# SWAMP TEST - Required reserve buoyancy?

Discussion in 'Stability' started by Bala5278, Feb 27, 2018.

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1. Joined: Feb 2018
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### Bala5278Junior Member

Hi,

I'm going to do a swamp test for 5.5 m motor boat which is under construction (With class), would like to know how to calculate the minimum required reserve buoyancy (To fill low density foam). So that it will be helpful to decide the foam volume and the boat will pass the swamp test. ISO 12217-3 was complicated and I didn't get any clear figures from it, any help would be grateful.
Thank you

Regards,
Bala

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### TANSLSenior Member

It would be necessary to calculate, by the boat's body lines plan or a 3D model of it, how it floats when, with the weights indicated in Appendix B.2 and B.3, the boat is heeled until the top of the gunwale is submerged 0.1-0.3 m. Add volume filled with foam until the boat complies with Appendix B, chapter B.3.5

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### Bala5278Junior Member

Hi TANSL ,

Thanks for your reply, are you mentioning this from ISO 12217-3 ? because B2,B3 is about the downflooding angle there.

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### TANSLSenior Member

Yes, I am referring to ISO 12217-3: 2002. Maybe it's outdated, a new version has appeared and I have not noticed.
In my version the chapters are the following:
B.2 Test condition
B.3 Swamped stability test
B.4 Swamped buoyancy tests

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### TANSLSenior Member

You're right, there's a February 2016 rule that I've forgotten. Let me review it and I will give you an answer, if I am able to understand it.
ISO standards for small boats are never easy.

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### TANSLSenior Member

OK, apparently what the 2016 standard says in its Annex C is exactly the same as what the 2002 rule said in Annex B.

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### Bala5278Junior Member

Yes I have a different version, but I got your point. So, as far as I understood I have 90 Hp so from ISO they have asked to replace it with 220.5 kgs ,and 8 crew member for design category C. So for that its 180d which is approx 200 kgs if I use Lead.
Engine + Control Weight - 220.5 kgs
As per Load test C.4.3 - 200kgs ( 180d)
Boat weight - 300 kgs
So the total buoyancy required is for 220.5+200+300 =720.5 kgs ... am i right , atleast is the concept what i got is right?

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### TANSLSenior Member

With all those weights you have to study if the boat heeled, for example 4 degrees (less than 5 degrees) only submerges the gunwale between 0.1 and 0.3 m. If you submerge more, you must add flotation reserve volume.
In a trial/error process you can determine the volume that you must add to meet that requirement.

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