The detailed small craft charts are the core of our business
At a scale of 1:10,000 and with depth contours at 2 and 3 meters, our detailed small craft charts provide entirely new opportunities for detailed navigation in our magnificent archipelagos. The detailed charts, with newly drawn depth contours, open up the archipelagos for new and safer routes, as well as the possibility of finding secure overnight harbours.
We mainly follow international charting standards, but allow for some minor deviations. We have produced a legend that explains most of the symbols used in our charts. The main difference is that we use a red 2-meter depth contour and a blue 3-meter depth contour—fully adapted to the needs of recreational boaters.
The charts are available in two formats—some are loose sheets in A2 size (42.0 × 59.4 cm), but we are increasingly moving to ring-bound A3 format in our detailed small craft charts, which most people appreciate for their convenient size.
All our small craft charts are printed on Polyart (though some earlier products were printed on regular paper).
We also produce charts on commission for municipalities, yacht clubs, and other organizations. For these, we adapt scale and material of the printed product to the client’s requirements. Some of these commissioned charts are available through our webshop, but most are sold locally by the commissioning organization.
Comparison with standard charts
Charts by the Swedish Maritime Administration are usually at a scale of 1:50,000 or 1:25,000, and feature depth contours at 3 and 6 meters in shallower waters.
Hydrographica’s detailed small craft charts are produced at a scale of 1:10,000, meaning that the same area is shown up to five times larger than in the official charts. Hydrographica’s small craft charts use a red 2-meter depth contour and a blue 3-meter depth contour—an excellent fit for the needs of recreational skippers.
| HYDROGRAPHICA | SWEDISH MARITIME ADMINISTRATION | |
| Scale 1:10 000 | Scale 1:50 000 or 1:25 000 | |
| 2- and 3-meter depth contour | 3- and 6-meter depth contour | |
| Based on newly captured aerial photographs and recent hydrographic surveys | Many archipelago areas have very old hydrographic surveys (over 100 years old) | |
| Contour lines at 2.5-meter intervals on land and islands | No elevation contours on land and islands |
How we produce the charts
Aerial Image Analysis
Hydrographica’s hydrographic survey technique is based on processing and analyzing aerial images in 3D. Using aerial imagery from Lantmäteriet, measurements and analyses are carried out with stereoscopic interpretation instruments, allowing us to determine depths down to approximately 5 meters under optimal water clarity. Shallow areas and depth contours are placed with high positional accuracy, and depths are determined to within a few decimeters. Before the field work begins, a digital chart manuscript is prepared.
Hydrographic Surveys
Hazardous shallow areas and rocks are measured in the field using a measuring rod and adjusted for current water levels to obtain precise depths. During the survey, the validity of depth contours is checked, and point depths in deeper waters are collected using sonar and GPS. Other information, such as navigational marks, buildings, and piers, is also verified.
Data Processing
After the fieldwork is completed, the collected data is processed and the chart manuscript is finalized as a print-ready original. Using laser data from Lantmäteriet, we produce elevation contours at 2.5-meter intervals, and for harbour charts, we can also generate terrain shading to highlight landforms.
Electronic nautical charts
All of our detailed small craft charts and harbour charts are available in electronic format through all major providers of electronic nautical charts. We currently have licensing agreements with Garmin/Navionics, Navico/C-Map, Chartworld/Raymarine/Seapilot AB and Skippo. The digital charts contain the same data as the printed charts but are presented with a different design depending on the distributor.