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Hauling a
boat out of the water always entails some risk no matter how it's done. Dry
storage facilities have long used fork lift trucks for this purpose, but
its hard not to notice that these machines just keep getting bigger and bigger.
The largest are rated at 15 and 20 tons or 30,000 to 40,000 lbs. These machines
are adapted from those used at port facilities to handle shipping containers.
Fork Lifts Several
years ago my jaw dropped when I saw one of these behemoths hauling a 40’ sportfisherman
which probably weighed around 35,000 lbs. In fact, a nearby marina is now
routinely handling 35 – 40 footers with this monster.
The question came to my mind as to whether boats are designed to be handled
this way.
When a fork lift lifts a boat, all the weight of the boat settles onto the
forks, obviously. What is less obvious is that how the weight is distributed
on the forks depends entirely on the shape of the hull. When first used, fork
lifts lifted outboards and stern drive boats. These boats all have their engines
in the rear and their chines are relatively straight lines. That means that
most likely the boat weight will be fairly well spread out on the forks. But
what about boats with curved chines?
The potential for damage exists when too much of boat weight rests on one
spot, as would be the case with a curved chine boat. FRP has many strong points,
but point loads attack the weakness of the material. We see this all the time
when untrained boat yard personnel set boats down on only two small blocks,
sometimes resulting in the keel crushing.
Mid engine boats are much
more at risk of being damaged when lifted with a fork lift. This is because
this type of boat usually has a curved chine line. This makes for a load
point rather like a basketball sitting on concrete – only
a very small area of the hull bottom is bearing the entire weight of the vessel
on the lift fork. The potential for damage is therefore very high. The risk
is even higher for cored bottoms since these are even more vulnerable to point
loading damage.
For example, Sea Ray made
the mistake of coring its 54 footer all the way around the keel. The right
way is to have only solid fiberglass where the two halves of the hull meet.
In several cases, when set down on five 10” timbers
as keel blocks, the keel crushed at all five points. The blocking was adequate
but the construction of the keel with a core was not. Since most boats are
bottom cored, this presents the same problem as the above example.
Typically a bottom core terminates right at the chine, the very point at which
the fork lift will load the hull. This can result in crushing of the core as
well as core disbonding. The damage can occur and not be noticed. Two things
may then happen. First, the beginning of core disbonding is initiated and will
become progressive due to stress during vessel operation. Secondly, core failure
can occur through repeated hauling, eventually resulting in a fracture failure.
The question the reader
will be asking is how do I know whether this is a problem for my boat. If
you have an mid engine inboard engine boat chances are that it has not been
designed to be lifted with a fork lift. Secondly, if your boat is more than
five years old, it is very probable that it hasn’t
been designed for this. If you have a stern drive boat, it is a reasonable
assumption that it is designed with fork lifting in mind.
I’ve checked numerous
boat owners manuals and the vast majority were entirely silent on the method
of hauling, so the best thing is to call the builder before hauling on a
fork lift. This should include all inboard boats above 30 feet. Moreover,
as we see more and more boat yards replaced by condominiums, the probability
is that reliance on forklift type marinas will increase.
Travel Lifts This type
of lift uses nylon slings and usually only causes hull damage when a hull
is defective. On the other hand, damage to rub rails occurs routinely. Rail
damage typically occurs either when the lift is small and the boat is large.
In other words, the boat is wide enough that the straps will lift straight
up and pinch the hull somewhat. The nylon slings stretch and insodoing pull
the rail with them. If the rails are not strongly attached, they can either
bend or be torn off. Normally the yard personnel will place bumpers under
the rails to try to keep the slings off the rail, but this doesn’t
always work. Sometimes the rail is just too weakly attached and it bends or
pulls loose. The number of slings used doesn’t make much difference.
Hull pinching can occur
when the beam of the boat approximates the spread of the straps. The most
common lifts are 60 ton and 18 feet wide. Forty and fifty ton lifts are usually
wide enough to avoid causing damage, but older 20 & 30 ton lifts are
narrower and this is where I see most damage occurring. Boats around sixty
feet have beams in this range. However, vessel beam is not the only factor.
The depth of the haul slip plus the drop of time also affects the spread
of the straps. The further down the vessel is, the more likely pinching will
occur. Pinching by the straps places enormous loads on both the rails, deck
and hull sides. It is not unusual to hear loud popping sounds when boats
are lifted under such conditions. The popping, as you might guess, is fiberglass
breaking within the hull. Damage is occurring though people are usually unaware
of this as there are rarely any outward signs. However, visible damage does
occasionally occur, typically in the form of cracks.
The best way to avoid
these serious problems is; don’t haul larger vessels
in smaller lifts such as the 30, 40 and 50 ton models, where the beam is approaching
the maximum width of the lift. You know this when the vessel is a tight fit.
Secondly, if there is a deep tidal fall – say four to six feet or more
-- avoid hauling at low tide. If this is unavoidable, locate the internal bulkheads
and get the straps placed on the bulkheads. Some builders mark the lifting
points in this way, but many do not. Lifting on bulkheads will go a long way
toward eliminating compression damage.
Now a word about large late model boats that have huge windows down near the
deck, or even in the hull. The area in way of these windows is extremely weak
and placing a lifting strap in way of the window can cause compression that
results in the window seal being broken with resultant leakage. Some Carver
boats are a prime example of this problem.
Whose fault is
lift damage? In most cases it is the boat builder’s for
not making the boat strong enough to be lifted by normally available means.
Dry storage marinas that use fork lifts have proliferated in the last decade
or so. That means that builders should be well aware of the stresses placed
on a hull when lifted this way, and should engineer their hulls accordingly.
Thus, they cannot claim that abnormal handling is at fault. For larger, heavier
vessels, this is not the case. It is very doubtful that 35-40 footers are designed
with fork lifts in mind. If damage ensues as a result, assessing fault will
be much more difficult.
If your rub rails tear
loose on a travel lift, it's really not the yards fault; the boat should
have been able to take it since most can. I can tell you from long experience
that such cases brought against builders for damage rarely succeed because
larger vessels are normally hauled this way. The rails should be designed
to withstand these stresses. One exception might be that the builder fails
to place fender blocks between the strap and rail, below the rail. Fender
blocks will lessen the load on the rail, but not eliminate it. I’ve
seen many rails damaged even with the use of fenders.
Having viewed several
thousand boat haulings first hand, it’s an understatement
to say that most hauling crews are sloppy and inconsiderate. It’s not
unusual to see one man trying to handle the whole show, nor is it unusual for
damage to occur simply through carelessness. It is prudent to whip out your
digital camera and take a few picks of the hull before delivering the boat
to the yard, particularly if you won’t be present when hauled. That’s
because when your hull scrapes against that low, unprotected concrete piling,
plowing a large gouge in the side, unless you can prove that it didn’t
occur previously, you don’t have a supportable claim. Oh, yes, and be
sure to turn on the camera’s photo dating facility.
Keel Blocking A boat owner
should not leave it to a boat yard to know how to block his boat. The yard
cannot know whether the hundreds of hulls he deals with are strong or weak,
or require special care. It is the boat owner’s
responsibility to know this – this is a ship owner tradition hundreds
of years old. As a rule of thumb, there should be one block for every 10 feet
of vessel length on deck. Whenever in doubt, add one more. Never, ever suspend
any hull between only two blocks – one at each end. The minimum is three.
The width of the block is important, for this affects load bearing area of
the keel and that is what this is all about. Block width should be no less
than 8” for boats 40 feet and over. Under that, six inches minimum. No
4 x 4’s should be used.
What about jack stands?
Occasionally I see boats in the 25-30’ range
sitting on jack stands alone. Not good because boats are NOT designed to bear
weight in that manner. The purpose of jack stands is hold the boat upright,
not to hold the weight of the boat.
It is wise to draw yourself
up a blocking plan – in old nauticalese
known as a graving plan. It doesn’t have to be fancy, a rough drawing
will do, e.g. keel blocks go here, here and here. Add any special instructions,
such as sizing of keel blocks. Make a dozen copies and put them onboard. When
needed, give to the yard manager telling him this is the way it should be done.
Winter Lay Up Over the winter a boat will be resting on its keel for a very
long time. For this reason it is extra important that adequate shoring be used.
One very important feature that is often overlooked is that the keel blocks
need to be level. Usually the yard men just throw them down and plunk the boat
down on them. Think of what happens when two blocks are high and one is low.
Effectively a three block shoring now has only two supporting blocks! Its not
hard to imagine the effect of a heavy boat sitting like this for six months.
A good yard will run a string level across the blocks to ensure that they are
level.
So what’s the big deal about shoring except for possible keel crushing?
It’s a misshapen hull. This is much less a problem for a short haul but
for winter layup its definitely a big deal. The way they build boats today,
it is a mistake to think that a fiberglass hull won’t distort; they can
and they do.
Good yards have well prepared
storage areas that have been compacted by years of travel lift operation
over a heavy gravel surface. Before contracting for winter layup, make an
inspection of the storage area. What you don’t
want to see is soft ground where the travel lift wheels have sunk into the
surface, causing ruts. Note whether the area appears swampy or prone to standing
water. Frozen wet ground is bad news since it will turn to pudding come spring.
Posted October 29, 2006
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