<<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>>

  Given your criteria, combined with your design, I'm not sure you'll find any definitive reasons to go with one option versus the other.  There are a number of good reasons to go with rigs in the leeward hull, but if your goal of an 8.5' trailer width is a fixed one, the reasons to go leeward might not be showstoppers. 

  I also think that the design is a masterpiece of ingenuity, and have a hard time arguing against  keeping all the steering components in the same hull.

  That said, I'd still like to comment on the rudders, and then get your thoughts on wracking forces and sail handling.  I know I brought this up before, but I didn't catch a response.  Not that you need to provide a response -- I'm just interested in what you have to say.

 Rudders.

  I love the idea of losing leeway prevention as you progressively fly a hull -- I'm a fan of using the windward daggerboard in catamarans for the same reason.  I'm not as much a fan of losing steering ability as the hull rises.  As long as you sail conservatively, and have someone who can dump your sheets, the pros might equal the cons.  Or outweigh them if you stick with keeping everything in the windward hull (which would obviously radically simplify your steering setup for a trailerable proa).

  Keeping the whole steering system in the same hull is wonderful.  I'm having a hard time coming up with a steering system that allows me to collapse the boat on the water while still maintaining steerage.  Stopping the spray could also be useful.  One downside, though, could be more difficult access to the rudders and steering system if a problem were to develop.

 Twisting/wracking forces.

  I agree that the windward hull design would be very strong in terms of bending moment, particularly with the masts transferring loads directly into the beams.  However, there are huge fore/aft loads on the sails and the leeward bows that will need to be translated through the beams into the opposite hulls.  The leeward rig, which has all its major fore/aft sailing and rig forces in line, should make for a design that requires less structure and perhaps less engineering. 

 Sail handling.

  I'm still not quite sure how you'll safely handle the sails in a big wind and sea when it's time to reef, or take care of a blown sheet or jammed halyard.  That windward hull has beautiful lines, but not much in the way of protected area to stand on while the boat is pitching.  With the rig in the leeward hull, you have the leeward hull to leeward, and the trampolines/ deck to windward.  Wings would largely eliminate this issue, but I'll personally be going with sails.

---
 
  For me, the choice of a single tall leeward rig comes down to how my wife and I sail.  90% of what we do will be daysailing, typically in the light summer winds, with several miles of short-tacking against a sea breeze before we hit open water.

  Thus, I'd go with the tallest rig I can fit in the ICW, in order to take advantage of wind aloft, even if the water is a mirror.  I'm not so concerned with hitting 20 knots in big wind as I am being able to do 5 knots in almost no wind.  That's why the height matters, even if it has a higher COE than a schooner rig.

  If the boat does suffer a knockdown, it would likely be from a sudden gust when most or all of the sail is up, while traveling at low or reasonable speeds.  Such as if a friend has the helm while we're ghosting along, and we pass between islands and catch a big burst of air that he or she didn't plan on.  Your point of the mast not necessarily helping at 20 knots is a good one, but at 5 knots, it's much more likely to help.  As you said, any chance at all is at least something.

  Finally, a few hours of shunting a schooner rig up the channel could get old pretty quickly.  Having one rig means half the work.  Unless the boat tacks in very light wind, which is something I wouldn't be willing to bet on before building.  If someone else does it first, I'll be most grateful.

  None of these criteria matter the same way if you're cruising, so the ideal live/cruise/ trailerable boat might not necessarily be the ideal daysail/cruise/ trailerable boat.

        - 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  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