Subject: [harryproa] Re: On starting another boat,
From: "Robert" <cateran1949@yahoo.co.uk>
Date: 1/29/2009, 1:29 AM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

G'day Doug,
I have been thinking about double easy rigs as it would be lighter on
the sheets rather than two una rigs. But I thought about the extra
effort in making it and wondered about the inteference and decided it
would be too much hassle. Twin Una rigs would keep the deck clearer. I
reckon to go to one easy rig or two unas. The twin unas allow shallow
water steering and clearer decks. It could also allow the rigs to come
down a bit closer to the water as you have more clearance of the booms
from the cockpit.
.
I have been thinking about the bows on the boats and have been playing
around with rough models. A reverse stem of about 15-20 degrees with a
bit of a tear drop, fatter end on the bottom, with a cut at the keel
and the bilges for the last 1.5m of a 15m lw hull, gives quite a nice
entry and a V bow to take stress out of coming down off a wave. There
is a nice transition from the soft bilges to the hard chine. I tried
it with a vertical bulkhead from the top of the stem and is probably
worth doing the rest in extruded polystyrene foam. (I reckon it looks
less boxy as well).

For the lw hull I plan to try putting creases in the core using a
couple of aluminium rails on an iron. I roughly worked out a series of
creases about 20 mm apart and about half to 2/3 the depth of a10 to
12mm core should control the bending of polyprop over a 120mm radius
without showing obvious creases on the outside. For the ww hull where
a more parabolic shape is wanted, if there is too much trouble trying
to bend the sheets without creasing I have been thinking about going
to a thinner core, then adding another skin and core on the inside
afterwards. If the core was 6mm instead of 10 mm, there would end up a
sandwich of 600g glass, 6mm core, 200glass (or maybe kevlar for
puncture proofing), 6mm core, 400g glass., extra weight would be 200g
glass plus 400g resin plus 2mm core. about 20-30kg extra for the ww hull.

Into what radius could you easily bend a single-skinned 6mm core
without creasing? Theoretically it should be about a third of a
skinned 10mm core.

If the ww hull is parabolic in cross section, then there should be a
gradual decrease in waterline as the hull lifts. It seemed to me that
that was behind the different profiles of the lw and ww hulls. The lw
hull being more of a box with rounded corners, maximising bouyancy for
the waterline beam. The parabolic section is easier to do than a semi
circular or almost square section as the bending almost naturally
takes this shape.
If the ww hull is more flat bottomed, then maybe it should go
skinnier or you need to move over to the lw hull in medium light
conditions and reduce the amount of water it is trying to push out of
the way.

--- In harryproa@yahoogroups.com.au, Doug Haines <doha720@...> wrote:
>
>  
> Rob,
>  
> Sort of thinking about next boat (harry/rapscallion sort of extended
lw hull),
> And if using rudders like harriette, I know you gave me some
instructions on not using balsa core because the shaft is taking
diffrent loads to the other full blade shape ones.
> Plus carbon went on the front and back sides as well as the sides
all was wrapped round db. The blade is not there to take twisting into
the case.
> Could you remind me about that because I procured some pootential
balsa shaft pieces and was not liking a solid wooden core like is on
harriette.
> Or is a hollow one better?
> Just thinking ahead, now stuffs finished off.
>  
> Also - this thing with the two easy rigs (schooner), it seems you
could fiot two easy rigs, 3m main foot and 2m jib foot, or some
combination adding to less than 5.3m total which is the clearence from
one beam/mast to the other. Apart from the extra sail area/ lower
effort, Any guesses as to how the sail interaction would work?
> I would try it if it wasn't such a big decision regarding building
work just to test out a theory.
> In fact I've just talked myself out of it because of the extra
sailing work during shunting two masts instead of one.
> Simplifies things I  think.
>  
> I tend to think the ww hull should be finer L/B ratio, it is double
the lw ratio!
> Unless it lifts a lttle ( would it lift a small amount under average
sailing conditions?)
> , then you get same legth and less beam in the water. Though the
flat bottom floorless ww hull design would negate that advantage.
>  
> Dooug
> Sailing again soon
> --- On Thu, 29/1/09, Doug Haines <doha720@...> wrote:
>
> From: Doug Haines <doha720@...>
> Subject: [harryproa] Original Harry still in Cairns?
> To: harryproa@yahoogroups.com.au
> Date: Thursday, 29 January, 2009, 3:09 PM
>
>
>
>
>
>
>
>
>
>
>
> To whom it may concern,
>  
> Just wondering if ever get that far if it (painted bright yellow,
with a motor pod), is still in Cairns as read in website report. Ans
is it sailing?
>  
> Doug
>
> --- On Thu, 29/1/09, Robert McArthur <rjmcarthur@gmail. com> wrote:
>
> From: Robert McArthur <rjmcarthur@gmail. com>
> Subject: Re: [harryproa] Re: launched today - sails good
> To: harryproa@yahoogrou ps.com.au
> Date: Thursday, 29 January, 2009, 1:59 PM
>
>
>
>
> Tsan Akou wrote:
> > why don't you download the downsizer at
> .....
> > It is very easy and fast, I use it a lot.
>
> Um, because it's no use *me* downsizing the photos because they've
> already had to come through my ISP and into my email client! While some
> online systems and local clients, especially those who monitor whether
> it's a mobile device or not that is asking, will check with you whether
> you want to download large attachments, most won't. Irfanview has been
> around for, IIRC, 8-10 years and it my favorite for downsizing *my*
> photos (Lanczos downsampling, little sharpening, jpeg 50-70
depending on
> the detail). Takes a 7MB file down to 50KB and is quite good for web
> viewing.
>
> Sorry, no proa or Harry content. Oh, except for 'arrying Doug on image
> size ;-)
>
> Rob Mc
>

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