The Boat Design & Boatbuilding Site
Mast and boom: Matching set for emergency dismasting
- Thread starter JosephT
- Start date
JosephT
Senior Member
- Joined
- Jun 26, 2009
- Posts
- 859
- Reaction score
- 108
- Location
- Roaring Forties
The key word is "should". The vessels in the GGR race were specifically chosen based off of their solid designs & long history. They're not the fastest, but they're solid. There are so many additional variables in very stormy (more like psychotic) sailing conditions.
The next GGR race will introduce a steel hulled Joshua class. It's not fast either, but it is a very rugged boat. It looks like a tank all stripped down. Let's hope it fares better in the nasty conditions.The referenced article below offers a pessimistic view though.
JosephT
Senior Member
- Joined
- Jun 26, 2009
- Posts
- 859
- Reaction score
- 108
- Location
- Roaring Forties
I found a good reference that provides guidelines for creating an emergency mast. I like it. It leverages a mast stump, boom or spinnaker pole and some extra gear. Three cheers to the author for taking the time to include this info. These steps will help future skippers prepare detailed instructions for their boats. If I were doing a long ocean passage or race no question detailed steps for this would be on my checklist.
"Dismasting
The normal cruiser-racer's mast should outlive its owner-assuming that its owner treats it with reasonable care. There are two common causes of dismasting. One is allowing the mast to bend to far, either sideways or fore and aft. If the mast is not straight, it goes out of column and loses much of its integrity. In rough seas, the mast must be as straight as possible and running backstays should be used to keep it straight. The second and by far most frequent cause of mast failure is a broken fitting-a collapsed spreader, a snapped shroud, or a parted turnbuckle.
The crew's first response to a dismasting will be shock, but as soon as they recover they must spring to the broken spar and keep it from holing the hull. In rough weather, the mast will be jackknifed over teh leeward rail and every wave will slap the boat down onto it. If possible, drag the mess back on board. Otherwise you'll have to pull or cut the sails off, cut the halyards, pull the cotter and clevis pins out of any remaining turnbuckles, and allow the mast to sink before it holes the boat. In the next chapter we'll show how to rig cotter pins so they can be pulled out quickly in emergencies.
You may be able to save the sails without their being torn too badly and later use them on a jury-rigged (improvised) mast. You can set a sail either from the top of the mast's stump or from a spinnaker pole or boom stepped as an emergency mast. some sailboats have made long passages under jury rigs.
Broken stay. Should a shroud, the headstay, or the backstay break but the mast not collapse, immediately cast off all sheets to luff the sails and alter course so the broken stay is to leeward. A halyard might be rigged as a temporary stay, leading it over the end of the spreader if it replaces a shroud. Tighten the halyard as much as possible. Nurse the boat along gently, since the replacement is weaker than the original stay. Some modern-day rope is as strong as wire and can be used for this purpose.
It's a good idea to carry a spare stay as long as the longest stay in the rigging with a terminal (eye) installed at one end plus a spare, large turnbuckle. Using bulldog clamps, you can fashion another eye or attach this wire to a shorter stay, taking some of the load with halyards."
Ref: The Annapolis Book of Seamanship: Fourth Edition. By John Rousmaniere
https://www.amazon.com/Annapolis-Book-Seamanship-Fourth/dp/1451650191
Keywords: dismast, GGR, Volvo, Vendee Globe, Clipper, Whitbread, BOC Challenge
"Dismasting
The normal cruiser-racer's mast should outlive its owner-assuming that its owner treats it with reasonable care. There are two common causes of dismasting. One is allowing the mast to bend to far, either sideways or fore and aft. If the mast is not straight, it goes out of column and loses much of its integrity. In rough seas, the mast must be as straight as possible and running backstays should be used to keep it straight. The second and by far most frequent cause of mast failure is a broken fitting-a collapsed spreader, a snapped shroud, or a parted turnbuckle.
The crew's first response to a dismasting will be shock, but as soon as they recover they must spring to the broken spar and keep it from holing the hull. In rough weather, the mast will be jackknifed over teh leeward rail and every wave will slap the boat down onto it. If possible, drag the mess back on board. Otherwise you'll have to pull or cut the sails off, cut the halyards, pull the cotter and clevis pins out of any remaining turnbuckles, and allow the mast to sink before it holes the boat. In the next chapter we'll show how to rig cotter pins so they can be pulled out quickly in emergencies.
You may be able to save the sails without their being torn too badly and later use them on a jury-rigged (improvised) mast. You can set a sail either from the top of the mast's stump or from a spinnaker pole or boom stepped as an emergency mast. some sailboats have made long passages under jury rigs.
Broken stay. Should a shroud, the headstay, or the backstay break but the mast not collapse, immediately cast off all sheets to luff the sails and alter course so the broken stay is to leeward. A halyard might be rigged as a temporary stay, leading it over the end of the spreader if it replaces a shroud. Tighten the halyard as much as possible. Nurse the boat along gently, since the replacement is weaker than the original stay. Some modern-day rope is as strong as wire and can be used for this purpose.
It's a good idea to carry a spare stay as long as the longest stay in the rigging with a terminal (eye) installed at one end plus a spare, large turnbuckle. Using bulldog clamps, you can fashion another eye or attach this wire to a shorter stay, taking some of the load with halyards."
Ref: The Annapolis Book of Seamanship: Fourth Edition. By John Rousmaniere
https://www.amazon.com/Annapolis-Book-Seamanship-Fourth/dp/1451650191
Keywords: dismast, GGR, Volvo, Vendee Globe, Clipper, Whitbread, BOC Challenge
UPSIDE DOWN JIB JURY RIG
I have been thinking some more about this concept. I have done a few calculations based on the following assumptions: one, that the Boom is going to be about one third as long as the length-on-deck of the boat (some will be longer; some will be shorter); two, that the boat will have a relatively short fin keel (with or without a skeg); and three, the boat will be relatively light for its size. My third assumption is that a 40ft boat will displace around 300 cf or roughly 18,800 lbs.
The boats which will have the shortest Booms will be the IOR influenced masthead rigged sloops, many of which are still sailing the oceans of the world. This type of boat provides the following difficulties: one, the height of the jib is often longer than the deck; and two, the Boom is often just three tenths as long as the deck, considerably shorter than even the foot of the jib.
For these reasons, the working jib is useless as a jury rig sail. If it is to be used for this purpose, it will have to be re-cut and more or less redesigned. New cringles will have to be added, as well as new re-enforcement patches. This would be a major job on land not to mention an extraordinarily difficult one on a rolling pitching sea.
A smaller jib would have to be used. It will need to have a height of roughly three-quarters of the boat's length. This is so its Horizontal Center of Area will end up very close to the Horizontal Center of Lift, for the Hull and Keel. The better these two line up, the better the balance of the boat is likely to be. This smaller jib will need a foot length which is roughly half its height. This is so the Boom extender doesn't have to be overly long. Preferably, it should be the length of the Boom or less.
As you can see, this will not only limit which jib can be used (a specially made one may be needed for this purpose), but will severely limit the SA as well. My rough estimation is this will mean an SA of about 220 sf for our 18,800 lb forty footer. This will net an S/D of slightly less than 5.0.
This is not the only problem. Another one is that this jib will not only have a very low Aspect Ratio but would also have a mostly vertical lift vector. This will hamper its efficiency even further. Indeed, there could be several surprises if this jury rig were used. The balance might not work out as hoped. And the driving power may be so poor that it may not be able to make windward progress at all. It will also likely need to sail down wind in tacks, instead of straight downwind.
Another issue is where the new Mast will end up. There is a good chance that it will end up on top of the trunk cabin. It could also end up in the companion way. In this case, it will have to be stepped forward of the companion way then canted aft. It could be stepped in the cockpit and canted forward, but this will create very unfavorable geometry for the back stays.
If it merely ends up on top of the cabin trunk, a compression pole will be needed to handle the compression loads. Such may be lighter and less inconvenient than re-enforcing the cabin top. There are a few advantages of this form of pre-designed jury rig.
One is that except for the sail and Boom extender and three or four support stays and attachment points, this rig would require very few added parts.
Two is that it ends up being a mast aft rig, so the Mast and all but one of the rig support attachment points will end up very close to the cockpit where they are easy to watch.
And three is that existing sheeting points may be useable for sheeting this sail.
A possible fourth advantage could be the vertical lift component. It may reduce the compression loads on the rig and may even help steady the boat. This may be especially appreciated when one considers how little rolling resistance such a small, low sail rig will otherwise offer.
Some sloops with fractional rigs cruise the oceans. My guess is that they are far fewer than the masthead variety, but I wouldn't be surprised if their numbers are increasing. Such a rig usually has a much longer Boom and a much shorter jib. In this case, the Boom may be useable without lengthening. The smaller jib may be useable, as is, too. If this sort of jury rig will actually work, this would be a happy situation indeed.
I happen to have a scale model of a “Lightning”. I am tempted to take its rig apart, step the Boom in the cockpit, then raise the jib upside down. I would then load it down so that it would have similar scale displacement to a light cruising yacht; then see if I could get it to sail upwind. If it managed to do so, I would consider the experiment a success.
As for the masthead sloop, I have thought of an alternative jury rig which would use the mainsail rather than the jib. I will discuss it in a future post.
I have been thinking some more about this concept. I have done a few calculations based on the following assumptions: one, that the Boom is going to be about one third as long as the length-on-deck of the boat (some will be longer; some will be shorter); two, that the boat will have a relatively short fin keel (with or without a skeg); and three, the boat will be relatively light for its size. My third assumption is that a 40ft boat will displace around 300 cf or roughly 18,800 lbs.
The boats which will have the shortest Booms will be the IOR influenced masthead rigged sloops, many of which are still sailing the oceans of the world. This type of boat provides the following difficulties: one, the height of the jib is often longer than the deck; and two, the Boom is often just three tenths as long as the deck, considerably shorter than even the foot of the jib.
For these reasons, the working jib is useless as a jury rig sail. If it is to be used for this purpose, it will have to be re-cut and more or less redesigned. New cringles will have to be added, as well as new re-enforcement patches. This would be a major job on land not to mention an extraordinarily difficult one on a rolling pitching sea.
A smaller jib would have to be used. It will need to have a height of roughly three-quarters of the boat's length. This is so its Horizontal Center of Area will end up very close to the Horizontal Center of Lift, for the Hull and Keel. The better these two line up, the better the balance of the boat is likely to be. This smaller jib will need a foot length which is roughly half its height. This is so the Boom extender doesn't have to be overly long. Preferably, it should be the length of the Boom or less.
As you can see, this will not only limit which jib can be used (a specially made one may be needed for this purpose), but will severely limit the SA as well. My rough estimation is this will mean an SA of about 220 sf for our 18,800 lb forty footer. This will net an S/D of slightly less than 5.0.
This is not the only problem. Another one is that this jib will not only have a very low Aspect Ratio but would also have a mostly vertical lift vector. This will hamper its efficiency even further. Indeed, there could be several surprises if this jury rig were used. The balance might not work out as hoped. And the driving power may be so poor that it may not be able to make windward progress at all. It will also likely need to sail down wind in tacks, instead of straight downwind.
Another issue is where the new Mast will end up. There is a good chance that it will end up on top of the trunk cabin. It could also end up in the companion way. In this case, it will have to be stepped forward of the companion way then canted aft. It could be stepped in the cockpit and canted forward, but this will create very unfavorable geometry for the back stays.
If it merely ends up on top of the cabin trunk, a compression pole will be needed to handle the compression loads. Such may be lighter and less inconvenient than re-enforcing the cabin top. There are a few advantages of this form of pre-designed jury rig.
One is that except for the sail and Boom extender and three or four support stays and attachment points, this rig would require very few added parts.
Two is that it ends up being a mast aft rig, so the Mast and all but one of the rig support attachment points will end up very close to the cockpit where they are easy to watch.
And three is that existing sheeting points may be useable for sheeting this sail.
A possible fourth advantage could be the vertical lift component. It may reduce the compression loads on the rig and may even help steady the boat. This may be especially appreciated when one considers how little rolling resistance such a small, low sail rig will otherwise offer.
Some sloops with fractional rigs cruise the oceans. My guess is that they are far fewer than the masthead variety, but I wouldn't be surprised if their numbers are increasing. Such a rig usually has a much longer Boom and a much shorter jib. In this case, the Boom may be useable without lengthening. The smaller jib may be useable, as is, too. If this sort of jury rig will actually work, this would be a happy situation indeed.
I happen to have a scale model of a “Lightning”. I am tempted to take its rig apart, step the Boom in the cockpit, then raise the jib upside down. I would then load it down so that it would have similar scale displacement to a light cruising yacht; then see if I could get it to sail upwind. If it managed to do so, I would consider the experiment a success.
As for the masthead sloop, I have thought of an alternative jury rig which would use the mainsail rather than the jib. I will discuss it in a future post.
JosephT
Senior Member
- Joined
- Jun 26, 2009
- Posts
- 859
- Reaction score
- 108
- Location
- Roaring Forties
Very good points Sharpii2. I agree on your point about a smaller jib being necessary. I have always sailed with a storm jib and a in many cases (while racing) a large inventory of jibs/head sails. A medium sized jib of medium weight (for overall conditions) that covers about 65-75% of the typical jib sail area. If a storm comes just raise the smaller storm jib. Always good to have extra cloth. A portable sewing kit is also vital for offshore sailing so reinforcing & patching go along with the territory.
On the notion of an aft mast step further aft, would it not make sense to spec out a heavy duty hinged mast step? That would make raising/lowering it a lot more manageable. Here's one that is rated up to 35ft boat. This design could be enlarged and thickened to accommodate a 40ft boat. I would probably go with stainless vs aluminum. I've seen too many aluminum fittings corrode and fracture over time. You can't go wrong with stainless. I would probably mount this foremost in the companionway or cockpit so it was out of the way, but sitting on a stable deck with some strong back plates underneath.
In any case, each boat will be different depending on the layout. Ideally this alternate sail plan is thought out by the nautical architect in advance and offered either with the boat or at a minimum as an option for offshore sailors. There is nothing like just hooking up parts that fit the first time! Having to "jury rig" anything introduces potential failure and possibly safety issues for the crew.
On the notion of an aft mast step further aft, would it not make sense to spec out a heavy duty hinged mast step? That would make raising/lowering it a lot more manageable. Here's one that is rated up to 35ft boat. This design could be enlarged and thickened to accommodate a 40ft boat. I would probably go with stainless vs aluminum. I've seen too many aluminum fittings corrode and fracture over time. You can't go wrong with stainless. I would probably mount this foremost in the companionway or cockpit so it was out of the way, but sitting on a stable deck with some strong back plates underneath.
In any case, each boat will be different depending on the layout. Ideally this alternate sail plan is thought out by the nautical architect in advance and offered either with the boat or at a minimum as an option for offshore sailors. There is nothing like just hooking up parts that fit the first time! Having to "jury rig" anything introduces potential failure and possibly safety issues for the crew.
Angélique
aka Angel (only by name)
- Joined
- Feb 15, 2009
- Posts
- 3,003
- Reaction score
- 338
- Location
- Belgium ⇄ The Netherlands
Maud Fontenoy also set up her boom to jury rig her boat (of 85'), she did that solo in a still rough sea, while having herself about half the weight of the ± 220-lb (100 kg) boom, then jury rigged she sailed the remaining 2,000 NM to reach her destination...
On a smaller boat if you carry two long oars, you can row a not too broad beamed boat solo in case of an engine failure, or sitting side by side on the bridge deck on a beamier boat, and you can set up an A-frame mast with those two long oars to jury rig the boat, or use one of them as a jury rudder when it might be required, some are known to always have a plan B & C and their needs in stock, which as everything is easier on a small boat...
↓ Solo voyager Roger Taylor and his boat Mingming II (engineless, both MM I of 20' & MM II of 24')
‘‘ . . . (MM I) . . . The 15 ft ash sweeps lying along the fore deck, which Roger uses to propel himself in and out of harbor when there’s no wind, will also double as a jury mast or a jury steering oar, should either be required. . . . ’’
↓ still before the video start, left MM I, center Roger, on the right MM II while complete rebuilding.
On a smaller boat if you carry two long oars, you can row a not too broad beamed boat solo in case of an engine failure, or sitting side by side on the bridge deck on a beamier boat, and you can set up an A-frame mast with those two long oars to jury rig the boat, or use one of them as a jury rudder when it might be required, some are known to always have a plan B & C and their needs in stock, which as everything is easier on a small boat...
↓ Solo voyager Roger Taylor and his boat Mingming II (engineless, both MM I of 20' & MM II of 24')
‘‘ . . . (MM I) . . . The 15 ft ash sweeps lying along the fore deck, which Roger uses to propel himself in and out of harbor when there’s no wind, will also double as a jury mast or a jury steering oar, should either be required. . . . ’’
↓ still before the video start, left MM I, center Roger, on the right MM II while complete rebuilding.
Last edited:
JosephT
Senior Member
- Joined
- Jun 26, 2009
- Posts
- 859
- Reaction score
- 108
- Location
- Roaring Forties
Excellent Angélique. Maud did a very nice job on that jury rig. On the notion of rowing a big sailboat, if you’ve the oars, crew and food to do it (rowing = many calories burned) it’s definitely a good idea. The wind would need to cooperate as well. It would a very good option on a smaller sloop. Many teams racing the big ocean skulls these days.
Angélique
aka Angel (only by name)
- Joined
- Feb 15, 2009
- Posts
- 3,003
- Reaction score
- 338
- Location
- Belgium ⇄ The Netherlands
Engine failure on a sailboat often occurs near shore when the apparatus is used and you also dependent on it, otherwise it's mostly not such a big problem, so having the option of rowing a short distance could for example save your ass by not getting smashed against a breakwater while entering or leaving a harbor . . 
I've added a few links about Roger and his boats to my previous post, and added a bit to the text too, and of course when having the long oars aboard the preparations also need to have ready to fit in oarlocks for rowing and sculling and steering, as well as prepared fittings for an emergency A-frame mast, which also can be used as an A-frame in normal situations to raise and lower a mast in a tabernacle.
P.S.
I've added a few links about Roger and his boats to my previous post, and added a bit to the text too, and of course when having the long oars aboard the preparations also need to have ready to fit in oarlocks for rowing and sculling and steering, as well as prepared fittings for an emergency A-frame mast, which also can be used as an A-frame in normal situations to raise and lower a mast in a tabernacle.
Last edited:
Angélique
aka Angel (only by name)
- Joined
- Feb 15, 2009
- Posts
- 3,003
- Reaction score
- 338
- Location
- Belgium ⇄ The Netherlands
Oh, from one of the above added links ‘‘The (2014) talk is open to the general public for £ 5 (US$ - €) which includes lunch’’ usually I can't get a lunch in a in a Yacht Club for that, while it there and then included a master lecture, which later luckily appeared (also linked) on the web . .
P.S. - I've only found the first hour before the lunch, the second hour which came after the break seems to be lost . .
P.S. - I've only found the first hour before the lunch, the second hour which came after the break seems to be lost . .
Last edited:
Angélique
aka Angel (only by name)
- Joined
- Feb 15, 2009
- Posts
- 3,003
- Reaction score
- 338
- Location
- Belgium ⇄ The Netherlands
Carbon fiber masts are strong, but don't handle the smashing of a knock down and a capsize so well, it's a lot of race boats that get dismasted, stronger would mean more mast weight and so less sail pressure aloft can be handled, and/or a stronger mast would give more mast air drag, meaning not being the fastest in races compared to those who take more risks and do not end up in an emergency situation which is still most of the time the case, so it looks to me like the mast and the whole winning race boat is a compromise for what usually would be just strong enough, this to enable winning, hence there's a lot of break downs on race boats, with often also experimental equipment, to reach the main goal of getting faster all the time, so they have to accept the risks of mast snaps or are out of the game, unless the weather gets more extreme than anticipated, than the heavy constructed boats get lucky, which isn't often.
A lot of racers just set off their bucket full of EPIRBs in a distress situation, the sponsor and/or insurance pays for the lost mast or boat, if they don't win no one pays anymore.
Another kind of on the money behavior goes for a lot of cruisers, the constant changing loads cause fatigue in the rigging and precaution maintenance seems to cost unnecessarily paid money as you never see the results until it's too late, of which most seem to think this won't happen to me, and they're right most of the time with that, and a lot have never thought about jury rigging, they also just set off their bucket full of EPIRBs in an emergency situation, as that's what they're for, and insurance pays for the lost boats, insurance usually asks for the same service and replacement intervals for light and heavily used boats, and insurers have to compete with each other, so for them a few losses are better than no customers at all, so besides prices they have to compromise between risks and their requirements to be able to make a profit, calculated losses are a part of their trade.
Last edited:
JosephT
Senior Member
- Joined
- Jun 26, 2009
- Posts
- 859
- Reaction score
- 108
- Location
- Roaring Forties
Agree on the need for prepared fittings Angélique. Regarding insurance, I have read a good insurer will request a rigging report prior to long distance sailing. This makes good sense. Even with a good insurance policy though an alternate rigging/sail plan is simply good planning.
I don't believe that the evidence from the current Golden Globe race supports a conclusion that further advance preparation for jury rigging would be beneficial.
Of 5 dismastings:
- 2 were able to fashion jury rigs. 1 self-rescued (Wiig), and the other chose to be taken off given the proximity of a ship (McGuckin)
- 1 was badly injured such that he would not have been able to work on deck even with prepared materials (Tomy)
- 1 abandoned due to taking on water (Lepage). Prior to this he did not request assistance, suggesting he was confident in his ability to self-rescue
- 1 did fail to jury rig (Goodall). Note however that she lost her spinnaker pole which was entirely separate from the rig at the time. This makes me question the merit of jury systems that rely on the retention of specific spars after dismasting.
It seems to me that more fruitful areas of development would be in more robust wind-vanes, and in preventing skipper injury in the event of knockdown. I also feel that many of the solutions in this thread introduce artificial weak points in the rig structure (e.g. at an above-deck tabernacle). NB I don't disagree with Roger Taylor's approach of carrying additional spars (in the form of sweeps) as this increases the likelihood of something being left aboard.
Of 5 dismastings:
- 2 were able to fashion jury rigs. 1 self-rescued (Wiig), and the other chose to be taken off given the proximity of a ship (McGuckin)
- 1 was badly injured such that he would not have been able to work on deck even with prepared materials (Tomy)
- 1 abandoned due to taking on water (Lepage). Prior to this he did not request assistance, suggesting he was confident in his ability to self-rescue
- 1 did fail to jury rig (Goodall). Note however that she lost her spinnaker pole which was entirely separate from the rig at the time. This makes me question the merit of jury systems that rely on the retention of specific spars after dismasting.
It seems to me that more fruitful areas of development would be in more robust wind-vanes, and in preventing skipper injury in the event of knockdown. I also feel that many of the solutions in this thread introduce artificial weak points in the rig structure (e.g. at an above-deck tabernacle). NB I don't disagree with Roger Taylor's approach of carrying additional spars (in the form of sweeps) as this increases the likelihood of something being left aboard.
JosephT
Senior Member
- Joined
- Jun 26, 2009
- Posts
- 859
- Reaction score
- 108
- Location
- Roaring Forties
I would disagree. No question it's a good idea to prepare an alternate rig. In fact, I would go so far to say that future GGR race participants should be briefed and/or trained to ensure they understand how to rig an alternate sail configuration. At the rate they had to abandon vessels I would consider it a high priority.
Agree on the need for more robust wind-vanes. Hopefully the GGR rules will allow a change of design if needed.
Angélique
aka Angel (only by name)
- Joined
- Feb 15, 2009
- Posts
- 3,003
- Reaction score
- 338
- Location
- Belgium ⇄ The Netherlands
JosephT
Senior Member
- Joined
- Jun 26, 2009
- Posts
- 859
- Reaction score
- 108
- Location
- Roaring Forties
That’s a lot of shredded masts! Fortunately it’s a small lake so hopefully the rescues/recoveries go well.
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making any potentially dangerous or financial decision, always employ and consult appropriate professionals. Your circumstances or experience may be different.
When making any potentially dangerous or financial decision, always employ and consult appropriate professionals. Your circumstances or experience may be different.
Advertisement:
