What is Draught?

[DERF]

If your boat has a draught of 1m for example, were is this measured from?

The bottom of the hull to the tip of the props/rudders?
From the waterline to the bottom of the hull (excluding above)?
From the waterline to the tip of props etc?
Is the draught dry boat no load?

A fellow forumite recently didn't seem too concerned about the depth reading 0.8m. Quote "thats the depth under the keel".... the boat eventually touched bottom.

So if your guage reads 1m, how much clearance does one really have under the boat? My guess half that actual figure, and less if the boat is wet and laden.

Am I wrong?

 

[duncan]

not right or wrong as there are variations in how people set up thier depth guages etc

draught is surely equivilent to the depth of water you will occupy when normally loaded - ie waterline to lowest extremity on boat.

depth guage reading to clear will all depend on where the transducer is relative to above or software settings if the unit permits a 'keel offset' to be entered to allow for this.

All of this can of course end up confusing people when looking at tide tables and charts too............

As an example my 'ducer is in the hull and therefore water depth is reading plus 0.4m. At a reading of 0.7m I do not expect to touch the bottom and the manufactures draught for the boat is 1m so it adds up!

 

[jhr]

On a depth gauge Isn't it normally the depth below the transducer? Mine is positioned near the stern and about 3 in above the bottom of the boat. So, I start to get very twitchy when it reads 1 metre because there's only about 12" of water underneath the bottom of the leg /forums/images/graemlins/shocked.gif.

(Before everybody piles in, this is a state of affairs that only arises at about 3 knots, approaching my mooring at LWS).

 

[TigaWave]

If you just install a depth guage and switch it on it will measure the distance from the transducer to the bottom, as the transducer is usually a foot or so below the water level, then the actual depth is usually greater.

But......to help people and confuse people you can add an offset to what is displayed, manually in the set up....which subtracts the distance from the transducer to the deepest part of the boat, maybe rudder or keel. Thus what you actually see displayed is the depth under the deepest part of the boat.

So transducer reads 5m its mounted .25m below surface..actual depth of water 4.75.......

Distance from transducer to deepest part of boat is 1.5m (total depth below surface of keel would be 1.75m) so you put in an offset of 1.5m ...the guage now reads 5.0 - 1.5 = 3.5m which is the depth under the deepest bit of the boat......the water depth being 5.25m

Did that confuse you?

 

[Divemaster1]

[ QUOTE ]
If your boat has a draught of 1m for example, were is this measured from?

The bottom of the hull to the tip of the props/rudders?
From the waterline to the bottom of the hull (excluding above)?
From the waterline to the tip of props etc?
Is the draught dry boat no load?

A fellow forumite recently didn't seem too concerned about the depth reading 0.8m. Quote "thats the depth under the keel".... the boat eventually touched bottom.

So if your guage reads 1m, how much clearance does one really have under the boat? My guess half that actual figure, and less if the boat is wet and laden.

Am I wrong?

[/ QUOTE ]
Draught is ... waterline to deepest part of the boat ... that being skeg, rudder, or prop.

Depth reading is reading from sounders transmitter down the way. This can be adjusted so it is the sounder readers display reads anything from between waterline to bottom or from deepest part of boat to bottom. Your fellow forumite probably had his sounder ajusted as the latter... and as such, he/she did have 0.8m underneath the deepest part of the boat..., which may easily have been 2m waterdepth.. With 2 m waterdepth, my sounder would have read 0.4m, as my boat has 1.6M draught and the sounder reads from deepest part of the boat, which is my props....

 

[DERF]

Huh???

 

[hlb]

Course. The sea bed aint flat, so just cos the DS reads .8, it might be much more or less only a few feet away. I get twitchy with less than 2 mtrs under the keel.

 

[mjf]

Draught or draft?

Its the measurement from the waterline to the deepest part of the vessel. This will vary dependant on the salinity of the water in any given loaded (fuel water etc) condition.

What echo sounders read is a different story as it depends on where the transducer is located and what calibration/offset has been introduced.

On my boat for example the normal draught is 1.0m SW with normal fuel/water and a couple of peeps. I was at anchor in shallow SW water and measured the depth of water I was floating on with a boot hook or similar. Then compared this to what my sounder said. My sounder showed the actual measured depth less 1.0m so it therefore reads the depth underneath the lowest part of my boat. ie underwater clearance

 

[D3B]

boat draught and depth on echo sounder are totally different things.

draught is depth of lowest part of boat in water. skeg/hull/leg etc....

depth on echo sounder is depth of water under the transducer with, as stated, allowance for offset.

so if deepest part of boat is 0.5m under transducer it may be prudent to put that offset onto the echo sounder so that the depth you see is the actual clearance the boat (under the skeg/leg/hill) has in the water. ditch crawling up the River Great Ouse from Kings Lynn to Denver taught me to do this. When it shows 0.5m on my echo sounder me ringpiece starts twitching /forums/images/graemlins/blush.gif
Doug

 

[Deleted User YDKXO]

Without wishing to be too pedantic, is it draft or draught? I thought draught is a decent pint of beer or a flow of air whereas draft is the distance between the waterline and the lowest point on the boat. Anyone got an OED out there?

 

[mjf]

Mike its one and the same.

I always used to use draught but have to say draft seems to be more common these days.

I blame the yanks!

 

[Deleted User YDKXO]

Is that the OED definition?

 

[tcm]

all wrong: draught = zero

Hm you're getting some bizarre replies here i must say, over-complicating the whole issue, and it is important to understand the true situation. Essentially, on all boats under about 90-100 feet long or so, there is almost invariably NO DRAUGHT at all. That's right, zero! Forget what the dials say - ALL the beer is bottled.

 

[mjf]

Actually no! However a quick poke into my Collins english Gem Dictionary in mt desk draw says Draft: see draught.....for christsake!


Draught has all the usual suspects and says at the last line see also Draught.


In times gone by the depth a vessel was floating at was read using draught marks for'd, midships, and aft. But we used to say the draft is xxx. The vessel was said to "draw" xxx

 

[Talbot]

Your echo sounder is relatively useless unless you have calibrated it yourself. Some people like to read from the lowest point of the hull, others from the waterline, personally I jsut keep it calibrated from its own position on the hull cause its near enough. When the guage reads less than 1 metre I still have a few cm to play with but its definitely shallow!

 

[compie1]

I prefer draft instead of draught, why?
Because of this:

perfect draft

I like it best with Jupiler works super!

 

[CaptainThames]

Draught is correct although often abreviated to draft. Then of course there is air draught.........

 

[Lakesailor]

It's what whistles round my ankles come December. Log fires are OK but they create draughts.

 

[DERF]

definition of draught Draught

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The act of drawing or pulling

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The act of moving loads by drawing, as by beasts of burden, and the like.

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The drawing of a bowstring.

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Act of drawing a net; a sweeping the water for fish.

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The act of drawing liquor into the mouth and throat; the act of drinking.

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A sudden attack or drawing upon an enemy.

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The act of selecting or detaching soldiers; a draft (see Draft, n., 2)

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The act of drawing up, marking out, or delineating; representation.

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That which is drawn

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That which is taken by sweeping with a net.

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The force drawn; a detachment; -- in this sense usually written draft.

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The quantity drawn in at once in drinking; a potion or potation.

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A sketch, outline, or representation, whether written, designed, or drawn; a delineation.

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An order for the payment of money; -- in this sense almost always written draft.

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A current of air moving through an inclosed place, as through a room or up a chimney.

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That which draws

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A team of oxen or horses.

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A sink or drain; a privy.

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A mild vesicatory; a sinapism; as, to apply draughts to the feet.

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Capacity of being drawn; force necessary to draw; traction.

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The depth of water necessary to float a ship, or the depth a ship sinks in water, especially when laden; as, a ship of twelve feet draught.

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An allowance on weighable goods. [Eng.] See Draft, 4.

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A move, as at chess or checkers.

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The bevel given to the pattern for a casting, in order that it may be drawn from the sand without injury to the mold.

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See Draft, n., 7.

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Used for drawing vehicles, loads, etc.; as, a draught beast; draught hooks.

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Relating to, or characterized by, a draft, or current of air.

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Used in making drawings; as, draught compasses.

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Drawn directly from the barrel, or other receptacle, in distinction from bottled; on draught; -- said of ale, cider, and the like.

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To draw out; to call forth. See Draft.

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To diminish or exhaust by drawing.

 

[IanH]

[ QUOTE ]
Without wishing to be too pedantic, is it draft or draught? I thought draught is a decent pint of beer or a flow of air whereas draft is the distance between the waterline and the lowest point on the boat. Anyone got an OED out there?

[/ QUOTE ]

According to my, admittedly, old eighth edition, draft is a first stab at a document and other similar definitions, while draught is, amongst other things such as a bit of a breeze, the depth of water needed to float a ship. So it does matter which is which, except in America where it is always draft. Mind you this is not necessarily an americanism since many words considered such are in fact old English spellngs and words that the Americans haven't changed whilst we have.

phew /forums/images/graemlins/smile.gif