Chopcat : Actually there is a great risk that you will fold the hull, (that's what I think happened to Hobie's entry into the EC challenge in I think the 2011 Everglades challenge race). (probably the main reason the jib option was never offered by Hobie).
Unfortunately as with most of my posts which always end up too long, I try to explain in detail the reasons why I do the things I do, so that others understand and then you can make your own decisions on how to proceed based on knowledge and understanding of the problems, and come up with your own solutions, and/or improve on the ideas.
There are 3 or 4 design problems with the TI that make it unlikely that Hobie will ever offer a jib or jib/spinnaker option, however all of these shortcomings can be easily overcome.
1. The weakest area on the TI is the bow, caused by the huge opening created by the front hatch. With a jib mounted on the bow, the extra stress causes the bow to wave around making the front hatch leak like a screen door in a submarine. This needs to be overcome by adding external bracing. Your idea of using Yakattack mounts is fine, however I suggest you mount two up near the bow, then two more just in front of the front AKA brace (the strongest area of the boat). Then your aluminum V shaped external brace which needs to clear the hatch area will support the weak area of the bow (the hatch opening), most of the rest of us used 3/4 sq aluminum tubing for the external brace, which is plenty strong). So bottom line, your vision of becoming a poster child for Yakattack will work just fine as long as your OK with drilling holes in the hull, and you mount them as I described (the rear mounts behind the hatch).
2. The front lifting cleat would probably work fine for adding a 22sq ft Hobie Kayak sail, but not much bigger (a 22 sq ft jib might be a little small for a TI (but perfect for an AI). It's not a good idea to mount a huge spinnaker ( or a spinnaker/jib combination) to that cleat. Since you are planning to use Yackattack mounting, as long as you mount the sail(s) to your brace vs the front cleat you should be fine whatever size jib or jib/spinnaker combo you put on. I actually like your idea, as long as your willing to drill your hull (BTW, those drill holes are actually easy to fill with the Hobie welding system if/when the time comes). Most of us follow the Hypocritic oath just like doctors (thou shall do no harm), which is probably silly (especially coming from the guy with the most modified TI's out there LOL)
3. If you look at the TI you will notice that the main sail is mounted really far forward on the hull. This severely limits how much sail you can add to the boat. That's why I added a 2 ft bow sprit to my TI, for two reasons, the first being if you have both a jib and a spinnaker there is simply not enough room for both up there. The second reason is with the main sail mounted so far forward on the boat, when on a downwind the bow of the boat gets pulled underwater (nautilus mode). By angling the jib or jib/spinnaker and moving the base forward, this creates lifting force that lifts the bow out of the water. When I added my bow sprit I completely eliminated the need for my hydrofoils so they were removed (their now sitting in my garage collecting dust). Just to clarify, this is a problem only to the TI, the AI mainsail is mounted much further aft, so adding an extended bowsprit to an AI might only be marginal (the hull bracing is still needed though). I like Jims setup, which I think is perfect for an AI. The AI and TI are different boats with different problems and solutions.
So now you have the bow sprit and the necessary hull re-enforcements to start adding additional sails, where do we go from here..... Here are 3 or 4 more things to keep in mind when adding sails to the TI.
1. The mainsail on the TI is a boomless furl-able very modern square top sail design ( a really good design), specifically designed to work best on a very flexible carbon mast. This is direct contrast and opposite from the design of almost every other sail/mast design out there. The last thing you want to do when adding additional sails is to destroy the built in abilities of the basic mainsail design. By adding all kinds of side and rear stays making the mast rigid, basically destroys the mainsails ability to work efficiently. You could actually go backwards if not careful, making the boat slower instead of faster and more capable. Now you have the hull prepared for the future whatever design you decide on, keep in mind not to interfere with mainsails basic design, and in my opinion it's best to keep whatever you add sail wise as simple, easy, and fast to rig/take down, and use as possible (KISS principle), otherwise you will get bored with it quickly. And keep in mind a jib designed for say an H16 (with a rigid mast) may not work as well as it would on an H16 unless you can design around a few things. 2. Whatever you add to the TI sail wise you have to be aware that the mast holder in the bottom of the boat, was only designed to withstand the forces of just the mainsail, adding too much sail will over stress that small 1/4" bolt on the bottom of the mast holder unless you can relieve some of the forward force. As an example if you were in a strong downwind run (15mph plus winds) with the main pointed to one side and say a 40 sq ft jib pointed to the other (a batwing setup), the stress on that small bolt would be too much and it would snap. With a setup like that or adding a spinnaker you pretty much have to add a rear stay line to the top of the mast to prevent it from bending forward too much, and also to relieve some of the stress on that little bolt. The design of Hobies metal brace system inside the hull regarding side to side stress goes is ok as designed, it's just forward to back that you have to adjust for. As far as side to side force goes, the mast will snap long before the braces give out so your reasonably safe. The Hobie mast is extremely strong and well designed. If you are only planning to add a smaller jib (under 25sqft) and not adding a spinnaker you can probably forego that rear stay line, however you'll need it on anything larger especially on downwind (my rear stay line is actually slack when on an upwind or on a reach). 3. Keep in mind that the flotation on the AMA's are only sufficient for the mainsail only in winds under 12mph, otherwise the boat tips over. That's why you have to furl the mainsail on a reach in higher winds currently. If the boat were slightly wider it would help but it's not. This means whatever sail area you add this will require you to hike out to counter balance the boat in higher winds. If you ever watch videos of Tom Kirkman on his Weta (or any cat or A class mono for that matter, you will see the crew hiked out, you will also have to do this (an rudder control/extension rod is highly recommended), and either Haka's or tramps (something to hike onto), and this pretty much eliminates driving the boat from the rear seat (your pretty trapped back there anyway). With the bow sprit and the additional lift it provides to the bow (because of the increased angle of the jib/spinnaker), the boat performs perfectly fine from the front seat (plus you have better access to the sails and sail controls from up front anyway). 4. It's a very good idea for safety reasons, that the main mast and the jib are independently furlable, and whatever you add doesn't interfere with the furling ability of the stock mainsail ( a mast topper design like mine or Jims does all this). I recommend you use a halyard line to raise and lower the jib to the mast top, this allow you to raise and lower your jib or change jibs/spinnakers while out on the water, and also makes it easy to drop the mast if needed to go under low bridges. If you do get out in really strong winds, the halyard also gives you the ability to take the jib down and work your way home with the main furled almost completely, while your hanging on for dear life (we have all had to do that). That's the main reason for yours and my Honda Motors (LOL). My TI actually has two halyard lines, one for the jib, and the second for the spinnaker that also doubles as the rear stay line, (remember the rear stay is only really necessary for the spinnaker, or a really big genoa sail, and only on downwind, upwind it does nothing). Hope this helps you. Bob
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