water line - making a new one for anti-fouling

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roam

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does anyone have any nifty suggestions as to how to create a new waterline mark for a boat already out of the water to mark where the anti-fouling needs to go?
the current lines are not even so we need to start again.
we've a rough idea where the line needs to go, but how do you create a straight line?
i'm sure there must be some old salty tricks to help.

cheers
 
You can mark a straight line using a manometer. Clear plastic tubing with some coloured liquid. Hold it up in a U shape and the two positions of the liquid will be level. You need to know where the marks of the boat should be though to make a waterline, if the waterline marks are level out of the water then this method will be perfect.
 
I'm sure that one of those cheap laser pointer levels on a tripod, could do the job, I haven't actually done this myself though.
 
Yes that's what I tried to say. If he knows the rough waterline then at least he will get a straight line by walking the manometer along the length of the boat doing say a couple of feet at a time.
 
[ QUOTE ]
....we've a rough idea where the line needs to go, but how do you create a straight line?
i'm sure there must be some old salty tricks to help.

[/ QUOTE ]
In the same situation I was advised, by a very knowledgable boatyard craftsman, that the best-looking 'waterline' is NOT straight.
Due to the shape of (most) yacht hulls and perception by the human eye/brain, a strictly horizontal line looks 'wrong', but a line that curves very gently upwards from midships towards bow and stern looks 'right'; i.e. aesthetically pleasing.
The difficulty is knowing how much 'lift'. I did it by trial and error with masking tape. It works!
 
I have and it works a treat provided that you have sufficient clearance on either side of the boat to swing it. If the boat is not quite level fore and aft you can usually bias the tripod it sits on to compensate but it is best done on a dull day for obvious reasons. Wait for the sun to go down is best. In the evening when it is dark you can mark out with a felt tip and run masking tape around the next morning.
 
If you don't have access to a laser level, rig up a line between two poles one ahead of the stem and the other aft of the stern and project a shadow of it onto your hull with the headlamps of your car. Adjust for height and position as required. Mark at regular intervals with a felt tip and mask up accordingly.

Steve Cronin
 
Er that would require your car headlights to be at the same height as your WL then? /forums/images/graemlins/confused.gif
 
I used a home made water level to mark the waterline on Piper.

Parts required:

1 plastic bottle about 1 litre capacity

20 metres of clear soft plastic tubing about 4 - 6mm ID.

Some sticky tape.

Make a hole in the top of the container and insert one end of the plastic tube. Fill the container about 3/4 full of water, you can add some food colouring to make the water more visible.

Hang the bottle on the boat at the same height as the waterline.

Suck on the tube until the water fills most off the tube.

Adjust the height of the bottle so that the water is level with waterline.

Go round the boat marking the waterline as required.

Boat needs to be level of course.
 
You know....

..the last time I used that method we had a lift keeler and a 4x4. Don't suppose it would work now with almost 2 metres draft and a Z4 but the Halogen worklight clipped to the top of the stepladder might!

Steve Cronin
 
Set up a batten on a trypod or frame far enough away from the boat so that the when eying through, one tip is inline with the stem and the other inline with the stern. Adjust the batten so the tips are level with the antifoul line at the stem and stern. The boat does need to be level for this. Then shine a light behind the batten, the shadow will give you the line, just mark off along the shadow line.

We do the same for marking out a drilling pattern on a tunnel face, a piece of board or steel plate is drilled for each charge hole. The plate is position a set distance from the face, shine a light behind the marked board and hey presto spots appear on the rock face.
 
Set up a batten several feet back from the boat, eye in the batten so its level with anti foul at stem and stern. Shine a light behind the batten so the shadow projects on the hull. The boat does not have to be level for this method.
 
We did ours by stretching masking tape.

Attach the masking tape at the bow or stern, at the correct height. Then unroll tape holding it just tight but not touching the hull yet. Once enough length is out, then walk in to the hull holding the tape and let it stick where it touches the hull. If it looks right, then smooth down the tape properly.
 
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