XRT stands for Experimental Racing Trimaran. The Length is 24 foot. Hull width at widest point is 22″ and below that at the Waterline is 18″ which gives it a length to width ratio of 16 which is the same as the inflatable amas. Width when amas extended is 14′ and 4′ folded. Amas can be lowered 10 inches which reduces the draft when in rivers to 4-5 depending on load. Normal draft at full load of 650 lbs is 7″. Weight is 295 lbs. empty and 325 with portage equip. Useful load is 325 lbs.
The struts bottom attach points for the amas are approx 4-5″ above the waterline(the struts hold up the akas) but they do create spray from waves due to the flat plate area of the sq. support tube going through the hull. I added a plastic airfoil shaped flaring to the front to streamline it and what spay it creates now mostly stays low and trails straight aft. The tubing still creates spray but not a constant soaking. Waves can still break into the boat as well but water drains straight out the Hobie Drive well. The spray is also reduced from tramps that go up to the fwd akas so it is further reduced. It is a wet boat in rough conditions since water will still make its way through the tramp material.
The reason for the struts is not strength which most folks assume. They are there so that the amas can be positioned where needed and folded quickly. They can swing 3 foot forward or aft and so do not have to be the same, one can be forward and one back. Tramps have to be lowered to do this and can only be used in the neutral position but stow quickly by releasing 3 snaps and rolling up. Using straight akas the amas would not rotate so I gave up some drag for what I hope to be a benefit of position and folding. Being able to sweep the amas fwd helps keep the bow from plowing when going downwind and swinging them fwd and aft while on a beam reach is useful to get the ama fwd and weight aft on the windward side. The amas can be folded in approx. 20 seconds for portage. If they were straight the boat would have to be disassembled for bridges or portage then the breakdown time would have been maybe an hour.
click here for video-http://www.youtube.com/watch?v=79kbBJgOZKo
Click here for more photos taken by “J” during the launch of the Everglades challenge 2012. Thanks J. http://s1263.photobucket.com/albums/ii631/rogermannorg/XRT%20Canoe-Ultimate%20Florida%20%20Challange/
During the race the rudder failed after 170 grueling miles in small craft warning weather. That is why I build prototypes. It was not a failure but a lesson learned on how not to do it and how to do it better. Once it was redesigned it has worked fine. The boat has been sold to an overseas customer and now works like a charm. This boat turned out to be a real speedster.. it normally reaches 12- 14 knots and top speed to date has been 17.5 knots. No plans were drawn and none will be offered.