I was listening to a video about SHLV's (Super Heavy Launch Vehicles), and Sea Dragon's first stage engine was mentioned.
In terms of combustions stability, the suggested fix would be large combustion baffles, and high pressure combustion.
However, I have never heard much about how the second stage engine would have functioned...
Basically: How did the plans for sea dragon factor in potential instability
The large, low pressure engine proposed for the Sea Dragon second stage was thought to be at low risk of developing combustion instability:
The combustion chamber is of conventional design, The 30 (degree) cone half angle and contraction area ratio of 1.8:1 allows more than enough combustion chamber volume. The conical chamber tends to inhibit longitudinal pressure fluctuations. The large chamber volume provides efficient combustion and flexibility in injector design. A possible injector configuration utilizes a shower head pattern which produces a combustion flow field over a relatively large portion of the chamber volume. Thus, the combustion reactions would not be as concentrated as for other injector types, and large perturbations that trigger combustion instability are less likely to occur. A discussion of combustion stability is included in Appendix II-2 for a Sea Dragon engine.
(emphasis mine)
A rigorous test campaign was proposed during which the presence or absence of instabilities would have been determined.
Unfortunately, the mentioned Appendix II-2 and its discussion of combustion stability are not included in the version of this document found on NASA NTRS or the Internet Archive.
Source: Report No. LRP 297, Volume II, page III B-8
