water line

[captain charlie]

I just recently turned my boat over and am in the process of getting ready to fiberglass. After that is complete, I'm not sure how to go about drawing the water line. The manual talks about using a laser level. Exactly how is that done? I'm working in half of a standard garage so I don't have a whole lot of side room. Is the level something you buy at Home Depot? Any advice would be helpful, and thanks, Captain Charlie in Arkansas

[chaertl]

Hi Captain,

This was probably the single most annoying part of the whole construction process for me. I was working in about the same amount of space with a cheap level from Home Depot and just couldn't get a straight line out of it. I'd be willing to bet a contractor grade laser would be better since the main problem was the cheap one would only light up about half the hull before needing to be moved, then it required feeler guages to get it lined back up with the previous line. There's other methods out there but they're usually done with the hull right side up.

Chris

[Diving Duck]

You may not need contractor grade, but you need a pretty good laser level, at least in the $40 to $60 range. The two main points are that it needs to be bright enough and there needs to be a way to make sure the level itself is level! It needs to be plenty bright because the boat is curved and you have to back away a bit to light it end-to-end. A problem in tight spaces. And it needs to be fairly dark in the garage or shop unless you have a very bright laser.

I believe the best inexpensive lasers are self-leveling, i.e., they rely on gravity to come to level. The others rely on you leveling them using a bubble, which could be mis-calibrated and it's hard to get the bubble exactly centered. It the level is the tiniest bit off, it can be off by inches at the ends of the boat.

As to the need for a water line, my knowledge is much more limited, but do you absolutely need one? If you build the boat properly, she'll float "true to her lines" even if they are imaginary. Others will be able to refute me on this I'm sure. Or maybe you could "float your boat" in absolutely calm water and use a wax pencil to make several marks at the waterline. Paint the line later when the boat is out of the water and dry. Probably not a very easy thing to do on a trailer, though.

The "bottom line" it seems to me is that it is better to have no water line than to have one that is off!

[JonLee]

I used a cheapy self-levelling laser level from Harbor Freight. If you are going to use a laser level, you really want to go the self-levelling route!

To mark the waterline, you first have to level the boat, both longitudinally and athwartships. A bubble level on the keel will get you level fore and aft. Athwarthships, I drew a line between the two upper corners of the transom and jiggered the boat until that line was level. Spend lots of time on this step and double check everything four times (octuple check?). The boat must be level.

Now, pick where you want your waterline. You can scale the waterline off the plans...measure from the bottom of the keel to the waterline. Generally, you paint the waterline a couple o' inches above the waterline shown in the plans. Mark the waterline on the aft end of the keel. Now, line up your laser to that mark. The laser line has to be level...easy is you have a self-leveling laser, a pain if you don't. Now, just make a series of pencil marks along the laser line. I had to reposition the laser several times...each time, just line up the laser with your last pencil mark, and off you go. Work your way around the boat. If you've done everything right, by the time you make it around the boat, you're final line should line up with your very first one!

Now, check your work. About midships, the waterline dips down over the chine and onto the side of the hull. I measured down from the chine to the waterline on both the port and starboard sides to make sure they were the same. The first time I marked the waterline, it was actually off, and I had to re-level and re-mark it.


If you don't want to spring for a laser level, you could also buy ~25' of clear plastic tubing. Tape one end to the keel (having the end of the tube even with the bottom of the keel would be about right). Hold up the other end of the tube and then fill it with water until the level of the water comes up to the water line that you marked. Now, walk the free end of the tube around the hull, making a series of pencil marks at the level of the water in the tube. Since water seeks its own level, your waterline should be be level.

[Diving Duck]

A lot of good information in that last post. I have used the water-in-tubing method before and I actually like it better than using a laser level. Once you have the water level lined up with your mark (may take two or three tries) then it will be absolutely the same wherever you take it. Laser levels are nice, but they can be a pain if you have to keep moving them to complete the line. The old-fashioned water method is tried and true and the laws of physics make it totally accurate (as long as you wait for the water to settle). If you do go with a laser I want to reiterate--make sure it is self-leveling. (And wait for it to settle also.)

[tattoo]

Captian Charlie -- I've put waterlines on 4 of the 8 wooden boats that I've made. On Anna, my Penobscot 14, I tried to use a laser level -- but I didn't have a surveyor's tripod and couldn't make a sturdy exactly-level platform. Also the laser wasn't bright enough to easily see its projection. And you have to duplicate the setup on the other side of the boat. I gave up on it. My alternate method has worked well for each boat. You do need a level (or at least "flat") floor to work from. And it is easier to scribe the line on the boat when it is upright because in that position the space between the waterline and the floor is without obstruction. I've scribed the line after the last epoxy (has been sanded smooth) and before the 1st coat of paint.

A waterline marking bracket . .

WL-Bracket.jpg (24.94 KiB) Viewed 9269 times

Make sure the boat is level with the floor (side to side and end to end). If the floor isn't quite level, then make the beam parallel with the floor and set the keel so that the floor is parallel with the design waterline shown on the plans. For PocketShip the keel is paralled with the design waterline. Then fabricate a bracket so that its top is the right height above the floor as shown in the attached diagram. It helps to wax the bottom of the bracket so that it slides easily on the floor. Find (and sharpen to a chisel end) a carpenter's pencil with a soft lead. Just move the bracket around the boat and make pencil marks on the hull at frequent intervals. If you are going to paint a "boot" on the waterline, then extend the bracket the height of the desired boot -- and make another water line. Then when your eye is in the plane of the water, the boot will look like it is the same height all around.

The scribed line is only temporary. I would take an old and "dull" center punch and carefully "dimple" the hull along each waterline every inch or so. If you are careful, the dimples won't damage the hull, but will show up (in oblique light) even after the paint job and can be guides for masking future paint jobs.

Pete McCrary
Skipper and builder of Tattoo

[Diving Duck]

I just hope I can meet Pete "Tattoo" the next time I am in the Baltimore area. This guy is always coming up with great, simple ideas that work--probably has a lot to do with his aeronautical engineering background. (I still like the water-in-a-tube method best in this case, though. No construction necessary, and as long as your boat is perfectly level, the floor doesn't matter--water seeks its own level no matter what.) One of Pete's best ideas in this latest post is the small, almost invisible dimpling of the surface at the waterline--a huge help when it comes time to repaint.

Just an idea: Pete, do you think it might be possible for you to compile all your ideas into a single post that we could download and print? It could be added to over the years. You've obviously already done all the composition and drafting work.

John might need to chime in here on whether this single post idea might be too large for the forum. If that is the case it could be placed somewhere else on the Web. I'm sure downloaders would be more than willing to make a small donation to cover costs.

[Pascal]

I will have to agree with that. I was lucky to have spent a short time with Pete. I did get to use the teller/motor bracket on Tatoo, what a great idea. I still did not have time to work on mine but I will copy this asap. I am very jealous of Pete for all the time he is able to use on his Tatoo . Thank you again Pete for all your great ideas .

[kayakgirl]

I liked Bruno's idea where he followed the sheer line instead of the waterline for his hull paint scheme. I thought it accentuated PocketShip's graceful lines beautifully. I noticed his PocketShip is featured in this year's CLC calendar. I'm thinking of painting mine following the sheer line as well. haha when I finally get there!