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

There are several measurements for a given boat. The most common a

1) LOA-Length overall, which measures from the front of the boat,
including any bow sprit or platforms, and back to the stern, including
any swim platforms or over hangs.
2) LOD-Length of Deck-Which is the length of the deck from bow to stern
3) LWL-Length WaterLine-which is the length of the boat, as measured at
the waterline.

Hope that helps. Also, most marina's go with LOA.


On 2006-04-07 21:33:50 -0400, David Manthey said:

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

"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?

Usually the 'length' will be stated as "length at waterline" or "length
overall" to help explain.

details: http://tinyurl.com/js99b

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

It's worse than that.
Dory (and maybe bateaux) builders reckoned their boats by the length of the
bottom planks. If there's a bowsprit or boomkin or overhanging boom, the
extreme length of that mess is Length Overall (LOA) or 'sparred length'.
Hull designers talk about length between perpendiculars, which is the length
of the hull, not including protrusions, sometimes called length on deck
(LOD)..

So, pick the one taht serves your purposes. If you're reserving dock space,
it's LOA. For most purposes, LOD is indicative. For your local assessor,
LWL or even bottom length might be worth a try.


"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

Yes, but since the bow is higher than the stern, you'll get a bum
measurement if you just run a tape measure over it. You should drop a plumb
bob off each end and measure between those vertical lines. LOA is the
length of the boat measure in this way, to the outer dimensions of the boat
....not including pulpits, rails, motors, etcetera ...measure the hull itself
(rubrails are part of the hull.)

Brian D




"gonefishn" wrote in message
news:CwFZf.1104$wH1.498@trnddc03...

"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?

Usually the 'length' will be stated as "length at waterline" or "length
overall" to help explain.

details: http://tinyurl.com/js99b

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

Dories were traditionally measured along the gunnel. A "16 foot dory"
measures only about 14 feet LOA when following industry standard measurement
rules for LOA (do not include bowsprits, rudders, swim platforms, motors
etc, just measure the hull.) Designers also use this definition of LOA, but
there's a reason why... it's the legal definition.

Brian D



"Jim Conlin" wrote in message
. ..
It's worse than that.
Dory (and maybe bateaux) builders reckoned their boats by the length of
the
bottom planks. If there's a bowsprit or boomkin or overhanging boom, the
extreme length of that mess is Length Overall (LOA) or 'sparred length'.
Hull designers talk about length between perpendiculars, which is the
length
of the hull, not including protrusions, sometimes called length on deck
(LOD)..

So, pick the one taht serves your purposes. If you're reserving dock
space,
it's LOA. For most purposes, LOD is indicative. For your local assessor,
LWL or even bottom length might be worth a try.


"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

This question for anybody.... so I'll tack it on here...

How does one measure the waterline length of a Cathedral hull? Mainly
wondering about how to deal with the bow area.

Rick

On Fri, 7 Apr 2006 19:54:49 -0700, "Tom Dacon"
Tom-at-dacons-dot-com-nospam wrote:

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

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