Butty weight

[Cloudinspector]

We are making arrangements to have a 30ft butty lifted out of the water. Apart from a stove, wooden flooring and ply lining it's completely empty. I need to know roughly what it's likely to weigh.

Our boat is 62ft and about was about 18 t when we had it surveyed so I'm guessing the butty will be about 5 ton?

Anyone got a more accurate figure?

[Robbo]

You can calculate how much water it's displacing, that will give you the accurate figure.

[MtB]

I'd guess three-four tonnes would be closer but the ballast in it is probably the biggest determining factor. What ballast is there? What draft is it?

 

A photo of the boat would be good...

Edited February 12, 2017 by Mike the Boilerman

[David Mack]

Tell us how much it draws.

[Tam & Di]

Our boat is 62ft and about was about 18 t when we had it surveyed so I'm guessing the butty will be about 5 ton?

 

As said, you need to say how much it draws. However your estimate sounds odd - if your 62' boat weighed in at 18ton why do you reckon one that is only half as long would be just over a quarter of that weight? As you call it a butty it presumably has no engine and that obviously affects the estimate, but it still seems strange on the face of it.

Edited February 12, 2017 by Tam & Di

[Steilsteven]

The rule of thumb calculation ( in metres ) is Length at waterline x Width at waterline x average draught x 0.80.

This will give the displacement in square metres which is equal to tonnes. The 0.80 represents the fact that the boat isn't rectangular.

 

Keith

[Cloudinspector]

As said, you need to say how much it draws. However your estimate sounds odd - if your 62' boat weighed in at 18ton why do you reckon one that is only half as long would be just over a quarter of that weight? As you call it a butty it presumably has no engine and that obviously affects the estimate, but it still seems strange on the face of it.

Well it was a stab in the dark to be honest. It's a butty so no engine, no water tank, no fuel tank etc. Basically just a lined out shell.

At half the length of our motor it's obviously under 9 tons and with no engine etc I guessed at roughly 5 tons. No science behind it just guesswork.

[Chewbacka]

 

As said, you need to say how much it draws. However your estimate sounds odd - if your 62' boat weighed in at 18ton why do you reckon one that is only half as long would be just over a quarter of that weight? As you call it a butty it presumably has no engine and that obviously affects the estimate, but it still seems strange on the face of it.

But there may be more ballast to compensate for the lower fit out weight, so best just measure the draft and warm up the calculator. Or if you are not sure how to calculate it, then tell us the draft at both ends - just the vertical depth, don't follow the curve of the boat and whoever reads your post first can have a go at calculating it.

[Cloudinspector]

 

 

Basically I'm only interested in what the maximum weight is likely to be. A former work colleague owns a hiab company and he's going to crane it out and transport it for me. The cranes on his trucks have huge capacity so it's not really going to be an issue but I just wanted to be sure.

[Peter X]

Based on the photos and the other information so far, I think the average draught would be around two feet or 0.6m, so you have about 8 tons, and definitely under 10 tons.

[alan_fincher]

I feel sure the 5 ton estimate is low, but it will certainly be less than 10 tons.

My pure guess would be 6 or 7.

[ditchcrawler]

 

 

Basically I'm only interested in what the maximum weight is likely to be. A former work colleague owns a hiab company and he's going to crane it out and transport it for me. The cranes on his trucks have huge capacity so it's not really going to be an issue but I just wanted to be sure.

I have slept on that boat long before it looked like that.

[MtB]

Based on the photos and the other information so far, I think the average draught would be around two feet or 0.6m, so you have about 8 tons, and definitely under 10 tons.

 

 

Really? I think the average draft will be around a foot.

[Horace42]

Like others have said you need to know the draft front, and rear (or should I say draught^1*, bows and stern).

I did this with my boat by using a stick with a nail close to one end. Hook the nail under the keel in the vertical straight section both sides and mark the waterline at each place. Then measure the distance from the nail to the water line. That gives a pretty accurate depth. Then measure the distance along the straight section of the boat between the points where the depth was measured.

Also measure 'V' section of the bows - the bit underwater - at the waterline. Similarly at the stern.

With the outside width of the boat at each point. With You can then calculate the volume in cubic metres of the water displaced - which gives the weight in tons.

If not sure, then post your measurements here (as already suggested) and Archimedes will do the maths for you.

 

PS ^{note 1*} The spellchecker doesn't like 'draught'

[MtB]

 

With the outside width of the boat at each point. With You can then calculate the volume in cubic metres of the water displaced - which gives the weight in tons.

 

 

Point of order M'lud...

 

It will give the weight in metric "tonnes", not English "tons". Similar but not quite the same. One cubic metre of water weighs one tonne

 

 

PS ^{note 1*} The spellchecker doesn't like 'draught'

 

Now this is a curious one. I always imagined 'draft' was American spelling and 'draught' was English but on checking many years ago, it seems there is much confusion (IIRC).

 

There are mutliple meanings of the word too, for which one or the other spellingis correct, or wrong.

 

Draught under the door

Drafted into the military

Draught of a boat

Draughtmanship as in drawing a diagram

Draft of beer

 

I have no idea which is right and which is wrong. Perhaps one of our etymologists has time to waste setting us straight!

[howardang]

 

 

Point of order M'lud...

 

It will give the weight in metric "tonnes", not English "tons". Similar but not quite the same. One cubic metre of water weighs one tonne

 

 

 

 

But, only with fresh water. Brackish and salt water would give different results!

 

Howard

[MtB]

 

 

But, only with fresh water. Brackish and salt water would give different results!

 

Howard

 

 

Distilled water at 4 degrees C, if we are getting really picky! (IIRC.)

[koukouvagia]

 

 

I have no idea which is right and which is wrong. Perhaps one of our etymologists has time to waste setting us straight!

Not being able to resist the challenge, I've consulted the OED, which is authoritative in such matters.

s.v. "draft" it says: "a modern phonetic spelling of DRAUGHT, found in many senses of the word." It then goes on to list umpteen uses of the spelling draft, but most of these date from no earlier than the 18th century. The spelling "draft" appears to have been adopted when the gutteral "gh" sound in Middle English was superseded by the "f" sound.

I shall continue to spell the word as "draught" in all its senses, but equally anyone can spell it "draft" and not be wrong.

[MtB]

Not being able to resist the challenge, I've consulted the OED, which is authoritative in such matters.

s.v. "draft" it says: "a modern phonetic spelling of DRAUGHT, found in many senses of the word." It then goes on to list umpteen uses of the spelling draft, but most of these date from no earlier than the 18th century. The spelling "draft" appears to have been adopted when the gutteral "gh" sound in Middle English was superseded by the "f" sound.

I shall continue to spell the word as "draught" in all its senses, but equally anyone can spell it "draft" and not be wrong.

 

 

Excellent, thank you KK!!

 

How old does a recent new spelling have to be before OED stamps its authority on it? "Gunnel" springs to mind. I've only noticed that spelling around in the last decade or less.

 

 

 

(Edit to remove some redundant worms.)

Edited February 13, 2017 by Mike the Boilerman

[howardang]

Not being able to resist the challenge, I've consulted the OED, which is authoritative in such matters.

s.v. "draft" it says: "a modern phonetic spelling of DRAUGHT, found in many senses of the word." It then goes on to list umpteen uses of the spelling draft, but most of these date from no earlier than the 18th century. The spelling "draft" appears to have been adopted when the gutteral "gh" sound in Middle English was superseded by the "f" sound.

I shall continue to spell the word as "draught" in all its senses, but equally anyone can spell it "draft" and not be wrong

 

The Admiralty Manual of Seamanship, and Nicholls Seamanship - both respected books on the subject - spell it Draught, and one of the definitive textbooks on ship Stability - Derretts - spells it Draft. Both spellings have been in use for many, many years and I agree that there is no right or wrong way!

 

Howard

[koukouvagia]

 

 

 

How old does a recent new spelling have to be before OED stamps its authority on it? "Gunnel" springs to mind. I've only noticed that spelling around in the last decade or less.

 

 

 

The OED doesn't recognise "gunnel" - it simply refers the reader to "gunwale". The first spelling of "gunnel/gunnal" appears in the late 17th/ early 18th century and sporadically thereafter. It seems to have been fairly frequently used as alternative form from the 19th century onwards. An angler(!) writing in 1878 is cited, "I leaned over the gunnel of the boat in watching the fish."

Edited February 13, 2017 by koukouvagia

[ditchcrawler]

 

 

Distilled water at 4 degrees C, if we are getting really picky! (IIRC.)

Or that stuff you put in your manometer

[MtB]

Or that stuff you put in your manometer

 

What? Batteries you mean?

 

Here's my manometer...