To retrieve the anchor (or shot line) some electrical power is helpful. I mostly anchor with my Fortress anchor (FX16) which is quite light (5Kg) and has only a short length (3m) of 10mm chain - but it is still nice to be able to get assistance. My main anchor (Manson Supreme 11Kg) also has mainly rope warp (55m) with just 10 metres of 8mm chain at the bottom end.
I decided to get a capstan, with vertical cylinder, that could fit on the cockpit side easily and which could pull in warp (rope). I have 24 volt electrics and sought such a model. After some discussion, I decided to get a 12 volt model since that was readily available.
I bought a 12 volt EC1000 which fits neatly in the required spot. The
cables were run directly from one of the 12 volt service batteries (with a
circuit breaker and a foot switch). This model (from South Pacific Industrial
in Australia) is described as having a motor wattage of 1100 watt input. But
electrical consumption is 25 amps at 12 volts which corresponds to 300 watts.
  So someone is telling porkies... Indeed the small print says power
is "equivalent" to a 1100 watt model. Fishy.
  Even so, 300 watts is quite a help and it is rated at that for 20
minutes continuously. Maximum load is 72Kg - more than enough for an anchor
and chain but not enough to pull a boat against a strong current. The retrieval
speed is 18m per minute, so a few minutes should suffice.
In practice, the capstan has been a useful aid. I found it useful to fit a cleat near it, so that warp could be belayed around the cleat while manoeuvring to get above the anchor (rather than pull directly on the capstan) or when pulling the anchor out of the seabed if it was well dug in. It is quite noisy - but most capstans are.
Capstan on side with footswitch below.