Trolling motor installation on skiff with a small outboard

Bit of an odd one for a narrowboat forum but bear with me — I reckon there's crossover here with what a lot of you are doing.

I'm looking at fitting a small electric trolling motor to a 14ft aluminium skiff I use on a local reservoir, alongside a petrol outboard for when I need to cover distance. The trolling motor would be for slow, quiet manoeuvring — fishing spots, mostly.

My question is around the battery setup and BMS. A few things I'm trying to work out:

• Single vs dual battery bank — does it make sense to run the trolling motor off a dedicated bank, isolated from the outboard's starter battery?
• LiFePO4 or AGM? — weight matters on a small skiff, so I'm leaning LiFePO4. Looking at Fogstar Drift cells potentially. Anyone used them in a marine environment?
• BMS considerations — trolling motors can pull hard under load. Does the BMS need to be rated well above the motor's peak draw, or is there a smarter way to spec it?
• Victron overkill? — I'd normally reach for a Victron SmartShunt to monitor state of charge, but is that excessive for a relatively simple setup like this?

I've done similar installs on my narrowboat and a static caravan, so I'm not starting from zero. The marine environment is the bit that makes me pause — vibration, moisture, the fact you can't just pull over if something goes wrong.

Has anyone done something similar on a small boat? Particularly interested in how you handled cable routing and whether you went with a proper marine-rated BMS or just used something off-the-shelf.

@ExFirefighter Not my usual territory but the battery chemistry crossover is definitely relevant here.

For a trolling motor application you'll want to think carefully about discharge rate — trolling motors pull surprisingly hard at full throttle. A standard 100Ah LiFePO4 (Fogstar Drift or similar) handles 1C continuous comfortably, but check your motor's peak draw against the BMS rating.

Key considerations for a marine environment specifically:

• IP rating on the BMS — aluminium skiff means splash exposure is inevitable
• Cell balancing under variable load matters more than people realise
• Keeping connections above the waterline where possible

I run a similar discharge profile on my garden office setup with a Victron SmartShunt monitoring everything — the data logging really helps you understand actual usage patterns before you size the battery bank properly.

What's the motor's rated wattage? That'll determine whether a single 100Ah pack is realistic or you need more capacity.

Bit niche for here but yeah, battery side I can help with.

For a trolling motor you want LiFePO4, full stop. Don't mess about with lead acid — weight matters on a 14ft skiff and the flat discharge curve means consistent thrust right to the end.

Fogstar do decent 12V 100Ah cells that won't bankrupt you. Slap a proper BMS on it that handles marine moisture — Victron's stuff is overkill for this but their SmartShunt for monitoring is worth it so you're not guessing your state of charge mid-river.

Main thing people get wrong: wire gauge. Trolling motors pull serious amps at full throttle. Undersized cable = voltage drop = weak thrust = frustrated fisherman. Size your cable properly from the off.

What motor are you actually looking at? Thrust rating matters for sizing the battery.

Great thread, and yeah the crossover is real — we're all just moving electrons around at the end of the day.

One thing worth flagging that hasn't been mentioned yet: with an aluminium hull you'll want to think carefully about your earthing arrangement. Galvanic corrosion can be a nasty surprise if you get stray currents finding their way through the hull. A proper sacrificial anode and keeping your battery negative isolated from the hull (floating earth setup) rather than bonded to it is worth looking into before you start running cables.

@GrumpyBuilder is right about LiFePO4, and I'd add — size your battery for roughly twice the runtime you think you need. Trolling motors are deceptive; you'll always be out longer than planned. What thrust rating are you looking at?

@GrumpyBuilder makes the LiFePO4 call correctly, but worth elaborating on which configuration for a trolling motor specifically.

Most trolling motors run on 12V, but higher-thrust units (55lb+) perform noticeably better on 24V — you halve the current draw for the same power, which means thinner cabling and less heat in connectors. On a 14ft ally skiff that matters; you're not swimming in space for beefy 35mm² runs.

I'd look at two 12V Fogstar Drift 100Ah cells in series for 24V — decent price point, genuine UK warranty support, and the integrated BMS handles most of what you'd need for a simple trolling application.

One thing people consistently underestimate is the connector spec. Anderson SB50s at minimum; I've seen cheap XT60s melt on sustained motor draw. Don't scrimp there.

@CrispyMender is right to flag the configuration point — this is where people get caught out.

Trolling motors draw peak current in short sharp bursts when you're manoeuvring, then drop right back at cruise. That cyclic load profile is brutal on a BMS that's configured for steady-state draw.

Make sure whatever BMS you go with has a high continuous and burst rating — don't just look at the headline figure. Cheap units on Amazon will throttle or trip on peaks even if the average draw looks fine on paper.

For a 14ft aluminium skiff I'd probably look at a Fogstar Drift in the 100Ah range — specifically designed for cyclic/marine use and the BMS handles transient loads well in my experience. Compact enough not to upset your trim too badly either.

What thrust rating is the motor you're looking at?