Riva Superamerica 48

Discussion in 'Powerboats' started by Ithaka, Dec 9, 2023.

  1. Ithaka
    Joined: Dec 2023
    Posts: 2
    Likes: 1, Points: 3
    Location: Sozopol, Bulgaria

    Ithaka New Member

    Could you help me evaluate the performance and safety of the Riva Superamerica 48 in heavy seas, say typical east Mediterranean short waves, strong winds... say gale force winds? Here is my experience with the boat so far and some of the questions I have been pondering:

    - Old but solid design, mine was built in 1980
    - 48 ft overall, 41 ft LWL, current displacement 14 tons, 12 degree deadrise angle
    - In my opinion, minimal superstructure compared to other examples, see photos
    - Powered by 6CTA 450 Cummins, max speed 31 knots (approx. 1.2 tons lighter than originals)
    - Original engines were VT903s, leaflet max speed was 26 knots
    - Has one real fully watertight bulkhead behind the crew cabin in front
    - Two bulkheads (in front and behind engine compartment) can be made watertight with minimal effort (I have not seen many designs in this size that can have three real watertight bulkheads)

    The boat has been in medium weather in the Aegean sea (force 6-7) on long passages. When running into the waves, I need to reduce speed to prevent pounding but otherwise no issues. Sometimes, a bigger wave could swamp the whole boat (bow is pretty low) but I never felt uncomfortable. Still, it was hard to make more than 11-13 knots to prevent jumping from one wave to the next. When running in beam seas (force 4-5), the boat would roll a lot at times but snaps back fairly quickly. A higher speed could be maintained 14-15 knots.

    Some of my questions. Would another boat design of similar displacement give me significantly higher speeds or higher margin of safety? What are the dangers when seas build up? If a wave rolls the boat, will it come back immediately? It looks from the design that it has fairly good stability. How quickly would the engine compartment flood through the side air intakes? It looks as if even inverted, the intakes will be above the water? Is this really a concern? Are there ways to close them automatically or may be find alternative source of air in heavy weather? Would it make sense to install tanks in the bilge areas along the keel and in the lazarette, all below the waterline, that could be used either for fuel or as water ballast to improve stability and trim? Especially, since I have 1.2 tons of displacement headroom due to the lighter engines. Is this ever done? Why or why not?

    Thank you. Riva 48 Hull.jpg
    Last edited: Dec 9, 2023
    bajansailor likes this.
  2. TANSL
    Joined: Sep 2011
    Posts: 7,349
    Likes: 690, Points: 123, Legacy Rep: 300
    Location: Spain

    TANSL Senior Member

    Welcome to the forum.
    Beautiful boat, congrats.
    To answer some of your questions, with concrete data, not with simple opinions, it would be necessary to study the plans of the boat and carry out quite a few calculations. Do you have the plans?
    bajansailor likes this.
  3. Ithaka
    Joined: Dec 2023
    Posts: 2
    Likes: 1, Points: 3
    Location: Sozopol, Bulgaria

    Ithaka New Member

    Thank you. I do not have the plans but I will take opinions :)

  4. bajansailor
    Joined: Oct 2007
    Posts: 3,545
    Likes: 1,521, Points: 113, Legacy Rep: 37
    Location: Barbados

    bajansailor Marine Surveyor

    If you are not already a member of the YBW Forum in England, then please do sign up and copy your post above to their Motor Boat Forum -
    Motor Boat Forum https://forums.ybw.com/forums/motor-boat-forum.14/

    I can (almost certainly) guarantee you that you will receive an enthusiastic response on this Forum - there are quite a few posters on there who have similar sized motor boats in the Mediterranean.
    Including one gentleman who has an Itama - he will find your question below quite irresistible, and he will probably tell you that an Itama is far superior. :)

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