In the case of a hand operated windlass, I think you're right: it really needs to be well forrard where you can see the anchor, whereas a powered windlass can be well aft, as long as the control is forward
(Scarcely Relevant Waffle Warning
In some ways, the simplest and lightest manual idea, offering the best sightlines, would be to make the bow roller a chainwheel.
You'd have a ratchet pawl from the bow fitting to the wheel
, another on a long upstanding lever driving the wheel
(and possibly a backup pawl which could be dropped directly on the chain)
In my experience, heavy gravity pawls are better than light springloaded ones.
To eliminate the need for gear
reduction, a lever extension could socket on, so you could crank standing on the middle or top rail of the pulpit, if need be. A long up-standing handle is a very efficient way to crank, and the efficiency is high because there's no gearbox
needed ... admittedly it's even better if it can be doubleacting but that gets a bit more complicated.
But of course the pulpit would have to be divided for the lever arc
to be unimpeded...
And there'd need to be some sort of friction brake for dropping the tackle, unless you chose to build a chain compressor
aft of the roller (but that's hard on chain if you use it for controlling the drop. I guess it could be lined with UHMW PE).
(The following is also likely to interest hardly anyone, being also highly unconventional and all ... but ... I'm planning almost the exact opposite: I'm going to have a very strong mast-lowering tabernacle, extending high enough to take the gooseneck loads, IOW the boom pivots off the tabernacle, not the mast. So the bottom panel fo the mast is "built-in" as it would be if keel stepped, except it's deck-stepped and the "deck collar", in terms of calculating the bending loads, is at gooseneck height.
I'm seriously thinking of mounting a low-profile planetary-geared hydraulic wheelmotor with a direct-mounted chainwheel at the top of the tabernacle.
If I did this, I'd run the chain to the bowroller direct, over the top of the dinghy and the arc
of the forward hatch when opening. Self launching shouldn't be too difficult but a fallback position would be some sort of springloaded pusher - perhaps a torsion-bar or Dura-Torque style...
Set up tight, the chain would make a great centreline handrail... but I freely acknowledge this layout wouldn't work
It would have the advantage of reducing the extra load involved in wrapping the chain over the bow roller, and it would increase the effectiveness of the chainwheel by the extra wrap angle as the chain rises steadily towards the wheel. Possibly a separate snubber would not be needed, if a cross-line relief valve was fitted to enable the chainwheel to rotate far enough to absorb occasional jerks.
To take the severe forward moment, the foot of the tabernacle needs to run forward to pick up the ring-frame ahead of the mast, which is primarily to take the forrard chainplate loads.
(I'm planning on having a small self-draining chain well at the bow to take the last 10m of chain when inshore, so the chain doesn't have to be scrupulously cleaned every time you pull it up. That implies some sort of rudimentary chainwheel for the bowroller to get that last big of chain, and the anchor back up, in muddy bottoms... full circle back to the first idea. Also a backup if the hydraulic supply, or motor