okay as for charging the general rule i have heard is with wet batteris you want around 20 to 25 % in you alt size to the battery bank. ie if you have a 200 amp hour bank you want around 50 amps of alt, if you have 400 you want 100 amps from the alt. going bigger is not a problem due to the way the batteries accept the amps.
the advantage of bigger batteries is its normally cheaper to get 2 batteries that add up to say 200 amps than 3 batteries that do. if the boat can fit bigger batteries then go for it.
as for having more amps that another discussion entirely. unless you do nothing but single day sails with motoring or shore power time with a charger you want more amps than what a group 24 gives you.
the deep cycle thing applies to this as well. the less % of discharge you do the longer the battery will last. ie if your day sails use 50 amps, and your bank is 100 thats a 50 % discharge. then if the battery is say 125 amp hour and you use the same 50 amps its only a 40 % discharge which will mean you will get more discharge cycles out of the battery before it needs to be replaced
the advantage of bigger batteries is its normally cheaper to get 2 batteries that add up to say 200 amps than 3 batteries that do. if the boat can fit bigger batteries then go for it.
as for having more amps that another discussion entirely. unless you do nothing but single day sails with motoring or shore power time with a charger you want more amps than what a group 24 gives you.
the deep cycle thing applies to this as well. the less % of discharge you do the longer the battery will last. ie if your day sails use 50 amps, and your bank is 100 thats a 50 % discharge. then if the battery is say 125 amp hour and you use the same 50 amps its only a 40 % discharge which will mean you will get more discharge cycles out of the battery before it needs to be replaced