I don't have any direct answer to your question,
but try to use the search function with this forum with the word "Davit"
You will find some previous discussion including 278's, and this one with pictures on a 268:
http://www.smwebhead.com/phpBB3/viewtopic.php?f=6&t=10577&p=101622&hilit=davit#p101622Regarding a Jetski, here is a good one:
http://www.smwebhead.com/phpBB3/viewtopic.php?f=2&t=7502&hilit=jetski
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"Knot Easy" 2000 Horizon 240 Volvo 5.7GS /SX
tow: 2017 Honda PILOT EXL-AWD
prev. boats:
'87 Chaparral 198CXL 4.3 OMC Cobra
'69 Jetstar 16ft Ski Boat, 115hp Yamaha
'68 Aluminum Jon Boat, 3hp Sears
'64 Water Wings