Jib Physics & "the slot effect"

Trap and harness is what they wear on F18 type boats so they can hike out on their tippy toes on the hulls suspended by the trapeze wire.
Mine was a poor mans version, basically a 1/4 inch rope tied to the top of the mast then down to a rope tied around my arm pits and clipped on with a big carabiner. I would get going with the wind at around 90 to 120 degrees open up all the sails (all 265 sq ft). In heavier winds it required both my wife and I to hike out to keep the boat from capsizing. I balance my weight with the trapeze line and to prevent the mast from bending too much. The whole thing on tri's is to keep the AMA's out of the water using your body weight for balance.

The tiller is ran with a hiking stick. The problem I have is my spinnaker is not a code zero screacher like on a WR 17 so I can't get any closer than 90 degrees to the wind with it (mine is more like a G1 or G2 downwind only spinnaker (similar to Hobies new sail)). Someday I'll make a new one thats cut more like a code zero, or a screacher whatever the correct name is. I think will be more useful vs what I have now which I kind of stopped bringing along with me everytime out a couple years ago because I seldom use it anymore (I'm pretty happy with my current wing jib and main where I get good enough performance downwind by running them in a batwing setup downwind with a barbor hauler on the main ( my slotted paddle).
FE

Wooow!!!, thank you guys for all the tips .... I will keep you updated about the progress

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Biagio

New prototype following Fusioneng suggestion:



Comments are always welcome?

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Biagio

What your showing will probably work fine, the pvc may bend a little under load, but it's pretty durable stuff, shouldn't hurt anything if it bends and flexes a little.

I ended up using a little smaller dia rope for my halyard up haul line. I use 3/16 dia paracord (500 lb test) with a clip on one end, looped up and thru the mast topper, then back thru a pulley at the back of the boat, then forward to the passenger compartment. You will need to add a cleat up there in a convienent spot or just tie it off around the rear AKA bar (thats what I do with a slip knot). Thats the halyard I use for my roto furling spinnaker. On my rig I have a second pulley mounted in front of the main (jib pulley needs to be at least 3-4 inches away from the main mast or it gets tangled when furling the main). My roto furling jib is mounted about a foot behind the spinnaker at the bottom (any closer and they tangle in to each other).

My jibs are always on a mast (1" aluminum painter poles). To raise the jib I clip the line to the top of the jib, then haul it up with the second halyard (3/16 paracord line), then back down under the front aka brace, then looping into a cleat mounted as far out on front aka cross brace as possible (on my 2012 TI hobie provided the mounting holes for the cleats (I have all 5 cleat positions mounted with Harkin cleats, you can never have too many cleats on a boat (lol)).

To keep that jib halyard line from getting tangled in the main while furling the main I run the jub halyard line thru some 3/8 dia PVC water pipe which is tied at the top to the mast topper (I do the same with the spinnake halyard line), the up haul line runs thru that 6 ft long pipe. The lightweight water pipe prevents the lines from tangling on the main when furling the main in and out. An added benefit is it prevents all the lines from becoming a tangled mess when you break the boat down. Once you start adding all these lines halyards and sails the boat becomes a complex boat that most TI owners just don't want to deal with ( this is likely why mine is the only one out there). Most would just give up on the TI and end up with a Windrider 17 or a Weta, but you can't car top either of those.

To the best of my knowledge mine is the only car toppable complex boat out there. The reason for this is we have a house in Key West (where we mostly like to sail) and there are only two trailer parking stalls on the entire island ( next to the Simonton street ramp). It costs 4 dollars per hr to park your trailer there, you have to unhook the car and park that someplace else (another $4 per hr to park your car). Also our house is in old town (back to back with Hemingways house) where there is no place to park a trailer so we have to car top when down there (sometimes the TI is strapped and locked on the roof up to a couple weeks at a time (when down there we try to go out sailing every day if we can). Lol I would rate Key West as the most small boat and sailing unfriendly place on earth.
Actually we just came back from there yesterday, we were there for fantasy fest week. My wifes company sold their store down there so we won't have to go as often moving forward (thank goodness).
FE

I thought you might be interested in a little history on the names of stuff and how they came about.

Screacher--the sail name was invented by Randy Smyth "Screaming Reacher" = Screacher. Basically a flat cut (flat cut=little camber) sail flown from a sprit. Randy made them from Pentex which was colorful but didn't stretch like nylon. A screacher generally does not meet the definition of a spinnaker (by definition, a spinnaker midgirth must be more than 80% of the foot length--it may be 70, I haven't checked in a while).

Code Zero--The original code zero spinnaker was a cheater sail (literally it cheated the rules to give an advantage). It met the definition of a spinnaker but it was designed to be used more like an extra genoa. The fabric became very high tech to handle the luff loads without deforming...now most sailmaikers don't make code zero's that actually meet spinnaker definition. It is amazing to me that a lot of people are drawn to code zero's because of the cheating aspect.

Asymmetric spinnaker or cruising spinnaker; usually full cut and usually meets the definition of spinnaker and made from nylon.

Windseeker and Reacher; They are made of nylon and are flat cut usually. They may or may not meet the definition of a spinnaker.

Basically, there is a very wide range of nomenclature to describe very similar sails. If you want the sail to go to weather, you pretty much have to make it out of something other than nylon since nylon is too stretchy. You'd be better served to call those screachers or code zero's when speaking with your sailmakers. If you want a nylon sail that can be used upwind in very light wind but is mostly designed for off the wind use, then call it an asym spin, windseeker or reacher.

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R/Thom
SeaRail 19
Triak
BMW C600
Formerly Getaway with Custom Spinnakers
Formerly raced F24 Mk II

Hi All,
yesterday I had the opportunity to do a test of my top mast prototype. I added a rope (both in front and in rear position) in order to simulate the tension of the jib.
Basically it was working, but for sure it needs some upgrades before it can be used.
First of all, the rear braket must be longer and higher (easy to fix), than I must improve the joint rotation.
I found out that it wasn't fluent in its rotation and I had to apply too much tension both in the mainsheet and furling line.

Here is a short video of the test:



Suggestions always welcome

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Biagio

First, try some lubricant at the swivel. If that doesn't work, you may have to start over with a couple thrust bearings and a different cap arrangement (links to photos below-don't know why the img embed codes didn't work). Be advised, though...it DOES take a lot of tension to keep it pointing at the front of the boat no matter what else you do.

https://goo.gl/photos/S4JaZAyM37fPA2uA6
https://goo.gl/photos/oQpgbQecLddWP1hZA

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R/Thom
SeaRail 19
Triak
BMW C600
Formerly Getaway with Custom Spinnakers
Formerly raced F24 Mk II

Blasius, an easy way to make a mast top swivel is to adapt a swivel caster.
I made this for a rotating gopro mount but it would work with your sails as well


Google helmet swivel mount for more info. There are lots of ideas out there like this:
http://www.gospin360.com/diy.php

Thank you for the idea.
I will give it a try next week end.

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Biagio

The mast topper I used has a point bearing in the center (similar design to Hobies mast holder down at the bottom of the mast).
If you look at the attached pic the slender rod sticking out the bottom sits and spins on the 5/16 cross bolt on the brass tube.



That's the original mast topper I made back in 2010 and used for several years, it just hangs in my garage now, on the newer version I went to epoxy filled PVC tubing (with aluminum re-enforcement inside) and a fiberglass pulltrusion 32 inches long (10 x stronger than the 1/2" steel rod in this design.

Here is a pic of the brass tube slid over the top of the mast. That's a 5/16 stainless bolt crosswise thru the center (the fabric sail top strap hangs on the bolt (covered with electrical tape so it doesn't cut the sail).
I just build up the mast diameter with electrical tape to get the brass tube to fit a little tighter ( I have never removed the brass tube)


Here is the actual brass tube I bought at Home Depot that slides over the end of the mast

The brass tube shown on the mast is the original brass tube I mounted on the boat the second week I had my first TI back in spring 2010, I have never replaced that tube, (it's still the original tube, never been replaced). Whenever I get a new boat I just transfer it to the new boat.

Here is a pic of my new mast topper which is much stronger and weighs less than two lbs.


To test it I tied a rope to each end in a loop hoisted the mast then sat at the bottom (like a child swing), I estimate the fiberglass pulltrusion withstands around 300 lbs of force (it's actually the guts of an Ames ax handle with the polypropylene cut off). I also use the mast topper as a trapeze once in a while (not very often).

Here is a pic with all the sails and rigging.


Here is a pic with the spinnaker full of air (though it's an Asymmetric spinnaker similar to Hobies to sail, however it's a little larger and cut more like a G2 gennaker, designed only for downwind, and designed and cut to create extra high lift on the bow (to get the bow way out of the water when pushing hard (I used to have a serious diving and pitchpole problem so I over compensated....)). Hobies new reacher design is way better, and I plan to get one as soon as they come out.


I don't recommend going this extreme unless you plan to go far offshore and don't mind operating a complex boat (aka... a complicated boat with jibs, spinnakers, hydrofoils (260 sq ft or so of sail area), engines, etc (there is a lot going on)). Not really worth the effort to most.
Most of the stuff on the boat is the original stuff I made back in 2010, and all of it looks pretty rough after 5 yrs of really hard use, but if it ain't broke don't fix it is my motto.

Here is a pic of my original motor mount and mast topper hanging on the wall in my garage (they both still work fine, I made them both the first week I had my first TI in May 2010 (we are on our third TI now), took me a couple hrs to make them in my garage with just a drill and hacksaw, with stuff I had laying around the garage), I retired and replaced them both recently. I have no idea how many actual sailing miles I have on all this stuff, but I'm typically out most weekends year round and usually do 10-15 miles each week (pedaling my boat is my exercise program) and occasionally do 50-60 milers (going up to Egmont key and back).


Same applies with the Bowsprit, I am still using the original bowsprit I made originally (no changes), still going strong, every time I get a new boat I just strap it on. Nothing I have ever made requires any mods of any kind to the boat itself, everything just bolts on a stock TI.


The crazy part is I lift that darn boat by the bow sprit all the time and drag the boat around, I'm pretty amazed how strong it is. (it's made from an old fiberglass pultrusion (an old overmolded ax handle (just like the mast topper) that I had laying around in my garage for the last 20 yrs or so (I designed the handle and the tooling originally 20 yrs ago). In the factory where we made them we used to put a brick under each end of the ax handle, then jump up and down on them like on a trampoline (actually holding contests (lol), true story). I've had to stand out on that bow sprit more than once untangling spinnakers.

If you can use any of this stuff and ideas great, if not no biggie. Everything here was originally posted on the ultimate Tandem Island thread. What's kind of wierd to me is in all this time, not a single person has ever tried to implement any one of these designs (kind of a wast of time posting all this stuff), oh well.
Hope this helps
FE

Bob (Fusioneng):
I red your long thread (the ultimate tandem Island) one week ago, and I tried to get as much as possible from your experience.
I will be going to do some other test trying to improve the PVC mast top I already made, I have some ideas about how I can improve the rotation under stress. The svivel caster usage maybe can be also a good solution. I will take your solution as last chance, just in case I will not be able to make the PVC one working as I would expect.

I have a question for you: is it easy to furl and unfurl the mainsail with your mast top on? how much additional force you must apply?

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Biagio

I'm sure reading the ultimate island thread was a long boring read (lol too many tangents)
Yea the castor idea is a pretty good idea.

That's kind of why I re-posted some of this stuff here (a little clearer hopefully).

My original plan was to split the brass tube near the top and place this cage pin bearing in there, then clamp it in with a hose clamp.
http://www.grainger.com/product/BL-Need ... ?$smthumb$

The bore OD on the bearing is 1.625 and the ID is 1.250.

The ID of the brass tubing is 1.4 dia and the PVC upright pipe is 1.312 dia (I would have to turn the PVC down to 1.250 dia).



I never bothered ever getting to granger to get the bearing ($13 bucks), and just use the mast topper with no bearings at all. The pinpoint bearing does the majority of the work (kind of like watches work (a one jewel movement (lol))
I'm sure there are plastic pin bearing cages somewhere that would work, but I gave up on looking. The perfect plastic cage bearing size would have been 1.250 id, then 1.375 OD, and maybe an inch long, but I never found one so I gave up on the idea, and just used nothing.
Hope this helps
Bob

There are lots of ways to skin this rabbit. For me, simpler is better. Just embed a nut in the top center of the mast. Then you can screw clamp a bracket into it. The screw would have needle thrust bearings (the same sort of bearings you would use in a lazy susan) so the bracket can stay in one place while the mast rotates (I use two sets, one on top and one below the bracket). I fly both my jib and spinnaker from this. As long as I remember to lube (one drop of motor oil) the bearings, the mast rotates reasonably freely with reasonable tension on the haylards. Granted, the thrust bearings are not stainless so I have to replace them every other sailing season ($20). I haven't found a source for stainless small needle thrust bearings.

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R/Thom
SeaRail 19
Triak
BMW C600
Formerly Getaway with Custom Spinnakers
Formerly raced F24 Mk II

In my first prototype I tried a similar approach but I changed idea because I was afraid that it was not strong enough.
My next prototype will be a mix of the first two, I will not use any bearing at the beginning, but maybe I will change idea and I will add one or two as you suggest ... unfortunately I am not at home at the moment, I will try the new prototype during next WE.

Thanks

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Biagio

Here you are the 4th prototype:



It looks to be better than the previous ones, expecially it is much more fluent.
Maybe the bracket is too long, I will try it during next WE.

Just in case it will be my last prototype, I would be going to make a provisional jib using polytarp sheet. Do you think it is a good idea or it would be better to go directly to a sailmaker to order one?

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Biagio