Anyone else using their motorhome battery setup as a boat backup? Confused about marine compatibility

I've been toying with the idea of getting a small river cruiser and I'm wondering if my existing motorhome setup would translate across. Currently running a Victron SmartSolar 100/30 with a pair of Fogstar Drift 100Ah LiFePO4s — works brilliantly for the van and also doubles as my home emergency backup when needed.

The thing is, marine use seems to involve a whole different set of regs and kit requirements. Things like IP ratings, corrosion resistance, and whether standard leisure/motorhome inverters are actually safe in a boat environment. My Victron Multiplus 12/1200 is rated IP21 which I think is fine for indoor marine use but I genuinely don't know if that's good enough for a bilge-adjacent install.

Also wondering about battery placement — obviously LiFePO4 is inherently safer than lead-acid for enclosed spaces (no hydrogen gassing), but is there anything specific in the RCD/MCA guidelines that would affect how I'd need to install them on a narrowboat or small cruiser? I don't want to spend a fortune duplicating kit I already own.

Has anyone here successfully bridged the gap between a motorhome 12V system and a boat setup, or is it basically a complete rebuild?

@ExTrucker73 the Victron kit translates across beautifully — the SmartSolar doesn't care whether it's sat in a Transit conversion or a narrowboat, it's just a charge controller. The real gotcha on boats is ingress protection and ventilation. Your motorhome setup likely has panels facing skyward in a fixed position; on a river cruiser you'll be dealing with more condensation, potential spray, and the occasional idiot on a hire boat creating a wake that sends water everywhere.

Main things to address:

• Cable routing — marine-grade tinned copper is worth the premium, standard automotive cable corrodes alarmingly fast in damp environments
• Fusing — ABYC/BSS compliant positioning near the battery terminals
• Battery compartment — proper ventilation if you're running AGM/lead, less critical with LiFePO4

What chemistry are your existing batteries? That changes the answer considerably.

Great thread this. @ExTrucker73 one thing worth flagging that nobody's mentioned yet — moisture and corrosion protection is your biggest concern moving from motorhome to marine use. Even on a river cruiser you'll get condensation and damp that'll hammer unprotected terminals and connectors over time.

Worth grabbing some Duralac or Vaseline on all your battery terminals, and consider whether your existing cabling has adequate UV and moisture-rated sheathing. Marine-grade tinned copper cable is the proper stuff for boats rather than standard automotive wiring.

Also check your Victron is mounted somewhere with decent ventilation — bilge areas can get surprisingly humid even on inland waterways. The SmartSolar itself handles moisture reasonably well but I wouldn't push it without some protection.

@Renogy_Pro makes a fair point about compatibility generally — just don't underestimate how different the environment is! 🚢