How to Water Ballast for Kayak for no capsize

I will build a generic oru kayak and I have 80 miles of route to complete. I will be at black sea , istanbul to bulgaria with following the coast line. I am looking for additional safety , a water ballast. How many liters and where to locate it ?

 

I suggest a bunch of about this size plastic bottles.https://www.amazon.com/Schweppes-DPSUSC800020345-Club-Soda/dp/B00061EOIC/ref=sr_1_10_f3_0o_lucky?adgrpid=1229254989193588&dib=eyJ2IjoiMSJ9.e-MjwHzhxGVIdGY1kPgivXYPK1iIel0yl9GH7D-gNe4a1hbRIEBCNQA5GUSvRjH8qsBJh80Eks4lTCi2FMBzQhs6xHHXIzwWoZtHh_fjF0YSkgGRWpN9BcjP4oIJYY1beqbl52EJNuevZJ88Qu5vpZ0OZcUwdzpWP0BVBFpMv9Tua9GrH-0PwQSCowFf-YRtFrn3WqfM7zQ211muP5V7aBt2Z-SmbOdNKiXsRD2zW_1YofaMwF2Fdg2R8XPTEKWkf3lbgt1EnAQSvB-QxYRCC0aXsckZuu19DUPp05JmDQs.3bmRdZK0t-NbN01nukP2V0dtKtDpL1OR9M3qKc2Qzhg&dib_tag=se&hvadid=76828566859987&hvbmt=bp&hvdev=c&hvlocphy=88155&hvnetw=s&hvqmt=p&hvtargid=kwd-76828681820459:loc-190&hydadcr=21972_13439066&keywords=bottled+club+soda&qid=1732841786&sr=8-10

I think you will find that a little ballast makes a big change, and after a few practice you will not want it. Maybe fill the bottles 1/2 of water and lay flat just behind seat and under knees, and secure with velcro straps. 1/2 full they will also be flotation.

Edit: figure 80 miles you will want some drinking water (and other supplies). Start out with "water ballast" and reduce it as you gain skill.

 

Bad idea. Focus on paddling and self-rescue technique.
Study how arctic hunters survived in kayaks.

 

Very bad idea.
One must learn and experience safe kayaking practices,
have safe kayaking equipment, and know how to use it.
Choosing an appropriate kayak design is also very important for stability.

Do you have all that available to you?

 

I would put the water outside for maximum safety.