Finding the waterline

[Rat-Fink-A-Booboo]

Can anyone enlighten a beginner how to find the waterline on the completed hull when it is not parallel to the keel. I.e on a boat with a large drag. I'm building Lynx by Panart.

 

Many thanks all.

[ca.shipwright]

R F,

There are many ways to do this. But the key is to have a reference point.

 

1. If there is a base line that is horizontal below the keel and parallel to the water line, all you need to do is measure the  distance between them at several stations. Transfer these measurements from the base line to the water line on the hull and connect the dots to give you the water line.

 

2. If there is no base line, it gets a little more complicated. Place the aft end of the keel on the building board. Raise and block the fore end of the keel until the distance from the waterline to the keel is equal to the distance shown on the plans at any particular station towards the bow.

This will give you the forward reference point for the horizontal waterline and the proper amount of drag on the hull.

 

3. In either 1 or 2, it is imperative that you make sure that the hull is centered, not tilted port or starboard. Laying a level across the bulkworks  and keeping the bubble centered should get this done. This will give you the same waterline port and starboard.

 

It all sounds more complicated than it is.

 

Hope this helps

 

 

[Snow]

Get a book called ship modelling simplified by frank mastini . It helped me heaps to the waterline mark the front of the ship then the back even if they are different heights make the marking jig and adjust the height of the ship as needed .i made mine in half hour its in the picture hope this helps.put felt on the bottom so it slides and just run the marker around the hull, the wingnut is so it's adjustable to height needed.

[Pete Jaquith]

Rat-Fink,

 

I use a surface gauge to mark the waterline with the hull positioned in a building cradle that holds the hull level to the waterline.  Counters for the building cradle are taken from the building plans.

 

Regards,

Pete 

[Mickgee]

Marking the waterline is one thing and fairly simple.

 

Finding, or determining the waterline is a new ball game.

 

I've found no better way than to just eyeball the hull.  The Lynx, a Baltimore Clipper type, has two masts.  My Dos Amigos a very similar build.

 

No matter which way, it always seems to be the midline between the masts.  When this is level, the boat just looks right.

 

So, from the deck, or even the gunwales at each mast, find the level point between the two.

 

Certainly not mathematical or scientific, but I absolutely cannot deduce this line with any of the available equations.

 

The boat just sits right, my opinion, when the fore and main masts at the deck, are level.

 

Nice model RF, good luck to you.

 

Michael