Build log of a fast Bulker
Welcome to the site.
The rubber caps on your SLA batteries are a safety device and should not be covered whilst charging. if the cells gas an explosive gas (hydrogen) can be produced so I suggest you do not continue with this idea. SLA batteries need a special constant voltage charger and should not be charges with a car battery charger, there are many trickle chargers available that will safely charge your new SLA's.
I think a bow thruster would be a good addition to this model as it will be difficult to dock in any sort of breeze unless you have tug assistance.
We actually have a Build Blog section and you may wish to repost your build to that section as you will receive more comments/suggestions.
Looking at your pics I can see you have already fitted cardboard formers to the hull. I have built many models with fiberglass hulls and usually run longitudinal stringers round the inside of the hull to keep everything square and provide a base for the decks. You may find that the hull has flexed in once you removed the flange casting. You can still apply stringers between your formers to keep the hull sides flat if these have been fixed in place. A straight edge along the outside of the hull should help you, but do follow any natural curve.
The markings on the hull are meant as a guide and are rarely spot on. Looking at your rudder it is slightly out of alignment but the model will sail OK with this positioning. The alternative would be to open the rudder hole with a file so that the alignment was central. You can make good the damage with some body filler as used on your prop shaft.
You are progressing well and please keep the pics and info coming 😀
Dave