SmallBoats.com wrote:
On Tue, 19 Aug 2008 16:25:56 GMT, Buzzihd Beah
wrote:

In article ,
Short Wave Sportfishing wrote:

On Tue, 19 Aug 2008 06:17:37 GMT, Buzzihd Beah
wrote:

Gentlemen,

Say I want to make sure my boat does not sink even if it's full of
water.

It weighs 4330 pounds. Does that mean I have to add about two cubic
meters of foam somewhere? There isn't enough space for that much.

Or can I somehow take into account the buoyancies of fiberglass, fuel
tank, engine, and all the other stuff? Is there a method to calculate
things like that?
Yep - ABYC H-5 (Capacity) and ABYC H-8 (Swamped Bouyancy).

What you want is ABYC H-8.

H-8.7.2 Calculations - Basic Flotation
H-8.7.2.1 Perform the following steps to calculate the volume of
flotation material required to support the swamped boat (Fb), the
submerged propulsion equipment (Fp), the persons capacity (Fc1), and
the dead weight (Fc2).
H-8.7.2.1.1 Step 1: Determine the flotation needed to support the
swamped boat (Fb).
Formula: Fb = (Wh x K1 + Wd x K2 + .69 We) ÷ B
Where
Wh = dry weight of hull, i.e., everything below swamped water line
Wd = dry weight of deck and superstructure
We = dry weight of factory installed equipment, hardware, and
accessories
K1 and K2 = conversion factors for materials
B = buoyancy of flotation material in pounds per cubic foot


EXAMPLE
Calculate the flotation material needed to support the swamped boat
(Fb).
Assume
Wh = weight of hull (fiberglass) = 600 lbs.
Wd = weight of deck and superstructure (plywood) = 120 lbs.
We = weight of equipment, hardware and accessories = 50 lbs.
Fb = ((Wh x K1) + (Wd x K2) + (0.69 x 50)) ÷ B
Fb =((600x0.33)+ (120x-0.81) + 0.69x50)) ÷ 60.4*
Fb = (198 - 97.2 + 34.5) ÷ 60.4
Fb = 135.3 ÷ 60.4
Fb = 2.24 cu. ft.

However, depending on how old your boat is (and/or how big) CG
regulations require level floatation.
Yes! This is what I was looking for. Thanks!
The boat is 1988. I doubt level flotation is an option - there isn't
almost any space around the engine to fill with foam.

Get some 4" sheets of closed cell and put it on the outside of the
transom, make a nice back rest for the swim platform Couldn't
hurt...


Oi! Oi! Oi!

On Tue, 19 Aug 2008 16:30:10 GMT, Buzzihd Beah
wrote:

The only "flotation
device" is the 160 gal fuel tank (if I'd keep it nearly empty). The
other possible one is the toilet, if I'd make a new door and find a way
to seal it.

You would need some attention to avoiding simple hydrostatic crush.

Casady

"Buzzihd Beah" wrote in message
...
In article ,
Short Wave Sportfishing wrote:

On Tue, 19 Aug 2008 06:17:37 GMT, Buzzihd Beah
wrote:

Gentlemen,

Say I want to make sure my boat does not sink even if it's full of
water.

It weighs 4330 pounds. Does that mean I have to add about two cubic
meters of foam somewhere? There isn't enough space for that much.

Or can I somehow take into account the buoyancies of fiberglass, fuel
tank, engine, and all the other stuff? Is there a method to calculate
things like that?

Yep - ABYC H-5 (Capacity) and ABYC H-8 (Swamped Bouyancy).

What you want is ABYC H-8.

H-8.7.2 Calculations - Basic Flotation
H-8.7.2.1 Perform the following steps to calculate the volume of
flotation material required to support the swamped boat (Fb), the
submerged propulsion equipment (Fp), the persons capacity (Fc1), and
the dead weight (Fc2).
H-8.7.2.1.1 Step 1: Determine the flotation needed to support the
swamped boat (Fb).
Formula: Fb = (Wh x K1 + Wd x K2 + .69 We) ÷ B
Where
Wh = dry weight of hull, i.e., everything below swamped water line
Wd = dry weight of deck and superstructure
We = dry weight of factory installed equipment, hardware, and
accessories
K1 and K2 = conversion factors for materials
B = buoyancy of flotation material in pounds per cubic foot


EXAMPLE
Calculate the flotation material needed to support the swamped boat
(Fb).
Assume
Wh = weight of hull (fiberglass) = 600 lbs.
Wd = weight of deck and superstructure (plywood) = 120 lbs.
We = weight of equipment, hardware and accessories = 50 lbs.
Fb = ((Wh x K1) + (Wd x K2) + (0.69 x 50)) ÷ B
Fb =((600x0.33)+ (120x-0.81) + 0.69x50)) ÷ 60.4*
Fb = (198 - 97.2 + 34.5) ÷ 60.4
Fb = 135.3 ÷ 60.4
Fb = 2.24 cu. ft.

However, depending on how old your boat is (and/or how big) CG
regulations require level floatation.

Yes! This is what I was looking for. Thanks!
The boat is 1988. I doubt level flotation is an option - there isn't
almost any space around the engine to fill with foam.

Level floatation is only required in 20' and under boats.

On Aug 19, 5:55*pm, "Calif Bill" wrote:
"Buzzihd Beah" wrote in message

...





In article ,
Short Wave Sportfishing wrote:

On Tue, 19 Aug 2008 06:17:37 GMT, Buzzihd Beah
wrote:

Gentlemen,

Say I want to make sure my boat does not sink even if it's full of
water.

It weighs 4330 pounds. Does that mean I have to add about two cubic
meters of foam somewhere? There isn't enough space for that much.

Or can I somehow take into account the buoyancies of fiberglass, *fuel
tank, engine, and all the other stuff? Is there a method to calculate
things like that?

Yep - ABYC H-5 (Capacity) and ABYC H-8 (Swamped Bouyancy).

What you want is ABYC H-8.

H-8.7.2 Calculations - Basic Flotation
H-8.7.2.1 Perform the following steps to calculate the volume of
flotation material required to support the swamped boat (Fb), the
submerged propulsion equipment (Fp), the persons capacity (Fc1), and
the dead weight (Fc2).
H-8.7.2.1.1 Step 1: Determine the flotation needed to support the
swamped boat (Fb).
Formula: Fb = (Wh x K1 + Wd x K2 + .69 We) ÷ B
Where
Wh = dry weight of hull, i.e., everything below swamped water line
Wd = dry weight of deck and superstructure
We = dry weight of factory installed equipment, hardware, and
accessories
K1 and K2 = conversion factors for materials
B = buoyancy of flotation material in pounds per cubic foot

EXAMPLE
Calculate the flotation material needed to support the swamped boat
(Fb).
Assume
Wh = weight of hull (fiberglass) = 600 lbs.
Wd = weight of deck and superstructure (plywood) = 120 lbs.
We = weight of equipment, hardware and accessories = 50 lbs.
Fb = ((Wh x K1) + (Wd x K2) + (0.69 x 50)) ÷ B
Fb =((600x0.33)+ (120x-0.81) + 0.69x50)) ÷ 60.4*
Fb = (198 - 97.2 + 34.5) ÷ 60.4
Fb = 135.3 ÷ 60.4
Fb = 2.24 cu. ft.

However, depending on how old your boat is (and/or how big) CG
regulations require level floatation.

Yes! This is what I was looking for. Thanks!
The boat is 1988. I doubt level flotation is an option - there isn't
almost any space around the engine to fill with foam.

Level floatation is only required in 20' and under boats.- Hide quoted text -

- Show quoted text -

I noted that earlier, but in a Toleman, or even a Simmons Skiff, I
would suggest getting as close as possible to it..

In article ,
(Richard Casady) wrote:

On Tue, 19 Aug 2008 16:30:10 GMT, Buzzihd Beah
wrote:

The only "flotation
device" is the 160 gal fuel tank (if I'd keep it nearly empty). The
other possible one is the toilet, if I'd make a new door and find a way
to seal it.

You would need some attention to avoiding simple hydrostatic crush.


I am not sure I was serious... Doesn't seem to be doable, you are
right.

In article ,
hk wrote:

Buzzihd Beah wrote:
In article
,
wrote:

On Aug 19, 2:17 am, Buzzihd Beah wrote:
Gentlemen,

Say I want to make sure my boat does not sink even if it's full of
water.

It weighs 4330 pounds. Does that mean I have to add about two cubic
meters of foam somewhere? There isn't enough space for that much.

Or can I somehow take into account the buoyancies of fiberglass, fuel
tank, engine, and all the other stuff? Is there a method to calculate
things like that?
What year and size is your boat? Newer boats already are required to
have floatation. Usually it's expanding foam under the floor and in
the sides. US Composites has a good expanding foam.

This one is 1988, 25.5', and there is no foam in it. The only "flotation
device" is the 160 gal fuel tank (if I'd keep it nearly empty). The
other possible one is the toilet, if I'd make a new door and find a way
to seal it.


It is unlikely you are going to be able to stash enough flotation in a
boat that large to keep it floating upright and level if it is holed or
swamped. Keep it insured, be careful, and spend enough to buy first
class lifejackets and other safety gear.

There are several small compartments that can be filled with foam
without doing much harm to anything, and for now I just want to make a
preliminary calculation, to see if I can get close to flotation. Not
necessarily upright and level.