The older your classic, the further two figures drift apart

Reading the chart

How to read the value gap chart

The chart above sets the market value against the yard invoice for one boat and one year, and it is driven by two controls. The slider sets the year of build, and the three buttons switch the construction: wood with classic carvel planking, a mahogany runabout, or a steel or riveted hull. For the chosen year the grey line shows the market value, the sum an ordinary policy would pay after a total loss, and the coloured line shows what a yard would charge to rebuild the boat to the same standard. The shaded area between them is the gap, and the three boxes on the right repeat the two figures and their difference for the year you have selected. The dashed horizontal line marks where an agreed value would sit for the selected year: at the yard figure, as a fixed amount that no longer moves with age.

Age is the factor that moves the curves most. Market value falls quickly in the first decades and then flattens, because an old boat in sound condition still has a floor price, while the yard invoice climbs steadily, because every additional decade means more hours for the same result. Construction shifts both curves at once: a mahogany runabout is expensive to rebuild and holds its price, a steel hull is cheaper to rebuild, and carvel wood sits in between. Drag the slider from right to left and watch the gap open; it is small for a young boat and widest for the oldest years on the scale.

The curves are a model calculation, not market data, and the amounts are rounded. The chart does not know the state of your boat, its equipment or its history. A fully restored classic with new rig and engine has a market value far above the grey line, and a neglected one far below it. The scale runs from 1925 to 2015 because that is where the effect is visible; a boat outside that range simply sits at one end. Only a valuation survey can put an actual figure on your own boat.

The typical mistakes are easy to avoid. Do not read the yard figure as a sale price: it is a rebuild cost, and nobody would pay it on the used market. Do not assume that any policy pays an agreed value automatically; read the wording and check whether the total loss basis is the market value at the time of the loss or a fixed agreed value, whether partial repairs are settled without a deduction for age, and how the value is reviewed after a refit. And when comparing offers, do not compare the premium alone. Two policies with the same premium can pay very different sums for the same boat, and the gap in this chart shows what that difference can cost.