ranger58sb
Guru
Still, a wet 8D is hard to beat for dumping big amperage into things like starters and thrusters.
But a pair -- or sometimes three -- G31s can provide as much as or more cranking amps than some single 8Ds. Certainly enough to start most engines, I'd guess enough for thrusters given installers often use a pair of Odyssey G31s.
For an extreme example, a pair of PC2150s would give 2300 CCA, 2740 MCA... and each individual battery is much easier to schlep than would be a single 8D.
-Chris