Life jackets for boat floatations

[timddo]

My foam in the boat is looking pretty bad. Was wondering if I can buy about 15 life jackets and keep under the floors as floatations. The jackets support say 70 kg so that's 1050kg.. It's $10 each.

[fishing111]

Human body is naturally pretty buoyant, so 10 or 15 kilos will support. I don't think it would would give you 1050 kg, but others smarter than me will give a definitive answer. Still better than nothing and it would have to be way better than polystyrene.

[chris69]

The foam density in the life jackets is soft and condensation might turn them into moldy smelly floatation,double that money and shop around you might get a lot of 2 part expanding foam and do it right.

[tjotter]

I find it easier to think of foam volumes in Litres.

Using a rounded figure a life jacket might contain approx 10 litres of foam ?.
A 100 Kg human may be kept afloat with 10 litres of Foam [depending on conditions],
because a human contains lots of material that floats eg blood fat lungs[hopefullyinflated].

[tjotter]

I looked at how much Foam would be needed to increase from Basic to Level Floatation.
http://boatandjetski.com.au/Buoyancy.pdf (http://boatandjetski.com.au/Buoyancy.pdf)

Page 2 example formula is of a 425Kg Alum vessel with 135Kg Motor
& it would need a total of 0.496 cubic metres foam,
ie 496 litres.

....
If you are curious & want to use the formula on page 2
[someone please correct me if this is wrong]
I found it easier to do as 3 separate calculations, eg calc
M [Hull], then
F [Motor], then
D [Foam] density.

eg using the example of
M= 425 Kg Hull of Aluminium & a
F= 135 Kg Machinery/Motor &
D= 3.5% Density of foam [ie 1000/35 buoyancy weight]
& rounding figures.

M HULL
M= 425 Kg of Alum
K= 0.62 for Alum
..1.2 x (M x K)
so
= 1.2 x (425 x 0.62)
= 1.2 x (263.5)
= [U]316 Litres

F MOTOR
F= 135 Kg of Motor
..1.2 x F
so
= 1.2 x 135
= 162 Litres

add [M+F]
316 + 162 = 478 Litres.

D 3.5%
add on 3.5% for Density/weight of foam
478 + 3.5% = 495 Litres Buoyancy needed.


ps
I suspect the 1.2 is a safety margin ??

ps
re K= 0.62 for Alum,
I think that means 62Kg of Foam will float 100Kg of Aluminium.

[scorpo92]

Use solid pool noodles. Made of foam that isnt destroyed by fuel and can be easily cut in to places

[LittleSkipper]

My foam in the boat is looking pretty bad. Was wondering if I can buy about 15 life jackets and keep under the floors as floatations. The jackets support say 70 kg so that's 1050kg.. It's $10 each.

I must say this is the funniest if not the most ridiculous post I've seen in along time....lifejackets as foam flotation!!

What planet are you one?

[FNQCairns]

Life jackets...at least the ones I have cut apart are actually low quality foam...poly something?(pool noodles) forget now..not urethane ...but of coarse good enough for a few days in the water.

I just finished the boat foaming exercise...I re-foamed an entire 6m long wide bodied under floor tinny styled boat...bottom line and I did the looking for good options research too, although I would like to have found an alternative the only actual truly cost effective V flotation ability option is Styrofoam bought in bulk...cut to size even.

[seatime]

excellent info provided! suspect MaST have sourced it from AS 1799.1 - the standard for recreational/pleasure craft, this is the premium advise to follow :)





I looked at how much Foam would be needed to increase from Basic to Level Floatation.
http://boatandjetski.com.au/Buoyancy.pdf (http://boatandjetski.com.au/Buoyancy.pdf)

Page 2 example formula is of a 425Kg Alum vessel with 135Kg Motor
& it would need a total of 0.496 cubic metres foam,
ie 496 litres.

....
If you are curious & want to use the formula on page 2
[someone please correct me if this is wrong]
I found it easier to do as 3 separate calculations, eg calc
M [Hull], then
F [Motor], then
D [Foam] density.

eg using the example of
M= 425 Kg Hull of Aluminium & a
F= 135 Kg Machinery/Motor &
D= 3.5% Density of foam [ie 1000/35 buoyancy weight]
& rounding figures.

M HULL
M= 425 Kg of Alum
K= 0.62 for Alum
..1.2 x (M x K)
so
= 1.2 x (425 x 0.62)
= 1.2 x (263.5)
= [U]316 Litres

F MOTOR
F= 135 Kg of Motor
..1.2 x F
so
= 1.2 x 135
= 162 Litres

add [M+F]
316 + 162 = 478 Litres.

D 3.5%
add on 3.5% for Density/weight of foam
478 + 3.5% = 495 Litres Buoyancy needed.


ps
I suspect the 1.2 is a safety margin ??

ps
re K= 0.62 for Alum,
I think that means 62Kg of Foam will float 100Kg of Aluminium.