Wayward_Son
Well-Known Member
The helm is usually the most neutral position on a boat, which is why helming generally delays motion sickness.
Seasickness explained
- Thread starter peteandthira
- Start date
BrendanS
Well-Known Member
The position is almost irrelevant. It's the actually doing something that takes concious thought away from how you are feeling. It also keeps your eyes largely aimed at horizon, and gives back the visual cues to the brain on which way you are moving
Micky
Well-Known Member
We do a lot of fishing in rough sea's at anchor.
When under way, everyone is fine, once we stop, now that's when the trouble starts..best cure tell someone that you feel sickness coming on so they can give advice, don't just sit and try to fight it off.
On our boat if you feel ill, it's drink a small amount of Ginger, this stuff is magic when it comes to curing sea sickness, it works every-time.
Even Ginger biscuits with tea on the way out will help to prevent illness.
When under way, everyone is fine, once we stop, now that's when the trouble starts..best cure tell someone that you feel sickness coming on so they can give advice, don't just sit and try to fight it off.
On our boat if you feel ill, it's drink a small amount of Ginger, this stuff is magic when it comes to curing sea sickness, it works every-time.
Even Ginger biscuits with tea on the way out will help to prevent illness.
G
Guest
Guest
Position can actually make a big difference. The best point to stay is about 2/3rds of the way back along the boat. If lying down, get your head as close to this position as possible. This is because at the pivot point of the boat the motion is least violent.
If sitting in the cockpit, people sitting at the back of the cockpit are much more liable to get sick than those sitting at the front.
If sitting in the cockpit, people sitting at the back of the cockpit are much more liable to get sick than those sitting at the front.
bilbobaggins
N/A
Motion sickness. Learned about it in mil-flying. Did I ever!
Some aircraft vibrate at a frequency which predisposes to airsickness e.g. the Canberra T4. So also did aerobatic manoeuvres, such as the monthly pilot's check-ride 'Recovery From Unusual Positions' on 'Limited Panel' instruments. The nav ( me ) in the back could see only an altimeter and an airspeeed indicater. I used to last about 45 minutes, then 'Hughie!' Continuously.
I remenmber one trip being so bad, I was taking up the first pressure on my 'bang-seat' - but the QFI called 'time'. I had to be carried out of the a/c.
What triggers me in boats? Cold and wet around the lower back, pressure on the belly, one or more of several stenches - diesel; cold stew; food that's 'on the turn'; foetid feet; 'honk'
What helps? Work to do on deck; asleep; crystalised ginger - this last is so good ( for me ) that I carry some every trip, and stache some on all my mates' boats.
Habituation helps. After several days' sailing, I'm usually fine for the rest of the season - unless there's a 'trigger' as above.
Heaving-to ( not a pun ) also helps.
Some aircraft vibrate at a frequency which predisposes to airsickness e.g. the Canberra T4. So also did aerobatic manoeuvres, such as the monthly pilot's check-ride 'Recovery From Unusual Positions' on 'Limited Panel' instruments. The nav ( me ) in the back could see only an altimeter and an airspeeed indicater. I used to last about 45 minutes, then 'Hughie!' Continuously.
I remenmber one trip being so bad, I was taking up the first pressure on my 'bang-seat' - but the QFI called 'time'. I had to be carried out of the a/c.
What triggers me in boats? Cold and wet around the lower back, pressure on the belly, one or more of several stenches - diesel; cold stew; food that's 'on the turn'; foetid feet; 'honk'
What helps? Work to do on deck; asleep; crystalised ginger - this last is so good ( for me ) that I carry some every trip, and stache some on all my mates' boats.
Habituation helps. After several days' sailing, I'm usually fine for the rest of the season - unless there's a 'trigger' as above.
Heaving-to ( not a pun ) also helps.
BrendanS
Well-Known Member
To understand how to counteract seasickness, you have to understand what causes it from a medical perspective. Amplitude of motion is not a huge contributory factor, it is the visual cues being at odds with what the other senses are telling the brain. Even very slight movements cause this, as do psychological factors to some extent.
Other than taking drugs etc, reducing amplitude has very little effect compared to taking away the disorientating visual cues - hence looking at horizon, doing something active, or lying down with eyes closed
Other than taking drugs etc, reducing amplitude has very little effect compared to taking away the disorientating visual cues - hence looking at horizon, doing something active, or lying down with eyes closed
G
Guest
Guest
Possibly, but it is a fact that a greater amplitude of motion can be one of the biggest contributory causes. I agree that sometimes a very slight swell can set it off too, so amplitude of motion isn't ALWAYS the key.
In fact, I gather that medical science knows very little about seasickness beyond what was put in the original post. For example, it doesn't know WHY the brain decides that the lack of coordination between visual and balance makes it think that there is poison in the stomach. The relevant chapter in Heavy Weather Sailing is worth reading about this.
About the amplitude of motion, I know from my own experience that a person lying down in the cockpit with his head towards the stern is almost certainly going to get worse. Turn that person round, and he/she stands a good chance of recovery. Similarly, moving a patient from the main cabin to the forecabin is a 100% certain way of making them violently ill in a few minutes! If medical science hasn't worked that one out yet, then I am afraid it has never been to sea!
In fact, I gather that medical science knows very little about seasickness beyond what was put in the original post. For example, it doesn't know WHY the brain decides that the lack of coordination between visual and balance makes it think that there is poison in the stomach. The relevant chapter in Heavy Weather Sailing is worth reading about this.
About the amplitude of motion, I know from my own experience that a person lying down in the cockpit with his head towards the stern is almost certainly going to get worse. Turn that person round, and he/she stands a good chance of recovery. Similarly, moving a patient from the main cabin to the forecabin is a 100% certain way of making them violently ill in a few minutes! If medical science hasn't worked that one out yet, then I am afraid it has never been to sea!
tome
Well-Known Member
Interesting, but not sure I 'd agree. The divergence between visual and aural cues to the brain seems to be the cause of the involuntary nausea. We are programmed to operate on terra firma at walking pace.
Some people experience the same motion sickness in a car, especially if sitting in the rear where visual cues are compromised and become separated from other motion cues.
As such, cue divergence must be related to acceleration which will certainly increase with amplitude of motion. After all, the inner ear is well damped against acceleration for our design envelope. In sailing (and motoring or flying) we venture outside this envelope.
You seem to be considering visual cues only as the cause, and not considering that it is the divergence of several cues which causes confusion and hence the effects. It is also telling to note that the profoundly deaf suffer none of these effects.
Some people experience the same motion sickness in a car, especially if sitting in the rear where visual cues are compromised and become separated from other motion cues.
As such, cue divergence must be related to acceleration which will certainly increase with amplitude of motion. After all, the inner ear is well damped against acceleration for our design envelope. In sailing (and motoring or flying) we venture outside this envelope.
You seem to be considering visual cues only as the cause, and not considering that it is the divergence of several cues which causes confusion and hence the effects. It is also telling to note that the profoundly deaf suffer none of these effects.
Spyro
Well-Known Member
Sorry about the lenght of this article but it is good if you can be bothered reading <span style="color:red"> </span> it
That’s the way things are. Man is a land creature. Raised up on two legs, we stand up straight. This vertical position, which gives us our superiority, is constantly under challenge from the laws of equilibrium. Put a bottle upside down on its neck and you have a good idea of what we achieve each time we stand up. For a baby, it takes months of trial and error to get up, and remove their hands from the ground. It is the vestibular system that looks after our balance and controls and corrects us when we lean over.
Its main function is located in the inner ear with the semi-circular chambers. There are three chambers in all, which are arranged on every plane. They work rather like a mason’s spirit level, with the equivalent of the bubble in the glass tube.
Continuing with this comparison, we can say that when we move, this causes the bubble to touch the little electrodes inside the tube. Through the nerve, each electrode, which has thus been stimulated sends a signal to the nerve centre in the brain. Putting together all the information from every chamber, the brain has a fairly good idea of the body’s position and especially the movements, which could cause you to fall over. It is helped in this by the information coming from the eyes, which gives geometrical positions (vertical, horizontal). In addition, the ligaments situated on the feet, ankles, knees and stomach, give precise details about the posture, what the body is resting on and the state of the ground.
All this information examined instantaneously in the brain leads to a reflex reaction with tightening or relaxation of the muscles, leading to a correct balancing position. Perfect harmony between the various elements is therefore necessary for the system to work correctly. But in a boat, things are more complicated and this harmony can no longer be found.
In fact, the “ground” is no longer the stable reference surface, but something in perpetual emotion. While it may be stationary, the body, seen from the outside is in constant motion, as it accompanies passively the movement of the boat. The “bubbles” follow this movement and transmit this information to the brain. Because the body is still, the ligaments are not used and send no messages to the brain to confirm the signals from the “bubbles.” There is therefore disagreement and a conflict about the information coming from the inner ear (pitching and rolling) and that coming from the ligaments (standing up, sitting down, lying down).
If the subject is out on deck, the conflict is resolved by the eyes, which offer the geometrical markers, such as the horizon or the coast. It is thus better controlled. Inside the cabin, without this visual help, the situation becomes impossible to resolve.
The conflict also has consequences for the brain, which is completely lost because of these misleading messages from the various sensors. How can it act on the muscles to compensate for the imbalance signalled by the inner ear, if the body is resting?
Faced with an incoherent situation with the different signals, which are impossible to accept, the brain can only do one thing to eliminate the problem. This tidying up leads to an uncomfortable feeling, headaches, nausea and sometimes more radically with an evacuation, which leaves the stomach aching and suffering.
We don’t all react in the same way to this type of problem. Some people are sick for an hour or two, others remain permanently suffering. It takes time for the nerve centre to appreciate that the information it is getting is not important. Getting used to it shows itself clinically by the gradual easing of the symptoms and finally their complete disappearance (after a maximum of 48h in most cases).
This phenomenon is the same with regular and persistent noise (an air-conditioning unit for example). After a while, this noise is no longer considered to be relevant information. It drifts into the background to the extent that you no longer notice it.
Back on dry land, the movement of the “bubbles” linked to the movement of the boat suddenly stops, but the brain continues to imagine they are there. It’s the same phenomenon with the noise presented above. When it stops, you think you can still hear it, and it takes a while to realise that it has gone. This continued perception of the previous movements is felt as land sickness, giving the impression that the land is moving around all the time.
However, the entry into the forties isn’t the return to dry land. It is quite the opposite. Here, the sea moves around much more, with rough seas, and sudden violent shocks. It takes the body a little time to get used to these new movements and its “bubbles” being shaken around much more. This Southern Seas sickness will in any case not last long. Whatever type we are talking about, preventing seasickness means identifying and avoiding the factors that lead to it, including firstly tiredness, cold, a bad diet and stress.
That’s the way things are. Man is a land creature. Raised up on two legs, we stand up straight. This vertical position, which gives us our superiority, is constantly under challenge from the laws of equilibrium. Put a bottle upside down on its neck and you have a good idea of what we achieve each time we stand up. For a baby, it takes months of trial and error to get up, and remove their hands from the ground. It is the vestibular system that looks after our balance and controls and corrects us when we lean over.
Its main function is located in the inner ear with the semi-circular chambers. There are three chambers in all, which are arranged on every plane. They work rather like a mason’s spirit level, with the equivalent of the bubble in the glass tube.
Continuing with this comparison, we can say that when we move, this causes the bubble to touch the little electrodes inside the tube. Through the nerve, each electrode, which has thus been stimulated sends a signal to the nerve centre in the brain. Putting together all the information from every chamber, the brain has a fairly good idea of the body’s position and especially the movements, which could cause you to fall over. It is helped in this by the information coming from the eyes, which gives geometrical positions (vertical, horizontal). In addition, the ligaments situated on the feet, ankles, knees and stomach, give precise details about the posture, what the body is resting on and the state of the ground.
All this information examined instantaneously in the brain leads to a reflex reaction with tightening or relaxation of the muscles, leading to a correct balancing position. Perfect harmony between the various elements is therefore necessary for the system to work correctly. But in a boat, things are more complicated and this harmony can no longer be found.
In fact, the “ground” is no longer the stable reference surface, but something in perpetual emotion. While it may be stationary, the body, seen from the outside is in constant motion, as it accompanies passively the movement of the boat. The “bubbles” follow this movement and transmit this information to the brain. Because the body is still, the ligaments are not used and send no messages to the brain to confirm the signals from the “bubbles.” There is therefore disagreement and a conflict about the information coming from the inner ear (pitching and rolling) and that coming from the ligaments (standing up, sitting down, lying down).
If the subject is out on deck, the conflict is resolved by the eyes, which offer the geometrical markers, such as the horizon or the coast. It is thus better controlled. Inside the cabin, without this visual help, the situation becomes impossible to resolve.
The conflict also has consequences for the brain, which is completely lost because of these misleading messages from the various sensors. How can it act on the muscles to compensate for the imbalance signalled by the inner ear, if the body is resting?
Faced with an incoherent situation with the different signals, which are impossible to accept, the brain can only do one thing to eliminate the problem. This tidying up leads to an uncomfortable feeling, headaches, nausea and sometimes more radically with an evacuation, which leaves the stomach aching and suffering.
We don’t all react in the same way to this type of problem. Some people are sick for an hour or two, others remain permanently suffering. It takes time for the nerve centre to appreciate that the information it is getting is not important. Getting used to it shows itself clinically by the gradual easing of the symptoms and finally their complete disappearance (after a maximum of 48h in most cases).
This phenomenon is the same with regular and persistent noise (an air-conditioning unit for example). After a while, this noise is no longer considered to be relevant information. It drifts into the background to the extent that you no longer notice it.
Back on dry land, the movement of the “bubbles” linked to the movement of the boat suddenly stops, but the brain continues to imagine they are there. It’s the same phenomenon with the noise presented above. When it stops, you think you can still hear it, and it takes a while to realise that it has gone. This continued perception of the previous movements is felt as land sickness, giving the impression that the land is moving around all the time.
However, the entry into the forties isn’t the return to dry land. It is quite the opposite. Here, the sea moves around much more, with rough seas, and sudden violent shocks. It takes the body a little time to get used to these new movements and its “bubbles” being shaken around much more. This Southern Seas sickness will in any case not last long. Whatever type we are talking about, preventing seasickness means identifying and avoiding the factors that lead to it, including firstly tiredness, cold, a bad diet and stress.
BrendanS
Well-Known Member
OK, I was simplifying. Notice I said psychological effects as well. I did a study on this at Uni whilst a kid. Amplitude has little effect, it's the disparity between the clues the brain is getting, as well as learnt effects from previous encounters with seasickness.
Removing some of the inputs, such as visual cues, removes some of the efffects. Removing learnt behaviour is more difficult. Amplitude of motion is not a primary factor unless things have changed significantly since I did the project, but admittedly it was a while back
Removing some of the inputs, such as visual cues, removes some of the efffects. Removing learnt behaviour is more difficult. Amplitude of motion is not a primary factor unless things have changed significantly since I did the project, but admittedly it was a while back
hylass
Well-Known Member
I belong also to the familly of those 'macho guys' who swear they never get sea sick.. and after 13 years of full time living aboard and sailing.. I'm still waiting for the "first time"???
What does it means??
Would my brain be developped enough to analyse motion signals from both sensors??
What does it means??
Would my brain be developped enough to analyse motion signals from both sensors??
G
Guest
Guest
I'm sure the crew of your typical boat that vomits it's way through a gale will be depressed to know that amplitude has little effect, so there is little hope of recovery when the gale passes.
Moving away from practise and back to theory for a moment, surely the amplitude is key in creating the disparity of which we speak. The bigger the amplitude, the greater the disparity.
BTW, gazing at horizon and.or closing eyes definitely helps, but only to a certain extent. There are more important factors, such as diet - acidity in the stomach etc.
I also find that on an anchorage with a pitching motion I can get unwell even if I'm sleeping if I happen to be in the forecabin - which can be immediately cured by moving to the main cabin. All of which sleeping is done with my eyes shut and in the dark!
Moving away from practise and back to theory for a moment, surely the amplitude is key in creating the disparity of which we speak. The bigger the amplitude, the greater the disparity.
BTW, gazing at horizon and.or closing eyes definitely helps, but only to a certain extent. There are more important factors, such as diet - acidity in the stomach etc.
I also find that on an anchorage with a pitching motion I can get unwell even if I'm sleeping if I happen to be in the forecabin - which can be immediately cured by moving to the main cabin. All of which sleeping is done with my eyes shut and in the dark!
BrendanS
Well-Known Member
Some people instinctively do the things required to remove the adverse cues. Some simply don't suffer for reasons unknown - probably because they filter out the adverse motion internally. For others, it's a purely psychological effect
G
Guest
Guest
[ QUOTE ]
For others, it's a purely psychological effect
[/ QUOTE ]
The brain being unable to reconcile signals from ear and eye is also a "purely psychological effect" - it all takes place within the brain. The difference is that for the former we have some idea of WHAT psychological effect, for the latter, we have little idea.
Coming back to amplitude, I think that it is an undisputable fact that the bigger the waves then statistically the more people are going to go down with sickness. To say that it is not a major factor is to bend the facts to fit the theory (sorry!)
My other point (to expand it a little) is that what is going on in the head is only half the story, the other half is what is what is going on inside the stomach. If the stomach is fully of acidy crap, then the brain's message that the stomach is full of poison is far more likely to be triggered.
For others, it's a purely psychological effect
[/ QUOTE ]
The brain being unable to reconcile signals from ear and eye is also a "purely psychological effect" - it all takes place within the brain. The difference is that for the former we have some idea of WHAT psychological effect, for the latter, we have little idea.
Coming back to amplitude, I think that it is an undisputable fact that the bigger the waves then statistically the more people are going to go down with sickness. To say that it is not a major factor is to bend the facts to fit the theory (sorry!)
My other point (to expand it a little) is that what is going on in the head is only half the story, the other half is what is what is going on inside the stomach. If the stomach is fully of acidy crap, then the brain's message that the stomach is full of poison is far more likely to be triggered.
BrendanS
Well-Known Member
You are mixing up body to brain signals and psychological.
Body to brain are signals sent to the brain as a result of many things. Motor neurones, inner ear, eyes, etc. Psychological are learnt responses on the whole - eg I'm going to spew because every time I get on a boat I do.
Simplistic, but not sure how to get this across any other way.
In most, but not all, actual scientific studies on the subject, it was type of motion, rather than amplitude of motion, that caused problems. If you can point me at studies that say amplitude is of most importance, I'd be happy to read them. What causes the problem in rough conditions is the way the boat starts moving erratically, rather than in a steady up and down or side to side motion.
It's the erratic-ness that causes problems, not amplitude, hence sea sickness when anchored or fishing, compared to boats which are motoring or sailing, when direction of movement is more predictable and stable.
Body to brain are signals sent to the brain as a result of many things. Motor neurones, inner ear, eyes, etc. Psychological are learnt responses on the whole - eg I'm going to spew because every time I get on a boat I do.
Simplistic, but not sure how to get this across any other way.
In most, but not all, actual scientific studies on the subject, it was type of motion, rather than amplitude of motion, that caused problems. If you can point me at studies that say amplitude is of most importance, I'd be happy to read them. What causes the problem in rough conditions is the way the boat starts moving erratically, rather than in a steady up and down or side to side motion.
It's the erratic-ness that causes problems, not amplitude, hence sea sickness when anchored or fishing, compared to boats which are motoring or sailing, when direction of movement is more predictable and stable.
CodStewart
Well-Known Member
Seasickness is weird. You feel like you can cope with it whilst up on deck, but as soon as you head below, you feel like crap again. I was seasick on the Cortez crossing. Quite liked it when I reached the frothy foamy stage - when nought else was left in my stomach. I guess that I was lucky though. I'm sure that terrible bouts of seasickness exist on deck, too.
I'm going to stock up on lots of Korean ginger tea.
Seasickness in Japanese is 'Funa Yoi'. Sweet, huh.
I'm going to stock up on lots of Korean ginger tea.
Seasickness in Japanese is 'Funa Yoi'. Sweet, huh.
A
angelsson
Guest
You can add my SWMBO to the list of macho's, she is amazing, first time on a boat was 18 months ago, took to it like a duck to water, all weathers no problem to her... whilst in some conditions I still get a little queasy which I deal with by drinking lots of tea.
I have been informed, and this is by no means as technical as many other posters have been good enough to inform us with, that there are 2 stages of sea sickness
Stage 1 is where you are so sick you are afraid you will die
Stage 2 is where you are afraid you will not die.
Thanks to all for their remedies and experiences, what a wealth of knowledge here.
Regards
Mike
I have been informed, and this is by no means as technical as many other posters have been good enough to inform us with, that there are 2 stages of sea sickness
Stage 1 is where you are so sick you are afraid you will die
Stage 2 is where you are afraid you will not die.
Thanks to all for their remedies and experiences, what a wealth of knowledge here.
Regards
Mike
G
Guest
Guest
I had understood that the problem was not with the body to brain signals themselves, but rather with the way that the brain reacts to the conflict in these signals.
OK Brendan, come sailing with me. When we come to some big seas, we will lock you in the forecabin blindfolded and see how long it takes you to be begging to be allowed out! /forums/images/graemlins/wink.gif I will tell you that your vomiting is all in the mind and that you should learn to get over it /forums/images/graemlins/smile.gif
OK Brendan, come sailing with me. When we come to some big seas, we will lock you in the forecabin blindfolded and see how long it takes you to be begging to be allowed out! /forums/images/graemlins/wink.gif I will tell you that your vomiting is all in the mind and that you should learn to get over it /forums/images/graemlins/smile.gif
hocus
Member
Brendan's done a good job of responding to your comments tho you seem to be at cross purposes with him. Perhaps further facts may help- as well as the amplitude of the movement, consider the direction. There is pitch- up & down and probably least vomit producing, roll side to side & a bit more emetic but most emetic of all is said to be yaw. In aviation circles it is yaw which is least likely to be noted visually but most likely to make people puke, especially pax down the back who are furthest from the pivot point of the aircraft( thus exposed to greater amplitude of change).On boats we usually notice pitch, if only because the boat goes crash into the wave, & roll is easily detected, but less so yawing. Bear in mind if you change attitude eg laying down, especially on a side or, heaven forfend, transverse across the vessel, the most emetic action of the boat changes correspondingly- hence the unpleasant forecabin.
If you can work out the orientation of the planes of your semicircular canals, you can move to find the position of least discomfort, but for that look at a standard text on anatomy or Ear Nose & Throat medicine
If you can work out the orientation of the planes of your semicircular canals, you can move to find the position of least discomfort, but for that look at a standard text on anatomy or Ear Nose & Throat medicine
G
Guest
Guest
[ QUOTE ]
In aviation circles it is yaw which is least likely to be noted visually but most likely to make people puke, especially pax down the back who are furthest from the pivot point of the aircraft( thus exposed to greater amplitude of change).
[/ QUOTE ]
That's very interesting about orientation, and I appreciate Brendan's point that the type of motion is very important. I entirely agree that it's possible to be ill in a very light wind if the swell if of the "wrong type". But you also seem to be agreeing that amplitude is important, which is my point. It is a fact that more people will be ill in a gale than in calmer weather, and it is also a fact (coming back to the original point) that the further forward or (to some extent) back you are in a boat, the more likely you are to be ill. Just like you passengers in the plane "who are furthest from the pivot point of the aircraft( thus exposed to greater amplitude of change)".
In aviation circles it is yaw which is least likely to be noted visually but most likely to make people puke, especially pax down the back who are furthest from the pivot point of the aircraft( thus exposed to greater amplitude of change).
[/ QUOTE ]
That's very interesting about orientation, and I appreciate Brendan's point that the type of motion is very important. I entirely agree that it's possible to be ill in a very light wind if the swell if of the "wrong type". But you also seem to be agreeing that amplitude is important, which is my point. It is a fact that more people will be ill in a gale than in calmer weather, and it is also a fact (coming back to the original point) that the further forward or (to some extent) back you are in a boat, the more likely you are to be ill. Just like you passengers in the plane "who are furthest from the pivot point of the aircraft( thus exposed to greater amplitude of change)".