wrote

>     Some 172s did, too. We have here a 172M that had the factory
> seaplane stuff installed (forward strut lugs on the firewall, diagonal
> braces behind the windshield, and the backside of all metal primed),
> and they included a couple of springs between the aileron and rudder
> cables in the belly. You hardly know they're there. I wonder if it was
> a means of avoiding an extra keel surface like you see on Beavers and
> some other floatplanes.

Not likely.  No way an interconnect is going to correct for insufficient 
tail area, when the floats add area ahead of the center of aerodynamic 
pressure.

More likely that the 172 has enough extra vertical fin to be OK, even with 
the floats added.  Most likely, there is not as much extra area after the 
floats are bolted on! 
-- 
Jim in NC
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