Adding more reserve capacity for my boat.

Question
Ron, I have a 1989 Searay 390 EC. It has three group 27 batteries. One for each engine and one house. The house battery is the same as the two others with a very low (115 minutes) reserve capacity; far too low to meet our needs when at anchor. The entire bank discharges copmpletly very quickly under the smalest load.
To replace the single group 27 house battery, I have purchased two Trojan T-125 Deep cycle golf cart batteries wiith a reserve capcity of 447 @25amps, which will yield a total of 894 total minutes.
What is the correct wiring hook-up between the two new batteries, and between the new batteries and the existing two batteries.
Thanks, Roger

Answer
Hi Roger...Thank you for selecting the undersigned to reply to your question.

First of all, I'm not an electrician, so best you consult a more knowledgeable source.

Given the size of your vessel and the need for electrical power while at anchor, why not consider installing a generator?

Safe Boating
Ron