Here's a few translations of 1 Pet 3:20
New International Version
to those who were disobedient long ago when God waited patiently in the days of Noah while the ark was being built. In it only a few people, eight in all, were saved through water,
New Living Translation
those who disobeyed God long ago when God waited patiently while Noah was building his boat. Only eight people were saved from drowning in that terrible flood.
English Standard Version
because they formerly did not obey, when God’s patience waited in the days of Noah, while the ark was being prepared, in which a few, that is, eight persons, were brought safely through water.
Berean Study Bible
who disobeyed long ago when God waited patiently in the days of Noah while the ark was being built. In the ark a few people, only eight souls, were saved through water.
Berean Literal Bible
at one time having disobeyed, when the longsuffering of God was waiting in
the days of Noah, of
the ark being prepared, in which a few--that is, eight souls--were saved through water,
New King James Version
who formerly were disobedient, when once the Divine longsuffering waited in the days of Noah, while
the ark was being prepared, in which a few, that is, eight souls, were saved through water.
New American Standard Bible
who once were disobedient when the patience of God kept waiting in the days of Noah, during the construction of the ark, in which a few, that is, eight persons, were brought safely through
the water.
NASB 1995
who once were disobedient, when the patience of God kept waiting in the days of Noah, during the construction of the ark, in which a few, that is, eight persons, were brought safely through the water.
NASB 1977
who once were disobedient, when the patience of God kept waiting in the days of Noah, during the construction of the ark, in which a few, that is, eight persons, were brought safely through
the water.
Christian Standard Bible
who in the past were disobedient, when God patiently waited in the days of Noah while the ark was being prepared. In it a few—that is, eight people —were saved through water.
Holman Christian Standard Bible
who in the past were disobedient, when God patiently waited in the days of Noah while an ark was being prepared. In it a few—that is, eight people—were saved through water.
American Standard Version
that aforetime were disobedient, when the longsuffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls, were saved through water:
English Revised Version
which aforetime were disobedient, when the longsuffering of God waited in the days of Noah, while the ark was a preparing, wherein few, that is, eight souls, were saved through water:
Literal Standard Version
who sometime [ago] disobeyed when once the long-suffering of God waited, in [the] days of Noah—an ark being prepared—in which few, that is, eight souls, were saved through water,
NET Bible
after they were disobedient long ago when God patiently waited in the days of Noah as an ark was being constructed. In the ark a few, that is eight souls, were delivered through water.
World English Bible
who before were disobedient, when God waited patiently in the days of Noah, while the ship was being built. In it, few, that is, eight souls, were saved through water.
Young's Literal Translation
who sometime disbelieved, when once the long-suffering of God did wait, in days of Noah -- an ark being preparing -- in which few, that is, eight souls, were saved through water;
The Greek word wrongly translated "by" is di':
dia: through, on account of, because of
Original Word: διά
Part of Speech: Preposition
Transliteration: dia
Phonetic Spelling: (dee-ah')
Definition: through, on account of, because of
Usage: (a) gen: through, throughout, by the instrumentality of, (b) acc: through, on account of, by reason of, for the sake of, because of.
The lexicon NEVER uses the word "by".
I recommend exchanging your kjv for a better translation.
Seems you are trying really hard to avoid the truth here.
The FACT that Eph 2:8,9 doesn't mention water baptism is because it ISN'T required for salvation. Really simple. Really.