Portland Marina, Osprey Quay, 6 Hamm Beach Road, Portland, Dorset, DT5 1DX.
Latitude: 50° 34.46' North
Longitude: 2° 27.26' West
Follow the recommended channel from the north entrance marked with red buoys and a safe water mark.
Some useful links are below;
https://www.portland-port.co.uk/Leisure+Nav
https://www.nci-portlandbill.org/
https://www.gov.uk/government/publications/lulworth-firing-notice