AHA! you mean the 'Rivarama'! 😉
Have a look here one of these might do.
https://www.pinterest.com/pin/843650942667212823/
or
https://www.google.de/search?q=Riva+Rivarama+model+boat+plan&dcr=0&tbm=isch&source=iu&ictx=1&fir=4AgYifsQDHEO4M%253A%252CuxM9mWCVuc1e0M%252C_&usg=__N6MkQDGWZNJL9e_0bm7jnDztxvA%3D&sa=X&ved=0ahUKEwiA7bLzgcnYAhWE3KQKHadxDxoQ9QEIODAE#imgrc=4AgYifsQDHEO4M:
Cheers Doug 😎

Thank you so far.
I have to clearify; it's the RIVARMA I'm looking for plans for. The auqarama is no problem to get plans for, but it's not what I want.

here, but that Plan cost 94,99 € ( italian language )

http://shop.vth.de/riva-aquarama-in-italien-sprache.html

After original documents completely revised plan. Completely dimensioned drawings from the original with complete interior. All ribs individually drawn.

Hi Jonand, welcome aboard 😉
Try here for your plans
http://www.john-tom.com/ForSale/ForSaleModelling.html#RivaPlans
or here
http://www.cornwallmodelboats.co.uk/acatalog/mar2552.html
Hers a set for free!
http://freeshipplans.com/free-model-ship-plans/riva-aquarama-scale-model-plans/
Happy building and sailing, Doug 😎
PS if you have trouble downloading the free plans send me your e-mail by Private Message and I'll mail you the Zip file. 👍