Thickness of RIB hull

[elbarcolutra]

Hi
We have a used ~20 ft french or canadian zodiac RIB. We'd like to add a platform across the bow as a step, and a fiddle underneath to keep the anchor under the platform. I've never modified a RIB, and am not sure how to tell the thickness of the hull. How do I know what's between the inside and outside of the hull? What size and type screws are appropriate for making this type of modification? Can anyone point me to a source of general information for attaching things to RIBs?
Thanks

[Poly]

Do you need to know the thickness of the hull or just the deck?
Is it a flat deck (probably ply wood encapsulated in resin) or is it moulded?

[office888]

Originally Posted by elbarcolutra

Hi
We have a used ~20 ft french or canadian zodiac RIB. We'd like to add a platform across the bow as a step, and a fiddle underneath to keep the anchor under the platform. I've never modified a RIB, and am not sure how to tell the thickness of the hull. How do I know what's between the inside and outside of the hull? What size and type screws are appropriate for making this type of modification? Can anyone point me to a source of general information for attaching things to RIBs?
Thanks

Post some pictures?

Nominal thickness of the hull is probably somewhere between 8mm and 12mm.

Hull will not be cored.

Deck will be cored, likely.