The last two live aboard cruising boats I have owned were Eclipse and Romany. The Eclipse is a conventional bridgedeck cabin boat. So going forwards means either a clamber over a high cabin or walking round the edge, and thus walking close to the gunwales. The Romany, on the other hand, has a central cuddy with walkways on each side. So going forward is much easier, with nothing to climb over and the hull acting as a deep bulwark between crew and the water. Of course this advantage also applies to open deck boats, but they don't have the extra room and comfort of the cuddy.

So despite the disadvantage of the three separate cabins (which has the advantages of increased privacy and of being an efficient use of space) the deck layout and working the boat feels much safer with a cuddy design.

Having said that, it is still important - even on an open deck design - to have hatches with washboards. The photo below (of a Romany) shows what I mean.

The most dangerous design is one where there is only a deckhatch for access. Not only is it difficult to open and climb in (and remember that when on top of the cabin you are in effect standing on top of the bulwark) but also it is much further to climb up/down when in the hull itself. That can be very dangerous in a seaway with a great risk of falling overboard or slipping and injuring yourself during the climb out. It is all too easy to fall overboard, however experienced you are. Both Rob James and Eric Tabarly died that way. So a good boat design should include features that make moving around the boat safe and easy.

While on the subject of hatches the smaller boats often have the choice of a side opening (as on the Romany) or an aft opening hatch. The side opening divides the interior nicely into two ends and as explained above, is a safe option.

However the aft hatch makes sense on trailable boats as the sails, beams and boom can be easily slid into the hull for transport. Furthermore it is easier when steering to grab items from the hull with an aft hatch - but that only works on a small boat when the tiller-steering helmsman is near the hatch.