My first official attempt at the SRC Water Speed World Record

Achieves over 1150m/s on water
Passively stable.
Vizzy programming used for overal progressive attitude control as envelope changes with acceleration

Proof

As per the official rules (SRC):

Category format:'TypePlace' (ie: 'SpeedLand', 'BudgetCyleroLanding')
Proofs don't have to be public but we need access
Entries with wrong formats may be discarded
The game has to be in the latest main branch version in the stock System
The craft has to be yours. If not you need clear permission

For a record to be verified all parts need to be stock
No glitches, xml editing, outdated parts, tinker panel, dead mass and/or mods
The use of the buoyancy slider and fuel lines is allowed
Means of propulsion can't be majorly clipped between themselves
Parts have to be visually connected to something and can't be floating
Heat damage has to be enabled
Astronauts can only be used for aesthetic purposes
It's up to us(SRC Admins) to decide if a craft abuses the game mechanics

Disclaimer:

I am publishing this craft publicly, as well as the proof, to hopefully help others improve.
I hope that there is someone who can properly improve on this craft, or leverage it as a base for another craft.
I give my permission to use this as a base for your own submission only if the following 3 conditions are fulfilled:
1) The craft you submit must be public
2) The craft you submit must properly tie into this craft as a successor craft in the simplerockets.com crafts section.
3) Your submission has a marked performance improvement over this default craft. Successors with only minor improvements upon this craft/record are not sufficient, and will not be accepted.