Perceived Sea State and Freak Waves.

[Tiger]

I agree that sinking the boat and making it part of the wave would give far better stability, but there are so many reasons in terms of seamanship that this is the wrong thing to do surely.

This is going rather hyperthetical, but thats part of the risk management process and a good tool for thinking about sea survival (do the RYA / professional course, its interesting & fun).

I agree that in principle your RIB should float on the surface when flooded. How high it floats, for how long and if it is any use to you in that state is another matter.

Firstly, you should be able to stablise the vessel with a sea anchor (or a bodge for the same effect) without getting soaking wet sitting in a pool waiting for hypothermia to set in.

Secondly, do you keep the engine running or save fuel.

Thridly, do you want to short out your electrics (radio, engine etc).

Forthly, we know you should stay with the boat, how you going to do that if it rolls over and does not kill you?

You could go on and on with this, but there are some simple things to remember in boats.
Nothing is waterproof
Nothing is unsinkable
Nothing is indistructable
You may find something close, but will work when you need it too?

Tiger

[Alan Priddy]

Hello Tiger. The name of this thread is Perceived Sea State and Freak waves. What you are indication are your views on bad weather. What I am talking about is REALLY BAD weather which in reality most of you will never be in. My advice is built on thousands of miles of open sea work, not any rules that have been written by peolpe who think that have been in bad weather!
I hope you never have to face extreme conditions because it is not very nice, but I can assure you that if you do not sink your boat, the chances of living are not very good at all. None of my comments are "Hypethetical" they are bourne about by having been there and done it. It is not often I will blow my own trumpet but I am afraid that I will only accept your version of how to survive in a RIB in big Seas when you have got the T Shirt. As for us, out T shirts have worn out. Alan P

[Julian]

If you are caught in really big seas and did'nt flood the boat then you stand a very high chance of the boat capsizing. At least when flooded you are part of the wave which will carry you in its pattern. If the boat is built properly the electrics and engine bay will not get wet. Water will only get in if there are build defects and the boat is not water tight. I sunk our with water over the tubes and console on my way to belgium in a force 9 and not a drop of water got in anywhere. The engine is water tight and kept running with no problems.

I've not been in any where near the size of seas that Alan has experianced but with out a doubt I would flood the boat and sit it out till we could move on again.

Julian

[dgpw]

Points for thourght

in that situation do u

Clip on to the boat and risk being trapped in a capsise

Stay out of the water maby on the concle or seat. would stop you becoming hypothermic as quickly but could end up with you being throne in.

simply let the boat go broardside to the waves and become part of them or try to hold nose to the weather with a sea anchor ect which may defeet the point of flooding the boat in the first place.

any ideas

[Alan Priddy]

The chances of the boat turning over are very remote as it will have an inherant keel weight greater than the weight of the boat, but in experiance I would recommend holding on.

You would be proberbly wearing a dry suit so the cold should not effect you that much but in any event you would not be stationary so you can wiggle your toes and fingers to keep warm.

Again in experiance, let the boat be part of the wave, if you try to hold the bow into the wave it will proberbly tip you bow over stern anyway.
I, more than anyone like a good laugh, but on matters of safety I would only state the true facts on how to survive in extreme conditions.Alan P

[Allen]

i had a freak wave at me once.

[dgpw]

Ok thanks Alan I agree with all of that I will just add a Hat to the dru suit as 80% of the bodys heat is lost through the top of your head. Everyone should carry enough hats for all of the crew. The human body gives out an average of 1 kilawaht of heat per hour so food is a must to refule the body for prolonged amounts of time in the cold. o an sit close together you may aswell use some of your friends kilawhats!!!

Good thead this!

[narked]

How about only taking 1 hat, which you wear, and then line your crew up, and use them as a nice heated sofa?

Flooding the boat does seem like a good idea, unless you get into the habit of doing it and then end up flooding a normal boat when conditions get nasty out of habit...

Matt

[Keith Hart]

Here is a tripple freak wave!

[Tiger]

I'm certainly not questioning your experiance in big sea's Alan!

I hoped this thread would encorage everyone to share experiances that work, rather than what I people have been taught or have read in books. Its also an opportunity to ask questions (hence my hyperthetically) and I think thats exactly whats happening!

How often do people talk about free surface affect in Rib's?!?!
Never, but its happened now and I found it rather worrying at the time.

I admit I have confused things from the start mentioning deep sea then coastal.
Should this thread split into deep sea and coastal?

I don't have any experiance of wheelhouse Ribs or big sea's, my knowledge of big sea's is from working in shipping.

My experiance is built on Rib's and Sib's mainly under 6m and not far offshore, but I have been out in weather (up to F8) that demanded 100% concentration due to the small size of the boat.

Deep Sea, I think Alan is quite right to minimise the exposure to the waves and I take onboard that flooding would be necessary.
I just wondered how sure you can be of the equipment onboard?
Ultimately, as I think Alan has made clear, if its that bad you just need the boat to keep afloat and keep you alive, after the storm you can make good.

In my experiance being in small boats with little protection, the last thing I want is a boat full of water and hinder my manoverability. That said, though it would be a last resort to flood the boat, thanks to Alan's input it's one I would not dismiss!!

Tiger

[Keith Hart]

As I understand it (and my opinion does not count for much here), Alan P is talking about a LIFE THREATENING and EXTREME situation.

If the choice is between drowning immediately and loosing your instruments due to water ingress, then the choice would be to risk your instruments etc. You would at least be alive to worry about it!

Recent story on the TV about a fisherman whose arm was caught in his wynch. He had a choice, cut off his arm or die. He cut off his arm. He lived. He has lost an arm, but he is only alive today because he made that choice.

Hopefully most of us will NEVER be in such a situation.

Keith (oooh, serious for a bit then eh) Hart

[narked]

Keith, but would YOU throw the BACON SARNIES overboard if it would save your life?!

But seriously Keith makes a good point there, if it's a choice between financial loss and loss of life, or putting up with severe discomfort or pain versus losing your life, then I think we'd all agree and go for choice numbero uno.

Matt

[Mike Garside]

Now, this IS getting interesting.

Yesteryear's accepted wisdom for sail boat survival in deep sea heavy weather conditions was to slow the boat down and use a sea anchor.

A vast amount of practical experience by world renowned mariners showed that this was the way to go. Sea anchor development became very sophisticated and included variants like those that consisted of a very long line with hundreds of mini drogues at close intervals.

When water ballast came along there were those that recommended flooding the tanks as well.

But then along came a French sailor called Christophe Augin who achieved victory in three consecutive round the world races and he changed all this. Another French Open Class racing superstar, Yves Parlier, did the same the same thing.

And what they did was to lighten the boats and let SPEED be their saviour. They flew faster than the seas that threatened to overwhelm them.

I chose to follow this example in my own "rocket ship" during the 1998-99 Around Alone and it served me well.

Approaching Cape Horne from the west in what was the worst storm on the planet at the time I chose to give my boat her head and we outran the storm.

The 50 foot boat weighed only 6 tons, and which was no more than a giant wind-surfer, was able to speed down the back of waves and up the other side before crossing the breaking tops to out-run them down the far side.

Now, I have to admit that my experience of heavy weather sailing in RIBs is very very limited and I read Alan's and Julian's advice with serious interest. But why, if an extreme sail boat can outrun heavy following seas, why can't a RIB do the same?

[Alan Priddy]

Mike, I am not 100% sure of this but did Magalen Alpha have some sort of keel and how heavy was it? Unfortunatly a RIB is reliant on is't centre of Gravity / Bouyancy. Interesting thought though. Can we go out in Alpha and do a back to back test off of Lands End in a force 12? We could try Your way first and if it works than we have created another altenative Alan P

[John Kennett]

Originally posted by Mike Garside
. . . able to speed down the back of waves and up the other side before crossing the breaking tops to out-run them down the far side.

This is fine so long as you are absolutely sure that your boat, whwtever it happens to be, will go up the other side.

The real problem comes when you are going fast (as you will by definition in this scenario!) and your boat tries to go through the next wave, not over it.

Whether it works or not will depend on various factors such as the wave shape and pattern, along with the type and design of boat. Most ribsters caught in heavy weather are unlikely to be mid ocean, so waves will tend to be relatively steep and short, making a stuffing more likely.

The faster you're going when things go wrong, the more it hurts!

John

[toby.budd]

I found Alan’s comments very interesting and have been thinking about this matter since. I will not begin to dispute experience as this technique has obviously worked for Alan, his crew and others like Julian for some time. But although I don’t doubt and understand the principle I can’t get my head around the details?

How many of those who post on this site would be happy to go out to sea and flood their boat and be confident that there systems would continue to function and get them home? Mike?

If you decide to fill your boat you will lower its water line by? Say 100mm. Lowering the CoG by the same amount. Now I would guess that the centre of gravity for a RIB, with a console and inboard is just above deck level. By filling your boat with 400 mm of water, Will you not be placing the weight above the CoG? hence raising the boats CoG, making it more unstable. This is not to mention the effect of the FSE that can significantly reduce the stability of a vessel. When a RIB heels over the centre of buoyancy moves outboard quickly because of the sponsors. So I am unsure how this effects the standard equations concerning the FSE but I am sure it is still a relevant consideration.

As Mike said a number of offshore sailors like himself who have chosen to run before the weather. I understand that stuffing could then become a problem but is the serious of this only proportional to the speed you are travelling in comparison to the wave not through the water. So can you not reduce your speed and run at the same speed as the wave systems? Alan. Making this a feasible option.

Just a thought but this is the sort of article that would be good to see in RIB Int. They could take a RIB out in steep over falls and test these different techniques! Maybe.

Toby

[Alan Priddy]

Toby, I understand everything you are saying but what I am suggesting is what to do in a life threatening condition, not steep over falls. I fully aggree with Mike's theory but not nessesarly for a RIB that has a great big bubble on the front. A sail boat with go under on the back / front of a wave where as a rib will proberbly rip it,s bow off in a short time.As for the increase in weight, a typical 6 metre RIB will hold around 2.5 ton of water. That is one hell of a keel. As I said, you have to sink the boat and make it part of the sea Alan P

[toby.budd]

With regard to ripping the tubes off the bow. Could you not fit a preasure release valve to stop this happening? Like on liferafts.

Toby

[Garygee]

Hi folks

This is all very good info, given me info that I would have never tried before. I think if it got really bad before I would have been pumping out like mad to keep the boat dry, how wrong I would have been.

Everyone talks about how would the boats survive, and that Scorpion do this test as standard, does anyone know if Ribcraft do this test or how Ribcrafts stand up to being flooded. If its a problem for them maybe I can change some things before my new boats fully built. Being a inboard there is lots of extra things to go wrong when flooded. eek:

Would love to see peoples faces at the maina when all the RIB oveners are stood up their knees filling their boat with water, they they will think these funny RIB folks have really lost the plot

Regards Gary:

[Julian]

Hi Garygee

I'm not sure if Ribcraft sink there boats when built but I do know they make very good boats and very strong boats. Just make sure that the engine box is watertight. Diesel engines and sea water do not mix all that well.

Julian