Ian McColgin
02-07-2007, 03:20 PM
Below is a bit that I'm writing up. It's specifically aimed at catboats but applicable to other rigs with suitable modification. Once I get down to the "air jibe," some controversy may arise. Please make both con- and destructive remarks, editorial suggestions, quibbles, warnings against crackpot practices etc. both as PMs (HehHehHeh) but better, right here.
It's serialized as it's a bit long by itself.
# # #
Catboats are unusually safe to jibe yet many fear the evolution.
The textbook jibe is to bear off while trimming the sail to amidships by the time the boat's straight down wind. The sail flops over and is let out. The problems with this jibe for catboats are severe. The boat
fights the trimming sail by attempting to round-up, often overpowering the rudder. The sheet is so long that the sail's rarely trimmed amidships before it comes whanging around. The flying bights of sheet can remove boat and body parts. Shockloading as the sail snaps full can break a gaff. The boat wants to round-up fast as the end of a jibe, perhaps broaching.
Sheet management, helmsmanship and sail trim are the Delphic secrets of jibing. The specifics here pertain to traditional catboats, but the generalities apply to all rigs.
SAILS AND SPARS
Traditional catboats have heavy booms and highly peaked gaffs. The
heavy boom keeps the boom from lifting excessively when sailing off the wind and when jibing. The highly peaked gaff provides wonderful sail shape with the aerodynamics for safer jibing than can be had from gaffs at a flatter than 60 degree angle, especially if they are long.
SHEET LAYOUT
Traditional catboats are rigged for safe sail-handling. The simple
sheet horse, pretty much a very large staple, is just abaft the cockpit
combing. Most of the sheet tackle is abaft the transom. Stern cleats
are out of fouling range. The great barn door rudder's long bowed top prevents lines from fouling. Most catboat transoms will not catch a line. Nothing's back there to foul a fishing line or a flying sheet.
Catboat sheets must have a stopper knot to stop the boom from going forward of straight abeam not just to keep the sheet accessable, but to protect the gooseneck. That knot is part of the control system.
LINE HANDLING
A coiled line running hot will make a block-jamming kink within a few
fathoms because coiling a line includes a bit of twist in against the
lay,. A line that's been coiled needs to be overhauled before use.
To overhaul a line for tangle free running, the sailor lays the coil
down with the standing part leading to the cleat on top, fakes the line
casually while working the twist out to the bitter end, and fakes the
line back the other way over the bitter end. This does not have to be
perfect figure-eights or anything.
Cats have miles of mainsheet that get hauled in and out quite a bit.
Where skipper and crew stand or sit to haul and where the sheet
naturally falls faked down determine the preservation of body parts.
The sheet must be laid out such that both the skipper and crew can trim and ease comfortably and safely.
STEERING AND SAIL TRIM
Modern short-boomed sloops can bear off from a beat right around and through a jibe without fooling with sail trim. Catboats cannot. As the wind pipes up, it become harder, eventually impossible, to bear off without easing the mainsail. A catboat sailing in a gentle to moderate breeze (Force 3 - 4), on a beam reach with the sail eased enough for almost no weatherhelm will round-up is the sheet is trimmed and will fall-off is the sail is eased. Putting the helm up to fall-off from a beat to a broad reach without easing the sheet is slower than the same turn combined with easing the sheet. Trimming accelerates rounding-up.
Downwind sailing presents interesting sail dynamics. It's mostly push,
but there's aerodynamic activity on the leach and luff. A dramatic
example of this is a spinnaker's self-excitation-induced wobble. With
fore-and-aft sails, these pressure differentials cause the jibe to
happen at a changeable point after the wind has passed dead astern and before the sail's leach is really pointed into the wind.
Cats sail well by-the-lee. This is the point of sail past a dead run but
the sail's not been jibed over. The boat might be nominally on the
starboard tack even though the wind is over the port quarter. A Marconi rig can't sail very far by-the-lee without jibing. A gaff sail has a lower center of effort than a comparable Marconi sail, but the gaff sail has more of its sail area above its center of effort, sagging off,
holding the gaffsail further by-the-lee. The lower the gaff angle, the
further by the lee a boat can sail but this is not really a good thing.
After an uncontrolled jibe, the gaff may remain where it started, to
terrible effect.
Sailing by-the-lee requires attentive helm control as a wind shift or
minor broach could jibe you all-standing. Sailing by-the-lee is a
catboat specialty to be mastered and utilized.
TEXTBOOK JIBE REVISITED
It's best to practice first jibes in light to gentle breeze. (Force 2 -
3) Lighter air sailing is good for the soul but the jibe forces are a
bit subtle for early education.
Jibing with no course change is excellent practice for both helm and
sheet handling. The skipper will feel increasing helm pressure while
sailing exactly downwind as the sail is trimmed amidships, and will have to put the helm well up to stay on course. The sail probably will not cross over without a good shove, and even then may come back. No worry. This just establishes why catboats need to get a bit by-the-lee to complete a jibe.
Once by-the-lee, the trimmed the main will carry around, usually just
before the boom is amidships. As the sail was trimmed, the skipper put the helm up to counter the sail's pressure. Once the sails starts its own travel, the sail pressure is off and the turn will accelerate unless the skipper reduces rudder angle. As the sail fills on the new tack, the skipper may need to put the helm up on the new tack. This will counter the sail's force as it fills and prevent oversteering. With
practice, the catboat will show her skipper how much and how fast the rudder must be swung.
Meanwhile, the crew is busy. At some point, the boom will go too fast for the crew to keep up and the sheet goes slack. A well laid-out sheet system and an alert crew will keep the resulting bights snagging boat or body parts.
All the books say, "Let the sheet slide." In practice, most novices
holds fast till the sail slaps up against the sheet on the new tack.
Only after that massive shock do they let the sheet run. This shock
load before the sail's run out its sheet is the cause of every
jibe-caused broken gaff that I've seen.
The real sailor trims with palms up. Trimming the sail across, not
really forcing it but not letting it get slack reduces the extent to
which the boom kicks up when the sail fills on the new tack. A jibe
from one broad reach to the other with no sheet control can result in
the boom and lower half of the sail slamming across with the boom
kicking up leaving enough sail belly that the gaff and upper part of
the sail stay put. This will likely tear the sail and may break the
gaff.
When the boom get going faster than the crew can trim, the sheet should be guided freely atop open palms. The friction of the sheet tackle provides slowing power. Many cats have 5:1 sheet tackle, which gives plenty of resistance. Smaller catboats' 3:1 or 4:1 give enough friction for the smaller sail area. The sail can be safely let to run to the stopper knot. The mild shock of the boom stopping flat out abeam while the boat's running or broad reaching is safe.
The sheet runs out hot. Even with gloves, holding the sheet that
whipping out at over fifty feet per second takes nerve. I've been known to fall in love for no other reason than that the beloved crew can handle a running line with has hands hard as my own. While many true sailors eschew gloves, cowboys don't find them unmanly. I try not to snigger at gloved hands so long as they handle the line.
Skilled crew can make a running snub on a cleat to slow the line before it hits the stopper knot, avoiding luffing or trimming if jibing to a tight reach. To make a running snub, guide the sheet over the far ear of the sheet cleat when the sheet goes slack. Once sail crosses and the sheet's smoking, guide it around the near ear and use a progressively acute angle to add friction, slowing the sheet's run.
Jibing from one broad reach to another takes coordinated helm and sail trim. The crew needs to trim fast enough that there's not too much slack in the sheet when the sail makes up its mind to cross over, but not so fast that the sail is fighting the helm as the boat's steered past downwind to by the lee. Every boat and every breeze will require timing changes. The crew should not begin trimming till the boat's at least downwind or a tad by the lee. Most catboats carry the boom straight out abeam even on a broad reach. If you are jibing from one beam or near beam reach to the other, it's still better to let the sail run out all the way unless the crew can make a running snub. It does not really hurt if the sail luffs a tad before being trimmed to the new tack.
Light air practice builds the skill and confidence. Light air practice
also lessens the hazard from pulling a Captain Ahab if a bit of sheet
fouls the someone. On light days cat boats are happier and faster
tacking down wind, going from one broad reach to another. Jibing once a minute is great aerobics and will expose line-handling blemishes after a couple of evolutions.
-more-
It's serialized as it's a bit long by itself.
# # #
Catboats are unusually safe to jibe yet many fear the evolution.
The textbook jibe is to bear off while trimming the sail to amidships by the time the boat's straight down wind. The sail flops over and is let out. The problems with this jibe for catboats are severe. The boat
fights the trimming sail by attempting to round-up, often overpowering the rudder. The sheet is so long that the sail's rarely trimmed amidships before it comes whanging around. The flying bights of sheet can remove boat and body parts. Shockloading as the sail snaps full can break a gaff. The boat wants to round-up fast as the end of a jibe, perhaps broaching.
Sheet management, helmsmanship and sail trim are the Delphic secrets of jibing. The specifics here pertain to traditional catboats, but the generalities apply to all rigs.
SAILS AND SPARS
Traditional catboats have heavy booms and highly peaked gaffs. The
heavy boom keeps the boom from lifting excessively when sailing off the wind and when jibing. The highly peaked gaff provides wonderful sail shape with the aerodynamics for safer jibing than can be had from gaffs at a flatter than 60 degree angle, especially if they are long.
SHEET LAYOUT
Traditional catboats are rigged for safe sail-handling. The simple
sheet horse, pretty much a very large staple, is just abaft the cockpit
combing. Most of the sheet tackle is abaft the transom. Stern cleats
are out of fouling range. The great barn door rudder's long bowed top prevents lines from fouling. Most catboat transoms will not catch a line. Nothing's back there to foul a fishing line or a flying sheet.
Catboat sheets must have a stopper knot to stop the boom from going forward of straight abeam not just to keep the sheet accessable, but to protect the gooseneck. That knot is part of the control system.
LINE HANDLING
A coiled line running hot will make a block-jamming kink within a few
fathoms because coiling a line includes a bit of twist in against the
lay,. A line that's been coiled needs to be overhauled before use.
To overhaul a line for tangle free running, the sailor lays the coil
down with the standing part leading to the cleat on top, fakes the line
casually while working the twist out to the bitter end, and fakes the
line back the other way over the bitter end. This does not have to be
perfect figure-eights or anything.
Cats have miles of mainsheet that get hauled in and out quite a bit.
Where skipper and crew stand or sit to haul and where the sheet
naturally falls faked down determine the preservation of body parts.
The sheet must be laid out such that both the skipper and crew can trim and ease comfortably and safely.
STEERING AND SAIL TRIM
Modern short-boomed sloops can bear off from a beat right around and through a jibe without fooling with sail trim. Catboats cannot. As the wind pipes up, it become harder, eventually impossible, to bear off without easing the mainsail. A catboat sailing in a gentle to moderate breeze (Force 3 - 4), on a beam reach with the sail eased enough for almost no weatherhelm will round-up is the sheet is trimmed and will fall-off is the sail is eased. Putting the helm up to fall-off from a beat to a broad reach without easing the sheet is slower than the same turn combined with easing the sheet. Trimming accelerates rounding-up.
Downwind sailing presents interesting sail dynamics. It's mostly push,
but there's aerodynamic activity on the leach and luff. A dramatic
example of this is a spinnaker's self-excitation-induced wobble. With
fore-and-aft sails, these pressure differentials cause the jibe to
happen at a changeable point after the wind has passed dead astern and before the sail's leach is really pointed into the wind.
Cats sail well by-the-lee. This is the point of sail past a dead run but
the sail's not been jibed over. The boat might be nominally on the
starboard tack even though the wind is over the port quarter. A Marconi rig can't sail very far by-the-lee without jibing. A gaff sail has a lower center of effort than a comparable Marconi sail, but the gaff sail has more of its sail area above its center of effort, sagging off,
holding the gaffsail further by-the-lee. The lower the gaff angle, the
further by the lee a boat can sail but this is not really a good thing.
After an uncontrolled jibe, the gaff may remain where it started, to
terrible effect.
Sailing by-the-lee requires attentive helm control as a wind shift or
minor broach could jibe you all-standing. Sailing by-the-lee is a
catboat specialty to be mastered and utilized.
TEXTBOOK JIBE REVISITED
It's best to practice first jibes in light to gentle breeze. (Force 2 -
3) Lighter air sailing is good for the soul but the jibe forces are a
bit subtle for early education.
Jibing with no course change is excellent practice for both helm and
sheet handling. The skipper will feel increasing helm pressure while
sailing exactly downwind as the sail is trimmed amidships, and will have to put the helm well up to stay on course. The sail probably will not cross over without a good shove, and even then may come back. No worry. This just establishes why catboats need to get a bit by-the-lee to complete a jibe.
Once by-the-lee, the trimmed the main will carry around, usually just
before the boom is amidships. As the sail was trimmed, the skipper put the helm up to counter the sail's pressure. Once the sails starts its own travel, the sail pressure is off and the turn will accelerate unless the skipper reduces rudder angle. As the sail fills on the new tack, the skipper may need to put the helm up on the new tack. This will counter the sail's force as it fills and prevent oversteering. With
practice, the catboat will show her skipper how much and how fast the rudder must be swung.
Meanwhile, the crew is busy. At some point, the boom will go too fast for the crew to keep up and the sheet goes slack. A well laid-out sheet system and an alert crew will keep the resulting bights snagging boat or body parts.
All the books say, "Let the sheet slide." In practice, most novices
holds fast till the sail slaps up against the sheet on the new tack.
Only after that massive shock do they let the sheet run. This shock
load before the sail's run out its sheet is the cause of every
jibe-caused broken gaff that I've seen.
The real sailor trims with palms up. Trimming the sail across, not
really forcing it but not letting it get slack reduces the extent to
which the boom kicks up when the sail fills on the new tack. A jibe
from one broad reach to the other with no sheet control can result in
the boom and lower half of the sail slamming across with the boom
kicking up leaving enough sail belly that the gaff and upper part of
the sail stay put. This will likely tear the sail and may break the
gaff.
When the boom get going faster than the crew can trim, the sheet should be guided freely atop open palms. The friction of the sheet tackle provides slowing power. Many cats have 5:1 sheet tackle, which gives plenty of resistance. Smaller catboats' 3:1 or 4:1 give enough friction for the smaller sail area. The sail can be safely let to run to the stopper knot. The mild shock of the boom stopping flat out abeam while the boat's running or broad reaching is safe.
The sheet runs out hot. Even with gloves, holding the sheet that
whipping out at over fifty feet per second takes nerve. I've been known to fall in love for no other reason than that the beloved crew can handle a running line with has hands hard as my own. While many true sailors eschew gloves, cowboys don't find them unmanly. I try not to snigger at gloved hands so long as they handle the line.
Skilled crew can make a running snub on a cleat to slow the line before it hits the stopper knot, avoiding luffing or trimming if jibing to a tight reach. To make a running snub, guide the sheet over the far ear of the sheet cleat when the sheet goes slack. Once sail crosses and the sheet's smoking, guide it around the near ear and use a progressively acute angle to add friction, slowing the sheet's run.
Jibing from one broad reach to another takes coordinated helm and sail trim. The crew needs to trim fast enough that there's not too much slack in the sheet when the sail makes up its mind to cross over, but not so fast that the sail is fighting the helm as the boat's steered past downwind to by the lee. Every boat and every breeze will require timing changes. The crew should not begin trimming till the boat's at least downwind or a tad by the lee. Most catboats carry the boom straight out abeam even on a broad reach. If you are jibing from one beam or near beam reach to the other, it's still better to let the sail run out all the way unless the crew can make a running snub. It does not really hurt if the sail luffs a tad before being trimmed to the new tack.
Light air practice builds the skill and confidence. Light air practice
also lessens the hazard from pulling a Captain Ahab if a bit of sheet
fouls the someone. On light days cat boats are happier and faster
tacking down wind, going from one broad reach to another. Jibing once a minute is great aerobics and will expose line-handling blemishes after a couple of evolutions.
-more-