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TOOLS FOR SURVEYORS

The sums, done on board

Calculators for the numbers you check during a survey and the quote before it. Free, no sign-up, and every figure has its source on the page

FREE TOOL

Wire size and voltage drop calculator

Work out the smallest marine DC conductor for a circuit from its current, length and allowed voltage drop, in AWG and mm², with the formula surveyors and installers use and how to cite an undersized cable in a report.

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FREE TOOL

Battery state of charge from voltage

Turn a battery's resting voltage into its state of charge, for flooded and AGM banks at 12 V and 24 V, from the maker's tables, with how long to rest it first and why a voltmeter can't read a lithium bank.

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FREE TOOL

Moisture readings log

How surveyors take moisture meter readings on a GRP hull, why the 0 to 100 scale is comparative, how to compare readings with a dry reference above the waterline, what gives false highs, and a free log that writes the readings up for your report.

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FREE TOOL

Survey quote calculator

Build a marine survey quote by length or by the hour, with oil analysis, travel and the yard's haul-out shown apart, in dollars or euros. Starts from rates surveyors publish and copies straight into an email.

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FREE TOOL

Capsize screening and sailboat ratios

Work out a sailboat's capsize screening formula from its beam and displacement, with the displacement-length ratio, sail area-displacement ratio and ballast ratio, where each formula comes from and what it leaves out.

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FREE TOOL

Hull speed calculator

Work out a displacement boat's hull speed from its waterline length in feet or metres, and the speed-length ratio for the speed you reached on the sea trial, with where the 1.34 comes from and where the rule stops working.

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FREE TOOL

Boat capacity and horsepower calculator

Check a small boat's capacity plate: maximum outboard horsepower from length and transom width by the US Coast Guard's formula, and persons from the pounds on the plate or the length times beam over 15 rule of thumb.

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FREE TOOL

HIN decoder

Decode a 12-character boat hull identification number: the manufacturer code, the serial number, the month and year of build or certification and the model year,, with where to find the HIN and what tampering looks like.

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FREE TOOL

Anchor chain size and scope

Work out the anchor chain size for a boat by length and displacement and check it against the ABYC anchor loads at 30 and 42 knots. Then get the rode length for the scope you want. All from Mantus Marine's published tables.

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FREE TOOL

Fuse size calculator

Work out the largest fuse or circuit breaker allowed on a boat DC or AC conductor from its size, insulation rating, location and bundling, using the US Coast Guard ampacity table and the 150% rule, and check the fuse fitted.

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FREE TOOL

Bilge pump size calculator

Work out how fast water comes in through a hole or failed through-hull at a given depth and how much a bilge pump really moves against its rating, with the capacity guides surveyors and editors publish.

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FREE TOOL

Compression test results

Enter an engine's compression readings cylinder by cylinder and see the spread and which cylinders sit more than 10% below the highest. Two low cylinders side by side point at a head gasket. With how to take the test and write it up.

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FREE TOOL

Boat depreciation calculator

Estimate what a powerboat, sailboat or personal watercraft is worth by age, using the California Board of Equalization's vessel depreciation factors, with BoatUS's depreciation curve for comparison and where the numbers stop being a valuation.

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FREE TOOL

Propeller slip calculator

Work out a boat's theoretical propeller speed from pitch, engine rpm and gear ratio, and the slip against the speed you measured on the sea trial, in knots or mph, with the 1056 constant explained and what the slip tells you.

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FREE TOOL

Fuel burn and range calculator

Estimate a boat's fuel burn at full power from horsepower, gasoline or diesel, or enter a measured burn, and work out endurance, range and the rule of thirds turning point, in US gallons or litres.

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FREE TOOL

Fuel tank capacity calculator

Work out a boat fuel or water tank's capacity in US gallons and litres from its dimensions, rectangular or cylindrical, in inches or centimetres, with why the usable fuel is less and how to compare it with the label.

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FREE TOOL

Battery bank size calculator

Work out the smallest house battery bank for a boat from each load's amps and hours a day, for lead-acid, AGM or gel batteries discharged to 50% and LiFePO4 to 80%, with why cold, age and charging call for more.

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Say the reading. Axsail puts it in the finding

Dictate as you inspect. Each finding comes out with its location, reading, recommendation and grade

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