47 to 48 design changes and 45


C

castines

Administrator
Ok,

Saw an older slow boat 47 yacht. Has the cummins 480's in her. I know the hull was redesigned and changed to the 48 and now has 660 QSM's.

My question is did the 47 have more of a tunnel drive set up then prop pockets? And was this fixed in the 48 redesign? I know tunnel drive can load up the props and actually decrease efficency, or at least speed.

I am trying to find out if the tunnels or pockets in the inboard 45 are the same as the 47, or the same as the 48. Have not seen a pic of the 48 out of the water.

tunnel drive would almost work better with an impellar i am told.

any ideas guys?
 
I WAS TOLD THE 47 WAS VERY SLOW, AND DID NOT PERFORM TOO WELL. VERY FEW OF THEM OUT THERE.
 
the 47 looks like a tunnel drive more then pockets. a few articles i found online say the 48 was hull re-design. but what did they do?

And is the 45 the same as the 48 when it comes to inboards.
 
THEY REALIZED IT WAS UNDERPOWERED, AND HAD TO MAKE MORE ROOM FOR THE 660 CUMMINS. IT WOULD NOT FIT IN THE 47.
 
I had heard they also needed more buoyancy with the bigger engines. When I had a tunnel drive (23' PennYan) I had the props cupped big time to pull more water into the tunnel. My 41 has prop pockets, not nearly as deep as the tunnel and I would suspect that is what was done on the 45 and 48 inboards. I was quite surprised to find out they were both V-drive boats. Seems like they would be more efficient with a less severe shaft angle.
 
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