There are frequent discussions regarding the various merits of
hull materials on this site. My own personal opinion is quite open; I own two FRG hulls and one plastic
hull, and I've lived aboard a
steel hull for years. Probably my natural preference would be
aluminum.
But it occurred to me that all of the material science posts, the anecdotes, and the discussions of
maintenance, damage, and degradation all really come down to one thing: Which hulls are best for survival?
Well, I'm a statistics person, especially when we're talking about risk of mortality, so I like to avoid stories about what somebody somewhere once heard, and go with the largest collection of good numbers I can find.
The USCG compiles the most complete publicly available numbers regarding pleasure
boat accident statistics, and they do track hull materials. Now, they don't track how many boats exist of a specific type, so there aren't numbers to say how likely a
boat is to have an
accident by hull type, but they do provide us with a more important number:
Given an accident, how likely is death or injury by hull type?
With no further ado, these are those numbers for the past three years, along with the three-year average (sorry about the crappy formatting, blame forum software):
2014 Accidents fatalities injuries f/a i/a
Aluminum 815 163 411 20% 50%
Fiberglass 3946 299 2041 8% 52%
Plastic 134 69 67 51% 50%
Rubber/Vinyl/Canvas 60 27 32 45% 53%
Steel 51 0 10 0% 20%
Wood 71 8 17 11% 24%
2013
Aluminum 862 190 425 22% 49%
Fiberglass 4087 253 2013 6% 49%
Plastic 126 48 55 38% 44%
Rubber/Vinyl/Canvas 55 19 28 35% 51%
Steel 36 1 12 3% 33%
Wood 84 13 22 15% 26%
2012
Aluminum 861 197 439 23% 51%
Fiberglass 4529 332 2357 7% 52%
Plastic 107 45 65 42% 61%
Rubber/Vinyl/Canvas 65 37 25 57% 38%
Steel 47 1 6 2% 13%
Wood 81 4 26 5% 32%
three-year Average
Aluminum 22% 50%
Fiberglass 7% 51%
Plastic 44% 51%
Rubber/Vinyl/Canvas 45% 48%
Steel 2% 22%
Wood 11% 27%
The bottom line is that the statistics for all hull types except Wood are very "normal", meaning there's enough data that they don't vary much from year to year.
The next results are pretty shocking: They show definitively that of boats involved in accidents, Steel boats are by far the safest, at 2% fatality rate per accident, fiberglass at 7%, wood at 11%, aluminum at 22%, and other materials at about 45%.
Now, it's important to understand that these hulls are of all pleasure boat craft (not just sailboats), that sailboats represent a very small number of the overall statistics, and that all accident types tracked by the USCG are included.
There is also a very strong "unseen attractor" in these numbers: Size of vessel. Steel vessels are the very largest. Rubber are the very smallest. Obviously larger vessels fare better in accidents. So there is some serious skew to the numbers that we can't divide out.
That said, for the hull types we really care about (steel, aluminum, fiberglass, and wood) we can
work out the sizes. Fiberglass fares particularly well considering that on average, they would be the smallest of these four hull types. There are very few 25' steel hulls, but there are hundreds of thousands of 25' fiberglass hulls.
These numbers are large numbers with real meaning. The fact that aluminum fares so poorly compared to FRG is shocking to me, especially considering that aluminum boats would be in the same size range or larger than fiberglass. The fact that steel is by far the safest material is also a bit shocking, and not what I would have predicted, but it may be that only the very largest boats are made of steel.
I have to wonder what it is that I don't know about aluminum that makes it three times more likely than FRG to have a fatality in an accident and ten times more likely than steel, especially considering that the average aluminum boat is larger than the average FRG boat.
Anyway, it's changed my opinions about hull material dramatically.
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