How is boat length measured?

1 February 2020

trailer boat length measurementHow trailer boats are measured in Australia differs between boat builders.

This inconsistency – along with confusion created by some manufacturers and salespeople claiming “their boat will fit inside our boat” – doesn’t help anyone!

Most leading Australian trailer boat builders measure their boats point-to-point from the bow sprit to the swim platform, excluding outboard motor and other appendages. This length is known as ‘length overall’ (LOA).

Some boat manufacturers still take measurements from the hull length. This is measured from the point of the bow to the transom, excluding bow sprits, outboard motors and other appendages.

To throw a real spanner in the works, a handful of boat manufacturers have been caught simply making it up! Putting a higher-value number on a boat’s graphics, to make a particular boat appear bigger than another boat, has been known to occur.

INTERNATIONAL STANDARD

Back 20 years ago, we used to measure our boats the old-school ‘hull length’ way, although we updated our model range to reflect the ‘length overall’ measurement when Bar Crusher boats achieved CE certification in 2010.

Inline with ISO standard for CE compliance, Bar Crusher model numbers have since reflected the length overall in metres. From our smallest 490C (4.90m LOA) through to our flagship 780HT (7.80m LOA), the internationally-recognised length overall boat measurement we use makes the process clear and simple.

trailer boat width beam measurement

ON THE BEAM

There’s much less confusion about the width (beam) measurement of a mono-hull trailer boat. Technically called ‘beam overall’ (BOA), the beam of a boat is its width at its widest point.

While some people directly translate a boat’s beam (as they see it online or in a brochure) to how much space they believe there is onboard, they’re very surprised when they physically get in various boats to compare them.

LENGTH vs BEAM

Most importantly (as experienced boaters know), a boat’s beam – specifically, its length-to-beam ratio – heavily influences on-water performance. This is particularly relevant in a following sea.

A wider beam (compared with boats of similar length) is one of the major contributing factors to the dangerous boat behaviour known as broaching.

KNOWLEDGE IS KEY

When researching the purchase of a new boat, it’s important to be able to decipher the conflicting information in the market and really understand what you’re looking at.

Check out this list of boat buying tips. It’s aimed at increasing your knowledge of plate aluminium boat design and construction to ensure you get the best boat for your needs.

We’re here to assist with your boat buying research and provide after-market advice, so feel free to contact us.

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