Catamaran vs Monohull Crew Safety

[smj]

Originally Posted by Hardhead

I agree - that's a huge factor. Everyone reacts differently, and there can be a huge difference as to what, specific, type of motion causes seasickness between people. As an example, I can handle the sharp, snappy motion, or pounding, of a catamaran no problem - but the deeepp, sloooow, wallooowing rhythmic, pendulum motion will make me turn green, especially with diesel fumes.

I have an inner ear imbalance and the slow motion of a mono, even at anchor makes me dizzy.

[boom23]

I just watched the video below of a Lagoon catamaran in a storm. It gives a little idea of how it is inside one in rough conditions. It is difficult to get a real sense of it without the movement/vibration and the actual noise, but you can get an idea. The good stuff starts around 7:15.

Sailing the Bay of Biscay

I'm not saying it's unsafe... It's just to compare the motion and noise.

[smj]

Originally Posted by boom23

I just watched the video below of a Lagoon catamaran in a storm. It gives a little idea of how it is inside one in rough conditions. It is difficult to get a real sense of it without the movement/vibration and the actual noise, but you can get an idea. The good stuff starts around 7:15.

I'm not saying it's unsafe... It's just to compare the motion and noise.

Not all multis are created equal. The creaking and groaning would drive me crazy

[mglonnro]

Originally Posted by Hardhead

I agree - that's a huge factor. Everyone reacts differently, and there can be a huge difference as to what, specific, type of motion causes seasickness between people. As an example, I can handle the sharp, snappy motion, or pounding, of a catamaran no problem - but the deeepp, sloooow, wallooowing rhythmic, pendulum motion will make me turn green, especially with diesel fumes.

I recall seeing a motion sickness study talking about this as well. (Apparently with virtual reality on the rise there's more energy than before going into motion sickness research.)

Anyway, they also said that the movement often needs to be slow enough to induce sickness. I think it's more common to get sick on a sailboat than in the dinghy, for example, although the latter can jump and pound quite wildly on the waves.

[daletournier]

Originally Posted by smj

Not all multis are created equal. The creaking and groaning would drive me crazy

That applies to monos as well. My old full keel Tophat 25 rolled gunnel to gunnel , my deep keel Catalina 470 with a fat wide bum is quite stable.

[Tupaia]

Originally Posted by mglonnro

I recall seeing a motion sickness study talking about this as well. (Apparently with virtual reality on the rise there's more energy than before going into motion sickness research.)

Anyway, they also said that the movement often needs to be slow enough to induce sickness. I think it's more common to get sick on a sailboat than in the dinghy, for example, although the latter can jump and pound quite wildly on the waves.

Motion sickness is a mental problem. it results from the brain not being able to interpret the conflicting signals from the ears and eyes.

A big chunk of astronaut training includes being able to mentally override these messages.

It is rare to get motion sickness on a dinghy because your eyes are always aware of the movement in yours ears and visually the sea around you. The signals are related and there are only rapid inertial forces. On a rolling vessel not only are the ears trying to interpret the angle of tilt but they are further confused by the additional false "tilting" imparted by slow inertial forces .

I remember reading a study done by a Navy (Danish I believe) that installed a gyro controlled 360 degree projected false horizon in the windowless control centres on their warships. The results in combating sea sickness in operators was dramatic.

[Tupaia]

Originally Posted by boom23

I'm not saying it's unsafe... It's just to compare the motion and noise.

I think this video in particular demonstrates that low wing deck clearance, slab sided hulls and mini keels are not the best arrangement for rough weather. It also demonstrates that things were not flying around.

These guys are on a mono crossing Biscay in much milder conditions. Take a look at the state of the saloon and the comment at 16:28 they don't sound comfortable.

https://www.youtube.com/watch?v=yTgOQYqeQEQ

What hasn't been mentioned is that catamarans are more noisy and at speeds above 10 knots the sound of the water rushing past the hulls can become very tiring. By design they are big hollow sounding boxes but they should certainly not creak.

[rapanui 2]

Originally Posted by mglonnro

Cheers,

I'm in the initial stages of considering moving from a monohull to a catamaran (maybe some years down the road).

When googling catamaran safety issues, the by far most mentioned topic seems to be whether a catamaran can capsize too easily.

This thread is NOT about that! (I think I've found quite reassuring answers to the capsizing questions.)

What I started thinking about, though, were all the other minor and major incidents that take place on recreational sailing boats (everything from tripping and bruising yourself to going overboard), and how sailboat heeling might affect the frequency of these.

Everything gets much more difficult in a heeling sailboat so my initial thought is that less heeling would, overall, result in fewer injuries?

What say you?

a correctly built cat will not sink, a monohull will sink very fast with 25% /30% of his weight in the ballast often in less than 5 minutes with a large hole.. .. so the only for a liferaft is if you hva a fire that destroy the cat.

[boom23]

Originally Posted by daletournier

That applies to monos as well. My old full keel Tophat 25 rolled gunnel to gunnel , my deep keel Catalina 470 with a fat wide bum is quite stable.

I found this true also.
I spent some time on a Super Maramu and I found it much more rolly than my Amel 50.

[KP44]

Parts of this discussion remind me of the Banderlog in The Jungle Book. All the Banderlog (monkeys) telling Mogli, "See? See? We all say it so it must be true."
Experience is a better teacher.

[tiMoun]

I didn't read the whole thread and you probably got some great answers. I've sailed monohulls for 60 years and catamarans for 20 (own a Leopard 43). After going to cats reluctantly, because my wife said she was done with the heeling and new wives are very costly in California, it took me awhile to become won over.
Safety wise:
1. The motion is radically different from a monohull, still getting used to it, and is disturbing for some. There is the sort of double wallow as you crest waves.
2. Comfort and ability to move about in general terms is so much better and safer, picture standing at the mast working on something with 12 feet of boat in all directions to keep you from getting swept over.
3. Boom swinging injuries are essentially non-existent unless you've decided to climb atop the coach roof for some reason.
4. Trip, bump injuries would probably be the same except generally there is more space to move around and more space between obstacles.
5. MOB recovery, over the stern, under power (2 engines) is much easier.
6. The dictum "When should you reef? When you first think about it" Is very true in a catamaran, don't get caught running before the wind with increasing wind as you may reach a point quickly where you can't reef anymore (can't turn across wind in heavy seas and wind without risk of pitch poling)
7. Comfort at anchor as you won't be rolling or tacking anymore.
8. Galley safety is a big plus, meal prep in 10 foot seas and 25kts is routine and easy, contributing to safety.
9. Two engines is a big safety factor (power, electrics, getting somewhere if necessary)
For me the change was very positive, biggest downside is cost and usually windward ability.
Michael

[a64pilot]

Originally Posted by mglonnro

I recall seeing a motion sickness study talking about this as well. (Apparently with virtual reality on the rise there's more energy than before going into motion sickness research.)



Anyway, they also said that the movement often needs to be slow enough to induce sickness. I think it's more common to get sick on a sailboat than in the dinghy, for example, although the latter can jump and pound quite wildly on the waves.

Depends on the person, we had one pilot that could not stand the full motion simulator, made him sick as Hell, but he had to log x number of hours in it per quarter, so he would lay on the floor and not watch the screen, he was fine as long as he didn’t see the screens.

I think it was three hours. He could also I think fly instruments as it was just a white or black screen depending on if you chose day or night, and instruments can and should be flown with very little motion

Plus more than one or two got sick flying night vision system that had FLIR video over your right eye and the viewpoint of the system was 10 feet in front of you and 3 feet lower than your head.
So for some, motion sickness is very very visual.

[boom23]

Originally Posted by Tupaia

I think this video in particular demonstrates that low wing deck clearance, slab sided hulls and mini keels are not the best arrangement for rough weather. It also demonstrates that things were not flying around.

These guys are on a mono crossing Biscay in much milder conditions. Take a look at the state of the saloon and the comment at 16:28 they don't sound comfortable.

What hasn't been mentioned is that catamarans are more noisy and at speeds above 10 knots the sound of the water rushing past the hulls can become very tiring. By design they are big hollow sounding boxes but they should certainly not creak.

Catamarans are very wide and it's very hard to make them solid (not flexible). I believe they all tend to creak, just like the average quality monohulls.

Riggers have told me that one cannot get the catamaran side stays as tight as the monohull, as the catamaran hull bends. If one keeps tightening the catamaran side stays, the interior doors will start hitting their frames and not close. That's when you know you tightened too much.

[smj]

Originally Posted by boom23

Catamarans are very wide and it's very hard to make them solid (not flexible). I believe they all tend to creak, just like the average quality monohulls.

Riggers have told me that one cannot get the catamaran side stays as tight as the monohull, as the catamaran hull bends. If one keeps tightening the catamaran side stays, the interior doors will start hitting their frames and not close. That's when you know you tightened too much.

All catamarans do not creak.

[Toujours]

Each hull on a catamaran can be on a different wave cycle. One hull can be in a peak, the other in a trough, so the rocking motion can be exaggerated. Catamarans can also exhibit oscillating yaw motion from following or quartering seas depending on the cycle of the waves hitting the stern. Have been affected by that and it's not a nice feeling.