Hi Mike,
By keeping the width at the top of the lw hull to about 500mm and the mast off set slightly to lw, you can leave the rig in the lw hull and not lose too much accommodation. It would also make it easier to pack onto a trailer. You could have your 2.5m width main hull and still be able to sail at 4.5m (very gently)or even trail at that 3m width side by side if the beams were removed, assuming a telescoping system . With a different system, you could possibly collapse it tighter.
If I wasn't going for accommodation in the lw hull, I would have such a lw hull, but would stick with the 3m wide ww hull. Tapering the top of the lw hull makes it much easier to pack
--- In harryproa@yahoogroups.com.au, Mike Crawford <jmichael@...> wrote:
>
> << I am certainly not implying any superiority of the Atlantic design>>
>
> Hey, no worries even if you are. They are both impressive ways to
> have one's cake and eat it too.
>
> Please note that none of this is an argument for Rob's Harryproa
> design. I'm just a fan of being as safe, simple, inexpensive, and fast
> as possible, and most of Rob's design elements work for what I'd like to do.
>
> At this point, arguing atlantic-vs-harryrpoa is almost like splitting
> hairs. But that's what forums are for!
>
> Perhaps your ideas will infect my brain, and I'll end up pining for an
> atlantic rig. Actually, most atlantic proas don't appeal to me, so it's
> not the rig that would sway my building plans. I'm sold on the leeward rig.
>
> What would cause me to consider an atlantic rig is the fact that
> you've solved one issue that is close to being a showstopper for me: how
> to have a trailerable multihull with an enclosed saloon, where my wife
> and daughter can stay warm while I'm out enjoying a nice fall or spring
> sail.
>
> Rig now the family debate is between an Etap 32 monohull (the next
> boat *must* be unsinkable) and a Harryproa. On July days when it's 80
> degrees, my wife and I are both for the proa. But as soon as the
> temperature dips down to 70, which means it will be cooler on the water,
> My wife is set on the boat with a heated saloon.
>
> Since I'm not willing to spend $350k on a Dragonfly, and wouldn't want
> to deal with a stayed rig even if I did have the extra cash, that puts
> us at an impasse. There's no real argument going on, but we're also not
> making any decisions either.
>
> ---
>
> My current ideal boat would be your design with a leeward rig, even if
> that means going to a 10' or 12' trailering width. I'd trail the boat
> so little, mostly just once in the spring and once in the fall, that I
> wouldn't mind getting the wide load permit.
>
> I would probably go with scissors beams like cat2fold, which would
> keep the boat together and vertical while expanding or contracting on
> the water. Rafe Francke quoted me $2,500 for a license to his patent to
> build a boat, and that's something I'd be willing to pay in this case.
> With the scissors beams and a wider collapsed width, the leeward hull
> can stay upright and "structural". In this case, putting the rig into
> the leeward hull versus the windward hull probably wouldn't make much
> difference in terms of setting it up or breaking it down. It would also
> be nice to be able to collapse the boat on the water to fit into a slip,
> if needed.
>
> Most people seem to be planning on telescoping beams, saying they'll
> cost less, and that they will be more than stiff enough. I can't
> imagine them being as stiff as the scissors beams (though they will be
> lighter), while also being easy to expand and collapse, but I'm not
> going to argue with anyone. I'm sure they'll both work, and I'd always
> welcome the chance to be proven wrong by Robert's upcoming build.
>
> The 8.5' design limit would probably preclude leaving the leeward hull
> attached, though. You could still use the scissors beams, but you'd
> have to demount the leeward hull to trail the boat.
>
> In any case, it's a beautiful boat. I must confess that the low,
> skinny leeward hull is particularly appealing.
>
> - Mike
>
>
>
> On 7/26/2010 7:17 PM, Dennis Cox wrote:
> >
> > Hey Mike, et al.
> >
> > I have the greatest respect for Robert's HarryProa. I am certainly
> > not implying any superiority of the Atlantic design. In fact, most of
> > the reasons are not performance related. Also, its interrelated with
> > the steering leeway resistance issue. I am hoping someone here might
> > take pitty on my fence riding and give me something definitive that
> > tips the scale either way for good... but hear me out, because these
> > are the things that am pushing me toward the Atlantic.
> >
> > *_Non Performance Reasons _*
> > These are reasons that have to do with the trailerable aspect or for
> > me personally. They have nothing to do with one design being superior
> > to the other.
> >
> > * When on the trailer, the first thing, I'd step the masts on the
> > windward hull. As you suggested, I was thinking of a relatively
> > small "crane" based on the cheap car engine hoists. Once up,
> > these can be used in conjunction with the boats winches to lift
> > the windward hull up and over and down.
> > * I've been watching a lot of Rick Willoughby's comments. If I
> > keep the leeward hull simple (without) mast and leeway
> > prevention structure, I can make it quite cheap. The one I'm
> > making now should come in complete for less than $2000 and
> > somewhere around 800 pounds if I don't get sloppy. The point
> > being, I could very easily make a second one using the squared
> > off sheet hulls that Rick's research suggests may have a
> > superior performance edge. It may go for less than a $1000.
> > IOWs, I can play Mr. Potato Man.
> > * The lee hull is lighter - for getting off the trailer and moving
> > it around.
> >
> > *_Structural_*
> > IMO and for a schooner rig, one design has no significant advantage
> > over the other.
> >
> > *
> > In a HarryProa or an Atlantic _Sloop_ the mast loads have to be
> > transferred from the mast base to the cross beams by torquing
> > the hull. In an Atlantic this would make things far more
> > difficult. It fully justifies Robert's statment about being
> > able to make the unstressed HarryProa windward hull far lighter
> > than the Atlantic. It would be clearly lighter. However, in
> > a HarryProa or Atlantic _Schooner_ there is no torque in the
> > hulls. If the masts are mated to the cross beams all moments
> > from the masts can be directly transferred into cross beams. My
> > contention is that both hulls could be made lighter in a
> > schooner rig and frankly there would be no advantage of one over
> > the other (that I can imagine yet).
> > *
> > The largest moment in the beams of a HarryProa (and thus largest
> > cross section of the beam) is at the base of the leeward hull.
> > In an Atlantic, the largest moment in the beams is at the base
> > of the windward hull. It is helped out by a significant
> > structure... the bridge deck. The beam (in an Atlantic) as it
> > goes into the lee hulls has nearly no moment... just shear. It
> > can be much smaller and thus offer less resistance to waves and
> > submerging.
> > *
> > I hear what has been said about leaning the mast out and keep
> > the boat from going past 70 degrees. I can easily see that
> > in Robert's smaller designs. I'm having a little trouble with
> > it for a 10,000 lb boat. Mast tend to come away in roll overs.
> > It is said any mast that doesn't... is way over built and way
> > too heavy. In my minds eye, a boat traveling 20+ knots and has
> > flipped at a rate that the helm couldn't save must have
> > significant angular velocity. When the mast and sail slaps the
> > water, IT will come to a dead stop while the linear and angular
> > inertia of the rest of the boat (27 feet up in the air) is
> > certainly going to continue... result (I believe) is a snapped
> > mast and flipping of the hulls. Arguably, the HarryProa having
> > a little chance is better than no chance at all with an Atlantic.
> > *
> > This may be a cardinal sin, but, I'm debating about putting the
> > rudders on the windward hull also... see
> > http://au.groups.yahoo.com/group/harryproa/photos/album/1001384692/pic/461401281/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc
> > <http://au.groups.yahoo.com/group/harryproa/photos/album/1001384692/pic/461401281/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc>
> > Structurally, I can tie all the major force producers into one
> > structure. See more in fluid dynamics section.
> >
> > *_Fluid Dyanmics_*
> > Out of my comfort zone, but...
> >
> > *
> > I guess the heeling moment does get larger with an Atlantic when
> > flying, but only as a result of exposing the bottom of the hull
> > in addition to the sail forces, while a HarryProa windward hull
> > shields the sail somewhat. But in this size of a boat, I don't
> > really thing exposing my bottom is really in the game plan...
> > unless I've unloaded all the soft personnel and am racing. And
> > even then, I wouldn't be flying... just kissing.
> > *
> > The main one that drove me toward a Harry Proa is the
> > significant decrease in COE by lowering the base of the masts to
> > the lee hull. At first this was clear cut. HOWEVER, strangely
> > enough, if I go to wings or oversize wing masts (still debating
> > that one also) the heeling moment is far less than a sail. My
> > calculations show I can not get the lard-ass, windward hull up
> > so I can get to the 25+ knots Michlet says the lee hull could do
> > if unburdened. So in this strange case, its better to put the
> > masts up on the windward hulls to actually encourage heeling.
> > Yes, I know, I could put larger wings/sails on the leeward hull,
> > but that adds to the trailering issues.
> > *
> > If I put the rudders under the mast bases (on the windward hull)
> > all that splashing and spray as seen on the all the videos, is
> > under the bridgedeck and we have a cleaner view from the
> > bridgedeck overlooking the lee hull.
> > *
> > With the rudders on the windward side, flying the hull reduces
> > leeway prevention and thus lets it slide.
> >
> > I think that's all, but I'll bring up more, when they hit me. HELP!
> > Stop the voices.
> >
> >
> >
> > Dennis
> >
> >
> >
> >
> >
> > ----------------------------------------------------------
> > *From:* Mike Crawford <jmichael@...>
> > *To:* harryproa@yahoogroups.com.au
> > *Sent:* Mon, July 26, 2010 5:07:09 PM
> > *Subject:* [harryproa] Re: 60' atlantic proa
> >
> >
> >
> > Dennis,
> >
> > That is extremely cool. Thanks for pointing out the video link.
> > You could probably do this with a purpose-built trailer and a stub
> > mast in a separate socket (1/3 full mast height, used to lift the
> > primary mast at its center of gravity) , no crane required.
> >
> > Now I *really* want to see you build it. I've said many times that
> > i want the largest trailerable boat I can get, and this would
> > certainly qualify. Actually, I'd be willing to put up with a 12'
> > width, but fitting into 8.5' is even more impressive.
> >
> > I had actually brought up atlantic vs. harryrproa in a post right
> > before the one you responded to, but for some reason the post didn't
> > make it. (thus my comment about ignoring my question about how the
> > boat goes on the trailer).
> >
> > I'm partial to the harryproa design for the following reasons: a)
> > more space in the windward hull, b) heeling moment decreases, or
> > remains the same, as you fly a hull, while heeling moment increases
> > with the atlantic design, c) stresses are in line with the hull,
> > while the atlantic has to translate rig stress through the beams to
> > that long leeward hull, and d) the possibility of popping back up
> > after a knockdown.
> >
> > As far as handling the sails, a leeward design might offer more
> > safety in a schooner configuration (from the tramp), while a single
> > mast would probably offer safer sail handling with the atlantic (from
> > the cockpit).
> >
> > But I'm sure you're familiar with all that. Your design has more
> > than enough space to deal with masts in the windward hull, and the
> > taller leeward hull needed for a rig there might get in the way of
> > your trailering setup. As long as you don't sail on the very edge,
> > there shouldn't be any issues.
> >
> > I wouldn't put on a pod for safety as cavalier suggests. If you're
> > sailing an atlantic proa hard enough to fly a hull, in anything other
> > than flat water, there's a good chance you'll be going fast enough to
> > trip over any pod small enough to justify its own weight penalty.
> >
> > What are you planning for steering and leeway resistance?
> >
> > - Mike
> >
> > / /
> > On 7/26/2010 2:43 PM, Dennis Cox wrote:
> >
> >>
> >> Hey Mike,
> >>
> >> Did you see the video... on post #9. It might clear things up.
> >> Unless you've already seen it... :)
> >>
> >> Also, I'm still bouncing between Atlantic and HarryProa placement of
> >> the sails (windward, leeward hulls). I've got pros and cons on both
> >> sides and the tally list is still balanced. Fortunately, the hulls
> >> and internal configurations don't have to be changed either way.
> >> So... I've got PLENTY of time to decide.
> >>
> >> Dennis
> >
>