Straight boot top line - use laser level, if so, how?

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npf1

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Hi - my boot top line isn't straight in places. I think I read on here some time ago that using a laser level was an easy way or getting it right, but I can't find the thread.

Can anyone explain the process and recommend a suitable (and cheap) laser level?

Thanks in advance
 
Never done it myself, but seems straightforward enough. The laser unit sits on top of a tripod, and projects a horizontal plane of light (actually they usually have a spinning mirror, so it's a single beam revolving very fast, but the effect is of a flat plane). You stand the tripod next to the boat, and the plane becomes a line projected onto the hull. Draw along the projected line and there's your horizontal line.

Does rely on the boat having been chocked up dead-level, though :)

Pete
 
Thanks for the link. So if I have a point at the bow and stern, can I use a laser level to mark a straight line between them even if the boat isn't 100% level?

Or do laser levels only project horizontal lines? Ids there a way to adjust them to project a straight line that is not level?

Thanks
 
npf1 said:
Or do laser levels only project horizontal lines?
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I think the clue is in the name :)

The ones I've seen, though, achieve their levelling by having a kind of weighted pendulum below a gimbal, with the laser part on top. I guess you could manually position the pendulum, and jam it in place using blutak or something, to project a line at whatever angle you want.

Pete
 
npf1 said:
Thanks for the link. So if I have a point at the bow and stern, can I use a laser level to mark a straight line between them even if the boat isn't 100% level?

Or do laser levels only project horizontal lines? Ids there a way to adjust them to project a straight line that is not level?
Click to expand...

Read post #12 in the link I gave you.
 
I think as long as you have a level that can be set manually you can choose your start and end point and get a straight line between. Others seem to have automatic leveling - they will need the boat dead level.

You will need to have it set to the right height as well though - otherwise the curves of the boat could put some interesting bends in your straight line.
 
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npf1 said:
Waterline is about 45', so I don't fancy my chances of finding that method more efficient that buying/borrowing/renting a suitable laser level. But thanks for the suggestion.
Click to expand...

I don't under stand what is wrong with the cheap solution. Any length of hose is will do - a garden hose 300 metres long would do - just join a metre of clear hose to each end and you'd be laughing.

Assuming you are doing it on dry land perhaps your biggest problem is getting the boat level in the first place!

However, if the boat is in the water then just use a chinagraph pencil at the water line
 
sailorman said:
The cheap & simple solution
http://www.factsfacts.com/MyHomeRepair/WaterLevel.htm
Click to expand...
The water level is very accurate and can be undertaken at a pace to suit youself. However it does rely on the boat being chocked absolutely level in both the longitudinal and vertical axis.
If you have a bow mark and a stern mark and the water level shows them to be equal, you only have to worry about the boat being vertical. Presumably if you can get the water level to each gunwhale at the same position along the length then it is vertical.

The laser method only requires you to have the boat vertical. You can tilt the laser mount so that the swing from stem to stern hits both bow and stern marks.
The disadvantage is that you need to be able to place the laser far enough away from the boat to achieve a full swing along the length and preferably as near the admidships position as possible. If the boat is surrounded by other boats this is unlikely to be possible.
 
alteredoutlook said:
I don't under stand what is wrong with the cheap solution. Any length of hose is will do - a garden hose 300 metres long would do - just join a metre of clear hose to each end and you'd be laughing.

Assuming you are doing it on dry land perhaps your biggest problem is getting the boat level in the first place!

However, if the boat is in the water then just use a chinagraph pencil at the water line
Click to expand...

I see your point, but still think a laser level with manual adjustment is surely much quicker than setting up the hose arrangement. The line I'm painting is about 6" or 8" above the waterline - yes, I could mark the waterline with a Chinagraph, but finding water still enough and being able to create a VISUALLY parallel (but in reality not just 6" higher up all round because of the curves of the boat) line higher up strikes me as approximate at best. I'd think I'd rather go with the laser level solution as the outcome will be quicker and more likely to be right. The current line is wrong because of such approximations in the past.

Also, as boat is around 30 tons, I'm reliant on the banksmen/travellift operators to set the boat level, so it being perfectly level is unlikely. As the boat will be in the yard in May, I'm keeping my fingers crossed that there's sufficient space to use a laser level.
 
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