Setting the waterline mark with a laser level

[Briarpatch]

I am planning to paint my steel sailboat hull's top coats/then bottom coats and was wondering if there was a laser level tool (and not too expensive) out there somewhere that can aid me in marking a straight and level waterline on my primed hull?

[US1Fountain]

Haven’t used a laser level, but you can use a long piece of clear tubing filled with water and do the same thing a lot cheaper

[Dsanduril]

You can use a water level, but there are a ton of laser levels around that will do the trick. You should be able to pick up a "cross line laser level" for < $100. The really cheap ones start about $50, but the more you spend the further they will go, and also the more visible they will be outdoors (green is recommended over red for outdoor use).

Bosch makes many of the units sold in big box stores. Or Dewalt, or.... You'll also need a tripod on which to place/adjust the level.

You can also rent them from construction tool places (usually the larger/more sophisticated units).

[psk125]

Of course you have to make sure the BOAT is level before going at it with any leveling device to mark the waterline.

[belizesailor]

...and boats are never level.

[chrisr]

imho you need a STRAIGHT line for the waterline, but not necessarily a LEVEL line.

is is the boat designed to float level ?

is the boat sitting level on the slips ?

cheers,

[Paul L]

One thing about using the cheapo laser levels is that they can be hard to see in the daylight at the distance you need. You can get everything setup and then use the level at night to get the marks you need.

[Reefmagnet]

I've done it with a cheap rotating laser on a tripod. Best to do it at night. You need a reference mark at the bow and stern and then you need a mark midships on each side. Set the laser perpendicular to this midships mark. Use a tripod to get the laser light exactly equal in height to this midships mark and then adjust the tilt of the laser to align the bow and stern reference marks. Mark out the laser line and you're good to go.

[coopec43]

When I did the waterline on my yacht (under construction) I used the designer's waterline measurement and then went up two inches.

I tried to use a laser level which worked fine in pitch darkness but was no good where there was light from street lights etc. As has been previously mentioned the laser has to be a fair distance from the yacht which was difficult as I had to set up the laser in my neighbors backyard. (The sale of more powerful lasers is illegal in Australia)

I found a tube filled with water and used as a level was the best way. As my yacht is 43ft I found it was a two man job. Even then I had use my sight to make sure the waterline looked alright. (To do that your eyes must be at exactly the same height as the waterline itself)

[HankOnthewater]

Most home builders, I would think, paint their waterline at least twice: the first time is as per the estimated guess/ as per drawing, and a few months, or year later to do that again, then taking into account deviations from the original plan, the various stuff loaded on board etc.

As others have said above, a boat on the hard is seldom perfectly level, therefore laser level or water-in-hose trick doesn't work.... except maybe when the laser level can be put at the same sloping angle as the boat.... maybe that is possible.

There was a boat builder in Fremantle, so the now popular story goes, who got the waterline of his (plywood) professional fishing boats always spot-on, without moving gear or ballast. His secret was to splash the boat the evening/night before final painting, mark the waterline with the boat in the water, take it out again, and then paint it (in daylight). The new owners were suitably impressed about the accuracy of the waterlines and contributed that to his skills as boatbuilder.

[AndyEss]

Originally Posted by Reefmagnet

I've done it with a cheap rotating laser on a tripod. Best to do it at night. You need a reference mark at the bow and stern and then you need a mark midships on each side. Set the laser perpendicular to this midships mark. Use a tripod to get the laser light exactly equal in height to this midships mark and then adjust the tilt of the laser to align the bow and stern reference marks. Mark out the laser line and you're good to go.

This.

Your boat does not need to be perfectly level.
Early morning, late evening or even a very cloudy day would work if the laser were powerful enough.

[GILow]

Originally Posted by HankOnthewater

...

There was a boat builder in Fremantle, so the now popular story goes, who got the waterline of his (plywood) professional fishing boats always spot-on, without moving gear or ballast. His secret was to splash the boat the evening/night before final painting, mark the waterline with the boat in the water, take it out again, and then paint it (in daylight). The new owners were suitably impressed about the accuracy of the waterlines and contributed that to his skills as boatbuilder.

I like this guy!

[coopec43]

Originally Posted by AndyEss

This.

Your boat does not need to be perfectly level.
Early morning, late evening or even a very cloudy day would work if the laser were powerful enough.

If the boat is not level do you put the laser on a lean to compensate?

I did think about getting a Surveyor mate in with his powerful laser because the lasers we are allowed to buy are literally toys.

"The government acted swiftly and banned the possession and importation of laser pointers with a power output greater than 1 milliWatt. Consequently, Australia has the most restrictive laser pointer laws in the world.Jun 23, 2014"

[Fore and Aft]

You guys are making it all to complicated. It’s not a new boat and the OP already knows his waterline. So why not do a rough broadside sketch of the port and starboard side and measure from the ground or toe rail to the waterline then mark the measurements on the sketch. Every stanchion could be a measuring point.
Re-reading the first post maybe it is a new yacht?
Cheers

[coopec43]

Originally Posted by Fore and Aft

You guys are making it all to complicated. It’s not a new boat and the OP already knows his waterline. So why not do a rough broadside sketch of the port and starboard side and measure from the ground or toe rail to the waterline then mark the measurements on the sketch. Every stanchion could be a measuring point.
Re-reading the first post maybe it is a new yacht?
Cheers

Yes I assumed it is a new yacht as he is talking about primer and so on.

If the hull had already been painted I doubt he would have started this thread.