G'day,

It is not that long (25% of the boat length), and apparently does not
need any more than it has. On Solitarry, there is a couple of 100mm
wide 450 gsm uni glass layers along the gunwhales and keel but this is
considerably narrower than Vis.

regards,
Rob

On Thu, Feb 5, 2009 at 6:51 PM, Robert <cateran1949@...> wrote:
> I was wondering about the side loads and compression loads on the long
> lee bow and whether some extra is needed for these.
>
> --- In harryproa@..., Rob Denney <harryproa@...> wrote:
>>
>> G'day,
>>
>> I have not read Gerr's book, but he is highly recommended. According
>> to our engineer he is way off. One layer of 600 inside and out,
>> doubled up on the inside between the beams is his recommendation. For
>> wider boats (1.6m vs 1m of Vis) with schooner rigs rather than one
>> mast in the middle, the second layer can be eliminated.
>>
>> This is a good indication of the reduced loads on boats with
> unstayed masts.
>>
>> I think Gerr is over simplified as there are too many variables and
>> other ways of increasing strength/stiffness than just the skin
>> laminate.
>>
>> regards,
>>
>> Rob
>>
>> On Wed, Feb 4, 2009 at 1:35 PM, Robert <cateran1949@...> wrote:
>> > -This seems too much glass. Maybe that on the bottom, but the rest
>> > about half that except maybe between the beams on the lw hull. The
>> > rest of the boat has very little in the way of sailing loads.
>> > I was looking at 600g glass for the skins of a 50'/32'Harry but was
>> > considering an extra layer on the bottom for abrasion resistance. I
>> > was also looking at either 10 or 12mm core, eeven considering double
>> > layers of 6mm for tight bends, but Rob reckons I can probably get away
>> > with not needing to do this-- In harryproa@..., Gardner
>> > Pomper <gardner@> wrote:
>> >>
>> >> Hi,
>> >> I finally got hold of a copy of Dave Gerr's "Elements of Boat
> Strength",
>> >> which looks to have lots of good information, but it states that is
>> > really
>> >> is not for multihull design, so I am not sure what to use and what to
>> >> ignore. From the various equations he lists, adjusted as best I can
>> > for a
>> >> proa design, it seems that a 50' proa hull for something like
> Visionarry
>> >> should be built with 3 layers of 600gsm fiberglass cloth on the
>> > outside and
>> >> 2 layers on the inside, with a 14mm core. Is that similar to the
> actual
>> >> construction? If not, please correct me. If you could explain the
>> >> differences, because of the proa design or my limited undertanding,
>> > I would
>> >> be grateful.
>> >>
>> >> Thanks,
>> >>
>> >> - Gardner
>> >> York, PA
>> >>
>> >
>> >
>>
>
>