US accident stats by time afloat

dylanwinter

dylanwinter

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I came across this table of stats from the states

it works out the accident rate for time the vessel is in use

DBW-bar-graph.jpg










no stats for driving to the boat or wobbly pontoons though


 
The left hand scale shows the number of incidents are very small. The graph is meaningless as just one additional incident would completely alter the graph. i.e. Take the numbers as +/- 20% and it completely skews it.
Also, what does 'time on the water mean'? A PWC will almost always be moving. Whereas all the other types may be stationary for a significant length of time.
It's almost as if the graph has been produced by someone trying to prove a point.
 
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I'm not sure that one incident would be that significant as it is per million hours.

What worries me more than a little, if I was going to use this data, is that it is estimated hours.

I should enjoy asking the originator to run through the methodology.

Nice video Dylan.

However.......What on earth is a pwc ?
 
estimated hours...

certainly they have to be an estimate....

otherwise you would have needed a tacho on every vessel

one assumes that the US coast guard did some survey work in an effort to create the etsimates

I think that given the size and power of the jet-ski and power boat markets in the USA that the US Coast Guard would need to be reasonably rigourous with its methodology

one way another PWCs and mobos would seem, from these stats, to be a lot more dangerous per hour afloat than sailing boats with auxilliary engines.

or did I misread it in some way?
 
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I got the following from the RNLI the other day. My cat is a yacht so I'm querying the categories. I was trying to find out why they were called out, such as engine failure, rigging failure, etc for sailing craft rather than dinghies.

2012 Launches to Yachts

Sail Pleasure Craft
Kite Board 93
Multihull with engine 41
Multihull, no engine 27
Sail training vessel 19
Sailboard 112
Sailing dinghy 173
Yacht no engine 50
Yacht with engine 1136

Sail Pleasure Craft Total 1651

Total (yachts) 1186
 
Why Do Outboard Powerboats Sink?
BoatU.S.' Seaworthy Scours Claims Files for The Answers
One Hint: Look to the Sky

...

The research confirmed that most boats sink while tied up at the dock,
outnumbering sinking-while-underway claims four-to-one. Nearly half the
outboard powered boats that sank at the dock were victims of heavy rain or
snow. Ironically, almost all had “self-bailing” cockpits. The results are
as follows:

Sinking At The Dock
Rain/snow 47%
Underwater Fittings 20%
Above the Waterline Fittings 10%
Poor Docking Arrangements 9%
Water Over Gunwales/Transom 9%
Other 5%

Sinking While Underway
Water Over Gunwales/Transom 32%
Livewell/Baitwell Plumbing 20%
Drain Plug 16%
Struck a Submerged Object 12%
Other 12%
Construction 8%

Seaworthy Associate Editor Chuck Fort said, “If you want to reduce the
risk of your outboard powerboat sinking at the dock, the best way is to
use a good-fitting boat cover that keeps out precipitation. Also ensuring
that Marelon or bronze fittings are used below the waterline can reduce
your risk. This is a more common a problem on a used boat when a new owner
may be unaware that a previous owner unwittingly installed a plastic
fitting below the waterline that eventually degrades and cracks. When
underway, outboard powered boat owners should be concerned about swamping
from the transom. Transom wells are sometimes poorly designed and every
effort should be made to prevent water, even from the boat's own wake,
from entering the cockpit or bilge area.”
 
Reasons Why Inboard/Outboard Powerboats Sink
BoatUS Goes to the Insurance Claims Files for Answers

After publishing a recent study identifying the causes for accidental
outboard powerboat sinkings, Seaworthy, recreational boating’s damage
avoidance magazine, has combed through the BoatUS insurance claims files
to identify the reasons why inboard/outboard (I/O) powerboats sink.
Interestingly, while outboard powerboats are similar in design to I/O’s —
and often made by the same manufacturer — the study found vastly different
reasons why each accidentally sinks.

Outboard powerboats tend to sink at the dock due to poor cockpit designs
that trap water, but an I/O’s weakest link is the delicate connection
between the inboard engine and the outdrive unit, called bellows.
“The use of bellows or boots — pleated, flexible rubber membranes — that
run between the inboard engine and partially submerged outdrive to seal
the transom where cables and shafts pass through have one weakness: a
limited lifespan,” said Seaworthy Editor Bob Adriance. He says that
bellows should be inspected annually — and more often in hot, sunny
climates. “Any bellows that is over five years old is living on borrowed
time,” said Adriance.

He adds, “Many boats have more than one bellows (driveshaft, shift cable,
exhaust, etc.) any one of which has the potential to sink the boat. And if
one shows wear, they all should be replaced.”

Here are the top reasons why I/O’s sink:

At The Dock:
#1 (44%): Leaking bellows. A surprising number were attributed the small
shift cable bellows.
#2 (23%): Failed below waterline fittings, hose clamps, and melted hoses
as a result of overheating.
#3 (15%): Failed above waterline fittings. Heavy rains overwhelm cockpit
scuppers.
#4 (11%): Poor docking arrangements: Boats or outdrives that snag on
docks.
#5 (6%): Uninstalled drainplug.
#6 (1%): Miscellaneous such as a cracked engine block.

While Underway:
#1 (36%): Struck a submerged object such as rock or logs.
#2 (24%): Failed below waterline fittings.
#3 (20%): Leaking bellows.
#4 (12%): Swamping.
#5 (8%): Miscellaneous.
 
WHY SAILBOATS SINK AND FIVE TIPS TO PREVENT IT
BoatUS Opens its Insurance Claims Files

Alexandria , Va. , Dec. 6, 2007 - A study of 100 sailboat sinkings from the BoatUS Insurance claims files could help prevent your sailboat from becoming a statistic. “The sinkings were found to be divided evenly into two broad categories – those that sank at the dock and those that sank while underway,” said BoatUS Marine Insurance Technical Director Bob Adriance.

“However, when it came to sinking underway, a sailboat’s deep draft became the obvious factor,” Adriance continued. Striking a submerged object was found to cause 40% of the sinkings while underway. Next on the underway list was a broken prop shaft or strut (16%) and damaged or deteriorated fittings below the waterline (16%). “Prop shaft corrosion seems to be a bigger issue with sailboats than with powerboats as auxiliary sailboat engines are not run as often, allowing corrosion to set in,” added Adriance.

The most common cause of dockside sinkings were found to be the result of deteriorated or damaged or corroded fittings such as intakes, seacocks, and drains below the waterline. Stuffing box leaks were number two on the dockside list.

The complete study results are as follows:

Sinking at the Dock
Below waterline fitting 44%
Stuffing box leak 33%
Keel and centerboard 7%
Rain 7%
Head back-siphoning 3%
Above waterline fitting 3%
City Water hookup 3%

Sinking Underway
Struck submerged object 40%
Prop shaft or strut 16%
Below waterline fitting 16%
Grounding 8%
Stuffing box leak 8%
Storm/knockdowns 8%
Above waterline fitting 4%

Five Tips for Prevent a Sailboat Sinking:

Any time your boat hits bottom, immediately inspect the bilge and keel bolts or centerboard pennant and hinge. To be safe, inspect again an hour later.
Routinely — twice a season — inspect all below the waterline fittings, hoses, and hardware. If the fitting is long enough, it’s good practice to have two marine-rated stainless steel clamps on all hose ends. Any hoses showing signs of rot should be immediately replaced.
When at rest, stuffing boxes should never leak. If leaking persists after the packing gland nut has been tightened, the packing must be replaced.
Don’t ignore through-hull fittings or hoses that are installed above the waterline. While they may appear to be “safely” above the water level, they can leak when heeled over in a seaway, or when snow or ice forces the boat under.
A winter haul out is the perfect time to inspect the prop shaft and cutless bearing.
 
Talulah said:
Jet ski
Personal Water Craft
Click to expand...

Strictly, not quite. A jet ski is the narrow-beam, stand up PWC which has almost no auto-stability and is quite tricky to ride. The beamy, sit-on PWCs are called wet bikes; any idiot can easily ride them, which is part of the trouble. Still, fewer than five accidents per million boat miles, or one every 23 years, doesn't exactly leave you quivering with anxiety.
 
Talulah said:
The left hand scale shows the number of incidents are very small. The graph is meaningless as just one additional incident would completely alter the graph. i.e. Take the numbers as +/- 20% and it completely skews it.
Click to expand...

Er - no.

For the sake of argument, lets say the PWC total is 100 million hours and the number of accidents is 450 which gives the graph number of about 4.5 per million boat hours. Then add one accident to that. What do you get? The number goes up by 0.01.

I havent got a clue how many boat hours there are on PWCs but there must be an awful lot given the size of the US and their inclination towards bad taste toys like PWCs and Harleys and Mustangs.
 
wotayottie said:
Er - no.

For the sake of argument, lets say the PWC total is 100 million hours and the number of accidents is 450 which gives the graph number of about 4.5 per million boat hours. Then add one accident to that. What do you get? The number goes up by 0.01.

I havent got a clue how many boat hours there are on PWCs but there must be an awful lot given the size of the US and their inclination towards bad taste toys like PWCs and Harleys and Mustangs.
Click to expand...

Agreed. The numbers wouldn't be skewed by a few more accidents.
Here is a link to some discussion about PWC and accidents. The writing is quite biased.
http://www.uvm.edu/~vlrs/doc/personal_watercraft.htm
 
wotayottie said:
Nice colour - or is it color? Do you own a wet bike and a Hardly too?
Click to expand...

The color is "Red Candy". I just have the Mustang. No Harley Davidson. No jets ski. I do have my standards.

Incidentally, all my Mustang-deprived friends in the UK will soon be able to buy their own Mustangs because Ford plans to bring the Mustang to Europe!
 
interloper said:
The color is "Red Candy". I just have the Mustang. No Harley Davidson. No jets ski. I do have my standards.

Incidentally, all my Mustang-deprived friends in the UK will soon be able to buy their own Mustangs because Ford plans to bring the Mustang to Europe!
Click to expand...
Does it go round corners now then? Cos that (& the rust) is usually why US Muscle cars don't last long in UK.
 
Does "time on the water" mean "time when there are some people onboard on the water"?

If yes, and considering the relative average speeds of sailing yachts, motor boats, houseboats, etc. a graph of the "accident rate per mile" would look a bit different. And if someone asks for help moving their houseboat, I would politely refuse.
 
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