I have a somewhat smaller boat, a Cal 2-27, and I had I think the same prop, originally turned by an Atomic 4. I repowered with the boat in the water and did not change props right away. This spring I did a haulout and took the opportunity to do a prop change. I had been given a pair of 14x10 RH 3 blade props, and I put the better one on the shaft, and had the more beat up one refurbished at a local prop shop for a spare. The difference in performance is significant. I am currently running a ME0201014201 5kw motor, 48v bank of 6v GC2 golf cart batteries, (FLA) and a 2:1 reduction enclosed gearbox. I may try a 3:1 gearbox this winter. Anyway, folding props are designed with significant compromises in efficiency in order to make them more streamlined for sailing. If you seldom motor, keep the folder, or go with a bigger folder. If you motor a lot, go with a fixed 3 blade prop, as big as you can swing under the boat, is my suggestion. Adjust reduction ratio as needed.
I will admit to having very little experience with AGM batts, and less with Lithiums. My flooded lead acid bank has served me well for going on 3 years now with no signs of imminent failure. The drawbacks are for me a reasonable tradeoff for the low price I paid at Sams Club for them. AGM are a little touchy when it comes to overcharging, etc. True, they offer a lot of advantages in installation orientation, and less maintenance, but if I were shopping for a battery with those advantages and willing to pay more, I think I would go the whole enchilada and get LiFePO4 batts. Deeper discharge, longer life, lighter weight. If cost is a significant factor, go with the golf cart batts. They are rockin for me. About as bulletproof as a battery can get. If they boil off a bit, no biggie. I got plenty of distilled water on hand and don't mind checking the electrolyte levels after every heavy charge cycle. Just be sure to mount them SIDEWAYS in a sailboat. IOW, ends pointing port/starboard, not fore/aft. Fore and aft mounting is incorrect when heeling is expected, because of the orientation of the cells. Remember, electrolyte does not just slosh from end to end within the battery. The cells are whole separate ecosystems, rectangular shaped, flat sides facing the ends of the battery casing.
Since your gp 27's still have some life left in them, why not move them back aft where you were going to put the second bank of AGM, as a reserve bank, and install the golf cart batts too? That would give you some pretty decent range on electric.
I am currently using a gang charger from West Marine, and each 12v cable pair is charging two of my golf cart batteries. Works fine for me. Honestly, I would actually rather have independent charge circuits for each of my 6v batteries. This would help keep them balanced, I believe. And a fault light or taking a longer time to charge one than the rest will tell me when one battery is underperforming, at a glance. I was using a 15a 48v single bank charger and it was not really doing the job, I don't think.
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