Subject: Re: [harryproa] Re: Beam width
From: Doug Haines
Date: 6/16/2006, 9:30 PM
To: harryproa@yahoogroups.com.au
Reply-to:
harryproa@yahoogroups.com.au

Hi,
 
WellI never thought much of the plan dimensions untill I layed out the beam walls out on the floor to put together. It was like, wait a minute I've got something wrong or forgot some part, that's not the full width is it. Putting the WW hull into one end of the beam and sitting on the floor with a measuring tape the LW side is just so close it seems like it's a little surf cat I'm making. I can see that trailering imposes a limit to width, but I wasn't sure that that was what was deciding the extended width in the plans. Rob indicates that the beam could be wider if trailering is not an issue.
 
Also as it seems most work has been done with the racing WW hull boat then the cruising side will mean a few alternative choices. REally, who wants to cruise say in a far of remote place on a narrow multihull, just so it fits on a trailer when you get back home?
 
REally there is no restriction to the beam, which asks the question - can you cruise, such as a regular short coastal cruise, while sailing with the WW hull close to flying?
How do you sail an Elementarry compared to other Harryproas or other multihulls?  Suerly you would want the same safety of not coming close to lifting off.
Racing is risky, cruising is comfortable
 
Doug

Robert <cateran1949@yahoo.co.uk> wrote:
Congratulations on the rate of progress. Hope you take plent of pics
and notes on your trip
Here is my two cents worth on the beam issue. If you are cruising
with stores in the ww hull, then you have plenty of righting moment
in contrast with a cat or a tri which has the weight distributed more
evenly across the boat, but can load the boat more aft to avoid
pitchpoling. Extra width adds to the weight and windage and torque
and increases the likelihood of waves hitting the crossbeams.It also
makes it more of a hassle to manoevre. I suspect the narrower beam
would make it easier to come in and out of the surf. For a cruiser
3.8m seems about the right width. Elementarry noncruising on a broad
reach with much less weight in the ww hull appears to be at the
juncture of pitchpoling and sideways capsize when pushing it to its
maximum-
regards,
Robert

- In harryproa@yahoogroups.com.au, Mike Crawford <jmichael@g...>
wrote:
>
> <<I thought you didn't like a nice wide safe multihull for a
minute.>>
>
>   Steve Fossett's Playstation maxi cat was originally built at 105'
LOA,
> with a beam of 60'.  I believe the choice was made to maximize
righting
> moment with a wide beam, while keeping weight down with the
shortest
> hulls they thought they could get away with.  However, it had a
tendency
> to pitchpole at this beam-to-length ratio, and was lengthened to
125' to
> make it more stable.  It added a lot of weight, but they are much
> happier with the boat now.  I've also heard rumors about upwind
> performance, but can't substantiate them.
>
>   In any case, while additional beam does provide more beam-wise
> righting moment, it doesn't increase length-wise righting moment. 
It's
> possible to generate so much righting moment with a wider beam that
the
> boat becomes too short to sail safely with the extra power. 
Playstation
> went from a length-to-beam ratio of 1.75 to 2.08 to deal with this
> effect.  A 3.8m beam on an Elementary gives a ratio of 1.97, while
> extending it to 4.5m brings the ratio down to 1.66, below that of
the
> original Playstation.
>
>   If you're going to be cruising with appropriately-reefed sails,
then
> this is a non issue, and the wider beam will be safer.  It also
won't
> matter if you're racing and don't mind the risk.  It's something to
> consider, though.  After a point, wider only means safer if you're
not
> pushing the boat.
>
>   Personally, I'd rather capsize than pitchpole, especially at
speed,
> but it all really depends upon what you want to do with the boat. 
As
> Rob says, it would be interesting to see what the additional beam
does. 
> Everything else is conjecture at this point.
>
>        - Mike
>
>
>
> Doug Haines wrote:
>
> > Rob,
> > 
> > Thats good - I thought you didn't like a nice wide safe multihull
for
> > a minute.
> >  The sail designer (Rolly Tasker) advises to use a bolt rope
luff ,
> > for reefing with some long cruise I've planned. So suppose strip
> > planking should now be an aero foil shaoe rather than the round
mast
> > that takes the luff sleeve. Not quite as big as your wing mast,
but
> > strip planked in the 6mm kiri and just straight all the way up.
What
> > would a good width/length be?
> > 
> > Doug
> >
> > */Rob Denney <proa@i...>/* wrote:
> >
> >     G'day,
> >     
> >     I meant than 4m.  For traillering reasons.  Be interesting to
see
> >     how it sails at 4.5
> >     
> >     regards,
> >     
> >     rob
> >
> >         ----- Original Message -----
> >         *From:* Doug Haines <mailto:doha720@y...>
> >         *To:* harryproa@yahoogroups.com.au
> >         <mailto:harryproa@yahoogroups.com.au>
> >         *Sent:* Friday, June 16, 2006 9:51 AM
> >         *Subject:* Re: [harryproa] Re: PLOYSTYRENE AS A CORE
MATERIAL?
> >
> >         Rob,
> >         
> >         What do you mean you wouldn't go wider 7.5 x 3.8 seems a
bit
> >         narrow?
> >         
> >         It'll stay in the water.
> >         
> >         6oz US dacron. Rolly Taskers Phuket
> >         
> >         Doug
> >
> >         */Rob Denney <proa@i... <mailto:proa@i...>>/*
> >         wrote:
> >
> >             beam is what fits on the trailer in the telescoped
> >             position.  Can go wider, but I wouldn't.  Good deal
on the
> >             sails.  What are they made of?  I will try to get to
> >             Maylands next week.
> >             
> >             regards,
> >             
> >             rob
> >
> >                 ----- Original Message -----
> >                 *From:* Doug Haines <mailto:doha720@y...>
> >                 *To:* harryproa@yahoogroups.com.au
> >                 <mailto:harryproa@yahoogroups.com.au>
> >                 *Sent:* Thursday, June 15, 2006 3:51 PM
> >                 *Subject:* Re: [harryproa] Re: PLOYSTYRENE AS A
CORE
> >                 MATERIAL?
> >
> >                 Thanks, thats a good idea about the 3mm ply, I'll
try
> >                 that as i have bought the polystyrene anyway.
> >                 
> >                 Laying out the beams now it strikes me as being
quite
> >                 narrow. The whole boat that is. I've got about
3.8m
> >                 overall beam. Can I widen this to 4.5m? Is that
length
> >                 3.8m to do with still fitting on the trailer?
> >                 
> >                 I've decided to kind of fix the beams in the
building,
> >                 and leave the option to maybe some other owner who
> >                 could convert this back to a demountable pinned
type
> >                 of beam. This is just easier for be right now.
> >                 Also I'm heading off from Mandurah next Tuesday to
> >                 complete in about 4 weeks at Maylands boat yard,
so
> >                 call in to Maylands later in the week to see me.
> >                 Ordered two sails, luff sleeves, 6m luf for
bridges
> >                 from Phuket US $960.
> >                 
> >                 I hope to make your rudder set up in a couple of
weeks.
> >
> >                 */Rob Denney <proa@i...>/* wrote:
> >
> >                     G'day,
> >                     
> >                     Sorry, I missed this.  Doug, please send any
> >                     questions to me as well as to the group as I
am
> >                     having continual problems with Yahoo.  Ta.
> >                     
> >                     Polystyrene will not work on areas where you
are
> >                     walking on it, as it dents, then leaves a void
> >                     under the glass.  Eventually it all falls
off.
> >                     You can put 1-3mm ply each side but it is
better
> >                     to use a decent core.  Foam, polypropylene
> >                     (Boatcote or Polycore Aus) or paper honeycomb
> >                     (ATL) are recommended.  
> >                     
> >                     regards,
> >                     
> >                     Rob
> >
> >                         ----- Original Message -----
> >                         *From:* Robert <mailto:cateran1949@y...>
> >                         *To:* harryproa@yahoogroups.com.au
> >                         <mailto:harryproa@yahoogroups.com.au>
> >                         *Sent:* Tuesday, June 13, 2006 10:31 AM
> >                         *Subject:* [harryproa] Re: PLOYSTYRENE AS
A
> >                         CORE MATERIAL?
> >
> >                         For long term use I'd stick with a quality
> >                         foam or honeycomb. The
> >                         resin , glass and exposure to nasty
materials
> >                         is still the same price
> >                         for a core that can out gass and
generally not
> >                         perform as well. For a
> >                         discourse on this there is something on
the
> >                         proafile yahoo group I was
> >                         wondering for the marginal extra cost of
going
> >                         to 20mm for the core in
> >                         polycore polypropylene honeycomb,
> >                         Robert --- In
harryproa@yahoogroups.com.au,
> >                         "doha720" <doha720@y...>
> >                         wrote:
> >                         >
> >                         > Could it be used to make the flat
platform
> >                         on the camper?
> >                         >
> >                         > 15mm expensive foam sandwiched with
400db is
> >                         stated on the plan.
> >                         >
> >                         > Was buying the polystyrene for the end
caps
> >                         today and thought...
> >                         >
> >                         > Doug
> >                         >
> >
> >
> >
> >
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