# calculating displacement for 16 by 35 houseboat

Discussion in 'Boat Design' started by fireguy, Feb 7, 2010.

1. Joined: Feb 2010
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Location: bahamas

### fireguyNew Member

I want to build a 16 by 35 foot houseboat, The hull is its flotation (not pontoons). How do I determine how deep to make it to float the home.

2. Joined: Jan 2010
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Location: Chicago, IL, USA

### ObsessionJunior Member

1 cubic foot of fresh water weighs 62.4 lbs
1 cubic foot of salt water weighs 64 lbs

You need to displace the weight of water = to the weight of your houseboat + all dead and live loads aboard + a reasonable margin of safety (you don't want the deck right at the water level so any wave splashes aboard). Also be sure you think about your center of gravity/mass so she sits level.

3. ### tugboatPrevious Member

Fireguy- are you building a barge type? if so Obsession has the calcs down but ill review it for you anyway
.
L X W X DEPTH of hull = volume x cubic ft of water = displacement.

. SO if your hull is 16 x 35 x 2 ft deep( i didnt know your depth of the hull. assuming its box shaped and square)- i get 1120 cubic ft. then times that by 1/2 since you want your houseboat to have some freeboard. so that brings you waterline down to half your barge depth. you would get 560 cubic ft thats your volume..now to figure out weight of what your barge hull can handle--times 560 by either freshwater or salt water in cubic ft...for wherever you plan to use the hull...

ill use freshwater for the example- 560 x 62.4 lbs per cubic ft = 34944!! a good solid foundation. thats over 16 tons you can have on your houseboat and still bring it to the waterline...btw- in practice you can edge out a bit more weight. remember to keep the walls low. so the wind doesnt blow it around too much...or if you build two stories keep the cabin smaller than your perimeter dimensions. i lived on my own designed houseboats for four years..you are gonna love it!!

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