Hi neo.. welcome to the forum.
I saw your first post which was basically asking the same question..but I didn’t answer it because I don’t know anything about the Hydroforce brand of SIB.
http://www.rib.net/forum/f50/sunsail...elp-74836.html
However as on one else has offered any advice..here are my thoughts.
I have done a quick search and note that HydroForce do make an airfloor and also an Aluminium floor in the 3.8m size SIB. Presumably you would be purchasing the floor..stringers and inflatable keel from them to do the conversion? If so..they will certainly be able to give you the answer you are asking.. ie..is it a straight swap.
If you are wondering about putting a solid floor into your hydroforce from another brand of SIB..or perhaps making a home made one.. its worth remembering that your safety is dependent on the integrity of the boat ... if you are at sea and the waves get up. As such it is not something I would do but that doesn’t mean others may not do it.
If its of any help .. I doubt if an airfloor would just slot into place on my solid floored Quicksilver Brand SIB ..so perhaps its not quite so simple as a straight swap ? There are no extra fittings in a SIB with a solid floor.. but it has a tight fit under the tubes when pressurised so it can’t come out..and its overall length is pretty exact too so it stretches the tubes out to their correct length.
Hope that helps some ..My opinion only .. others may have different opinions or even some experience with the Hydroforce Brand of boat