I am considering converting my '86 Hobie 17 to sport with a jib.
I notice that the lower bridles for the spreaderbar are solid stainless, but most close-up pictures I've found show the pieces badly bent (the Hobie parts are straight when purchased).
Questions:
Why are the lower bridles so long and solid?
Any reason the solid bridle could not be replaced with a heavy weight multi-strand wire with thimbles?
Why not change the geometry and put the spreader bar almost at deck level (using a long "D" shackle, and lengthen the upper bridles to compensate)?
I am planning to build the spreader bar from a Hobie 17 boom extrusion (as the "real thing" runs $400 to over $600 if I can find one) so I have the luxury of making changes. I know this will not be class legal.
Any help/suggestions would be appreciated.
Arthur
Hobie1822
Why not use a long "d" shackle to reduce "play" in the spreader.
Hobie 17 conversion to Sport with Spreaderbar
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Posted: Aug 13, 2014 - 12:03 PM
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Posted: Aug 14, 2014 - 03:43 AM
I think the problem with running the spreader bar at deck level would be that it would likely have a tendency to smack into waves often when sailing in chop. The H17 bows don't have a lot of volume and it's not uncommon for the tip of the bow to submerge occasionally. Having the spreader raised up slightly helps give it some wave clearance. Also, the two hulls need to move somewhat independently. If you had the spreader bar solidly fixed to the bow, you may introduce some stresses that the hulls were not designed to take which could result in cracking the hull or breaking the spreader bar.
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Posted: Aug 15, 2014 - 05:38 PM
~~~ I have a 17 with a ''super jib''.. Thats like 20-25% past the mast so my cross bar is fastened to the bows (no wires or solid steel).
If you have a ''sport jib'' Hobie set it up to have the ''solid-wires'' I don't know why ?? Dogboy: It's not to give it wave clearence and the bows aren't supposed to move independently. The spreader at the bow helps to keep the bows from ''collapsing'' from all the stress.
The bow would probably crack or break without the bar...
Arthur:: How do you plan on doing this with a ''boom extrusion'' ?? It should be right at the bows, or awfuly close... Thats alotta stress on the bows and the mast especially if you get some honkin winds... I remember reading somewhere on here someone wanted to put a spinaker on a 17H... I never chimed in, but they should think about ''diamond wires'' for that
I've had my 17 kinda scare me it goes so fast with white knuckles and a rip-snortin wind--- I don't take it out with wind like that anymore..... Give it some thought what you do, before ya do it ~~~~~~ SAIL SAFE
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Posted: Aug 18, 2014 - 02:38 PM
Without spreader, the tension of the bridles at each side is:
Tb = 1/2 * Ts / cos a, where:
Tb= bridle tension
Ts = forestay tension
a = 1/2 of the angle between the bridles
If you change geometry to lower the jib, the angle increase and the bridle tension increases. Taken to the limit, as the a angle tends to 90, the bridle tension tends to infinity.
With the spreader, the formula doesn't change for the lower bridles. But now the angle is kept low. -
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Posted: Aug 18, 2014 - 03:00 PM
Now look at the upper bridles. The formula is still the same. Decompose the upper bridle tension between a horizontal component, along the spreader, and a vertical (or so) component, parallel to the forestay. The "vertical" component is Ts/2, it doesn't vary with the angle. The horizontal component is the only one affected by the angle (the only one that tends to infinity on the previous reasoning ..)
So the spreader takes that horizontal component (or most of it) and releases it from the bows. That's its function. It´s all about how much it changes the angle of the lower and upper bridles.
The length of lower and upper bridles doesn't matter if you keep the angles.
Edited by Andinista on Aug 18, 2014 - 03:33 PM. -
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Posted: Aug 18, 2014 - 06:30 PM
Exactly.
The same function can be almost replicated, for very little cost, by using two bridles, & extending them right to the mast hound. The force becomes almost vertical, with little trying to pull the hulls inwards. There are several Cats that use this configuration. The compromise is they cannot utilize a jib.
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Posted: Oct 29, 2014 - 02:43 PM
I also would like to convert my H17 to a accommodate a jib. Realistically I do not think you would really save much money doing it yourself vs buying the kit for around $1000. The kit comes with all of the standing rigging and parts you need and includes the bow spreader. I am assuming that the jib is not included although they are fairly inexpensive.
I also think it depends on why you would like to install a jib on the h17. My H17 Flies without the jib in medium winds very easily. My reason for using the jib is to improve tacking in light winds, my 17 gets stuck quite easily if i do not execute a perfect tack in light wind.
I have a H14 that I built a spreader bar for so I could install a jib. I also built the standing rigging to company specs. By the time I bought the parts and tools to do this properly and safely I had spent almost the same as ordering a kit. I was not very happy with the results. While the jib fits and functions properly it is only useful in light winds. I feel like the boat is faster without the jib, has less bow drag and is easier to solo. I have not sailed my 14 since I have gotten the 17 but I will say that I was only using the jib when I was in winds less than 10mph, if the wind was stronger I would just use the traditional rigging. In light winds though the jib saves me from getting stuck in irons so I will give it credit there.
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Posted: Jul 19, 2023 - 11:23 AM
Can someone give the specs of the lower bridle for H17, size, thickness and diameter of the holes? -
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Posted: Jul 20, 2023 - 01:17 PM
Wire sizes are provided in the link below.
It’s not clear if you are talking about a 17 SE (no jib) or 17 Sport (jib).
On the Sport, the bridle spreader bar attaches to the hulls using sold metal rods, as discussed earlier in this thread.
https://media.hobie.com/2…pport/pdfs/WireGuide.pdf
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Edited by Dogboy on Jul 20, 2023 - 01:18 PM. -
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Posted: Jul 21, 2023 - 10:14 AM
I have been running a bow foil on a Prindle 19 and modified 18-2 for over 30 years now. Even with the bigger bows of the Prindle than the H17, the foil submerges in waves a lot. In lake flat water, not as much of an issue. If you feel you can tolerate it, go for it and try it out. Worst case is you rebuild some wires and acquire new hardware. Currently, on the modified 18-2, I built Dyneema loops to raise the foil about 6" off the deck. I have experimented with different heights and the 6" works best for the Gulf Coast. I will still bury the whole foil at times going through waves. Galveston Bay chop can be pretty nasty (just ask the A-Class guys who attended our last Worlds). The other factor is visibility under the jib. I have one jib the is high clew and one that is a deck sweeper. I always feel like a long tailed cat in a room of rocking chairs when I use the big jib; it's hard to see to leeward. In the past, I have used wire with thimbles (nicro sleeves and swage fittings, turnbuckles, chain, and shroud adjusters. The problem with the wire and thimbles is when raising and lowering the mast, the weird angles and positions the foil gets placed in starts to wear the wire at the nicro sleeve points. Eventually, the outer strands start to break. I have had turnbuckles bind up from sailing downwind and the forestay going loose. The turnbuckle bound up at the toggle and when we went upwind, it just tore the TB apart.
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Posted: Jul 25, 2023 - 02:38 PM
Sounds like you need a window near the foot of that jib.
Not unheard of.
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