The Steamboating Forum

My boat has a draft of .9m, if i measure on the boat sitting on the shop floor .9m verticle it puts me at about 2" for the gunwale, is this right?

johnp wrote:My boat has a draft of .9m, if i measure on the boat sitting on the shop floor .9m verticle it puts me at about 2" for the gunwale, is this right?

I think the 0.9M draft (from a brochure? plans? old tars tall tale?) probably refers to the interior measurement from the top of sheer at the lowest spot to the lowest point in the bilge. If this is so, then the term "draft" is being used in an old and/or technical sense - like 19th century or earlier shipwright "speak".

Boat was built in netherlands 1967 the plate says.
6.51 x 2.21 x 0.92 MTRS

I think the .92 m refers to what is usually called depth, or depth of hold which has nothing to do with draft. This is an interior measurement, most likely measured vertically from the sheer near amidships on the center line down to the bilge. It's used for figuring out the volume or gross tonnage for registration/certification purposes.

I guess I should read all the posts first! Ron beat me to it.

I guess the only way to figure out what she draws is to put her in the water ?

In boat design the draft is the distance from the baseline to the uppermost point on the sheerline, the baseline being the lowermost point on the skeg/keel when the boat is at a level corresponding to it's design waterline- if the keel is flat on the floor of your shop, but is at an angle when in the water your measurement will be incorrect.

In boat operation draft is the depth of the vessel that is below the water when loaded.

Air draft is the absolute height of the boat when finished- including funnels/canopies/jackstaffs/masts etc and is used when vessels are designed for harbour/inland use and come across bridges/locks and the like.

Greg

"I guess the only way to figure out what she draws is to put her in the water ?"

One can use freeware, "Deftship" to draw up the boat hull and then know all about its hydrodynamics including draft. That may be something you may consider, if you like that sort of thing. I do that kind of stuff for fun (measure a hull and work it up on Deftship), but it does take some time, depending on your inclination to computer work. You may also be able to get the lines for the hull off the innernet, or get something very similar from the Deftship library.