My ideas about a redesigned Mirror


Most of this doesn't relate to foiling, but because that was my starting point, I'll tell the story from there. A few years ago I was exploring the idea of making a foiling Mirror dinghy using carbon fibre just for the fun of it, but it didn't look like a practical idea other than as a ridiculously expensive one-off stunt. However, I may have written off the idea too easily on the basis that it would take more wind for it to foil than a purpose-designed foiler and that its performance wouldn't be great. I now realise that a foiling Mirror would likely handle a gale better than any current foiler, and that, in combination with other requirements, could make it a great boat for coastal cruising. I've had other ideas in relating to safe coastal cruising too for a non-foiling Mirror, such as filling in most of the floor with storage space so that it can't get swamped by waves (and then have a third of a ton of water stress the hull to breaking point). I've also been thinking a lot about the difficulties of taking a boat to events abroad, and now all my ideas are converging in such a way that the Mirror looks more and more like an ideal cruising boat. I was looking at the inflatable Tiwal sailing dinghy as a possible solution to taking a boat abroad, but it has no capacity to carry any gear.

Anyway, here's the big idea (or collection of ideas). When you buy a wooden Mirror kit, it comes in a box that's small enough to be able to transport at low cost, but you can't move the boat from place to place (e.g. across continents) so easily once it's been built. What you really want is a boat that can be assembled easily and disassembled equally easily so that you can put it back in the box and rebuild it somewhere else. Instead of gluing panels together, you would want to bolt them together. The big problem with that is how you stop water coming through between the panels. Rubber seals might work, but ideally you shouldn't need to worry about them leaking at all. Think instead about designing an inflatable boat with an exoskeleton. The panels for the underside, sides and transoms are bolted together, then a higher floor (made from several more panels) is bolted in above the waterline, and underneath that floor will be buoyancy bags which completely fill in the space below when inflated. Some water may come in through the joins between panels, but it would have nowhere to go and would just sit in the cracks adding less weight than the epoxy that would normally seal such cracks to make a boat watertight. With the bags inflated, the strength of the panels and floors is also increased significantly, leaving you with little to worry about when walking about on an inverted hull during a capsize.

Not only would such a boat be easier to travel with, but you could dismantle it for storage indoors over the winter, and if you ever hole the boat on a rock, you'd could just post a panel or two off to be repaired, and/or buy new ones. If part of the boat is upgraded to handle a new hydrofoil layout, you would only need to buy new panels for the ones that are changed, and the old panels could be sold to people needing to replace damaged ones.

But why do this with a Mirror? Why not something more modern? Well, if you want to pack it in a box, you need something that can be built out of reasonably flat panels, and the Mirror is already there. The Mirror is also a boat that you sit in rather than on, and it is wide for its size, which makes it a little draggy, but it also makes it roomy, comfortable and stable. The raised floor would take up a lot of that space, of course, but there would still be enough left over. I would put an inflatable layer on the floor and up the sides too so that you can sit or kneel in it comfortably all day without destroying your health, so this would make it like sailing a sofa. The side and rear buoyancy tanks are gone - there will be plenty of floatation without them, and while this redistribution of buoyancy will make the boat float deeper in the water when on its side, that isn't a bad thing as it'll be easier to right and will blow away from you more slowly if you become separated from it. Water will be able to run straight out through flaps in the transom, so there will never be any bailing. There will be no tank at the bow either - the space there can all be used for storage, and the foredeck will be raised to gunwale-level in order to end-plate the jib and maximise the storage space underneath.

Other innovations:-

The front transom will have a section that opens forwards like a drawer, and from this the spinnaker will be deployed (from ahead of the forestay). The spinnaker will be pulled back in using a line running up the inside where it doesn't interrupt the critical air flow round the outside, and once the spinnaker is down, the "drawer" will be closed again, bunching the spinnaker up into a smaller space than it normally takes, so you don't have an end of it trailing out into the cockpit.

The top of the centreboard case and thwart can be removed to create room for sleeping, leaving enough space for two adults to spread out in comfort, or an adult and two children (with one of them stretching their legs into the storage area under the foredeck there may just be enough room for two 12-year-olds of average height, although if they're that old they should have their own boat).

A door in one side of the transom will make it easier to get back in the boat after a capsize, so long as you aren't too fat - it would fold 180 degrees downwards and provide a shelf to kneel on on the way through.

Racks can be fitted to enable the crew to sit beyond the gunwale in comfort and without needing toe straps. Lighter crews could sit even further out to gain enough RM to handle the boat - I reckon two five-year-olds could handle such a Mirror on their own if the racks stick out three feet (so long as the ratios on the sheets are adjusted too to make the forces manageable). Another reason for the racks is to prevent people falling into the rear foils if hydrofoils are fitted, so providing structure to attach them to is essential. The racks can also be fitted to form the roof of a shelter when camping at anchor. The racks also include long floats along the outer edge - mini outriggers which help prevent the boat capsizing and remove all the worry from sudden lulls.

There is enough depth in the floor by the centreboard case to put in one or even two Japanese-style toilets which would also contribute to the boat's buoyancy tank-equivalent volume when the lids are on (meaning that these won't fill up with water when you capsize, despite going far down below the waterline) - this capability is vital for any serious cruising boat where many trips that could be made are simply not made with today's dinghies because there is no private place to go.

The vang may (optionally) be replaced by using a traveller which follows an arc from shroud to shroud, passing round behind of the centreboard case, so this would be a new thwart design. The part where the jib fairleads go would need to be higher up and further forward. The helmsman controls the traveller instead of the mainsheet to set the sail angle while the main sheet becomes the equivalent of the vang. The top of the mast has two pulley wheels in it instead of one - this allows the bottom of the gaff to be pulled up on a halyard of its own, and then the standard halyard can be used to adjust the gaff angle, thereby making it easier to flatten the sail in a gale without stretching it viciously using tension from the boom. Part of the luff below the gaff can also be pulled forward for the same reason - this all has the effect of bending the mast without bending it at all. There is more floor space forward of the centreboard case, and with the vang gone, this makes it easier for an adult crew to work in that position during tacks and gybes.

The skeg is gone and the rudder is more slender because it no longer has to fight against the skeg. The sharp edges of the hull around the front transom and floor of the bow section are softened for aerodynamic reasons - this reduces hydro drag a tiny amount too, although that is not the aim. The boat can still be raced as a standard Mirror, although it may need to carry weights for that, because if it can be made lighter than a normal Mirror, it will be, and it may also be necessary to bolt on a skeg and use the standard rudder.

A third halyard allows the sail to be reefed without lowering the gaff. A bendable track for the luff will continue down from the bottom of the gaff, and that will be tied to the mast instead of tying the sail to it, so the sail is always attached properly the whole way down. Roller reefing round the boom is not possible with centre sheeting, which is what we have if we are using the system I described to eliminate the vang, but it is possible to attach a roller to one side of the boom instead, and this could be more like a long plank so that it can serve as an end plate for the reefed main.

This could make the Mirror the most desirable cruising dinghy of all, in addition to being a great design for racing which solves the long-distance transportation issue. It could also become the most desirable foiler for the ordinary sailor who wants something that's much more than just an expensive toy. The Mirror can be turned into a cutting-edge design again, fifty years on from its original appearance, and that's an astonishing thought.

As for hydrofoils, this modular Mirror makes it easier to innovate because you can simply build new panels with attachment points specific to the foil system you wish to experiment with. I would start by making a rear transom with the ability to hold a pair of cases for rear foils, and a front transom designed to hold two more cases slightly closer together. All four passive foils would be used downwind and the two leeward ones would be used when going up, while the rear two would steer. The front foils would have twist in them to eliminate porpoising, meaning that if the bow dips and the effective foil pitch is reduced, the newly immersed part of the foil generates enough extra lift to compensate and maintain good stability. All foils would use lifting sections sloping at 20 degrees, but with three staggered lifting sections on each foil at different heights to provide the same heave control as a foil sloping at 50 degrees - this enables a foil to generate the same amount of lift to windward when going upwind as the Moth and Vampire, and when going downwind it will still generate less drag than a boat using Z foils which slope more steeply and waste more of their effort working against each other.

[Note: I would not use a single hydrofoil under the middle of the hull as it's too hard to launch and land with a foil there.]