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PostPosted: Fri Jan 21, 2011 12:50 am 
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Joined: Fri May 08, 2009 5:06 am
Posts: 1615
Location: Lake Macquarie NSW AUSTRALIA
They're right Bob. Don't be backward in coming forward. Perhaps we should have an inventors competition this year. Hmmmm.

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Don't take life too seriously................it ain't permanent.


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PostPosted: Fri Jan 21, 2011 9:37 am 
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Joined: Wed Jan 05, 2011 11:32 am
Posts: 9
Fantastic stuff!! Simple and efficient!
I'd be interested to know how you stiffened the mast? My favorite point of sail is as close to the wind as possible, on monohulls anyway.


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PostPosted: Fri Jan 21, 2011 3:17 pm 
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Joined: Sun Apr 20, 2008 6:18 am
Posts: 1408
Location: Sarasota,Key West FL
kevgrn114:
It was pretty simple actually, I went to home depot and bought a painting extension pole (longest they had, it was yellow). I took it apart and discarded the fiberglass and ends. For the top section I slid the 1 inch aluminum into some PVC pipe (for electrical insulation, the top section cannot touch the bottom section). For the bottom section I used an 8 ft pool cleaning pole that I bought at the local pool store. If you don't want to use aluminum, 1/2 inch dia pulltrusion rod will also work, but is more expensive) I was careful to make the joint below the mast split (where the mast is stronger). This stiffens the mast only slightly which was all I needed to be able to be able to sail pretty easily now into the wind (kind of like a Hobie cat). I could sail upwind in light winds (5-7 mph) almost directly into the wind and still make fairly good headway 2-3 mph (on GPS), and a little faster with the jib up. It even goes better if you pedal a little, the apparent wind from pedaling seems to suck you along almost directly into the wind (the sails have to be really tight). I don't think any other boat can do that. You know your in the zone when you see the tell tales streaming straight back, this appears to create a vacuum in front of the sails. Actually in real light winds (pretty typical where I live in Sarasoa,FL), my best direction is into the wind. The best I could ever do before making any mods, with just the mainsail was around 35-40 deg, and really didn't go anywhere at all in light winds. My best friend who lives in Sweden is an expert sailer, he went out with me a few times down in the Keys, and told me what mods to make the boat sail better especially upwind.
Use caution when making changes like strengthening the mast, the mast reciever is not strong enough to take the extra load in higher winds (> 15 knots), and will break (for sure). My boat has mast stays to take the extra load, but even with that I avoid winds over 18 knots. Also with the stronger mast the sail can no longer just spill the excess wind (like it was designed to do), so the whole bow will submerge, and the AMA's will completely submerge even in moderate winds so be careful. Remember you will break your mast reciever if you strenghten the mast, and sail like normal guarenteed.
Bob


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PostPosted: Sun Nov 23, 2014 11:16 pm 
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Site Rank - Captain

Joined: Mon Dec 21, 2009 11:00 pm
Posts: 49
Location: Jacksonville, Florida
fusioneng wrote:
In the last post I mentioned that because of the extra sail loading the front of the boat dives underwater, well I'm happy to announce that I solved that problem by converting the front Mirage drive into a hydrofoilImage


This looks incredibly simple and ingenious. Do you have instructions on how to make a pair of these?

Also, how does this design compare to the large spoon bill bow plates (in the Hobie AI surfing videos) in pitch pole prevention?


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PostPosted: Mon Nov 24, 2014 8:10 am 
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Joined: Sun Apr 20, 2008 6:18 am
Posts: 1408
Location: Sarasota,Key West FL
lboiv001:
This is a really old post, after making this post I took the suggestions of the guys and made a totally new thread called The ultimate Tandem Island (hydrofoils, spinnaker,jib,etc) viewtopic.php?f=69&t=33720
There I pretty much described all my escapades, trials and tribulations.
I'm not recommending to re-enforce the mast anymore, instead I just added a rear stay line, that helps the sail from putting too much stress on the mast holder.
The hydrofoils do work, but later on I added a bow sprit, that angled the front sails at a more acute angle which creates lift to the bow, thus eliminating the need for the hydrofoils. With the angled fore sails, the bow no longer dives, actually in strong winds the bow sprit and big sails actually lift the bow out of the water about 6 inches or so.
Here is a pic of my first mirage drive foils:
Image

Later on I made some more out of that white 1/4" thick kitchen cutting board material you can get at Walmart (for about $4 bucks), I use that stuff for everything. Making those foils is kind of a touchy feely thing, using a hack saw, file, and a dremel tool. Basically you start with a rectangle then drill and dremel the shape of the mirage fin out of the plastic, then just cut the top off at an angle to get the desired angle of attack (about 8 degrees) by having the edge of the cutting board up against the bottom of the hull with the mirage drive locked in the forward position.
Here is a pic of the foils themselves with a scale to get an idea of the sizes needed for a TI.
Image
Once everything is sculpted and fit, I just gobbed clear silicone caulking over all the joints to hold everything in place. Of course the dimensions would be slightly different on an AI. When pedaling or with the fins pointed down, they do nothing, they only engage when you lock the pedal to the forward extreme position with your foot. The way I did it was just sail like normal, if I felt the bow diving, I would just put my foot on the pedal to raise the bow back out of the water. Worked like a champ.
Of course there is a little drag from the foils, but at least on my boat with 260 sq ft of sail, without the foils the boat would dive and stay completely underwater (what I called nautilus mode), until I either backed off on the sails (not about to do that), or I changed direction. Having the bow completely submerged didn't seem to slow the boat down a lot, but you sure got wet in the cockpit (like a waterfall), with the foils just a tap on the mirage drive with my foot raised the bow back out of the water.
Like I said earlier, once I angled the fore sails, I no longer needed these foils, they have been just sitting in my drawer for 3 1/2 years now unused.
Hope this helps
Bob


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