Hobie Cat Forums

It is currently Tue Sep 02, 2014 2:48 am

All times are UTC - 8 hours [ DST ]




Post new topic Reply to topic  [ 402 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6 ... 27  Next
Author Message
PostPosted: Thu Mar 24, 2011 12:05 am 
Offline
Site Rank - Old Salt

Joined: Sun Apr 20, 2008 6:18 am
Posts: 1277
Location: Sarasota,Key West FL
JollyGreen:
If you are just putting an antenna up, then I don't see a problem just tying to the lifting lug, many people have attached standard hobie kayak sails to their AI's and TI's on the front lifting lug and have had no problems. I recommend using a stretchy type line for the forestay and optional rearstay line (like 3/16 or 1/4" nylon), if the line doesn't stretch you will adversely effect the wind handling characteristics of the sail in a bad way. Basically the mast has to flex quite a bit in order to work properly.
The bow re-enforcement is mostly for the additional sail area.
You also asked for more detail on the bow and stuff, this is a little more complicated, and goes into way too much detail below.
I have 260 sq ft of sail on the boat with all up, (way more than the boat was designed for), I felt that the small lift lug fitting on the front would not hold all that force. I ended up drilling a crossways 5 1/16 hole 1 inch in from the front and halfway down the front of the bow, I then put a 5 /16 stainless screw through the hole, protruding out each side about an inch. I then tilted the boat up on end and poured about 1 inch of epoxy into the end of the bow. embedded inside the epoxy is a 3/8 dia drill bit for structural strength. I then sewed up a strap system that wraps around the bow and under the 5/16 bolt. The nylon strapping is two layers of 800 lb test (1600 lbs lift). All the lines for the jib and spinnaker are now hooked to the nylon strapping (not the lift lug or the hull). It also needs to be noted that there is a structural weakness in the hull itself about 3 feet back from the bow front, the hatch opening weakens the hull signifigantly and the hull bends at that point and leaks in heavy seas (you can see the hull flexing when really pushing the boat with way too much sail out. I ended up tying two ultra low stretch lines from my bow strapping to the outside edge of of the front AKA brace, one on each side in a V shape to lessen the lateral force by 25% and forward force by 75% on the bow front. Looking at Jims rig at the EC challenge (Jim is the Engineering Director at Hobie) he had a beta version of Hobies new Jib sail in testing for the race (about 30 sq ft, roto furling jib). His solution was to add two aluminum braces from the front lifting lug to the outermost edge of the AKA braces in a V shape, which should solve all the problems (his design is way better than mine).
Hope this helps
Bob


Top
 Profile  
 
PostPosted: Thu Mar 24, 2011 9:46 am 
Offline
Site Rank - Admiral

Joined: Wed Dec 10, 2008 8:53 pm
Posts: 232
Can you show/explain in more detail how you created the mast topper and how it mounts to the mast?


Top
 Profile  
 
PostPosted: Thu Mar 24, 2011 10:54 am 
Offline
Site Rank - Old Salt

Joined: Sun Apr 20, 2008 6:18 am
Posts: 1277
Location: Sarasota,Key West FL
JollyGreen:
The mast topper cost around ten bucks in materials, I went to home Depot and bought a 1 1/4 inch dia chrome plated brass drain pipe (it's about a foot long, for a utility sink I think). I slid it over the top of the mast and drilled a 5 /16 cross hole through the very top of the mast, and thru my tube. I then cut through the top of the sail and put the bolt and nut through the whole works. The little strap that keeps the sail from falling, is loose enough to push to one side (around the tube). If I were to do it again, I would not drill the hole through the top of the mast itself. I would just put the bolt through the tube and let it sit in the notch on the top of the mast (where the strap usually goes). I would then tie the strap to the bolt outside of the tube with spectra string or you can lift the strap over the bolt on one side (all outside of the tube). The mast topper is standard 3/4 ( I think) pipe, it's basically a T connector with a 4 inch piece of pipe sticking down into the 1 1/4 tube (can be a loose fit), I reduced the thru fittings threads on the T down to something much smaller ( I think 3/8 pipe), I then took a 1/2 dia steel rod 3 feet long and glued it into the T about 1 ft from the end (look at pics in the original post). You will need notches in the rod for the marine epoxy to hold. I used mild steel for the 1/2" rod, and it tends to bend (from the big spinnaker in higher winds) so I had to add some guy cable to strengthen it a little (as seen in pics). If I had used stainless rod, I would have probably been ok strengthwise (without the guy cable, but who knew ( LOL)), plus the stainless doesn't rust. Make sure your front and back stay lines are stretchy rope like 3/16 or 1/4 dia nylon vs low stretch rope or you will adversely affect the sails design characteristics. The stay lines are mostly for anti-rotation, and provide just a little assist to counter the mast bending (mostly with the big sails). I design and build all my own sails, so it's only material costs for me ( about $60 in materials for each sail design) so I have tried several sail designs. The current designs which I have been running for about a year (about 600 miles) seem to work the best. The Assymetric Spinaker is 135 sq ft, and seems to do a nice job on any down wind from 90 to 270 degrees. The jib is about 30-35 sq ft now and I can still steer the boat ok. The old square top jib design was 40 sqft and I had severe whether helm in higher winds, plus it got damaged pretty bad when I tried to use it in 25mph plus winds about a month ago, this new design is better, I was out testing on Sunday and in 10-12mph winds I was able to get up to around 5mph using the jib alone (with the main furled up completely). I know it's all a little cheezy, but hey it all works.
Hope this helps
Bob


Top
 Profile  
 
PostPosted: Sun Mar 27, 2011 2:59 am 
Offline
Site Rank - Old Salt

Joined: Wed Dec 19, 2007 4:07 am
Posts: 598
Location: Punta Gorda, FL
fusioneng wrote:
Hammer:
Yes in Florida anything over 16 ft has to be registered, I was chased down and pulled over by the Kayak police (fish and game), and told to register, I tried to out run them, but they had a scarab (just kidding about trying to out run them). It's only like ten bucks or so.
Bob


You carry a motor around, so they've got you for both the length and the engine. Any motor on any boat, per this page:

http://www.flhsmv.gov/dmv/faqboat.html#3

Quote:
I only use a small trolling motor when I use my 12 foot vessel in the canal behind my house. Do I have to register my vessel?

Yes, all vessels used on public waterways with any kind of motor must be titled and registered.


Top
 Profile  
 
PostPosted: Sun Mar 27, 2011 5:20 am 
Offline
Site Rank - Captain

Joined: Wed Mar 09, 2011 7:37 pm
Posts: 52
fusioneng, Great postings/mods. Some pretty clever ideas. I have had the opportunity to crew on a trimaran Corsair 27. Though slightly different, many of your ideas run parallel to Ian Farriers ideas. If you get the opportunity, poke around one some to see the analogies I am talking about. I live in Gulfport, let me know if you want to look at the one in BCYC. Rich owns it, and has tweaked it a bunch for racing.

Regarding the Weta, I am looking at getting my own trimaran. Being on a student budget, I have limited funds. With a bit of patience and time, a Tandem AI will be affordable. The Weta costs about $11K. About the price of 2 Tandem AIs, or all the mods you can possibly dream about for 1. Certainly a nice boat, but not in my budget.

Thanks for your insight in to some of the mods you have posted.


Top
 Profile  
 
PostPosted: Tue Apr 19, 2011 6:18 am 
Offline
Site Rank - Deck Hand

Joined: Fri Dec 18, 2009 4:42 pm
Posts: 14
Location: brisbane queensland australia
fusioneng , could you possibly post on here a diagram and measurements of your homemade spinnaker , i'm thinking of useing ripstop material ....nice and light


Top
 Profile  
 
PostPosted: Tue Apr 19, 2011 9:57 am 
Offline
Site Rank - Old Salt

Joined: Sun Apr 20, 2008 6:18 am
Posts: 1277
Location: Sarasota,Key West FL
Jibsail:
This will be a pretty big undertaking, I designed the sail in 3D Solidworks, but didn't create a bunch of 2D drawings and stuff (I don't have a large plotter anymore), I just put up on my screen each section, then measured out and cut each panel one at a time. The sail is a standard Assymetric spinnaker sail. I use sailflow ( a free sail design software ) to design all my sails, then model the information into 3D using solidworks or Pro Engineer. The sailflow has a 2D drawing maker (but I didn't use it). You will need a large cutting layout area and a pretty high quality sewing machine ( I have a Swiss Pfaff quilting machine that does a nice job (but very expensive (about $2k). The important features to look for on the sewing machine are it needs at least a 6mm re-enforced zig zag pattern (with extra stitches in the center), and you really need upper and lower feed dogs, a pro machine is needed to go through multiple layers of mylar and sail quality dacron (my Pfaff can't). I used heavy duty polyester upolstry thread (about 8 rolls). There are 9 panels 2x4' sewn together. Here is a link to detailed instructions on how to construct and sew sails ( http://www.sailritesails.com/videoselections.aspx ). I had to read quite a few books and studied almost two years before attempting to make my own it's much more complex than I ever imagined. Total cost was around $200 in materials. The sail has been in service for about a year now with no issues. I sail every weekend (year round) mostly in South Florida and Key West. I used rip stop nylon on the spinnaker because it is inexpensive and very durable, and can be purchased at most fabric stores.
Good luck.
Bob


Top
 Profile  
 
PostPosted: Wed Jun 22, 2011 12:10 pm 
Offline
Site Rank - Old Salt

Joined: Sun Apr 20, 2008 6:18 am
Posts: 1277
Location: Sarasota,Key West FL
Update Sailing with no AMA's:
I described a keel weight system on this thread so the TI can be sailed without the AMA's for those times when we are out on rivers just kayaking but also want to be able to sail (like we do with our regular kayaks ( ie.. revo, Oasis, etc), or we just want to go out for a quick sail and don't want to go through all the hassle of loading the AMA's and all the gear (kayak mode). Well I went ahead and made a weighted keel that mounts into the rear Mirage drive holder and it works great (see pics below). The first version was the 25 lb keel weight I made 3 yrs ago for my Oasis (still had it), I went out last week and tried it on my TI and it worked for the most part, I could sail in light winds with normal TI mainsail but it was a little shaky and I if the boat tilted past 50-55 degrees it would keep on going over (yes I went swimming). With 50 lbs I can stand on the rail and the boat doesn't tip over (see pic), This latest version is 50 lbs and keeps the boat from tipping even with the sail up in light conditions similar to a monohull (have not tried it in heavier wind conditions) I am only using the main 90 sq ft sail for this and am not even going to attempt flying 260 sq ft of sail. The weight is supported by two spectra lines tied to the AKA mounts so as not to stress the Mirage drive pocket. The way I figure it is this keel weight weighs the same as the AMA's but is alot smaller and easier to transport and rig (just plug it in). It took me about 5 minutes to launch the boat vs the normal 30 minutes.
This is me standing on the rail (notice I'm wet, it was attempt #2)Image
Here is the unit ready to drop in, I used lead shot (old scuba weight belt) embedded in polyester resin to for the weight.Image
I can still transport with the scupper cart. Image
Bob


Top
 Profile  
 
PostPosted: Thu Jun 23, 2011 10:35 pm 
Offline
Site Rank - Old Salt

Joined: Thu Aug 16, 2007 2:25 pm
Posts: 1977
Location: Central Coast NSW Australia
Bob,
That is brilliant! 8)
It's something I've been meaning to try on my AI but haven't gotten around to it. I use it as an Adventure with the small sail a lot and when the winds are light often think of how it would go with the AI sail/mast but no Ama/aka.
Keep us posted on your sailing results. Great work. :)


Top
 Profile  
 
PostPosted: Fri Jun 24, 2011 1:18 pm 
Online
Site Rank - Old Salt

Joined: Fri May 08, 2009 5:06 am
Posts: 1569
Location: Lake Macquarie NSW AUSTRALIA
Very impressive Bob. I can see you have an engineering brain but have you gone to the extent of doing some calc's on the loading on the drive well ? Remembering the hull cracks in this area due to Mirage Drive loads, I'm sure this would have been in the back of your mind when designing this keel weight system.

P.S. nice pool.

_________________
Image

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


Top
 Profile  
 
PostPosted: Fri Jun 24, 2011 2:52 pm 
Offline
Site Rank - Old Salt

Joined: Sun Apr 20, 2008 6:18 am
Posts: 1277
Location: Sarasota,Key West FL
Slaughter:
Actually I thought about just making the unit without any support wires but chickened out. The weight and load is actually supported by the spectra lines attached to the AKA crossbars. The design is actually kind of cool because I have the spectra lines fed into harken blocks on the front AKA cross bar so if the boat is tilting a little too much I can steer the keel weight and pull it off center to counter the weight (basically the keel bar bends to one side and the weight turns into the desired direction (like a rudder). I can move it back and forth about a foot each way from center for trimming and leveling the boat. If the keel weight were to hit something I'm hoping the hobie well plug gives away before the hull. I took a standard well plug (I have bunches of them laying around the garage). I cut a slot through the well plug, removed the top then pushed in two short half inch rods and epoxied to the inside of the plug after drilling out the nylon plugs, I then put a little epoxy around the 1/8 x 2 riser bar (the old carpenters square in the pics) about 3/8" thick, I then filled the entire Hobie well plug with urethane foam and stuck the top back on. I can't imagine the stress being any more than if I were to run into something with the mirage drive ( we've all done that) if I were to hit something. We're long time kayakers and have ran quite a few rapids with our hobies, and sometimes don't get a chance to pull the mirage drives out in time so we have to ride it out with them in and haven't destroyed any drives yet ( we have damaged some though, they are suprisingly durable and easily repaired). The way this is designed we would unplug from the drive well before getting to shallow water. The plan is to use the sail to cross the big water, then put the sail and keel away when we get to the fun back woods or mangrove areas. The depth is adjustable so if we suspect shallow water coming up we can retract it closer to the hull.
Bob


Top
 Profile  
 
PostPosted: Sat Jun 25, 2011 5:47 pm 
Online
Site Rank - Old Salt

Joined: Fri May 08, 2009 5:06 am
Posts: 1569
Location: Lake Macquarie NSW AUSTRALIA
Gotcha, thanks for the explanation Bob. When you were saying that the keel bar bends slightly, how about if it was hinged via a pin connection at the top so that the centre of gravity can be altered. Some of the latest and greatest Maxi yachts now have this 'Canting Keel' feature where the keel can be raised sidewards as a counterbalance. Like here.

http://www.stockmaritime.com/modellboot ... gemein.php

Just a thought. :idea:

_________________
Image

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


Top
 Profile  
 
PostPosted: Sun Jun 26, 2011 7:36 am 
Offline
Site Rank - Old Salt

Joined: Sun Apr 20, 2008 6:18 am
Posts: 1277
Location: Sarasota,Key West FL
Slaughter:
Thats sorta the design I was shooting for, the high carbon steel blade (the carpenter square) bends easily and I can pull it to one side or the other about a foot, the old original design (that we used on our Revolution and the Oasis kayaks) I did 3 yrs ago used rubber hose (vs the steel blade) and I could pull the weight out of the water (90+ deg) on one side or the other and we could actually sail in very shallow water. The down side to that design was the large rubber hose created quite a bit if drag to the boats, and wasn't removable in the water (it was attached inside the scupper holes with an expansion plug). This design has minimal drag ( I lose maybe 1/2 mph on the top speed). I took the TI out again yesterday we had 10 mph winds but it was gusting and variable which made the ride a little scary, I only dared opened the sail about half way, if sharks or gaters were circling the boat eyeing me for their next meal I think I would have furled the sail. Basically the TI with this keel weight and the standard TI sail in those conditions is similar and functionally equal to kayak sailing a standard Oasis or Revo with a standard Hobie kayak sail (without any keel weight system), it's still easy to get tipped over in a gust or a big boat wake. The good news is the boat is suprisingly nimble and fast (much faster than the Revolution with a standard Hobie sail (even with the sail furled 3-4 turns in)). Basically this design works as advertised and allows me to river kayak/sail the TI alongside our other standard Hobies without the AMA's, I can't wait to try and run some rapids (our favorite thing) with my TI (with the keel weight unplugged and the AMA's removed of course) but will have to wait until the next time we go to Colorado, Wisconsin, or Michigan (not in the cards this year because of gas prices) there are no rapids in Florida that I know of, and all fresh water has gators down here. I like your idea though, I'm not going to modify my TI any more for ocean sailing, I love it just the way it is (why mess with perfection IMO, just use it). However I've designed and built several racing hydroplane type boats in the past, and am itching to design and build another boat, maybe it will be a mono hull with a swinging keel.
Bob


Top
 Profile  
 
PostPosted: Tue Jun 28, 2011 5:40 am 
Online
Site Rank - Old Salt

Joined: Fri May 08, 2009 5:06 am
Posts: 1569
Location: Lake Macquarie NSW AUSTRALIA
This new design work of yours makes the TI / AI even more versatile. Where will it end.
I'm just waiting for someone to stick blades to the hull and take it out on the ice.
Or add wheels and take it to Bonneville.

_________________
Image

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


Top
 Profile  
 
PostPosted: Tue Jun 28, 2011 7:36 am 
Offline
Site Rank - Old Salt

Joined: Mon Jun 14, 2010 10:43 am
Posts: 433
Location: Long Island NY
I'd be happy with a planing "slipper" that fits over bow, extends about 2/3rds back and allows the hull to get up on step

_________________
Alan W.
'07 Hobie Adventure Island #1
'07 Hobie Adventure Island #2 Golden Papaya AI LadyJane
'06? Hobie Outback SUV


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 402 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6 ... 27  Next

All times are UTC - 8 hours [ DST ]


Who is online

Users browsing this forum: Yahoo [Bot] and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group