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 Boat Design Forums How much wood (would a wood chuck ..)? Square feet/meter
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#1
02-14-2006, 06:06 AM
 DanishBagger Never Again Join Date: Feb 2006 Rep: 523 Posts: 1,543 Location: Denmark
How much wood (would a wood chuck ..)? Square feet/meter

I have just begun a thorough search for lumber, and since it will be mahogany, I don't want to buy too much, nor will I want to buy too little.

Here's my plan:
"Laura", a bay sloop, scaled down from 20ft to 16ft.
Ribs etc will be laminated, cb and rudder likewise.

I'm not asking for a total, as the deck will be ply, etc, but is there some way to figure it out? Before I go onto how I tryingly calculate it, I need to mention that mahogany apparantly are priced per cubic meter(1.000.000 cubic centimetres) here.

Here's how I have done it.

1cm thick planking=1,5cm raw lumber, loss incorporated.
4,8mtr lenght of boat= roughly 6 meter because of scarfing + loss
2mtr width of boat=2,4 meter as it isn't flat.

Now, what I get is 240cmx600x1,5cm = 216.000 cubic centimeters.

Just to be sure, I figured I'd round up to 250.000 cubic centimetres (i.e. a quarter cubic meter).

Does my estimate seem just about right, or way off, or?

I really want to buy enough, as I don't want to run out of wood and have to buy another type of mahogany, or worse. On the other hand, I don't want to buy way too much.

What do you guys think?

Andre
#2
02-17-2006, 07:59 AM
 DanishBagger Never Again Join Date: Feb 2006 Rep: 523 Posts: 1,543 Location: Denmark
Noone? Anyone?
#3
02-17-2006, 12:28 PM
 james_r Junior Member Join Date: Feb 2002 Rep: 10 Posts: 44 Location: Toronto, Canada
It seems a little high. Post the following dimensions and with the numbers you've already given us I'll calculate the surface area of your hull:
• Length at the waterline
• Beam at the waterline
• Draft
• Height of the bow from waterline
• Distance from the sheer to the deepest part of the hull
#4
02-17-2006, 01:39 PM
 DanishBagger Never Again Join Date: Feb 2006 Rep: 523 Posts: 1,543 Location: Denmark
Quote:
 Originally Posted by james_r It seems a little high. Post the following dimensions and with the numbers you've already given us I'll calculate the surface area of your hull: Length at the waterline Beam at the waterline Draft Height of the bow from waterline Distance from the sheer to the deepest part of the hull

Very cool that is really kind of you

I havent crunched those numbers yet (still waiting for the real drawings).

It's the laura -the 20.9 ft bay sloop, scaled down to 18ft (506cms)

Length at the waterline is the same, give or take 2/8ths.

Original beam 8ft 11" (271cm), trimmed down 20 percent as well=217cms/7ft 2".

At water line (the top one, 24 inches from base), the beam is 8ft/8inches/265cm - scaled down, that is 212cm/6ft, 11.5 inches.

At 12 inches from base (the lower w.l.) the width is 3ft 4inches in the original(101.5cms), and scaled down, that gives me 81.3cms or 32 inches.

The original drawing says that stem is 3ft 3inch/99cms above base, scaled down, that is 79cms/2ft7inches, but it begins at 10 inches above base. Scaled down that is 8 inches (duh!), equaling 20.3 cms.

From sheer to base, at stanchion six, the widest one, the original says 2-6-5/77cms, scaled down that gives 61.6cms/2ft (and a quarter inch).

I'm really grateful, that you're willing to do this, and I hope I'm giving you enough information like this, for you to do it properly, so I'm not wasting your time.

I haven't done any _real_ number crunching yet, as I'm still waiting to get the A3s from the smithsonian, but this is what I can gather from the bad copy of the lines.

Edit: I forgot to add, that these numbers are all external figures, but I doubt that matters much?
#5
02-17-2006, 01:44 PM
 DanishBagger Never Again Join Date: Feb 2006 Rep: 523 Posts: 1,543 Location: Denmark
Well, as you might have noticed, in the meantime, I have decided to only downscale it by 20 percent, not 25% percent as in the original post - I figured that I "needed" the longer waterline
#6
02-17-2006, 03:13 PM
 james_r Junior Member Join Date: Feb 2002 Rep: 10 Posts: 44 Location: Toronto, Canada
I wasn't too clear about the "height of bow from waterline" measurement. What I meant was the height of the bow above the waterline. In any case I recalculated your figures from the Standard ones and used the following metric figures to calculate the surface area of your hull:

LOA 5.10m
LWL 5.00m
BMax 2.17m
BWL 2.12m
Depth of hull 0.62m
Freeboard at bow 0.55m

The hull surface area should be aproximately 13.4 sq.m or 134,000 sq. cm. This does not include the deck. From here you should be able to calculate how much extra you would need for scarfs and sawdust. I always add about 10% more to the final figure just in case but I always end up with some left over.

If any of the figures are off let me know and I'll quickly recalculate the surface area for you but don't expect an answer before Monday (early afternoon in Denmark). I try to stay away from computers on weekends.
#7
02-17-2006, 03:43 PM
 DanishBagger Never Again Join Date: Feb 2006 Rep: 523 Posts: 1,543 Location: Denmark
Thank you so very much!!

Those measurements seems about right, from what I can tell from this [crappy] copy.

The upper water-line, again from what I can tell, is indeed just under 2ft at the bows.

If I were really stupid, (which, I apparently am), I'd explain the little difference in height between the stem and the middle of the boat, that, shapewise, it would be like the whole boat was flat underneath, then, by strapping down the middle and lifting at the front, gives it the sheerline.

Anyways, thank you so ever much. 134+ around 10 percent gives me 150sq.mtrs.

About the deck: My intention is to make it out of mahogany plywood, simply because it seems easier and a whole lot easier to make waterproof than using planks (or whatever they're called when on deck).

And, just for the hell of it, I'm going to make the gaff and boom like Spirit yachts used to do them - from two pieces of plywood, making sort of a miniature park-avenue boom. They stopped doing it because they couldn't make it strong enough, but they're boats are quite a bit larger than this one.
Oh, and if they break, I'll resort to making myself some "proper", traditional, round ones instead.

Thank you so much, James.

Sincerely,

Andre
#8
02-17-2006, 03:53 PM
 james_r Junior Member Join Date: Feb 2002 Rep: 10 Posts: 44 Location: Toronto, Canada
Hmm! Just to make sure that there's no confusion - the surface area is 13,4 sq. m not 134. That works out to 134.000 sq. cm. I forgot that you use "," where we use "." and vice versa.

Quote:
 If I were really stupid, (which, I apparently am)
That's ok. I originally calculated the surface area as 1340 sq. cm. That would be ok for a toy boat but I assume that you actually want to get into it.
#9
02-17-2006, 09:32 PM
 DanishBagger Never Again Join Date: Feb 2006 Rep: 523 Posts: 1,543 Location: Denmark
Hehe, 1340 sq.cm - that would indeed be small boat. it would be quite a lot less money to the harbour master

The reason for my miscalcutlation is that the hull is going to be one cm thick, so that would also make it 134000 cubic centimetres, I somehow got that mixed up. About the "," and "." - I tend to get those mixed up, because I speak to so many different people, so I use them interchangeably.

Btw, just to be absolutely sure, if I plus 10 per cent, then I should be in the safe with regards to square meter, i.e. 15sq.metres. And from that I add what ever much I inted to make to dust, right? The reason I'm asking is, because I am what I am, I might be inclined to think that you could also mean that the sawdust is included in those 15 sq. mtrs? I think it's the former, though.

Sincerely,

Andre

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