The most common measurements I see are:
1. LOA without platform or pulpit
2. LOA with platform or pulpit.
Both of those are centerline lengths. #1 is the documented length and #2 comes into play in determining slip size needed and charged for. The only time this becomes complicated to me is when the platform is an integral part of the hull. That's where LOD (length on deck) excludes it and hull length includes it.
LOA for documentation purposes does include any integral swim platform and excludes one that isn't integral to the hull.
LOA also called centerline length or documented length.
Fortunately, except as shown by the one marina in this thread, I haven't heard of anyone measuring along the outside of a boat in decades. However, before regulations there were some builders calling that LOA.
LWL is critical to knowing your displacement or hull speed. It's also important for bottom painting. You'd think it would be also for hull cleaning, but I don't know a single diver who uses it. The ones I know go by LOA.
Then there's the nominal length. Many say, the builder called it 62'. Well, look carefully. While some like KK do label it Krogen 52', more use model numbers which can represent anything they want. Don't assume a 550 is 55' or a 44 is 44'. We have a Sunseeker Manhattan 65. Same hull as a Manhattan 63. Look on their brochure or web site and the length is 69'1". Well, that's LOA with platform and pulpit. Nowhere on the brochure or website will you see the LOA without platform and pulpit. It is, and the documented length is 63'. You will also not see the LWL anywhere. Among other things you won't see, you won't see the air draft anywhere. And if you look at the water draft on their brochure it won't mention what engines. It's actually with IPS. With traditional drives it's 3" less.
Beneteau is a good example too. On the Swift Trawler 50, they never refer to it as 50'. It's just a model number. They are actually closest to their LOA including pulpit and platform which is 49'2". The hull length and documented length is only 43'9". Notice how Sunseeker and Beneteau took opposite approaches to numbering. Sunseeker numbers close to the hull length. Beneteau numbers close to their LOA with pulpit and platform. So model designations are generally useless.
Someone mentioned difficulty in determining centerline length or LOA for slips. Actually very easy. Pull it in and measure how much shorter or longer than a known slip length, or just dock it on a side tie anywhere. Mark on the dock the furthermost points of the boat. Measure. I have encountered marinas that measured for transient. That's exactly how they do it. Actually saw a bit of a dispute. They accepted my number without measuring because I gave them length including pulpit and platform, not documented length. They were trying to explain to another boat that they didn't care what his document said. They cared about how much space it took and if he didn't want to pay for the platform and bow pulpit, he should just remove them then.
1. LOA without platform or pulpit
2. LOA with platform or pulpit.
Both of those are centerline lengths. #1 is the documented length and #2 comes into play in determining slip size needed and charged for. The only time this becomes complicated to me is when the platform is an integral part of the hull. That's where LOD (length on deck) excludes it and hull length includes it.
LOA for documentation purposes does include any integral swim platform and excludes one that isn't integral to the hull.
LOA also called centerline length or documented length.
Fortunately, except as shown by the one marina in this thread, I haven't heard of anyone measuring along the outside of a boat in decades. However, before regulations there were some builders calling that LOA.
LWL is critical to knowing your displacement or hull speed. It's also important for bottom painting. You'd think it would be also for hull cleaning, but I don't know a single diver who uses it. The ones I know go by LOA.
Then there's the nominal length. Many say, the builder called it 62'. Well, look carefully. While some like KK do label it Krogen 52', more use model numbers which can represent anything they want. Don't assume a 550 is 55' or a 44 is 44'. We have a Sunseeker Manhattan 65. Same hull as a Manhattan 63. Look on their brochure or web site and the length is 69'1". Well, that's LOA with platform and pulpit. Nowhere on the brochure or website will you see the LOA without platform and pulpit. It is, and the documented length is 63'. You will also not see the LWL anywhere. Among other things you won't see, you won't see the air draft anywhere. And if you look at the water draft on their brochure it won't mention what engines. It's actually with IPS. With traditional drives it's 3" less.
Beneteau is a good example too. On the Swift Trawler 50, they never refer to it as 50'. It's just a model number. They are actually closest to their LOA including pulpit and platform which is 49'2". The hull length and documented length is only 43'9". Notice how Sunseeker and Beneteau took opposite approaches to numbering. Sunseeker numbers close to the hull length. Beneteau numbers close to their LOA with pulpit and platform. So model designations are generally useless.
Someone mentioned difficulty in determining centerline length or LOA for slips. Actually very easy. Pull it in and measure how much shorter or longer than a known slip length, or just dock it on a side tie anywhere. Mark on the dock the furthermost points of the boat. Measure. I have encountered marinas that measured for transient. That's exactly how they do it. Actually saw a bit of a dispute. They accepted my number without measuring because I gave them length including pulpit and platform, not documented length. They were trying to explain to another boat that they didn't care what his document said. They cared about how much space it took and if he didn't want to pay for the platform and bow pulpit, he should just remove them then.
