In searching for a new boat I'll see "boat length" or "nominal length." Since most boats that interest me have a bow pulpit or over hanging anchor at bow & swim platform at stern, are these figured into advertised length of a boat? I like to see LWL (length at water line).
What is boat length measured?
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MYTraveler
Guru
There are at least 4 different ways to quantify boat length:
1) Documented length -- I don't know the formula, but I believe it excludes swim steps and bow pulpits.
2) Length overall (LOA) -- this is what most marinas (at least on west coast of US, Canada and mexico) base their slip fees on, and is often used by owners to describe the size of their boat;
3) Length at water line (LWL) -- probably most useful, but least used,
and
4) manufacturer's "designation" (like a 550, implying 55 feet) -- practices are wildly inconsistent between manufacturers with many "stretching" (even beyond LOA), but a few, inexplicably, understating.
For an apples to apples comparison, I would suggest documented length or LWL
1) Documented length -- I don't know the formula, but I believe it excludes swim steps and bow pulpits.
2) Length overall (LOA) -- this is what most marinas (at least on west coast of US, Canada and mexico) base their slip fees on, and is often used by owners to describe the size of their boat;
3) Length at water line (LWL) -- probably most useful, but least used,
and
4) manufacturer's "designation" (like a 550, implying 55 feet) -- practices are wildly inconsistent between manufacturers with many "stretching" (even beyond LOA), but a few, inexplicably, understating.
For an apples to apples comparison, I would suggest documented length or LWL
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Britannia
Wannabe
I have heard your definition of 1) described as Length on Deck (LOD).
Unless they have changed since the '70s, if you had a sternpost they
measured to it.
Still valid?
Ted
And centre line length.
When referring to smaller (runabout size etc.) boats there was a
difference between Canadian or American measurements.
Canadian used the centerline length, American measured from
the bowstem to the transom around the gun'ell.
Ted
difference between Canadian or American measurements.
Canadian used the centerline length, American measured from
the bowstem to the transom around the gun'ell.
Ted
bogranjac1
Senior Member
So many different methods.
You would have to think that C.L.(centreline) from the actual bow to stern of the hull - disregarding bow spit, duck board , pulpit and pushpit etc. would be the only true indication of the vessels length.
You would have to think that C.L.(centreline) from the actual bow to stern of the hull - disregarding bow spit, duck board , pulpit and pushpit etc. would be the only true indication of the vessels length.
kthoennes
Guru
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My Mainship 37 is 41' 4" if I measure from the aftmost bumper molding on the swimstep to the forwardmost edge of the forward-angled bow pulpit rail. If I'm checking into a marina that charges by the foot I'm a 37. If I'm boasting, I'm a 41 or 42.
Britannia
Wannabe
It's all a question of why you want to measure the boat. If it's to fit in a slip then you need to include pulpit and swim step. If you want to show off to friends that's a good number too, rounded up of course! If you want an idea of the speed then waterline length is the most interesting. In fact, the LOD or CL is the least interesting in some ways. It gives you an idea of how big the boat is from a livability perspective, but to be of any use you really need to include beam and cabin height (and double decking if any).
I just wish there was not only some consistency from builder to builder, but that builders would also share how they denominate their boats. I have seen boats listed as a "34" or "52" but when looking at the measurements, LOD, LOA, LWL, whatever, not a single one of them will be 52! With Krogen, they clearly list their models by LOD and make it plain that is what they have done. I wish more builders did the same.
drb1025
Guru
The state of WA limits the use of their mooring buoys to boats 45' in length. My boat is a DeFever 46' but the length at the waterline is 43 and change, so how the boat is measured is important. I emailed the parks and rec dept for an answer and they stated that they go by whatever length is on the registration, so I am SOL for using state mooring buoys.
Get it documented, it'll come up a few feet shorter.
They were probably ex audio peddlers from the 70s as well. No 2 audio equipment manufacturers of components used the same standard for their specs. It was a jungle out there.
Our Krogen 42 is documented at 43'. We're 46' overall from the tip of the bow pulpit to the edge of the swim platform. The swim platforms 3' as is the bow pulpit.
I use two measurements. 31' (the LOA) if I'm bragging and 28' (the documented length) if I am paying for a slip.
Sometime between when my boat was manufactured and the end of production, the manufacturer changed the designation without any change in the boat.
Sometime between when my boat was manufactured and the end of production, the manufacturer changed the designation without any change in the boat.
drb1025
Guru
It is documented and it says the length is 46', which doesn't include the swim step. The DF 49 Euro version is the same as the DF 46, except it has an integrated swim step that extends the hull, thus it is labeled a 49. I don't understand your comment.
Britannia
Wannabe
My Krogen 54 is documented as 54.4 and the original brochure lists "Length Overall" as 54'5". Just for fun (and because I was home from work sick) I measured the length on deck and got to 54'9". I measured along the surface of the raked deck and it's likely that Krogen measured a horizontal straight line distance from stem to stern. That could easily account for the extra few inches I measured. The bow pulpit is 32" meaning that the boat is just over 57'. There is also an aftermarket swim step that a PO installed - it's about 2.5'. I'm in a 60' slip though I could manage a shorter slip given my bow pulpit is 10' off the waterline and can overlap the dock without being a hazard.
Richard
porman
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I had the same discussion with Wa state at the boat show. Our Mainship 430 is 43' on deck, 48' overall, and documented at 41.1'. They told me they would go with the documented length. However, I worry about the ability of their mooring buoys to hold my 40,000 lbs if the wind really starts blowing.
46 CFR 170.055 (k) defines vessel length as:
(2) Length overall (LOA) means the horizontal distance between the forward-most and after-most points on the hull.
(3) Length on the waterline (LWL) means the horizontal distance between the forward-most and after-most points on a vessel's waterline.
(4) Length on deck (LOD) means the length between the forward-most and after-most points on a specified deck measured along the deck, excluding sheer.
You can read the whole "Definitions Concerning a Vessel" section here:
https://www.law.cornell.edu/cfr/text/46/170.055
Boat builders are required to use those definitions in any model name or number. However, harbormasters only want to know how much dock length the boat will occupy (and therefore how much they can charge you), so they include bow pulpits and anything hanging off the stern on davits.
MYTraveler
Guru
I had arranged a slip based on my assurance that my boat was not longer than 70' -- it needed to fit in the slip with no more than 5' protruding beyond the slip, and the slip itself was 65'. I felt comfortable with that because the boat was documented at 64', and other marinas, which charged based on their measurement of LOA, had always come up with 68' or 69', based on the horizontal distance overall. I hired a delivery captain to move the boat about 100 nm to the new (temporary) slip, and got an urgent phone call when he arrived. It seems the dock master had measured the boat at something in excess of 70'. I assured my captain that it had been miss-measured and asked him to watch and verify the measurement process. An hour later he reported back that my boat was, in fact, substantially over 70'. Turns out the dock master was running a tape along the outside of the hull, from the stern to the tip of the bull pulpit, and my licensed captain thought that was the right way to measure. Never mind that the boat did not extend more than 5' beyond the slip.
It's not easy to get an exact LOA measurement of a boat unless you measure it when it's out of the water and drop a plumb line from the two extreme ends.
What's really a shame though is when someone bottom painting the boat wants to include the swim platform and anchor in the calculations. I had a quote recently that did that. Only the waterline length is being painted so that's all they should use to calculate if they are honest.
What's really a shame though is when someone bottom painting the boat wants to include the swim platform and anchor in the calculations. I had a quote recently that did that. Only the waterline length is being painted so that's all they should use to calculate if they are honest.
No Mast
Guru
Catching up on this thread... I owned boats in which the manufacturer added an inch or two to the model number so their 50 Ft model really wasn't. I understood their perceived marketing value in doing so. What I don't understand is why Selene goes the opposite way, and by quite a bit. Our Selene "53" is actually 60ft LOA. Why would you do that??
What's really a shame though is when someone bottom painting the boat wants to include the swim platform and anchor in the calculations.
The USCG definition of LOA used be (my wording from memory may not be exact, but it's very close) "the length over the centerline from the furthermost point on the hull, exclusive of any pulpit or bumkins to the aftmost point on the stern, exclusive of any motor mounts or other attachments."
And when bow/anchor pulpits and swim platforms were usually teak or mahogany bolted onto the boat, that definition made it clear that they were not to be included. But around 1980, boat builders began integrating swim platforms into the hull mold and and pulpits into the deck mold. Although the pulpits can't be included in the LOA because they're part of the deck, not the hull, swim platforms that are part of the hull can be...thus allowing builders redesignate a boat that was still 28' from bow to transom as a 30' or even longer, depending on the size of the "back porch" and increase the prices accordingly.
I remember a long weekend raftup of 5 or 6 boats...my 1979 32' Trojan F32 was tied to a friend's brand new 36' Carver....our transoms were lined up exactly even. When I took a garbage bag to the bow to get it out of the way, I looked over at his bow...it stuck out only a few inches beyond mine. The remainder of his additional 4' of LOA was all a two level "back porch" molded into his hull...from the transom forward his was boat was the same length as my F32, which also had a swim platform, but it was teak and bolted on...so not included in the LOA.
The USCG definition of LOA used be (my wording from memory may not be exact, but it's very close) "the length over the centerline from the furthermost point on the hull, exclusive of any pulpit or bumkins to the aftmost point on the stern, exclusive of any motor mounts or other attachments."
And when bow/anchor pulpits and swim platforms were usually teak or mahogany bolted onto the boat, that definition made it clear that they were not to be included. But around 1980, boat builders began integrating swim platforms into the hull mold and and pulpits into the deck mold. Although the pulpits can't be included in the LOA because they're part of the deck, not the hull, swim platforms that are part of the hull can be...thus allowing builders redesignate a boat that was still 28' from bow to transom as a 30' or even longer, depending on the size of the "back porch" and increase the prices accordingly.
I remember a long weekend raftup of 5 or 6 boats...my 1979 32' Trojan F32 was tied to a friend's brand new 36' Carver....our transoms were lined up exactly even. When I took a garbage bag to the bow to get it out of the way, I looked over at his bow...it stuck out only a few inches beyond mine. The remainder of his additional 4' of LOA was all a two level "back porch" molded into his hull...from the transom forward his was boat was the same length as my F32, which also had a swim platform, but it was teak and bolted on...so not included in the LOA.
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You're prob'ly including a pulpit that's part of the DECK mold, not the hull mold, in your measurement...the builder can't count that in the LOA. If there's a swim platform that isn't integral to the hull mold, they can't count that either. But a dock master can, and will!
