Help with Quilt Dimensions

[JW]

I’m making a synthetic insulation quilt, but am not sure what dimensions to make it. I’ve read all the relevent threads here (Fornshell’s tunic, 12oz. summer quilt, newb quilt, etc). Bill’s pattern and numbers are very helpful, but I would like some more beta.

Can someone with Ray-Way instructions plug my numbers in and post what dimensions their pattern recommends? Or post your own opinions based on my specs below.

I want to make the quilt fit me as efficiently as possible, allowing for a micro-puff jacket underneath and puffy pants, but not overly roomy. I can take a trim fit. I have a nunatak arc specialist down quilt (which I’ve measured, but being down it is apples to oranges).

Also, I would like the dimensions that apply to an experienced quilt user, as the newb pattern sizing is oversized for a margin of error.

I am 5’8″, 155lbs. with a 48″ shoulder girth (measured laying down, arms at sides, at widest point around outside of arms at shoulder joint, tee shirt on only).

Thanks!

[david chan]

One point which fooled me for quite a while is that “girth” varies depending on whether you lie on your back or your side.

Lie on your back and measure from ground on your left side, over your body and down to ground on your right side. Now repeat the measurements lying on your side. Jhaura, if that 48″ was measured with you on your back, I’ll bet it’s more on your side.

[JW]

David,

Thanks for that point. I measured laying on my back. One note by girth I mean circumfrence, all the way around as opposed to from ground over as you mention. I primarily sleep on my back as well.

Here are the measurements based on your comment:

“from ground on your left side, over your body and down to ground on your right side”: 29-30″

“repeat the measurements lying on your side”: 41-42″

[Peter McDonough]

In case anybody was wondering how much down to put in a quilt, I worked out the following.

This is a way to find out the exact quantity of down needed to fill a quilt. The formulation shown below is good for a 2 inch thick layer revolved around a 2 foot radius.

The basic idea is to determine the area between the two lines I used to construct a basic quilt shape and revolve that area PI radians around the x-axis.

QUILT EQUATIONS
Foot:
y=x^(.5)+1
y=x^(.5)+1.167

Body:
y=0.0283x+1.83
y=0.283x+2

Area/Volume Calcuation
(S will be used as integral sign)

Volume =
=(3.14/2) { S (x^(.5)+1.167)^2-(x^(.5)+1)^2 + S (0.283x+2)^2-(0.0283x+1.83)^2}

The first integral is evaluated from 0 to 0.723 and the second is from 0.723 to 6.

Volume = (3.14/2)(0.3985 + 3.60654) = 6.29109 ft^2

Fill Calculation

6.29109(12^3) = 10871 cubic inches

10871 / 800 = 13.6 oz

It should be simple to replace thickness layer with another thickness(like 1 inch or 1.5 inches), or to make the sleeping bag longer or shorter than 6 feet(just change the linear slope so that it intersects that point).

I hope this is useful for you guys.

[Author]

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