Twelve free calculators and live instruments built for the way boats are actually maintained out here — measure, plan, and turn the answer into an order or an email to us. No sign-up, and they keep working with no signal at the yard.
Anode selector
Hull, water and what's fitted below the waterline — get the right alloy and a full anode plan for your next haul-out.
Build my anode plan →Shrink wrap estimator
Three measurements and the job — film width, mil, tape, strapping and vents, itemised and ready to quote.
Estimate my materials →Battery bank calculator
Fit the biggest bank your battery box can take — or size by daily loads. House, engine start and golf buggy packs, with cable sizes and a cart-ready order.
Size my bank →Battery replacement finder
Old battery's group size or specs in, the drop-in Fullriver AGM out — with dimensions checked and a cart-ready order.
Find my replacement →Cable size calculator
Load, run length and voltage — the right tinned cable size for voltage drop, checked for ampacity, with a fuse suggestion.
Size my cable →Tank sender selector
Tank depth in, exact sender length out — fuel, water or waste, with the gauge standard sorted before anything is built.
Find my sender →A/C BTU sizer
Cabin measurements in, the right cooling capacity out — sized for tropical heat, not a European brochure.
Size my A/C →Boracol coverage
Measure the teak, get the litres — 3 m² per litre with an honest allowance, in the right pack sizes.
Work out my litres →Live instruments & anchor alarm
Your phone's GPS as deck instruments — live speed and trip log, a waypoint ETA readout, and an anchor drag alarm that watches all night.
Open the instruments →Cruising calculators
Course to steer with the tide allowed for, anchor scope for the night, tide height by the twelfths, passage time & fuel with a proper reserve.
Plan my passage →Thruster size calculator
Boat, windage and the wind you berth in — the right bow and stern thruster sizes, matched to genuine Sleipner models.
Size my thrusters →Valve schedule builder
Count your through-hulls, get a printable seacock schedule your yard and surveyor can work from — class paperwork included.
Build my schedule →Put these tools on your phone. Installs like an app, opens from your home screen, works offline in the shed or on the hard.
Heading into a yard period? These tools pair with our yard period planning service — send us any plan the tools produce and we'll check it by hand, no charge.