Perfect for your use, I had the same on a 27-footer.
I had two batteries that Costco sold as Marine batteries, i.e. slightly more robust automotive starting batteries, even smaller than the ones you linked to, I think about 60 Ah, $50 each.
Works perfect for day sailing and weekends.
A switch separating the two batteries is good to make sure you always have power to start in the morning.
Run one somewhat empty, but leave enough power to start, then use the other one. IF you run it empty over night, you can still start, and use almost all capacity.
And before the yaddaing by 'battery experts' starts:
Automotive starter batteries (which these are, in essence) DO survive the running REALLY low on occasional weekend use very well, for practical purposes. They last years.
Shorten theoretical battery lifetime by 50%, and you still have several years of use, and are out of $50.
As proven by people who have to jump-start their cars.
My CAL29 is in need of new batteries. The existing ones are shot and won't hold a charge. I wanted to solicit opinions about downsizing drastically.
My existing batteries are a bank of two of these: Trojan EV8D, 12Volt, 220AH@20hr, batteries. They are big and weigh a gazillion pounds a piece. More than I can easily remove myself, a big disadvantage.
My needs are modest. It primarily needs to start my Farymann A30, single cylinder, 10HP diesel. I have the usual running lights and house lights and VHF radio.
My sailing habits are almost exclusively day sailing. 2-3 times a year (on good years) I'll take it out for an overnight. I could use battery powered camping lanterns on those even, since it's not very often.
So I think I might be able to drastically downsize, allowing for easier and cheaper maintenance and replacement. Going to something like two of these:
[retarded sailnet policy counts your link as one I may not post; removed]
Am I crazy? What am I not thinking of?