Mister Lucky,
<br>I will tell you that the idea of having the Nacra 5.5 to do both is a great idea because it it a great race boat either way. There is a different mast for the sloop than the Uni and I have not seen anyone put the Uni mast together with the rest of the sloop (foiler and forestay, large jib and running rigging). I think this would be a great boat, however, the stock N 5.5 Sloop has a shorter mast and smaller mainsail than the Uni. There were a couple of people who raced the boat both ways. One had both rigs (competitive), and the other raced Uni with the smaller mainsail and shorter mast (considerably slower in the races). Since there are not many Nacra 5.5 Sloops racing in one design fleets, I would probably use the Uni mast and sail, add the foiler and jib from the Sloop and race that way when I wanted to race with crew, taking the correction in the Portsmouth tables for a larger mainsail. The Uni is a great boat to race as is.
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<br>Comparing the 5.5 and the I-17R, I have only sailed and raced these single handed. I love both boats. I could not go back to the 5.5 after sailing with a spinnaker, however, because the spinnaker adds so much speed and excitement to the downwind legs! Flying a hull all the way upwind and then turning the corner, setting the spinnaker and flying a hull all the way downwind is just so much more fun! The handling and feel of the Inter is vastly superior to any other catamaran I have sailed (Hobie 16, 17, 18, Nacra 5.5 Uni, Nacra 18 Square), and I wouldn't want to give that up for anything. The layout of the Inter is better, with nothing on the trampoline except the added lines for the spinnaker.
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<br>All single-handed boats are lots slower when you add another person without adding more sail area. There is no option for adding a jib to the Inter 17, therefore, the loss in speed you get on the H17 would also happen on the I-17 and the N 5.5 Uni. The Nacra 5.5 offers the option of rigging for one person or two and probably would offer the better solution for your situation. I don't think the hull flotation would be a problem for either the Inter or the N5.5. <br><br>Les Gallagher
<br>Inter 17R USA 104
<br>"little yellow boat"


Les Gallagher