Should I worry about bumps in the night?

Kelpie

Kelpie

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Expecting to do our first longer distance overnight sailing this year, and I have been pondering on what would happen if we were to strike a submerged tree trunk or shipping container. I know the odds are very low, but I was wondering about just how catastrophic it might be.
My boat, an Albin Vega, is designed to withstand grounding on rock at 6kt (and the ability to withstand this has been proven a few times!). Hitting something at the waterline is of course a different story. But when you think about it, a 2.5t yacht going at reduced speed for comfortable overnight sailing (say, 4 to 4.5 kt), is not carrying *that* much energy. Fibreglass is pretty tough, too. Remember the YM crash test boat article where they let a hefty guy attack the hull with a sledgehammer, to virtually no ill effect?
 
As you say its low chance, it can happen. It probably will not happen...

Worst things happen at sea?

Seriously it is unlikely as is often the case on boats its a risk you take.

Take all sensible precautions...

When something went a bit wrong on one boat I was on, it was pointed out

"You can think about these things, you did everything you could. If your going to worry about it you will never get on at sea".
 
You should look where you're going! :-)

Far more effective than worrying.

Yes if you collide with something, it could, worst case, sink you.
But it's not likely.
Most things solid enough to sink you can be seen in time to avoid, even on a dark night.
Even in lightly built dinghies, unless you hit a sharp object straight on, it is hard to make a hole.


Fishing gear is more of a worry, but that's a less dramatic threat.

I'm not saying there are no risks, but not many yachts sink by hitting flotsam.
 
Of course, there are things you can do to improve the impact odds for your boat, but can you be bothered? Pro active usually improves confidence so, in no particular order...crash bulkhead, watertight door to forecabin, watertight compartmentalising below the bunks, bit of rubber D section fending tied along the stem when cruising, spinnaker pole poking forward and down to absorb first energy from a hit, ....
I have bonked a railway sleeper which just slid down the stem and wedged across the bilgekeels-angled blows with lighter objects are insignificant really, it's Ships that you want to def svoid!:)
The big 'fear' is a waterlogged container, how long can they really stay afloat, days weeks, years after being swept off?
 
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Are there any recorded incidents of yachts being struck/holed by flotsam?
Any more tales of things bouncing off relatively harmlessly?
 
I haven't read this yet, but it's sure to be of interest to contributors/readers of this thread: http://www.arachnoid.com/alaska2007/collision.html

The author makes a good point - that shipping containers lost overboard, are likely to be stuffed with consumer durables, packed in enough polystyrene to keep the container afloat. Alarming.
 
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Unless I have a very experienced crew, I tend to be extra careful on night sailing, particularly on moonless nights.
I tend to err on the side of slowness rather than speed. I never put the kites up at night. I keep a powerful searchlight with a 700 yard range in the cockpit
and give fishermen as wide a berth as possible.
 
Robwhelton said:
Expecting to do our first longer distance overnight sailing this year, and I have been pondering on what would happen if we were to strike a submerged tree trunk or shipping container. I know the odds are very low, but I was wondering about just how catastrophic it might be.
My boat, an Albin Vega, is designed to withstand grounding on rock at 6kt (and the ability to withstand this has been proven a few times!). Hitting something at the waterline is of course a different story. But when you think about it, a 2.5t yacht going at reduced speed for comfortable overnight sailing (say, 4 to 4.5 kt), is not carrying *that* much energy. Fibreglass is pretty tough, too. Remember the YM crash test boat article where they let a hefty guy attack the hull with a sledgehammer, to virtually no ill effect?
Click to expand...

We've seen things during the day that would probably have sunk us if we had hit them at 5-6 knots - here's a delightful object we met between the Azores and Finisterre:

tank.jpg


We've also seen tree trunks and once an abandoned dismasted yacht.

We have adopted a bit of a fatalistic attitude though, otherwise long passages in a small boat simply become impossible. We do sometimes reef down at night, but we have also with a favourable forecast sailed at six knots in pitch darkness for twelve hours. Yes, you do sometimes see things that could sink you - but they are tiny compared to the ocean they float in.

The morbid apprehension I have sometimes suffered on board Fairwinds on offshore passages has mostly been weather related - I rarely lie awake off watch worrying about semi-submerged objects.Your mileage may vary . . . I think we all have our pet worry, whether it be storms, floating obstacles, ships, rigging failure, whales . . . my advice is, pick one and worry about it, forget the rest.

- W
 
The momentum of a yacht can be substantial and if you hit a solid heavy object below water line, in the right place, there is a high probability of making a hole. Any hole more than 4 inches (100mm) will be difficult to fill and manage the water flow.

Fibreglass is not the best material against breaking and holing; i rather have a steel yacht for blue water sailing. However, it is more likely to get a rope or fishing net around your propeller on a lee shore, at the wrong time and you will end up in a much worse situation than hitting a submersible object and holed.

I have two large, industrial submersible water pumps which I can quickly plug in the inverter, or in the generator, to get me out of trouble, if need.
 
There are undoubtedly cases of yachts sinking after hitting near-submerged floating objects - but very few.

IMHO a smaller yacht is more likely to get away with it than a large one. The weight and speed are less -thus much less momentum to dissipate. The strenght, however, would not reduce that much compared with a larger yacht.

I woudn't worry too much - you are much more likely to be killed driving to the marina.
 
Maybe your chances of spotting a semi-submerged object at night are slim - but how sure are you that you would spot the same thing during the day? Do you keep your eyes trained on the water ahead all the time? It's down to probabilities. People do hit things at sea but I've sailed around 50,000 miles and never hit anything. I've had a couple of close shaves including passing within 6 ft of a drifting Lanby East of the Azores but the probabilities remain low.

When taking part in the ARC we were one of 220 boats starting at the same time heading for the same destination yet after the first day we only spotted a couple of sails on the horizon the whole trip. Oceans are really big things - the North Atlantic covers 6 million square miles. You can lose a lot of stuff in that much sea.
 
Robwhelton said:
Are there any recorded incidents of yachts being struck/holed by flotsam?
Any more tales of things bouncing off relatively harmlessly?
Click to expand...

I've had the occasional un identified modest thump/bump from for'ard, nothing drastic. I think the probability of this is much increased in coastal waters, especially after heavy rain, when rivers in spate throw all manner of stuff into the sea - tree trunks in particular...
Such items further offshore will be more water-logged - and less visible of course.
I don't fancy meeting a submerged container mind you :eek:
 
I reckon it's reasonable to say it isn't worth worrying about - but that doesn't deny the risk's existence, or improve the odds of avoiding horrible, even fatal damage if one does ram massive flotsam, mid-ocean. Like worrying about heart failure!

The following thread starts rather negatively about forward-looking sonar, but it is from five years back and the concept seems to have fans, even if the system only functions as a very short-notice lookout & alarm:

http://www.cruisersforum.com/forums/f13/forward-scanning-sonar-8649.html
 
If you're really worried, then a (40-50mm wide 12-15mm thick) s/steel keel-band fastened to the stem of your GRP or wooden yacht, from bow down to the leading edge of your keel, will go some way towards offering protection.

If you strike a small object with sharp edges, the band will help prevent gelcoat being punctured or torn off. If you ram a serious mutha, then the band might just help spread the impact and prevent a single-point rupture through the structural material.

On drying out last week, I discovered a thumbnail-sized gouge right through my stem just above the waterline. I assume this was caused by some object being carried downriver at some speed while my boat was on her trot-mooring.
 
When I fitted a new lift keel a few years ago, I discovered there's a tufnol bash-pad built into the aft edge of the keel case, so that the tapered trailing edge of the keel plate doesn't knife into the hull if I hit something seriously; the makers never even mentioned it but it seems a good idea, maybe other lift keelers could fit something similar.

The very front compartment under my forepeak is filled solid, which may help; the only flotsam I remember hitting was a thin plank about 6' long, off Hayling foreshore - by a chance in a million it balanced perfectly crossways on the keel leading edge, no damage but the slowing effect was surprising, we had been doing over 6 knots in a good breeze.

Of course fin keelers tend to suffer damage at the upper trailing edge of the keel where it knifes into the hull if it hits anything, while twin keelers can funnel flotsam between the keels and to the prop, whipping out the shaft if really unlucky; you can't win !

When very experienced sailor Mike Birch disappeared without trace on the OSTAR in the well-found trimaran 'Three Cheers', a lot of people suspected he'd hit some nasty flotsam or been run down, though there is more to that sad tale...

I knew someone who had his propshaft try to shoot out of the back of his dodgily built boat when he engaged reverse gear for the first time, nearly sinking the boat; I'd be worried about flotsam, be it solid or something like a tarpaulin, dragging a shaft or saildrive out of its' mounting more than punching a hole in the hull.
 
Seajet said:
When very experienced sailor Mike Birch disappeared without trace on the OSTAR in the well-found trimaran 'Three Cheers', a lot of people suspected he'd hit some nasty flotsam or been run down, though there is more to that sad tale... QUOTE]

Was that Mike Birch, or Mike McMullen?

This article: http://www.graphic-park.com/VS_WIP/The Shop/Three_Cheers/index.htm

...seems to lend a possibly suicidal explanation to the Three Cheers disappearance. Very sad, whatever.
Click to expand...
 
Dancrane,

sorry yes Mike McMullen.

Everyone who knew him and saw him set off swore he'd never contemplate suicide, but as he'd just lost his dear wife who knows if or when the stress of solo sailing comes in.

As a warning to others who may not know the story, she was helping prepare the boat, dropped a power tool into the water and, by instinct, grabbed it...
 
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