Horizontal Baseline ??

[Mark David]

Hello All!

With OtJ adjusted in her cradle, hanging a plumb bob from the bow and confirming with a laser; I believe I have found the vertical baseline and continued it the length of the hull.

The top of the factory applied gelcoat boot stripe is aesthetically curved, but the bottom edge should be parallel to the waterline = horizontal baseline.

Can anyone offer an alternate or save me from myself??

Thanks!
Mark

 

[goldenstate]

Your approach sounds logical to me.

If it doesn't work out, just drain some water out of one of your tanks.
Or don't - my boat has a little starboard slant.

 

[Bob Robertson]

Our boat has a slight starboard slant when the starboard and the port tanks are full. We use both tanks, but we always empty the starboard tank first.

 

[Mark David]

Thanks for input!!

 

[Loren Beach]

Modern tech allows this to be done with a laser, once the hull is blocked level, both axis.
It takes some time with a tight string, and then you end up with a bunch of tick-marks on the hull and have to connect them.
Note that the stripe, viewed from its own level, will appear level and straight, to your eye. That's why it is actually wider/fatter as the hull curves some in front and a lot more at the stern.
Back when builders were leaping into the sailboat market in the (gas shortage) 70's with really cheap boats, they used to apply vinyl tape for these, and it looked really wrong for a waterline stripe. At the low end of the market, new sailors did not seem to care.

 

[Mark David]

....you see it Loren!

I have been able to adjust/block the hull in the cradle so the keel is plumb and aligned within the cradle, but the boat remains pitched nose down so the cockpit drains don't trap ice.

Just need to quantify how much.

Do you think the factory applied the gelcoat stripe accurately enough to work off of the bottom edge?

 

[Loren Beach]

Truthfully, I am having difficulty understanding the exact question!

Hopefully others here that are smarter and younger can assist... !

 

[Christian Williams]

I'm not smarter or younger, but my boat has a molded-in line for the boot stripe. Anything parallel to that would be accurate.

 

[Mark David]

a self leveling laser at the bow. positioned with the vertical on the known 'chain plate to keel' centerline

at ~80" back from the bow, the bottom of the port boot stripe is ~3.5 inches above the laser horizontal line....starboard side at same position is only ~2.75 above the laser line

guess I am being forced to choose between my 'rulering' skills and the factory's gelcoat application?

next step is to lock laser and shoot the bottom of the boot stripe from stem to stern to see if it even falls in the same plane

 

[Kenneth K]

A 3/4" difference over a, say, 28' waterline is about a 2.5% error. You may be the only one who ever notices the difference, and you may have to really be looking for it. How did the lines look while she was floating? I probably wouldn't make any changes that are hard to "undo" if you don't like the results. If you leave it as is but don't like it, you can always fix it at the next haulout.

 

[Parrothead]

You'll be hard pressed to do better than the factory waterline. It was specified by the designer, established on the original hull plug and molded into the hull mold. For each hull the waterline was masked in the mold prior to the application of hull gelcoat. After the hull color was sprayed the masking was pulled and the stripe color was applied, showing through only where the masking was. With this process on every hull, human error entered in the masking phase, perhaps a small fraction of an inch at any point.

 

[Mark David]

Thanks! I really appreciate everyone's input and wanted to follow up...

You'll be hard pressed to do better than the factory waterline. It was specified by the designer, established on the original hull plug and molded into the hull mold.

Looking at the water line as a line between a point on the bow and one on the transom, I marked the bottom of the boot stripe where it intersects the centerline of the boat. Drawn as waterline secant in the attached sketch.

Two minutes hanging / measuring with a plumb bob and it was easy to determine the forward pitch of the boat at ~2 degrees.

The 32-2 keel has a definite 'chin', line D-E.

A laser helped find the 'chin' and then shoot line C-D so it is parallel to the waterline.

Line A-B was used to check my work.

Q.E.D.