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A question about Waterlines

Posted: Sat Aug 26, 2017 7:37 am
by galamb
So being no different then my last two builds I am pouring over the plans for my next attempt.

For my last two builds I followed the plans, had great results and really didn't try to figure out "stuff" that was not necessary for what I was doing. I did make some modifications to my last build so did have the calculator out a few times to recalculate displacement etc but again, only figured out what I needed to know and ignored other pieces of information contained on the blueprints.

Anyhow, looking at my current plans there is two waterlines. The Design Water Line (DWL), which I understand completely. I even ran the calculations for that based on how I planned on rigging the boat. The weight of the passengers and other "stuff" we would have on board and came within less than 20 pounds of the displacement estimated by Glen when he designed it. So totally understand "that line" and what it's (purpose is).

But there is also a WL-2 noted on one sheet. I dug out the few books I have, spent a few hours on google etc but could not get a coherent explanation as to what this additional water line is telling me if anything?

Is this simply a reference line or is there some importance to it?

Re: A question about Waterlines

Posted: Sat Aug 26, 2017 10:58 am
by PeterG
It's likely a reference line. I haven't seen those plans but generally speaking a WL 2 or similar designation like WL 6, WL 12, etc. means a reference line used to describe the shape of the hull. It will show as a straight line in the profile or side elevation of the hull and be seen as a curve in the half-breadth or plan view. These lines along with the body plan or frame sections (shows slices through the boat at the frame stations along the hull) are used by a lofter to make templates or molds for the various hull pieces.

Re: A question about Waterlines

Posted: Sat Aug 26, 2017 11:16 am
by galamb
That's kinda what I figured.

With this build I'm just hoping to fully understand what and why I'm doing something. Although it's not necessary - you can build without questioning as long as you follow the plan and directions, I feel comfortable enough with the technique that I am starting to ask why :)

Re: A question about Waterlines

Posted: Sat Aug 26, 2017 12:14 pm
I dont have the plan you do but in classical lines plans they have buttock lines, stations, and water lines at determined intervals So on a body plan there might be a wl2 wl4 etc and these are the waterline at a particular even keel draft.