Buoyancy Calculation - Permeability % for bottles ?

[silverspiders]

I am doing a buoyancy calculation as part of a rebuild I am planning. The existing boat has bottles, which I plan to replace with Sondor foam.

I have the ''illustrative buoyancy calculation example'' from SAMSA, which shows the permeability % for bottles as 60%. Is this a standard ?

The reason why is I have used the old bottles and repacked each section that will be filled with Sondor foam. So, I have the volume of bottles each space can take, I want to now work out the increased buoyancy I will achieve by using Sondor instead of bottles.

Hope this makes sense ...

 

[willem wikkel spies]

60% is the minimum required buoyancy needed off shore.
so if you filled the hull with sondor and it comes to 75% you are okay.
thus 15% above required minimum.

but remember that buoyancy is about to have a level floating boat when capsized.
so you will need to calculate if the buoyancy in the aft of the vessel will give you a level floating platform.

 

[Scomberomorus]

Permeability

Loosely packed bottles 50%
Tightly packed bottles 60%
Closed cell PU foam 100%

In order t calculate the buoyancy fitted the dimensions of the vessel are required, which should be on your existing certificate. I can do the calc for your if you provide necessary dimensions.

 

[silverspiders]

Thanks,

Boat did not have a buoyancy certificate, but another member who has the same boat has kindly agreed to give me a copy of his certificate so that I have something to work from.

Once I have it, I'll do the calc and send it to you - I'd appreciate it if you could check I have done it correctly.

Thanks,
Ryan