https://www.commodoreaustralia.com.au/product/salt-water-batteries-aquion-s-line-battery-stack-48v-s30-0080/?gclid=Cj0KEQjwuOHHBRDmvsHs8PukyIQBEiQAlEMW0D-cZdkNhsl6UeuELSP_nGgZtGZHshn-9OGaFByd-uoaAlh38P8HAQ#tab-additional_information

My yacht has a internal weighted keel filled with lead .
These salt water batteries do weigh a reasonable amount but it they could be fitted and some of my keels lead was removed
and replaced with a salt water battery its doing two things storing power and also stabilizing my yacht.
But even in modern designed yachts perhaps the same thing could apply where as the bolt on keel could become a battery as well as its keel