as
we'd like to think so, and, of course the occasional lobster/crab pot warp I
don't see in the middle of the night) - which will require a longer shaft,
or...
.... a spacer - so why not a flexible one?
And, I was looking for input from those who'd had a use for one preferably
where the thing sheared and left the 'limp home' mode in place.
I agree about proper alignment - and that will happen before we insert a
spacer or drive saver...
L8R
Skip, back to the boat for two weeks in a few days
--
Morgan 461 #2
SV Flying Pig KI4MPC
http://tinyurl.com/384p2 The vessel as Tehamana, as we bought her
"Twenty years from now you will be more disappointed by the things you
didn't do than by the ones you did do. So throw off the bowlines. Sail
away from the safe harbor. Catch the trade winds in your sails. Explore.
Dream. Discover." - Mark Twain
"Roger Long" wrote in message
...
For what it's worth, I deal often with one of the foremost drivetrain and
propulsion specialists in the country in connection with designing boats
like this:
http://home.maine.rr.com/rlma/WHOIrv.htm
The shipyard that builds these boat specializes in fast, sophisticated,
high powered craft. Both told me that they hate "Drivesavers". The boat
in the picture has two 710 horsepower engines with the engines flex
mounted and the shafts connected with solid couplings. There is just one
bearing, in the shaft strut. They run smooth as silk.
I do have a drivesaver disk in my boat but they cut the shaft short when
they installed it so I have to buy a whole new shaft to take it out. It's
not causing any problems that I can see though other than making it a pain
to repack the stuffing box.
Skip the drive saver. Line up your shaft carefully calculating the
overhanging weight of the shaft and using a scale to hold the end up. Make
sure the flanges are true and the pilot concentric. Then hard mount it.
The metal parts will then be more precision than a plastic disk can ever
be and will stay that way. It will run fine.
There's a whole range of prop strike forces where the drive saver could
break but the solid coupling would still leave you able to limp off a lee
shore with the engine vibrating and shaking. I like that scenario better.
I've heard of a lot more broken shafts and totally trashed props than gear
boxes that failed due to prop strike. The gears are a lot more rugged
than you would think. Remember that there is a friction clutch in the
system that will give some under an extreme shock load.
--
Roger Long
"Skip Gundlach" skipgundlach at gmail dotcom wrote in message
...
Hi, Lists,
Thanks for all the responses to my line cutter question. To put one on
will require some more space, and, in general, I've come to think that a
break-away (with built-in safeguards to allow continued use until
replacement) spacer is also a good move.
Who here has had one, and, best, has had to use it to save their gear?
Thanks again.
L8R
Skip
Morgan 461 #2
SV Flying Pig KI4MPC
http://tinyurl.com/384p2 The vessel as Tehamana, as we bought her
"Twenty years from now you will be more disappointed by the things you
didn't do than by the ones you did do. So throw off the bowlines. Sail
away from the safe harbor. Catch the trade winds in your sails. Explore.
Dream. Discover." - Mark Twain