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Ok , I'm getting close to setting the waterline on the build. I'm planning on using a water level to mark the setup line to the outside of the hull. Any suggestions or advice?
Alternate method?


Robert

Robert- here's how I did it on my Gentry, using water level

You can also buy a cheap rotating laser level these days. I used a laser line level as there was one handy - just set it up on a tripod and rotated it a few degrees at a time and marked each spot, then joined the dots.

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By the time I have built a boat, I'll be ready to build a boat....

Great pictures
That iis what I was thinking...

Thanks.

RC

This may be a stupid question, but does the set-up level line, designed waterline, and actual empty & loaded waterlines have anything to do with each other in the point of level or listing in any direction? I was under the impression these lines were not actually related except bring on the same boat, due to a number of construction and outfitting variables. Please enlighten me... I would love to find out I have over thought this and am dumber than I thought.

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Built 4, repaired 30+, ...So many boats, ...so little time.

If I remember correctly on my True Grit the building form positions the hull making the waterline parallel to the shop floor. So the actual water line “should” be an equal distance up from the floor of the shop at any point along the hull. That is why the water or laser level will work. It is just shooting a level line down the hull at the location listed in the plans.

I say “should” because it is only accurate if the boat is built exactly to plans. Any change in weight or repositioning of weight can cause the water line to shift. Both of my boats suffered from fairly extensive modifications so I decided not to mark the waterline until I actually floated the boat. I did this by wading around the boat and every couple of feet sticking small pieces of masking tape about an inch above the water. Pulled the boat out and then used them for a reference.

Even then I still extended the bottom paint up about 4” to accommodate differences in load (gas, water and junk). Plus, like me, my boats seem to pickup weight with age. Always seem to be adding this or that, which will make it set deeper in the water.

In the photo below the change in color is the approximately 3" above the water line at the design's stated displacement. It is parallel to the shop floor. (Actually in the photo it is 3" BELOW the drawn water line but the hull is upside down. Does that make any sense? )

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So Many Rivers,
So Little Time....

ok - this one went great for me

1- Determine where the water line should be according to the plans! Not according to how it floats.
2- Mark that waterline on each corner of the transom and at the bow.
3- Make sure the boat is level from side to side (from front to back does not really matter, side to side matters in this case)
4- Buy an inexpensive laser that throws a straight line. You can get crazy with them, but is not necessary to have a rotating one or anything beyond a red line.
5- Connect the dots - across the transom - then transom to bow on each side. I found a spot across the room, then shimmed and fussed with the laser it until I got it through the points on the layout. Edited: You want to get both transom and the bow point all in the same plane - so set the laser out from one of the rear corners so you can connect all 3 points with it to make it perfect. Otherwise you run the risk of being to high or low and creating an arc for a waterline that was not intended.


Guaranteed to work perfectly.

The water level is fine - but then the boat has to be perfectly level front to back and to me it seems like a pain to set up correctly.

Two of my personal favorite pictures from launch day:





This is the designed waterline - perfect at both ends.

At launch time - you want the boat to balance on that line. Moving weight (battery - or adding ballast) will get you to this point. I got lucky and had to do nothing. If it floats right at rest - it will move correctly through the water. i.e. No porpoising or other bad behavior.

HTH

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Regards,
Bob Perkins

My Current Projects
http://h12restoration.shutterfly.com/
http://nutshellpramconstruction.shutterfly.com/

My Completed project
http://biscayne22.shutterfly.com

Bob is right! Mark the design waterline/set-upline. Trim/balance the boat to that line. That way the boat will be the way it was designed to be.

Bill

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Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
Tahoe 19 Build

Ideally the above suggestions are correct BUT not always possible because of modifications. If you are over design weight (and many homebuilts are!) even if you reposition equipment it may well float level to the drawn line but below it. Installing larger engines on an O/B or I/O hull would cause the transom to sink and there may not be enough stuff available to shift to compensate. Even if you can it will again float below the plans waterline. In my case with the True Grit I added more aft cabin structure as well as positioning the O/B 2' aft of the transom on a bracket (not to mention a 100 lb refrigerator at the back of the saloon!). I located as much weight forward as possible but it was just not enough. Plus, adding weight to the bow will not raise the transom - it will just sink the bow to the transoms level so again you end up low. In addition, if you can't adjust the hull's position with available equipment, dead weight would need to be added in the form of lead, water, concrete or whatever. But you then have to decide which will hurt performance more - the hull floating at an incorrect angle OR making a heavy boat even heavier. Particularly on a planing boat weight is a performance killer so do you multiply the problem?

My personal call was not to add the weight. I reasoned the hull position at rest really wasn't that important and underpower it would be adjusted by motor trim and/or trim tabs. If building an I/B with no form of trim I might have looked at this differently but in my situation not adding more weight seemed to make sense. That is why I floated the boat and marked the realized waterline and let it bump.

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So Many Rivers,
So Little Time....

I agree with all of the above if your built deviates from the plans to that extent.

The Runabout style hulls are less likely to have large deviations in weight as compared to other styles of hulls. In general, the plans and designs are quite accurate and for the hull to perform properly - the weight distribution should try its best to follow the designed waterline for best performance.

_________________
Regards,
Bob Perkins

My Current Projects
http://h12restoration.shutterfly.com/
http://nutshellpramconstruction.shutterfly.com/

My Completed project
http://biscayne22.shutterfly.com