#6 Top Gun straight bottom drive height
#1
I have a factory #6 95 Top Gun, appropriately named the Kangaroo Rat because it hops like a Kangaroo. This is more than the standard Top Gun porpoise, this gets violent at high speeds unless the boat is run extremely wet. Talking to people familiar with the boat from way back when, I have gotten conflicting reports on whether the boat came factory with boxes or not. Everybody did say though that back when this boat was new, it handled like it was on rails and it was very fast. It is neither of those things for me. Right now it does not have boxes and has wet sump 6's. I think the drive height may just be too high and this could be a significant part of the problem. When trimming up, when the porpoise starts it feels like the props are losing bite and the bow comes down, then they regain bite and the process starts all over. I would like to know where these drives should be height wise for the best performance. I have tried various diameter 4 blade and 5 blade props, spinning in or spinning out, and nothing simple like that is helping the issue. If anybody familiar with these boats and this setup could shed some light on what drive height works best I would greatly appreciate it.
#3
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Joined: Jul 2009
Posts: 8,527
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From: Taunton Ma
Old school II prop shafts are 1” below the running surface, when I ran that boat a few years ago it had a slight porpoise with one set of props, bad porpoise with the others. I know they were both 4 blades but don’t remember any other specs.
#8
#9
#10
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Joined: Jul 2009
Posts: 8,527
Likes: 706
From: Taunton Ma





