Zodiac ribo 420 screw question

[dij66]

Hello boys and girls,

I have a zodiac ribo 420 whichis the solas version with an orange hull and red tubes.

There are a number of stainless steel screws in cups, they are about 25 - 30mm long, they are in the holes as shown in the photos.

My question is what function do they perform as they screw through the fibreglass hull but there is a void underneath and I am struggling to ascertain their purpose.

Many thanks

[dij66]

sorry to bump this but am desperate for a reply. The boat is back in the water this weekend and I need to know whether to fill the holes or not

[Ross from Oz]

They hold the extra flotation tubes that go either side internally