Swapped out the old Victron shorepower setup on my narrowboat – few questions about the new install

Interesting thread — following this closely as I've got a similar dilemma coming up with my garden office setup, though I know boats add a whole extra layer of complexity with corrosion and damp.

Few things I'd want to know more about if I were in your position:

• Which Victron unit did you swap to? MultiPlus-II or the Compact? The MultiPlus-II seems to be the go-to recommendation on here but I've seen a few narrowboat owners mention the Compact suits tighter engine bay installs better.
• Shore power amperage at your marina — some UK canal moorings are notoriously stingy (10A or even less on older pedestals), so wondering if you've set your input current limit accordingly in VictronConnect. Caught a few people out with that.
• Cabling gauge between the inverter and your battery bank — on my van conversion I underspecced this initially and it caused all sorts of grief under load.

The moisture issue is the one I'd genuinely lose sleep over on a narrowboat. Did you mount it on a ventilated panel away from any bilge area? Victron's own install guidance recommends decent airflow but I imagine that's easier said than done below decks.

Also curious whether you kept the existing Victron BMV battery monitor or went with the SmartShunt instead — seems like a common upgrade people pair with a new inverter/charger swap.

What does your battery bank look like? LiFePO4 or still on AGM? That'll change quite a bit about how you've configured the charge profile.

Hey @ExJoiner19 — yeah, the marine environment really does throw a spanner in the works compared to a straightforward garden office build. The main things that catch people out on boats are ingress protection ratings on all the components (IP65 minimum as a rule of thumb in exposed areas), using tinned rather than plain copper cable to resist corrosion, and making sure any enclosures are properly ventilated to handle condensation.

For your garden office you'll obviously dodge most of that, but don't completely ignore moisture — an unheated office can get surprisingly damp overnight. Worth factoring in at the planning stage rather than retrofitting later.

What sort of capacity are you thinking for the office setup? That'd help give more relevant pointers when you get to that stage. 👍

@ExJoiner19 my garden office doesn't rock about in the rain either but somehow it still finds ways to be needlessly complicated — boats just turn the difficulty slider up to "why did I choose this lifestyle"

@ExJoiner19 garden office is actually where I started before moving on to a shepherd's hut build, and honestly the overlap with marine installs is bigger than you'd think — moisture ingress is still a real concern depending on how well the structure is sealed.

One thing worth considering early on is whether you're planning any EV charging from the setup, because that changes your inverter sizing conversation significantly. I went Victron Multiplus for the hut partly for that reason — the shore power integration is clean and it handles the transition between grid-tied and battery seamlessly.

What's your current thinking on battery chemistry? LiFePO4 is the obvious answer these days but the BMS communication with Victron kit is worth factoring in from the start rather than retrofitting later. Fogstar Drift cells paired with a decent JK BMS have been solid for me.

@ExJoiner19 the boat-to-garden-office crossover is more real than people think — I actually spec'd my narrowboat's 12V system first, then used almost identical logic for a shore-based EV charging setup on the pontoon.

The one thing I'd flag that nobody's mentioned yet: cable runs and voltage drop matter enormously on a boat because you're often routing longer distances through awkward bilge spaces. I lost probably 8% efficiency on my original install just from undersized cabling before I sorted it.

Victron's online calculator is genuinely useful for this — put in your actual cable length, not a rough estimate. Once I redid the numbers properly and upsized to 35mm² on the main run, everything transformed. Garden office is far more forgiving on cable routing, but same principles apply if you're pulling any meaningful load.