I have a Silva compass on mine, which is set correctly ie swung and compensated. Hydraulic steering causes less problems, as there is less metal changing sides (from experience, not necessarily technical expertise!!).
However, out of chice, I would go for a Plastimo Offshore compass. These are bullet proof, designed for powerboats, and have an optional bracket for fitting onto angled surfaces etc. They also incorporate a neat, and robust, hood to either shade the reading in strong sunlight, or protect the instrument when not in use.
Well worth the extra, and I don't work for them.
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