Taking of lines

Woobs, I never thought that you would make a "silly little drawing" and that's the reason why I insist that is not swayed by advice they will not get more than life difficult. I have offered you my help because I was sure you want to do something serious. You have all my respect. I performed the same work many times and know that, do it well, it is not easy. So bothers me that people try to trivialize it.
I am sorry that this misunderstanding has occurred. Again, if you think I can help you, simply say so.

 

That's correct Woobs, it's the end result that counts. On a hull like that, I'd be inclined to select a baseline that has the keel with some slope to it. This will permit the aft sections to separate a bit, so you can see what's going on. In other words, it's very likely that as the boat sits static in the water, the transom is lower than the rest of the boat, with an aft slope to the boat's centerline. This would be an ideal way to present the lines, to avoid any muddiness (multiple lines converging) in the aft sections.



This is a classic example of what I'm trying to describe. The whole of the aft sections are convoluted and very difficult to visualize, because the merge together on the bottom. This is because the centerline of the boat parallels the base line.

 

TANSL; no harm, no foul. I appreciate your advice.

PAR. I think You're "bang-on". If I level the keel that way, I expect my boat will look similar to your drawing

(pictured again so you don't have to flip pages)

I appreciate ALL opinions / comments. Thank-you.
S.

 

"If it's worth doing it's worth doing right"

 

You can also use one of those devices sold for hanging pictures that project a laser line over about 90 degrees. I bought one for about $9.95 made by Black & Decker (at Ollie's for those of you in the MD / PA area).

 

Yes you can. I have one of those and it measures distances up to 30 feet.

 

I'd avoid the lasers. I've used them for kitchen and bath work, and they're fine for that, or for dirt work, but this is going the other direction, and more accuracy is required. Particularly if you intend to produce a scale drawing. (That's the reason lofting is easier than drawing. A lofting pencil is a dozen times more accurate than a drawing pencil, depending on the scale.)

I prefer straight, flat grids. It gives you a solid base. It's a habit now.

 

Cheap lasers aren't very accurate, though do work with relatively simple shapes. These can be off an 1/8" across 30'. A good laser (non-contact) or a laser/tag (acuity) system is a different story and are impeccably accurate. These are easily identified by intal cost. I have a cheap Ryobi, I got for $50 at Lowe's and it's not very good, but I also have a $700 Pacific laser, that's unquestionably accurate and easily seen in bright daylight too. There's also photography systems (optical), direct contact CAD based systems (tactile) and a few other ways to pick up shapes, other the falling back on trapezoidal or Simpson rule mechanics. All have good and bad things to consider, though in this application most will be cost prohibitive or simply cumbersome to use. I'd consider an acuity or optical system as these are portable and relatively inexpensive. Maybe still a bit over the top, just to generate essentially artwork, but justification of the costs have to be on the OP.

 

I've made a lot of money on bridges picking up after "accurate" laser systems.

The longer the line, the greater the error.

 

In my case, a recent development has put me in touch with a local College. A professor there has been taking off lines for the ACBS Toronto for quite some time and has used several methods.

For a comparison study, one boat was measured using 3 different methods. These included a traditional square & plumb bob, an optical system and a laser system. After the measurements were taken and data was entered in the computer, three drawings were produced. While not exactly the same, the three representations were extremely comparable with only minor variances (probably caused by human error).

The traditional method took almost 4 days to collect the data. The laser more than halved that time and the optical system took 2 hours to complete. Of course, to get a real result, you have to add computer time to this. Further, the optical system did not require the boat to be blocked and level in fact, it could have even be done on the trailer!

The optical system is owned by the college and comes with considerable monetary costs for its use (about $1,000 +/- for a basic drawing). Final costs increase depending on the drawings required (apparently, their are several types of drawings that can be produced) and the level of detail on the final rendering(s). Basically, you are buying computer time. However, when you consider the cost of suitable space, manpower and time, this optical system looks to be a very good alternative. I will document this process and post it here when complete.

I realize this is not where I started this thread.... I appreciate the "old school" traditional method and the help offered here has helped me understand the process and some of the issues one must work through. I have no doubt that if I were to use this method myself I would have an even greater understanding (plus a working knowledge). However, since technology has presented itself in an affordable scenario, and I have serious reservations about a "rookie" producing quality data to make an accurate drawing (without direct supervision), I will most likely become a spectator in the process.

If in the end, the drawing is accurate (and other renderings can still be made) I will have achieved my goals. To understand the process manually, I believe, is invaluable! thanks to all.