David Manthey wrote:

Is there an official way to determine the length of a boat?

Title 46 of the US Code of Federal regulations defines vessel length as
the LOA (length overall) which is "a straight-line measurement of the
overall length from the foremost part of the vessel to the aftermost
part of the vessel, measured parallel to the centerline. Bowsprits,
bumpkins, rudders, outboard motor brackets, and similar fittings or
attachments, are not to be included in the measurement. Length must be
stated in feet and inches."

So any bow pulpits or bolted on swim platforms or davits would not be
inlcluded. However, swim platforms that are an integrally molded part of
a hull would be.

That's the length you'd need to state when registering or selling a
boat. Harbormasters, otoh, aren't required to use the legal
definition...they're concerned with how much dock space your occupies,
including anything that extends from the bow or stern.
--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://shop.sailboatowners.com/books...ku=90&cat=1304

Length on Deck (LOD) is the same as LOA when measuring the hull itself,
including caps but excluding bowsprits and other extensions (rudders, motors
etc). LOA is the term that has been used in more than one way by some
folks, but most commonly (and as legally described), it's the same as LOD.
For your slip bill, you'd be best off by asking at the marina which
definition they use.

Brian D



"MMC" wrote in message
m...
Brian,
Shouldn't the lenght without bowsprits and boomkins be LOD? Little hard to
convince the marina office to just charge for the lenght of the hull : }
MMC
"Brian D" wrote in message
. ..

Somebody else here stated that the definition for LOA included spars and
bowsprits and what not ...while this definition is truly given by some,
the
national (US) marine fisheries association and the oceanic racing (FICO)
organizations state that LOA does *not* include these other extensions,
but
just the hull and any bulwarks or caprails that exist. The fisheries
folks
say to round to the nearest foot, while the racing folks measure exactly.
Most companies will overstate a boat's length, always rounding UP to the
next highest foot.

Brian D


"Tom Dacon" Tom-at-dacons-dot-com-nospam wrote in message
...
Most people use "length between perpendiculars" (LBP). This is the
horizontal distance (parallel to the water's surface) between the
closest
points on the ends of the boat where you could drop a plumb bob and
have
it hit the water with the cord touching the boat. This doesn't include
spars such as bowsprits and boomkins. You'd use the stem, ordinarily,
and
the aftermost point on the deck of the boat, including any cap rail but
not including extensions like boomkins.

That's what most people mean when they say LOD (length on deck). Length
overall (LOA) includes the spars, meaning sprits and boomkins,
sometimes
also called "sparred length".

In the old days (before, say, the first world war), the waterline
length
was what they used when they said how big the boat was. So a 30-footer
would have been 30 feet on the waterline. The New York Thirtys were
thirty
(more or less) on the waterline, the New York Fortys were forty feet,
and
so on.

Without knowing what your boat's profile looks like in detail, it
sounds
to me from your account like it's 23' 9".

But really ... my own boat is 40' 3" between perps. When I bought it I
was
told it was 41', so that's what I tell people when they ask. When I
haul
it out in a self-service yard, I say it's just under 40', since a
couple
of yards I've hauled at in the past used 40' as a dividing line for
daily
charges. I'd call your bateau a 24-footer.

Tom Dacon

"David Manthey" wrote in message
...
Is there an official way to determine the length of a boat?

For instance, I am captain of a wooden bateaux that the builder
claimed was 23' long. Measured from the very rear of the sternpost to
the very forward of the stem, it is 23' 9". Measured at the height of
the gunwale and including the stem and stern posts, the boat is 23'
0'. Exclusive of the stem and stern posts, the boat is 22' 6". The
typical 'fullen laden' water line is 21', while the length along the
bottom (it is flat bottom, so has no keel), is 19' 6".

So, my questions a (a) when telling someone the length of the boat,
which number do I use, and (b) has there been any standard on this
over time?

Thanks much.

- David
David Manthey

Orbitals - Programs - Books - http://www.orbitals.com

A big thank you to everyone who answered.

I now know what the legal length of my boat is and the length a marina
would charge me for.

One of my concerns with length has been in reading historic accounts
of bateaux, the length is frequently cited. I guess that this number
is whatever the person writing a journal or account was told by the
boat men, the transportation booking agency, the builder, etc., and
therefore would vary just as the different answers have varied. I
have yet to see a historical account of a bateau give any qualifier
for a length (no handy LOA or LWL after the number).

Again, thanks a bunch.

- David
David Manthey

Orbitals - Programs - Books - http://www.orbitals.com

And if you think that's bad, try to figure out what the old books meant when
they spoke of a ship's tonnage. (Sometimes displacement, but often a
measure of interior volume excluding machinery spaces.)

Roger

http://home.insightbb.com/~derbyrm

"David Manthey" wrote in message
...
A big thank you to everyone who answered.

I now know what the legal length of my boat is and the length a marina
would charge me for.

One of my concerns with length has been in reading historic accounts
of bateaux, the length is frequently cited. I guess that this number
is whatever the person writing a journal or account was told by the
boat men, the transportation booking agency, the builder, etc., and
therefore would vary just as the different answers have varied. I
have yet to see a historical account of a bateau give any qualifier
for a length (no handy LOA or LWL after the number).

Again, thanks a bunch.

- David
David Manthey

Orbitals - Programs - Books - http://www.orbitals.com

derbyrm wrote:

And if you think that's bad, try to figure out what the old books meant when
they spoke of a ship's tonnage. (Sometimes displacement, but often a
measure of interior volume excluding machinery spaces.)

A couple of years ago Glen Ashmore posted the best explanation of ship's
tonnage I've ever seen..I saved it...here it is:

Tonnage has nothing to do with the weight of your boat. It is a measure
of how much wine a vessel can carry.

The word "tun" was originally a size of a cask used to ship wine from
Spain & Portugal to England. In 1347 a tax of 3 shillings per tun was
imposed and this was called "tonnage." A ship's size became known by the
number of casks it could carry, and the word tonnage started being used
to describe a ship's size.

It was found that if you took the length x the breadth x the depth of
the hold under the deck and divided by 100 it was close to the number of
casks. That is where we get the "Measurement ton" of 100 cubic feet per
ton.

There are several kinds of tonnage: The first two are used by the tax
collector. The next two are used by designers. The fifth and sixth are
used by freight salesmen and canal operators and the last one is used by
the USCG for documenting boats.

Gross Tonnage - is the internal volume in cubic feet of the vessel
minus certain spaces above the main or "tonnage" deck, like stacks and
ventilators, which are called "exemptions" .

Net Registered Tonnage - is obtained by deducting from the gross tonnage
the volume of space that can't be used for paying cargo or passengers,
that is to say the space occupied by the engines, the crew's quarter,
the stores, etc.

Displacement Tonnage - is the actual weight of the water "displaced" by
the ship and is usually quoted in long tons of 2240 lbs.

Light Displacement Tonnage - is the weight with nothing in it.

Loaded Displacement Tonnage - is the fully loaded weight to the maximum
and is on her summer draft in salt water.

Deadweight Tonnage - is the difference between Light and Loaded
Displacement Tonnage....the actual carrying capacity of the vessel.

Panama & Suez Canal Tonnages - these are different from the
internationally accepted definitions. There used to be a lot of
variations between countries and the canal owners thought they were
being conned, so they came up with their own definitions.

Simplified Measurement System - The USCG decided that all this was way
too much for bureaucrats to deal with for yachts so they came up with
their own formula:

Take the horizontal distance between the outboard ends of the boat not
including rudders and bow sprits. Multiply that by the maximum beam
outside to outside. Multiply that by the distance from the sheer line
not including bulwarks or cap rails to the outside bottom of the hull
not including the keel. Add the volume of the deck house/cabin top.
Multiply by .5 for sailboats and .67 for power boats. Divide by 100.

This will give you the "Gross Tonnage". Net tonnage is 90% of gross for
sailboats and 80% for power boats.

It should be obvious to anyone who's managed to get this far that your
boat's "tonnage" no longer has anything to do with anything real; it
only exists in the mind of some government bureaucrat.

A bit more maritime trivia:
Rummage was the manner in which the wine casks were stored in the hold
of the ship and came to refer to the whole ship's cargo. after a voyage
any unclaimed and damaged cargo was stacked on the dock beside the boat
and offered for sale - a rummage sale. another word of French maritime
origin.



--
Peggie
----------
Peggie Hall
Specializing in marine sanitation since 1987
Author "Get Rid of Boat Odors - A Guide To Marine Sanitation Systems and
Other Sources of Aggravation and Odor"
http://shop.sailboatowners.com/books...ku=90&cat=1304

Peggie Hall wrote:
Glen Ashmore posted the best explanation of ship's
tonnage I've ever seen.

This question for anybody.... so I'll tack it on here...
How does one measure tonnage of a Cathedral hull? ;-)

Rick
- well, since I've had no takers on my LWL question- -shrug- ;-)