More information about this unusual navigation instrument
A pelorus (essentially a pair of sights either side of a compass card) can be used to take relative bearings and so can be used in checking for compass deviation as well as transits.
The pelorus featured in last month’s Any Questions and in YM’s coverage of the ARC has caused much interest.
It was carried by Donal O’Driscoll, skipper of Re Shuanta, a Hallberg Rassy 42. It had been built for him (by his brother-in-law) using a compass rose from an Admiralty chart and some clever metal work.
Donal used it in conjunction with Practical Guide to Compass Correction by George H Reid (Thomas Reed, £9.99).
We have not been able to find a manufacturer who makes a pelorus suitable for a yacht though Lilley and Gillie in Tyne and Wear make a large brass ship’s pelorus, £499, Tel: o191 257 2217, web: www.lilleyandgillie.co.uk ).
The alternative is to track down a secondhand one (try www.ebay.co.uk) or ask your brother-in-law!