Why is the LWL so much shorter than LOA

[silver-fox]

Here are 2 photos of my boat out of the water. A quick look at the stern shows that the waterline extends to within a few inches of the sugar-scoop stern of the boat and whilst the stem is raked, a handily placed piece of scaffolding helps guess that the difference at the bow between waterline and LOA is around the 3 ft mark. Yet the specs for the boat say LOA is 41ft 8 ins and LWL is 34ft 3ins a difference of 7ft 5ins. How can that be? Can anybody explain this?

 

[DJE]

Perhaps the design waterline is somewhat lower than the black lines on the hull.

 

[silver-fox]

Perhaps, but that's actually the waterline and even if I dropped it 6 inches I still wouldn't shorten the LWL by another 4 ft!

 

[bobgarrett]

Pulpit and anchor?

 

[silver-fox]

Pulpit would account for 6". The anchor sticking out like that is my own invention and an extended bow roller

 

[prv]

Cockup in the paperwork.

Pete

 

[NormanS]

Here are 2 photos of my boat out of the water. A quick look at the stern shows that the waterline extends to within a few inches of the sugar-scoop stern of the boat and whilst the stem is raked, a handily placed piece of scaffolding helps guess that the difference at the bow between waterline and LOA is around the 3 ft mark. Yet the specs for the boat say LOA is 41ft 8 ins and LWL is 34ft 3ins a difference of 7ft 5ins. How can that be? Can anybody explain this?

Quite easy to check with a tape.

 

[Stork_III]

Pulpit would account for 6". The anchor sticking out like that is my own invention and an extended bow roller

Too much stuff stored in the aft lockers. Measured with empty tanks?

 

[onesea]

Cockup in the paperwork.

Pete

Cockup or designer cockup? If the boat was ever raced the measurements will have been taken to optimize its rating.

A good owner will ensure that the measurements will be as far from reality as they can be as long as it makes his rating better.

 

[Daydream believer]

.

A good owner will ensure that the measurements will be as far from reality as they can be as long as it makes his rating better.

What, you mean a good owner will cheat ??

 

[onesea]

What, you mean a good owner will cheat ??

Have you ever seen the length some owners will go to? Optimized to the extreme does that make it seem better?

 

[Babylon]

I think you might be using your boat the wrong way up.

 

[Steve Clayton]

Probably measured by a man. We all know how we (men) can tend to exaggerate the length/size of certain things

 

[rwoofer]

I'm surprised at a few comments you make, firstly that the pulpit only sticks out 6 inches and secondly that the actual waterline is the black stripes. The waterline really needs to be judged with the boat properly empty because a few inches of depth makes a considerable difference in length. Going from the photographs and my own experience of similar shaped boats I can well imagine the waterline being 7ft shorter.

 

[1bobt]

Was it not something to do with the OA length to the rudder stock?

 

[prv]

Cockup or designer cockup? If the boat was ever raced the measurements will have been taken to optimize its rating.

Unless my sense of the scale of those photos is way out, I just can't see anything like seven feet of overhang however much you mess about with the tape. My suggestion was that they've typoed the numbers, or copied and pasted from the next model down, or something like that. The magazines get the figures wrong often enough, as complained about on here from time to time, and I was looking at a boatbuilder's site the other day which claimed 5 metres of draught for a fairly normal 36 footer.

Pete

 

[johnalison]

I agree with the OP. I have always accepted that the designer must know best but have never got around to trying to measure. One difficulty is that the immersed waterline of an unladen boat may be far from the painted waterline.

 

[Martin_J]

That difference between LOA and LWL sounds about right to me.

I would expect in light condition that the pointed top of your rudder blade would be visible above sea level and the bow thruster would be only just under the water surface.

Looking at measurements for Moody yachts of a similar size (which have a similar hull form) and you will find similar differences.. http://www.moodyowners.net/Moody_Archives/moody_archives.shtml

 

[doug748]

Here are 2 photos of my boat out of the water. A quick look at the stern shows that the waterline extends to within a few inches of the sugar-scoop stern of the boat and whilst the stem is raked, a handily placed piece of scaffolding helps guess that the difference at the bow between waterline and LOA is around the 3 ft mark. Yet the specs for the boat say LOA is 41ft 8 ins and LWL is 34ft 3ins a difference of 7ft 5ins. How can that be? Can anybody explain this?

Well done silver fox, it is a bloody good question.

I have baffled myself with it a few times.

I have no doubt your figures are correct and look forward to the response.

 

[flaming]

That difference between LOA and LWL sounds about right to me.

Me too.

For example the difference between the LOA and the LWL of the J111 is about 4 feet, and it looks like this.

http://www.jboats.com/j111-tech-specs

Most of the difference in the OP's boat will be at the stern, the scoop will be well out of the water, and the top of the rudder blade will likely be exposed at rest.

Of course, this all changes once heeled or at speed, hence why rules that only measured LWL resulted in boats with enormous overhangs.