fiberglass hull thickness

Discussion in 'Boat Design' started by Gianf1041, Dec 18, 2019.

  1. rxcomposite
    Joined: Jan 2005
    Posts: 2,087
    Likes: 216, Points: 63, Legacy Rep: 1110
    Location: Philippines

    rxcomposite Senior Member

    Cb checks out Ok. Looks like a light displacement boat with high freeboard. Depth=Draught+Freeboard.

    Generally draught is 0.6 of depth but you have a high freeboard. Old sailing boats are like that to allow for more heeling angle or to keep the deck dry in adverse weather.

    As I have said before, divide the longitudinal into sections. Equal parts better but if you seek minimum, then designate first the subdivisions that needs to be isolated. 1. Collision bulkhead, Steering bulkhead, Engine room bulkhead (the red part). Usually the engine room bulkhead is extended and becomes part of the Phouse or cabin. Collision bulkhead should extend all the way to main deck. Add non watertight bulkhead/frames (the green part) if spacing is too large. As a rule, watertight bulkhead cannot be more than 6 m. apart or the longi length not more than 2m.

    Go to section view and identify keel width, width of bottom, width of side, by following Gerr's or ISO definition. Divide first by two for the stiffeners. Now you can get the panel size, the long (a) and the short (b) of it. It is the size bounded by the stiffeners/frames. That means it is the inside part. The a divided by b is the ideal ratio of 2 or more. You can go lower than 2 but that complicate things because there is an AR factor needed.

    Now that you have the panel size. you can apply whatever method you are using. If the panel is too large, resulting to very thick panel, you can go back again and add more divisions either longitudinally or transversely.

    Good luck.

    Attached Files:

    Last edited: Feb 16, 2020
    bajansailor likes this.

  2. Gianf1041
    Joined: Sep 2018
    Posts: 58
    Likes: 4, Points: 8
    Location: italy

    Gianf1041 Junior Member

    Thank you, the attachment helps me better to understand, I have some difficulty in translation but I think I'm on the right track.
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.