To provide my take on the issues you raise I have copied your headings below:
Holding tanks – to comply with various EU and local laws
The BIG issue with holding tanks is that you won’t find many places where you can get them pumped out (and not at a sensible price if you find it ) and the alternative is to go miles offshore. So no country actually takes this seriously. So what do you want to achieve here. If it is to satisfy a notional inspector then you could use a camping toilet (portapoty) or a built in holding tank. The built in tank will inevitably be far to small to be of any practical use. As Nick mentioned in his reply Calista has a holding tank fitted in the eyes of the boat in front of the toilet. It holds about 12 hours worth of use for 2 people. That is with a Lavac toilet which is frugal with flushing water. That said – it depends on what you want to achieve. Calista often spends a tide dried out on a sandy beach – and the holding tank works well for that. If you want to transit France by canal you will need a huge tank – and that just will not fit into an Atalanta. I would suggest the practical solution is a camping toilet which at least can be emptied at a canalside campsite.
A Bimini – possibly needing raising the goose neck to give sufficient headroom
I think that a Bimini is essential for what you intend. Temperatures in Southern Europe are getting warmer each year. Human beings need protection from that sun – skin cancer is a real issue which you must protect yourself against. Firstly a wide brimmed hat. I like the Tilley version. Calista as you already have been told has a Bimini. She is a Titania so slightly different. We can sail with it up – and if you cant it is no use to you. The Bimini is erected and stays up for the whole summer in warmer climes. Our Bimini has mountings to take a 100 watt flexible solar panel, sides front and back to convert it into a cockpit tent. We sometimes sail in wet welsh weather with the bimini up and the front attached. Oilskins are then totally unecessary!
Rejigging the pushpit to incorporate a swimming ladder, a platform for stern-to mooring
Adding a frame/arch to support solar panelling, most likely added to the pushpit
Installing some form of bowsprit incorporating anchor guide, bow roller, tack point for a code 0/1.
I am lumping these together because I detect a theme – and that is added weight. You must resist the temptation to add heavy items. There was a Titania which was refitted for a med voyage which sank when it was launched. Not a joke it happened. I was asked to advise when it had subsequently found a new owner who wanted to know why the water flowed from the cockpit into the cabin when it was launched. Most of the additions had been removed by then but the aft cabin still had a large fuel tank in it – which was full. You can guess what I suggested.
Anyway a swimming ladder will be used – just the sort you can get from any chandlery and fix to the transom. Resist that platform for stern mooring. It is totally uneccesary. Stern mooring is not the solution – you should moor bows in. Almost all mediterranean moorings now have laid lines so you won’t be using an anchor and backing in. You can go in bows first and fish out the line from the bows – or the “marinaro” will hold it up so you can reach it. Attach that to the stern and pass bow lines ashore. This way you protect your rudder from the shallows near the quay, avoid having a long raised rudder to keep you miles from the quay and gain privacy in your cockpit. which is now not open to passing eyes.
Solar panels are a good idea – 100 watt should run a proper fridge and instruments while sailing. But keep it simple and light. Possibly even movable.
Any form of bowsprit or appendage there has to be strong, and not damage the structure of the boat. Remember Atalanta’s are really lightly built and you could easily rip the deck off. The anchor fitting on your bow is designed to do the job without damaging the boat – I would stick with it. Some extension to enable a big jib to be flown? My experience is that their is enough wind for you to reach 1.5 knots under your normal rig – or there is not enough to wind to fill any sail – however big it is. (As an aside 3/4 rig Atalanta’s can fly a masthead genoa in up to force 3 without modification – and that might be worth while if you have 3/4 rig).
Adding an electric windlass – principally to aid stern-to mooring single-handed with the aid of an anchor.
An anchor winch is a worth while addition for anchoring full stop. I certainly won’t try raising anchors without mechanical aid. However electrical versions require large currents and only work when the engine is on. They need starter cable size wiring from the battery bank. They are not reliable. I certainly would not contemplate an electrical one – even though you may find it difficult to find an anchor winch in a chandlery which isn’t electrically powered. I also think you overestimate the need for laying an anchor for a mediterranean mooring.
Fitting boom roller reefing – means reefing and sail management can be controlled from the cockpit
I presume you mean one of the patent systems – because all Atalanta’s were fitted with boom roller reefing from new. I use the original roller reefing on my mainsail and I never leave the cockpit. Sometimes I stand on the cockpit coaming to reach the end of the boom. Perhaps I should explain that I like sails to set properly so I tie down the cringe at the gooseneck with a lashing after rolling the reef in. I then use a lashing at the end to pull out the foot of the sail and around the boom to take the strain off the sail canvas. Effectively it is points reefing without the points. I think there is no real need to spend lots of money on a clever boom reefing system. It adds weight – drains funds – and is probably no better in practice.
Tailored storage points for the rib/dinky on the rear deck – but this would impact access via the rear platform – is the idea of a foldable dinghy (a la Seahopper) a sensible option?
I am not really taken with the Dinky as a tender – it isn’t very stable as a tender. It must be really difficult to get on and off the rear deck. Most people carry an inflatable. They are horrible to row, but they are stable and comparatively easy to stow. They are a nuisance though – do you stow it on a bunk at sea, or on the aft deck. Either way it is in the way. On the aft deck it makes the aft cabin hatch difficult to open – its probably on top of it. However dedicated lashing points to hold it there seems a good idea – if that is where you are going to stow it. Since my sons have grown up I tend to keep it in the aft cabin, which is more often in use as a lazarette.
Autohelm versus mechanical self steering gear. Eg Navico TP1800 Tillerpilot?
As others have mentioned there have been mechanical self steering systems fitted to Atalanta’s. The advantage of wind powered systems is that they do not consume electricity from your batteries. The disadvantage is that they only work when there is WIND. You will find plenty of times when there is insufficient wind to enable wind powered self steering to work. The answer is an Autohelm – or other electrical tiller pilot. Solar panels will overcome the electrical consumption. I have an auto helm – which is reliable and consumes little enough power that I use it frequently.
Installing an ice box with a cooling powered by the solar panelling
There are really three options here. Firstly you can use products which do not go off quickly. Dried milk powder for example. Vegitarian diet to avoid meat going off. And so on. We have done it and it works – with limits of course. Do you really like dried milk powder in your tea?
Secondly a simple coolbox using ice cubes bought from a supermarket. The ice is available everywhere and it works. There is a cost but it is probably cheaper than a proper fridge.
The proper fridge is really the bees knees in this department. We bought a kit with compressor and holding plate, plus a kit for making the actual coolbox. That was sheets of plastic faced insulation which were cut and glued together with silicone RTV. The finished device will work as a freezer it is so powerful and well insulated. Running as a fridge we can leave it switched on all the time and the 120 watt of solar panels fitted to Calista will maintain the battery in clear sunny weather with long daylight hours.
In practice I have found that fridge auto helm and instruments will all run of the solar power and the engine hours that we naturally accumulate when cruising. We rarely feel the need to use shore power.
Adding extra portlights or hatches to increase airflow and natural lighting in fore and rear cabins.
While Calista is slightly different to an Atalanta I think that you are worrying unnecessarily here. Open the fore hatch – it will scoop air down into the boat when propped half open. Open the main and aft companionways and hatches.We sail like that most of the time when its hot. The MCA might not like the idea of an open fore hatch at sea but I cant remember getting water in through it. Certainly a Titania fore hatch is well clear of the sea. Some form of opening port might be of use in the aft cabin particularly in port. It is always hotter in port than out on the water. If you are going to be stopping in a marina or port for some time then covers over the decks make a big difference. Calista has a set of covers which go over the whole boat in three sections. We have used them – but not very often, probably because we don’t tend to spend ages in one place.
One issue you have not raised is mosquitoes. There are plenty of those in the med and the canals. We have net screens to cover all the openings. It is often hot when you need them so it helps if you can keep hatches and companionways open but covered with mesh to let air flow but catch the insects. That is worth some effort to make them. Simple light effective. Roll them up and stow in a corner under a bunk – and I guarantee you will be glad you have them!
Replacement inboard motor required – suitable power rating and make which would be easy to maintain in France/the med.
The manufacturers of inboard engines are now international – so it won’t matter what make you have. They are often based on another makers industrial engine anyway – so it might be useful to know the base engine make as well. Power depends on what you want to achieve. 3 knots entering harbour then 8 to 10 hp. If you want to cruise all day at 5.5 knots through a flat calm then 15 to 18hp might be more suitable. Remember when motoring into a head wind most of the power is taken moving through the wind – so a more powerful engine will get you into shelter when you really want to find shelter NOW. Most modern engines require some form of thrust block cordon shaft arrangement when fitted into an Atalanta. Modern engines are higher than old ones so need to be installed below the original shaft line.
230v shore power with distribution MCB board.
Yes Calista has shore power fitted. Do we use it – rarely. We rarely use marinas or places where shore power is available. It is useful when laid up though – I leave the batteries on trickle charge all winter via the shore power connection in our boat shed. I suppose you might use your Atalanta in a different way to us – and it might well be of use. If you spend a week or so in one harbour – and you can get shore power then it could keep the fridge cool, the batteries charged and all the gadgets topped up. In the summer you aught to be able to do that with solar power anyway!
Hope this reply is of use