Ship propulsion: Correlation
Prices it moves with, and why
The proxy is the US shipbuilding and repair index, dominated by naval work. Commercial ship prices, set mostly in Chinese, Korean and Japanese yards, follow steel plate, engines, labour and freight market booms, which drive orders.
Proxy US PPI: ship building and repairing index · monthly, Jan 2006 to Sep 2026There is no free public price for ship propulsion itself, so this tab uses the closest public series as a stand-in. Read the numbers as an indication, not as the price of this exact item.
What its price moves with
Selected linkShip propulsion and Steel
Monthly changes -0.08 little or none correlation 12-month changes 0.02 little or none correlation Last 5 years -0.08 monthly changes Lead or lag +6 mo Steel tends to lead by 6 months (r 0.16) Price function, Jan 2006 to Sep 2026 Ship propulsion ≈ 36.9 × (Steel)0.32 R² 0.55 On this fit, a 10% higher steel price goes with a 3.1% higher ship propulsion price over the long run. Units: index and index, BLS base period.Chart: Ship propulsion and Steel prices rebased to 100 at Jan 2006, log scale
Both prices rebased to 100 at Jan 2006, on a log scale so equal percentage moves look the same size.Chart: Ship propulsion price against Steel price, monthly, log scales, with fitted line
Each dot is one month; paler dots are older (2006), darker dots recent (2026); the ringed dot is the latest month. The dashed line is the fitted price function. Both axes are logarithmic.Hulls are built from steel plate, a major cost for commercial yards. The US proxy shows no link, with monthly moves correlating at -0.08, because it is driven by navy contracts priced on cost-plus terms rather than market steel prices.
little or none co-movement month to month · 249 months Show chartsHigh freight rates make shipowners rich and lead them to order new ships, which lifts newbuild prices. The deep-sea freight proxy correlates at 0.07 monthly and 0.19 yearly, little link because the proxy reflects US naval shipbuilding more than global orders.
little or none co-movement month to month · 249 months Show chartsMost ships are driven by large diesel or dual-fuel engines, a big share of construction cost. Monthly moves correlate at 0.19 and yearly at 0.68 with the engine index, a shared US manufacturing cost trend.
little or none co-movement month to month · 249 months Show chartsLNG carriers are among the costliest merchant ships, and LNG is a growing marine fuel. The LNG import price shows no clear link with the shipbuilding proxy, as US yards build few gas carriers.
little or none co-movement month to month · 249 months Show chartsMany new container ships can burn methanol, including green methanol, to cut emissions, which ties ship orders to methanol supply. The chemical proxy correlates at 0.06 monthly with the shipbuilding index, so this link is technological, not yet in prices.
little or none co-movement month to month · 249 months Show chartsAmmonia engines are being developed for zero-carbon shipping, potentially making shipping a large ammonia buyer. For now the link is about technology choice; the price series show no real co-movement with the shipbuilding proxy.
little or none co-movement month to month · 249 months Show chartsHow to read these numbers
Correlation of monthly changes (the number in the coloured pill) compares how much each price moved, month by month, since 2006 or the first month both series exist. It runs from −1 to +1: near +1 the two usually rise and fall in the same months, near 0 there is no link, and a negative number means they tend to move in opposite directions. Above 0.7 is strong, 0.4 to 0.7 moderate, 0.2 to 0.4 weak.
12-month changes compare year-on-year moves, which shows whether two prices share the same cycles even when the month-to-month noise differs.
Price function is a straight-line fit of the two prices on logarithmic scales: price ≈ k × (partner price)β. β is how much this price moves, in per cent, for a 1% move in the partner over the whole period, and R² is the share of the variation the fit explains. Two prices that both drift up with inflation can fit well without any real link, so read it together with the monthly correlation.
Lead or lag checks whether the monthly correlation is clearly higher when one price is shifted by 1 to 6 months.
Correlation is not cause. The reasons on each card explain the economic link; the numbers show how strongly it has shown up in prices. Proxy series are US producer price indexes or related prices and can blur the real link.
Data: World Bank Commodity Price Data (Pink Sheet), October 2026; US Bureau of Labor Statistics producer price indexes, IMF primary commodity prices and US EIA prices via FRED, Federal Reserve Bank of St. Louis, retrieved November 2026. Calculations by this site.