Go with the manual recommendation for oil quantity.
It sounds like you may have the wrong dipstick, or your engine is installed with some inclination, or your boat trim is off (are you on the hard?).
My conversion formulas put 1.9 liters at slightly more than 2 U.S. quarts.
P.S. We had a 2GM20F in our previous boat, and at 2 qts it showed full on the dipstick.
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Pacific Seacraft Crealock 31 #62
NEVER CALLS CRUISINGDAD BACK....CAN"T TAKE THE ACCENT