G'day,

Aroha has 600mm/2' beam clearance, beams are 200 high x 300 wide (8" x
12") waterline beams are 750 and 500mm (30" and 20").

I have not sailed on Aroha, so can't comment on the accuracy of these
numbers, nor how well it works. I would prefer more lee hull beam
clearance,and would see if the beams could be smaller. Probably go
with a mostly solid bridgedeck to help with this.

Only other change would be to make it from panels, if I was paying for
it. John in China is busting to give you a quote. Any idea when you
will have something for him?

regards,

Rob

On Mon, May 4, 2009 at 9:13 PM, Gardner Pomper <gardner@...> wrote:
>
>
> since my design turned out to be practically identical to harry in
> length, width and weight, I would like to check against that design.
> Can you tell me what the height is above the water for the beams, and
> about what the size of the beams is, since I am just using 1 foot
> squares for placeholders now?
>
> Also what is the waterline beam of each hull?
>
> Would you change any of that is you were redesigning harry now?
>
> Thanks
> - Gardner
>
> On Monday, May 4, 2009, Rob Denney <harryproa@...> wrote:
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>> G'day,
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>> The weight transfer does not happen until the breeze is pretty strong,
>> and the speed exceeds the hull speed of a short, fat hull very
>> quickly. eg, the 33' windward hull on Rare bird has a hull speed
>> (1.34 * the waterline length, in feet) of 7.6 knots, which it gets to
>> in under 10 knots of breeze, but the windward hull barely lifts at 20
>> knots of wind speed when the boat is capable of 15 knots plus, at
>> which speed the drag of the short hull would be immense.
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>> regards,
>>
>> Rob
>>
>> On Mon, May 4, 2009 at 4:37 PM, jrwells2007 <jrwells2007@...>
>> wrote:
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>>> Rob, I have read somewhere that cats and tris aim for a minimum of 8:1 to
>>> prevent stern squatting in the manner of a mono-hull. For the ww hull an
>>> 8:1
>>> would have lower surface area for a given displacement than an 11:1 so
>>> less
>>> resistance at low speeds. At higher speeds some of the displacement of
>>> the
>>> ww hull would be carried by the lw hull and therefore the greater wave
>>> making resistance of 8:1 would be less of a factor. Are there other more
>>> important considerations such as drag on the steering?
>>>
>>> Longer and skinnier is still better for speed probably.
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>>>> The longer and skinnier the better, but as long as it does not drop
>>>> below 11:1 l:b, you will be fine.
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