Well, I've never been a fan of "ratline looms" or any other gadgets that claim to make the job easy. It isn't - though it also isn't as hard as a lot of people think.
If both the "clove hitch" and "needle through the shroud" methods are more than you want to take on, in my opinion the best solution, in the case of a small-scale model like this, is simply to leave the ratlines off. If the rest of the rigging is done well, nobody - least of all me - is likely to mind that the ratlines aren't there.
A little terminology might be in order. The shrouds are the heavy ropes that support the masts - and pull the ship through the water. The ratlines are relatively thin lines that are knotted across the shrouds, to serve as ladders for the crew going up and down the masts.
Maybe a little ship model history is also in order. The term "Admiralty model" is usually applied to the exquisite models of English warships built in the seventeenth and eighteenth centuries. (Actually "Navy Board model" or "Dockyard model" is more accurate.) Most of them are characterized by beautiful boxwood or pearwood carved details, and by the omission of the hull planking below the wales - and often on sections of the decks. The curious thing is that the exposed frame structure of Board Room models doesn't accurately represent the way real ships were framed. The frames are too widely spaced for scale accuracy, and the frame layout in general is simplified (though plenty complicated enough for most of us.) For some reason or other, as time passed the frame spacing of the models got closer, and by the second half of the eighteenth century some Navy Board models were replicating the framing of the actual ships.
Some Navy Board models have masts and rigging (though the rigging on them now is almost always modern). A lot of them show nothing above the decks. So there's plenty of precedent for building a model of H.M.S. Prince with no masts or rigging.
Nobody is quite sure why the Navy Board models were built. There's actually very little contemporary documentation about them. There's no way the parts of such a model could be scaled up to build a real ship. And it wouldn't be of much use in estimating the cost of the real ship. The old story that the models were built before the ships in order to show the bureaucras what the real ships would like has also been pretty thoroughly debunked. (There are some - not many - records that date the models after the ships they represent were built.)
Current thinking among the experts (one of whom I most certainly am not) is that the models were built to serve exactly the purposes they're serving now: to serve as wonderful decorations, and to provide an historical record of what the ships looked like. One of our best sources of information about seventeenth-century English history is the multi-volume Diary of Samuel Pepys. Pepys was the secretary to the Board of Admiralty. Several of the diary entries mention that he bought models of warships because he simply liked having them around his house. He was the original owner of several models that still exist. In at least one case he said the model was "most handsome and delightful." Indeed.
The term "half model" usually refers to a method of ship design that was common in the late eighteenth through early twentieth centuries. The first step in the process of designing a ship was for the naval architect to peg together a stack of boards. Then he would carve the resulting big chunk of wood into the shape he wanted the ship to be. The next step was to separate the boards, and trace them onto linen or paper. Those tracings became the basis for the plans from which the shipwrights worked to build the ship.
A lot of half models have survived - including quite a few representing British warships beginning in the latter eighteenth century. And hundreds of half models of American warships and merchantmen from the nineteenth century can be seen in maritime museums. Most of them are pretty crude (and, if they're real builders' models, beat up). Half models were in use as late as the 1950s, mainly to help work out plating layouts. (Maybe they still are.)
A well-built half model, even with virtually no detail on it, can be a mighty handsome wall decoration. One member of our model club specializes in half models.
Fascinating stuff. For anybody who's interested, I can recommend three books: John Franklin's Navy Board Ship Models, 17th and 18th Century Ship Models From the Kriegstein Collection, by Henry and Arnold Kriegstein, and a recent book that's one of my very favorites, The Rogers Collection of Dockyard Models at the U.S. Naval Academy Museum, by Grant Walker. Here's a link: http://www.seawatchbooks.com/115005 . Pricey, but a superb book. It's the first volume in what we hope will be a series covering that collection, which is one of the best in the world.