When I had to rebuild the cross beam on Zeeforel I discovered that the bulkhead didn't actually meet the underside of the deck so I had to epoxy hardwood wedges in to the gap to prevent the deck sagging.
a. I would take option 1 and fit a second small charger for the engine start battery.
b. Why fit 2 x 100Ah batteries and not 1 x 200 Ah battery. The challenge of making the 2 batteries share load and charging evenly is removed and make wiring simpler.
c. A good battery monitor like the...
I have a full working set of Silva Nexus instruments, wind, speed, depth, GPS with all transducers and the central module to complete a fully integrated system. Its all older NMEA 0183 stuff and would make an ideal full set of spares for somebody that already has the same type of instruments...
Have a read here: https://support.seldenmast.com/files/597-200-E.pdf
Right at the end of the document there is reference to an anti-twist shackle, this is easily fabricated using a stainless rod and cutting a thread onto it. I found this a great help in reducing the necessary tension. I would...