Editing Proa (section)

==Other Western interpretations==
Western designers often feel the need to tinker with the proa. They are attracted by the minimalist nature and amazing speeds that proas are capable of (they may still be the fastest sailboats per dollar spent for the home builder) but they often want the proa to do more; adding cabins, different sailing rigs, and bidirectional rudders are common changes made. [[James Wharram]] was greatly influenced by the Proa design.

For example, unconventional boat and yacht designer [[Phil Bolger]] drew at least three proa designs; the smallest one (20&nbsp;ft) has been built by several people while the larger two, including his Proa 60, have not been built. For additional examples, see [[Proa#Individual proa designs|here]].

===Lee pods===
[[Image:Lee pod.gif|thumb|right|Diagram of a proa with a lee pod]]
The terms ama and aka have been adopted for the modern [[trimaran]]. Since trimarans are generally designed to sail with one ama out of the water, they are similar to an Atlantic proa, with the buoyant leeward ama providing the bulk of the stability for the long, relatively thin main hull. Some modern proa designers have borrowed trimaran design elements for use in proas.  Trimarans often have main hulls that are very narrow at the waterline, and flare out and extend over a significant portion of the akas.  This topheavy design is only practical in a multihull, and it has been adapted by some proa designers.  Notable examples are the designs of Russell Brown, a boat-fittings maker who designed and built his first proa, ''Jzero'', in the mid-1970s.  He has created a number of proa designs, all of which follow the same theme.

One of the design elements which Brown used, and a number of other designers have copied, is the ''lee pod''.  The akas extend past the main hull and out to the lee side, and provide support for a cabin extending to the lee of the main hull.  This is similar to the platform extending to the lee on some Micronesian proas.  The lee pod serves two purposes—it can be used for bunk space or storage, and it provides additional buoyancy on the lee side to prevent a capsize should the boat heel too far.  Crew can also be moved onto the lee pod to provide additional heeling force in light winds, allowing the ama to lift under circumstances when it would not otherwise. The ''Jzero'' also used water ballast in the ama to allow the righting moment to be significantly increased if needed. While Brown's proa was designed to be a cruising yacht, not a speed-sailing boat, the newer {{convert|36|ft|m|adj=on}} ''Jzerro'' is capable of speeds of up to {{convert|21|kn|km/h}}.

===Sail rigs===
One of the issues Western designers have with the proa is the need to manipulate the sail when shunting. Even Munroe's early sails discarded the curved yards of the traditional crabclaw for the more familiar straight yards of the lateen and lug sails. Munroe's designs likely lacked the tilting mast because he was unaware of it, but many designers since have used a fixed mast, and provided some other way of adjusting the center of effort.  Most sailboats are designed with the center of effort of the sails slightly ahead of the center of area of the underwater plane; this difference is called "lead."  In a proa hull, and in all fore and aft symmetric foils, the center of resistance is not at or even near the center of the boat, it is well forward of the geometric center of area. Thus the center of effort of the sails needs to also be well forward, or at least needs to have a sail which is well forward which can be sheeted in to start the boat moving, allowing the rudders to bite and keep the boat from heading up when the entire sail area is sheeted in.  Jzero, for example, and all of Russell Brown's other designs, use a [[sloop]] rig and hoist a jib on whichever end is the current "bow". Other designs use a schooner rig for the same effect.

One of the more practical rigs for small proas was invented by [[Euell Gibbons]] around 1950 for a small, single handed proa. This rig was a loose footed lateen sail hung from a centered mast. The sail was symmetric across the yard, and to shunt, what was previously the top end of the yard was lowered and became the bottom end, reversing the direction of the sail. Proa enthusiast [[Gary Dierking]] modified this design further, using a curved yard and a boom perpendicular to the yard. This allows a greater control of the sail shape than the traditional Gibbons rig, while retaining the simple shunting method, and is often referred to as the [[Gibbons/Dierking rig]].

===Foils===
While a proa is fairly efficient at minimizing the amount of wave drag and maximizing stability, there is at least one way to go even further. The use of underwater [[foil (fluid mechanics)|foils]] to provide lift or downforce has been a popular idea recently in cutting-edge yacht building, and the proa is not immune to this influence.

The [[Bruce foil]] is a foil that provides a lateral resistance with zero heeling moment by placing the foil to either or both of the leeward and the windward sides, angled so the direction of the force passes through the center of effort of the sail. Since proas already have an outrigger to the windward side, a simple angled foil mounted on the ama becomes a Bruce foil, making the already stable proa even more stable. Bruce foils are often combined with inclined rigs, which results in a total cancellation of heeling forces. Inclined rigs are also well suited to the proa, as the direction of incline remains constant during shunting.

Another use of foils is to provide lift, turning the boat into a [[hydrofoil]]. Hydrofoils require significant speeds to work, but once the hull is lifted out of the water, the drag is significantly reduced. Many speed sailing designs have been based on a proa type configuration equipped with lifting foils.

===Variations on the theme===

[[Image:Yellow pages endeavour layout.png|thumb|right|upright|The layout of the record-making [[Yellow Pages Endeavour]]. Commonly described as a trimaran, due to the three hulls, its layout is that of a unidirectional proa, as the trailing lee hull follows in the leading hull's wake.]]
In a non-traditional variant, first seen among Western yacht racers, the "Atlantic proa" has an ama which is always to the lee side to provide buoyancy for stability, rather than ballast as in a traditional proa. Because the Atlantic ama is at least as long as the main hull, to reduce wave drag, this style can also be thought of as an asymmetric catamaran that shunts rather than tacking. The first Atlantic proa was the ''[[:fr:Cheers (prao)#Histoire|Cheers]]'', designed in 1968 by boat designer [[Dick Newick]] for the 1968 [[Single-Handed Trans-Atlantic Race#The OSTAR.2C 1968|OSTAR]] solo transatlantic race, in which it placed third. Newkirk's designs are primarily trimarans, and the Atlantic proa's buoyant outrigger follows naturally from a conversion of a trimaran from a tacking to a shunting vessel.

Other proa designers blur the lines between Atlantic and Pacific style proas. The ''Harryproa'' from [[Australia]] uses a long, thin hull to lee, and a short, fat hull, containing the cabin, to windward. This would normally be more like an Atlantic proa, but the rig is on the lee hull, leaving it technically a Pacific design. This and other similar proas place the bulk of the passenger accommodations on the ama, in an attempt to make the vaka as streamlined as possible, and put much of the mass in the lee side to provide a greater righting moment.

Perhaps the most extreme variants of the proa are the ones designed for pure speed. These often completely discard symmetry, and are designed to sail only in one direction relative to the wind; performance in the other direction is either seriously compromised or impossible. These are "one way" proas, such as world record speed holding [[Yellow Pages Endeavour]], or ''YPE''. While the YPE is often called a trimaran, it would be more correct to call it a Pacific proa, because two of the planing/hydrofoil hulls are in line. This design has been considered by others as well, such as the ''Monomaran'' designs by "The 40 knot Sailboat" author Bernard Smith, and these designs been called ''3-point proas'' by some, a reference to the 3 point hulls used in [[Hydroplane (boat)|hydroplane]]s.<ref>{{cite journal|last=Jobson|first=Gary|title=Breaking the 50-Knot Barrier|journal=Yachting|date=April 1998|pages=28}}</ref> A previous record holding design, the ''Crossbow II'', owned by [[Timothy Colman]] was a proa/catamaran hybrid. Crossbow II was a "slewing" catamaran, able to slew her hulls to allow clear airflow to her leeward bipod sail. Although the hulls appeared identical, the boat had all crew and controls, cockpit etc. in her windward hull; the leeward hull was stripped bare for minimal weight.