[which craft] design considerations continued
Thursday, August 23, 2007
A compromise between purpose, cost and size
What do you want the boat for?
1] Cruiser;
2] Racer;
3] Cruiser/racer;
4] Off the beach, which won't be touched in this article.
Any sort of distance sailing, whether cruising or racing, is going to come down to either:
1] blue water sailing in the form of either long distance [35 to
2] island hopping or overnighters [rule of thumb is 19 to
Vital consideration and the choices are really:
1] Monohull - the traditional "boaty" boat, from dinghies up to keelboats
Most people's idea of a "yacht"
Advantages - boaty feel, slow and sure, beautiful on the eyes, traditional, if knocked over by the wind [a real danger], it can pop up again safely.
Disadvantages - always sails on an angle, keel sometimes falls off and boat sinks like a stone, cramped inside, wet, too slow [unless you're a millionaire].
2] Catamaran - two hulls strapped together with crossbeams
Stable and yet anything but stable
Advantages - utter speed, especially across the wind when it can't be touched by any but the sailing canoe or proa, immense stability allowing it to carry more sail, huge accommodation the larger it gets, sails flat, difficult to flip, utter comfort.
Disadvantages - buries the nose and can flip that way; though ultra-stable, once it does lift, the wind gets under and over she goes. Experiment - place a piece of board against a wall and press against the side. No movement. Now slightly lift the side and watch how easily it flips, once past a certain point. Also, people tend to take advantage of the huge accommodation and overload it so it becomes an unstable tub. It can give a hard ride as it crashes through the water, rather than rides over it. Has problems turning.
3] Trimaran - one largish hull and two smaller hulls, one either side
Fabulous cruising boat, immensely stable
Advantages - pound for pound, possibly the best configuration for the sea. Immensely stable, even under severe pressure. Experiment - take a soccer ball and try to push it under a bath full of water - that's trimaran stability. Slightly less speed than the cat across the wind but does better upwind and has the beauty and other advantages of the monohull and cat. Turns on a sixpence. Roomy feel to it overall. Lovely boat.
Disadvantages - cost [3 hulls, not 2 or 1], more sail needed for the heavier weight, narrow hulls make it the worst for accommodation, with a modern western rig is unbalanced fore and aft [front to back] and can dig in and flip this way, can be wet.
That's as far as the west usually goes but there are still other configurations from the east:
4] Proa - one narrow two direction hull with an outrigger
This boat goes forwards and backwards alternatively
Advantages - out and out speed with only one hull sailing upright and a long weighted log balancing it out to windward, sheer thrill.
Disadvantages - needs an athletic crew, constantly on the alert, to balance it and the optimum sail plan for it involves fiddling about every time it turns. Great day sailing boat but not much chop for cruising unless you have a large crew. Messy steering and messy sideways movement prevention too.
5] Outrigger canoe - like the proa but sails only forward
A crab claw rigged outrigger canoe
Advantages/disadvantages - depends on the configuration of the smaller hull. If it is just the right weight and size, it gives great stability like the tri in one direction but acts like a proa/cat in the other. So you'd go like the wind, constantly attending it in one way but on the other could set and forget.
Some people don't like the asymmetrical nature of this - it's personal preference and it militates agaist modern western thinking which likes "dial-in" power and everything minutely under control. Outriggers are more natural boats, suited to waves and requiring good sailing skills.
These configurations are the only really practical choices available.
Sail plan
Ho, ho - where do we start? The dispute of ages here.
1] Old square riggers
"Surprise" steaming along on full power
Well, all right - beautiful ships, beautiful but not immensely practical today. Excellent for long voyaging if following a path with the wind behind the whole way, useless into the wind and the advantages replicated by the Junk [below]. Tall masts which frighten the hell out of you if you have to go up to take the sails in - brrrrr, I'd prefer not, thanks.
2] Space age wing masts
The one on the left, Cogito, is the fastest multi-directional sailboat on the planet
Heavy, hideously expensive but immensely powerful and can't be touched, especially downwind. Racing only as there is a thig called reefing [shortening the sail when the wind gets up] and this solid wing can't be reefed. If you have a million dollar sponsor and intend to sail only on light afternoons, then this is for you.
3] Modern Bermudan
Extreme Bermudan, only good upwind - I sailed this class for some years
I hate them. OK - let's be fair. The modern western Bermudan is unchallenged into the wind and almost flat across the wind and has been designed for racing round courses which favour upwind sailing. I had one in extreme form - an A Class catamaran and it sure was efficient until it went downwind.
It is top-heavy, places immense stress on the hulls and rigging, has a leaning-over disadvantage, is expensive with modern materials [putting sailing into the rich-boys category] and upkeep is constant and expensive. On a long distance voyage, I'd not use it.
4] Gaff and 5] gunter rig
Gaff rigged cat, showing lower centre of effort and greater stability
The former can be seen in the cat here and the gunter in in the Mirror dinghy here. The gunter is virtually a Bermudan, with its advantages but the gaff is another thing.
This is the rig which followed square riggers and was itself replaced by the Bermudan in the 50s. Modern westerners snort at the old fashioned woodwork, the lines and cords [forgetting the immense number of lines on modern Bermudans] and how it can't touch the Bermudan to windward.
The gunter rigged Mirror Dinghy
Old timers in gaff riggers quietly go about their business and actually sail away from the Bermudans across the wind and with the wind behind, where any sane person would prefer to sail anyway [they think]. The Bermudans call after them; "Yeah, you can't do that into the wind, can you? We'd kill you!" to which the gaff sailor smiles: "Why would I want to?"
Quiet ride, comfort, lower centre of gravity meaning greater stability, less stress on rigging and easily lowered in a storm, this is the western cruising sailor's best choice.
6] Sloops, 7] cutters and 8] schooners
Sloops are the standard these days
A yacht with a large rear sail and a smaller front sail is generally known as a sloop. It's an efficient rig and the little front sail helps out of all proportion to its size. This is most people's preferred choice. Easier to handle, it does the job in short sailing.
Cutters are close to the optimum cruising rig
Cutters have two or even three sails out front and this has the effect of having smaller areas [easier to handle] and a more even spread down the length of the boat - it's a wonderful cruising rig. Not much use for short sailing.
Not strictly a schooner but close enough
Schooners are the big boys - two, three or four masts, sail everywhere, they're so beautiful and in the old days were the speedsters of the yachting world. For me, this is what sailing is all about - traditional beauty combined with power. You have two million dollars to buy one?
Those are the western rigs but hang on one moment - we haven't looked at the eastern rigs yet.
9] The lateen, dhow, whatever you want to call it
Disadvantage is the bit forward of the mast
One of the oldest, most simple and easiest. Good but not great sailing characteristics, it is cheap and does the job nicely. Downside is the non-reversibility on the other tack [when you change direction].
6] Crab claw
Beloved in the south seas on proas, it has immense offwind and across wind ability at a large range of attack [meaning it matters less, unlike western rigs, where the sail is actually pointing]. It goes like a bullet. Downside is that it can't be reefed in a storm [lines can be pulled across it to reduce speed] and it can blow out. It's also poor upwind.
7] Junk rig
Each panel individually controlled
The traditonal Chinese sail, it has huge advantages and disadvantages. On pure "cruisability", it has no rival. Nothing sticking out the front or sides, it is mild mannered, doesn't flap to death in a storm and is the quickest reefed sail imaginable on whatever angle you happen to be. If your crew are not keen sailors, this is possibly the sail to calm them down. It gives confidence. It's also the softest on the rig, placing no great stress at any point [cf. the Bermudan] and can therefore be made far more cheaply. It is lower aspect and therefore more stable.
Downside is that it is a bit slow, uses a lot of lines and though excellent downwind [like the old square rigger], it's not much chop across or upwind. Junk sailors don't care about that. They have all the time in the world to get where they're going. Great cruising sail.
There are other sails but these are the main choices today.
So - what to choose?
An issue I've been grappling with for years. I've designed everything imaginable, even hydrofoils and the central point is that everything in the end is a compromise between clashing parameters. So here's a sketch in the picture below of my boat [at this moment of thinking]:
Click pic for a better view
Notes
1] It needs to go from the Mediterranean to
2] I have virtually no money so it would have to be constructed to a simple design, from wood, in an Eastern European country with a seaboard. The rig would also have to be el cheapo.
3] My configuration then, despite it being primarily a south seas design, is the outrigger with high freeboard [space above the water line] and the outrigger [ama] must have accommodation and store all the heavy items - water, for example.
4] The main hull must be long and thin at the water line but flared into very broad at deck level to prevent splashing - it must be a dry design. It has to have a hard cover for the sailing station so as not to freeze to death. It must be sailable by one.
5] Multiple accommodation is irrelevant to me. There'll be one "nuclear family" and me or my girlfriend and me or something similar. There'll be one double, a three quarter bed for me and a smaller twin for children.
6] Privacy, on the other hand, is paramount and this is coupled with discrete, sealed compartments all the way along, each completely cut off from the other and various sealed spaces all over the place. This makes for a simpler and therefore cheaper build.
7] My own bed area is in the centre of the small hull, with a storeroom for loose items up front.
8] Toilet is at the rear of the small hull, doubling as a washing area with privacy from blinds. Main living area/galley is simple - epoxied ply bench with cushions. Weight is therefore so much less.
9] Cutaway ends to the boat are for lightness and better handling. All crossbeams are hand tied so they can be untied in an emergency. Simplicity. Ditto the deck planks [epoxied for strength] - they sit on tied beams, connected by webbing and can collapse and roll up in a storm.
10] Rig - decided on crab claws in the end so I could carry less sail overall, with fewer lines. They are reefable [unusual in this plan] by means of a shorter gaff which sits on a pull-outable levered base [too complicated to explain but I've checked it out].
They have immense power, except upwind but I don't want too much upwind. Their centre of effort is low. I placed them against Bermudan and Junk in diagrams and though the Junk reefs more easily and the centre is just as low as on my rig, mine is still carrying full sail. When mine is on its last reef, it's virtually on the deck.
11] Cutaway shoal keel eliminates the need for retractable boards and holes in the hull and rudder is protected. Simple again. Run aground, hit somethng underneath, e.g. a whale and the keel takes the brunt.
12] Crossbeams extend past the sides of the boat so that hitting anything like another boat or a harbour wall would hit the ends of the beams and not the boat itself.
Two negatives
1] Firstly, the nature of an outrigger makes one tack [angle against the wind] lively and requiring concentration and the other is OK. but we can get round this by reducing sail on the lively tack.
2] Secondly, I don't like the rear mast on that angle but there's no choice if it is going to allow full tacking plus the rear sail must lay down near horizontally to provide horizontal thrust forward. The other sail is then for trim. Not beautiful but the overall sail plan is pretty.
I've thought it through and imagined anything coming at us on a voyage with this configuration and think perhaps it's all covered. A westerner might not like the primitive nature of the boat but I'm more interested in its effectiveness and low cost.
posted by James Higham at 15:38
0 comments
