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PostPosted: Fri Aug 21, 2009 10:05 pm 
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Joined: Tue Aug 11, 2009 5:04 pm
Posts: 20
Starting point: I want to build 2 hydrofoils that I can clamp on (with a belt) to either the amas or the main hull. The idea is to test how the AI reacts if you just lift the front out of the water when going fast. I have been bothered a little by submerging amas because they create such a big drag that it stops your next speed record ;-) Also, I have no experience with hydrofoils, just experience watching youtube videos of other people having fun with them. So this project is to be taken with humor ... we'll see what comes of it..

I started at Home Depot with some standard framing hardware...

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The main bracket is a post base. It is used to anchor a 4x6 into concrete, but it can also be used to fit an AMA on one end and attach a hydrofoil on the other.

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With 2 twinposts, a tieplate, and 4 machine screws and nuts, you can already see what is coming.

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After flattening the twinposts, it allmost looks done ;-)

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Add some double sided carpet tape--- oh I love that stuff

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Time to build/frame a wing shape. Hydrofoils create lift in 2 ways: (1) angle of attack (for that you can put a flat board at a slight angle - like a water skier) and (2) foil shape. Constructed like an airplane wing, you can increase the distance the water has to travel above the foil compared to the distance under the foil. This creates negative pressure abobe the foil, thereby lift. So here I am trying to create a wing...

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Of course I only had plaster at home... need to see whether this works. Otherwise I will have to get some BONDO or some marine compound.

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Used lot's of duct tape, non-skid padding, electrical tape, and garage door rubber stops to make this scratchy post base a comfortable shoe for the AMAs.

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The next steps are to sand the filler and to create a skin over the foil. Right now I am leaning towards 1 round of duct tape followed by a round of water resistant foil tape. This may not last long, so fiberglass is on my mind ;-)

Please feel free to chip in...


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PostPosted: Sat Aug 22, 2009 6:32 am 
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Joined: Sun Sep 21, 2008 5:04 pm
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Location: Wilmington, North Carolina
Funny as I was watching youtube videos yesterday of people sailing International MOTH Hydrofoils and Hobie Catfoiler http://www.fastsail.com/catcobbler/ with pics of the foils used on the hobiecat which are very different. Looks like you are trying to make foils like the windrider Rave has but without the Foils under the main hull. Cool idea and fun interesting project.. I will be watching all updates Thanks for sharing.

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PostPosted: Sat Aug 22, 2009 7:25 am 
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Joined: Thu Aug 14, 2008 7:25 am
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Location: Kansas
Wow, you are quite the mod builder! You know, your post reminded me of some anti-pitchpole hydrfoils I purchased for my first catamaran, a Hobie 14. It always had a tendency to bury the bows and pitchpole, so I purchased a set of anti-pitchpole hydrofoils from the Murrays catalog, ref part number 01-3240. They were just a flat piece of aluminum sheet metal that you could bolt on to the top of your bow hulls in front. They worked great! I could then drive the boat without crashing and burning. Everytime the bows would start to bury, they would come right back up because of the hydrofoils. So, with that being said, how about it Hobie, how about offering a composite anti-bow plowing asssessory for our Adventure Islands! It could just bolt to the top of the fwd bow, just like these Murrays parts did. It would then eliminate or at least sugnificantly reduce the Island bow plowing we have all complained about, and allow the Island to stay more on top of the waves, rather than under them, slowing the boat down. They also would not reduce normal boat speed because they would not be under water unless the bow went under water, since they would be located to the top of the bow rather than underneath the water line. Your marketing and engineering groups would love them, because it would not need any modification to your existing hull mold, and would not cause any significant added stress to your overall design. And we would love them, because they would work great!!! And IkosTri, since you are quite the mod builder, maybe your next project can be one of these to offer Hobie as a protoype, and make some bucks on the side!

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PostPosted: Sun Aug 23, 2009 8:45 am 
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Joined: Sat Jul 14, 2007 11:46 am
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Location: sacramento
TS:14


I considered TAP Plastic an outfit in CA that advertise, bring in your requirments and they will try to fabricate... A wrap around molded to fit shape, two piece, to be secured at the AMA handle location. That mimics Hydrovisions..goggle up the site and have a look. I did see a Hobie look alike Tri-sail with deep / big molded, into design daggers in the AMA..I have tried a retofitted rudder on a motor side mount assy. ..no motor just for the additional rudder. It did provide additional control. At the same outing, adding a rear mounted V sail...spilling wind up to main sail..self rotational but secured...No preceived additional speed. Take a look at Backbay Boat Works site..Magnum 18/ 21 site. These may provide additional ideas.. I do hope this type of set up will provide some additional support. The referenced part# may provide additional ideas. I also wish Hobie would beef up the design and add the new Troqueedo motor rear mounted. I don't know if I could afford the upgrades if they did offer them. I will keep look out for the results of your test brackets. I have found nothing faster than skimming over the tops of waves, large boat created, headed for shore. I do not have gps so the speeds must be as others have posted...mostly in the 4-8mph range..up to 12 mph.. the humming sound heard only 3 times, in 3 seasons of use, at Lake Tahoe waves. In all cases additional rudder would be great. Have also fitted the rudder into a peddle cartridge, increase in control..yes, but the lost peddles were to much. I guess if increased rudder allows extened sail at high winds with control..The way I had mounted the rudder to the side did not allow rotation just in a slit mount. like additional dagger boards. In the cartridge hole it did rotate..and caused very.. increased turning.. to the point, I had to keep from allowing to much rotation. So nothing has been of much success, just increased types of use. The side mount of trolling motor is the only trick to allow expanded use.. The battery is to heavy...40# and good only for camping, fishing and removal at day camp..All things increase set up and loading times. Wish I could do some pictures with the motor assy. and additional sails as it looks like some kind of pirate deal. How about .. Wing sails... goggle that, stuck in the fishing rod holders with extensions. I work in CA and with furlough days, I can try stupid stuff up lake inlets, with no people about, but short on funds.


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PostPosted: Mon Aug 24, 2009 6:00 am 
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Joined: Fri Jul 17, 2009 11:16 am
Posts: 18
Check out this site for some ideas
http://www.humanpoweredboats.com/Photos.shtml


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PostPosted: Mon Aug 31, 2009 2:00 pm 
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Joined: Thu May 15, 2008 5:08 pm
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Location: Kaneohe Bay, Hawaii
Of course, the problem with trying to lift the main hull is that the rudder is too short. And even if it weren't moving the stress point lower down the rudder would create too much stress on the pin and transom. The main purpose for these foils would be to try to raise the leeward ama, keeping it from sinking.


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PostPosted: Tue Oct 12, 2010 2:44 pm 
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Joined: Wed May 05, 2010 9:52 am
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Location: Latrobe, PA, USA *** Show YOUR Location - Edit Profile ! ***
Whatever happened with these experimental foils?

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Raise your sail one foot, and you get ten feet of wind.
起你的一只帆,和你10英尺的。 -- Chinese Proverb
William D. Latinette @ Latrobe, PA, USA w. H14 Turbo X 2... wildlatin23@hotmail.com


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