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[kms]

Is there a fairly simple formula to figure out the inside sq. feet of a boat?

kms

[jbarros]

I've gotten fairly reliable results by taking the amount I need, and subtracting about 20%.

On a boat, square footage is at best misleading. Things are stacked to take take advantage of the walls, and so volume probably closer to what you're looking for. And that, unfortunately, has a lot to do with the shape of the hull, and is not really calculable from LOA or other common measures. The same problem would apply to getting Square feet from beam and LOA as well.

Sorry

-- James

[ronspiker]

In a nut shell NO. You are looking at finding the "volume of an Irregular Object" The easiest way to do that is the "water displacement method". You place the object in a large tub, submerge and measure how much water was displaced. Personally I don't want to submerge my sailboat. However If you assume the hull is part of a sphere you could calculate what part of a sphere it is which would give an approximate volume.

[nuffoftexas]

Originally Posted by kms

Is there a fairly simple formula to figure out the inside sq. feet of a boat?

kms

I'm assuming you mean CUBIC feet, or as above, "volume". Would this be for heat/ac? I believe CruiseAir has a little table on their website to help you determine approximate cubic feet of your vessel. Good luck.

[klem]

Assuming you want the volume, the number that you are looking for is the gross tonnage. Commercial vessels will actually state their tonnage as required by law (they include net tonnage as well which is the cargo carrying capacity of the hull, not the total volume). If the boat that you are looking at does not have a published gross tonnage number, then you can get an approximate idea from the formulas that the CG uses. I don't have them with me right now but a quick internet search should help. The inputs are length, beam, draft, vessel type if I remember right. If a ton isn't a unit that you can visualize, it is straight forward to convert it into cubic feet or gallons or another unit.

[GeorgeB]

Wouldn’t you just fill the cabin with ping pong balls, count them, and then multiply the sum by .001122685?

[CaptainForce]

If your purpose is to make a comparison with the square footage figures for housing; then, the easiest approximation is to calculate the sum as one half of the length times the beam. This figure is admittidly approximate and will vary with the design, cockpit size, etc, but it can be a quick generalization for estimating square feet available as living space. 'take care and joy, aythya crew

[scottyt]

i like the ping pong ball idea better than my idea

my idea is get a box that is one cubic foot, then start filling the boat with foam packing peanuts using the box. just count how many full boxes it takes, just dont lose count

or a gallon bucket of water then lots of refills of the bucket because it would be easier to get out, just do it on land and drill a hole in the bottom when done to drain it

[Boasun]

Originally Posted by scottyt

i like the ping pong ball idea better than my idea

my idea is get a box that is one cubic foot, then start filling the boat with foam packing peanuts using the box. just count how many full boxes it takes, just dont lose count

or a gallon bucket of water then lots of refills of the bucket because it would be easier to get out, just do it on land and drill a hole in the bottom when done to drain it

Now you know why this person isn't a naval designer...

[peptobysmol]

OR... you could do the skunk test. Release a small amount of "Skunk Scent" in the most forward part of the V-berth. Have someone in the aft part of the boat time the release and measure how long it takes to smell the "scent". We all know that gases expand at a constant rate. Factor in the temperature and calculate the rate of expansion. Badda Boom there it is!

You may need to repeat the test for validity and reliability.