DESIGN OF HOYT JIB BOOM?
Charless Fowlkes
Does anyone have guidelines for the design of the HOYT, self tacking jib
boom?
How do you determine the angle of the bearing?
How far is the bearing set back from the tack of the jib?
How stiff should the tube be?
Has anybody made or used one of these willing to tell me how it worked?
Thanks, Charless Fowlkes Bozeman, Montana
Paul Kamen
Charless Fowlkes <cfow...@imt.net> writes:
>Does anyone have guidelines for the design of the HOYT, self
>tacking jib boom? ...
No direct experience with the Hoyt system, but I've been messing around
with self-tacking jibs on my Merit 25 for the last year or so. Some photos
are on my web site (but they are a couple of versions out of date). I use
a floating track, not bolted to the deck, so it lies flat on the deck (or
can be stowed below) and not in use, and not foul the genoa sheets.
The main thing to keep in mind when setting up any self-tacker is that the
"high energy" condition should be on centerline, and the "low energy"
condition should be with the traveler or boom out to one side or the
other. That is, the geometry is such that the sheet gets *tighter* during
the tack and loosens slightly as the car moves back out to the sailing
position on the other side. This can be accomplished with a curved track,
a crafully set axis of boom rotation, or some slack in some of the
"sheets" holding a floating track in position.
Also, don't be afraid to use lots of battens in the self-tacking jib (5)
and put lots of roach in the sail to recover some of the area lost to that
forward clew position.
As I've mentioned here many times: I'll take self-tacking over roller
furling any day, if the object is to take the work out of sailing.
--
fish...@netcom.com
http://www.well.com/~pk/fishmeal.html
-"Call me Fishmeal"-
Terry Schell
fish...@netcom.com (Paul Kamen) writes:
<snip>
>The main thing to keep in mind when setting up any self-tacker is that the
>"high energy" condition should be on centerline, and the "low energy"
>condition should be with the traveler or boom out to one side or the
>other. That is, the geometry is such that the sheet gets *tighter* during
>the tack and loosens slightly as the car moves back out to the sailing
>position on the other side.
I am not entirely sure I understand this claim. Although I haven't
played with it, I see why you want the tension to increase as the car
moves inboard from the normally used jib positions. This prevents the
sail from partially "self-tacking" when you don't want it to and it
gives the sail the appropriate gust response. It doesn't seem to
follow from this requirement that the greatest tension occur at
the centerline. Don't you really need an energy "hump" just
inboard of the car when the boat is close-hauled (one hump for each
tack)? You could run a flat traveler section between the humps. This
would insure that the sail would not want to initiate a tack... but
once you force it to tack (i.e., over the hump), it will certainly
continue all the way to the other side.
I would propose a traveler that is flat in the middle, for easy
mounting, and is curved upward/forward only at the ends. Am I
missing some other rational for the highest-tension-at-the-centerline
condition? It would certainly be easier to mount if the traveler
could be flat over most of its run; it would also help to prevent a
floating traveler from "capsizing" .
Sincerely,
Terry
Robby Robinson
Paul Kamen wrote [http://www.well.com/~pk/fishmeal.html]:
Snip
> Also, don't be afraid to use lots of battens in the self-tacking jib (5)
> and put lots of roach in the sail to recover some of the area lost to that
> forward clew position.
Thanks for posting the detailed description on your web site. How far
off wind can you go before the top of the sail falls off? Did you ever
consider using a boom? -- guess it wouldn't work too well racing.
I walked into North sails in the mid-80's with the thought of setting up
a self-tacking system on Rolling Stone. They talked me out of it. It
seemed then to be a good idea, (large foretriangle) and still seems to
be a good idea. In visualizing this I assumed I'd need a boom & vang,
as well as the track, to keep the sail pulling when off the wind.
You've made me wonder if I couldn't apply your system to my stay-sail.
> As I've mentioned here many times: I'll take self-tacking over roller
> furling any day, if the object is to take the work out of sailing.
An individual choice which I have no dispute. In our case, Roller
Furling (not reefing) has been very useful to my wife & me when
cruising.
The system of most interest to me now is the Wyliecat-30. I haven't
sailed on one, but IMO anything Tom Wylie designs is interesting.
--
Regards Robby [rob...@pacbell.net]
S/V Rolling Stone http://www.selfsteer.com/rolling-stone.jpg
Visit home of MONITOR windvanes: http://www.selfsteer.com/
Brian Grant
Hoyt. I don't know if my formast rig is what you are describing as a
Hoyt Jib Boom but will describe the rigging of the traveller and
sheeting.
The traveler is located beneath the end of the boom and is free to
move. It is straight when viewed from above but is arched slightly to
follow the curve of the deck. There are no traveller lines to limit
motion of the boom. The sheet is attached to the traveller through a
4/1 purchase system and then led forward to a turning block on the boom,
down to a turning block on deck and back beneath the traveller through
fairleads to the cockpit. Trimming the sheet controls the distance that
the boom can move along the traveller. There is a vang, also led aft to
the cockpit, which is much more effective in controlling sail shape than
the sheet.
If this is the rig you are referring to, I could measure the boom and
attachment points for you.
Terry Schell
Brian Grant <bmg...@nospam.please.erols.com> writes:
<snip>
>If this is the rig you are referring to, I could measure the boom and
>attachment points for you.
This is an interesting rig that is often used on staysails, but it
isn't quite what Fishmeal had in mind. He is looking for a self-tacking
jib that has no boom and no vang.
Paul Kamen
tsc...@s.psych.uiuc.edu (Terry Schell) writes:
>...I would propose a traveler that is flat in the middle,
>for easy mounting, and is curved upward/forward only at the
>ends. Am I missing some other rational for the
>highest-tension-at-the-centerline condition?...
No, I'm just trying to describe the basic principle of making a
self-tacker work without getting into subtleties. The shape of the energy
hump can certainly be optimized. But my experience is that if there are
any significant "low points" between the sailing positions on each side, the
car is likely to stick there.
Paul Kamen
rob...@pacbell.net writes:
>Thanks for posting the detailed description on your web site.
>How far off wind can you go before the top of the sail falls
>off? Did you ever consider using a boom? -- guess it wouldn't
>work too well racing.
I thought about using a windsurfer style wishbone, but couldn't figure out
how it would work with a headfoil. I've tried it with a 90% jib on another
boat, though (Pearson Ensign, which was the right size for existing
windsurfer hardware), and it worked great. Note that if there is no
longitudinal sheeting force to balance the boom thrust, this system *will*
cause a kink in the forestay (like on the Freedom 30, the one with the
half-wishbone in a sleeve in the sail) and the sail has to be cut with
this dicontinuity in mind.
>I walked into North sails in the mid-80's with the thought of
>setting up a self-tacking system on Rolling Stone. They talked
>me out of it. It seemed then to be a good idea, (large
>foretriangle) and still seems to be a good idea. In
>visualizing this I assumed I'd need a boom & vang,
>as well as the track, to keep the sail pulling when off the
>wind...
Right now I have a 3DL self-tacker on order from North. I'm not as hot on
3DL as I was a couple of years ago, but I get Jeff Madrigali, Olympic
medalist in a class that races with a self-tacker (Soling) to help me set
it up. He insisted on limiting battens to four, and reducing area a bit
from the very big Pineapple dacron self-tacker I'm experimenting with now.
The system is also evolving into something a bit more conventional than
what's now shown on the web page. Because of the slow response easing
sheets and the poor trim reaching and running, and other problems with the
"sheetless" system, I've gone to a much more normal sheeting arrangement
that leads forward to the stem, just like on a Soling.
The track still floats, and is still easily removable when the big sails
are up.
The way I plan to deal with twist control while reaching (not much of an
issue for most race courses) will be to use separate traveler control
lines that can be unsnapped from the car and double as reach sheets. This
will also be a nice backup to the track: the sail attached to the two
traveler lines/reach sheets will be fully functional in non-self-tacking
mode. For self tacking, they snap back to the traveler car.
I'd love to see some experiments with large-roached self-tacking jibs on
typical masthead cruiser-racers. (Boats that would have been much better
cruisers with fractional rigs, imho.) Part of the conversion would be a
lower boom and a maximum roach on the main to make up for some of the lost
area. I suspect that this could equal the performance of a roller-furled
135 or larger in light air, and with full battens and a deck storage bag,
the jib wouldn't be significantly more trouble to set or douse.
Anders Svensson
I don't know if a Hoyt jib boom is similar to what we over here call a
Peter boom or a jib club.
However, I have a jib boom setup on my ketch. It is basically a aluminium
spinnaker boom cut down to size, so it fits between the base of the anchor
winch (inside the forestay) and the mast. This takes care of the problem
with booms fastened at the forestay but not at right angles to the stay -
that the sail need a special luff to be able to set and douse. Using a full
jib boom with a foil is IMO impossible.
It is sheeted with 2:1 purchase on a X-track as used some years ago for
mainsheet travellers on medium sized boats - nothing really fancy at all.
The spinnaker boom end (substantial!) makes the boom easy to set and stowe
away wich is essential for me. To facilitate this, both the sail wire
outhaul and the sheet is drawn thru a blok shackeled to the fore boom end.
The somewhat original idea is that (as I prefer roller furling) there is a
wire sheet( kind of a outhaul) from the boom end to the claw of the jib in
addition to the actual sheet, the one running on the track. This is IMH the
reason for this setup to work fairly well, as torsion can be adjusted via
the wire sheet and sheeting angle is et via the traveller. There is
probably no reason why a similar setup can't work on a semi circular track
as well - the boom is just another (heavier) way to insure a controlled
clew position. A clew board like the one Paul shows on his site is not
usable on a roller furled sail.
A self tending jib is really a boon when beating in confined waters, and
the easy tacking most probably outweighs any lost performance. The boom
doesn't give just as precise control as a correctly bent track would have,
but still works surprisingly good. I am quite happy with it.
***
As a side comment: I think that (after quickly scanning Pauls setup) that
it could be possible to put a track on two U formed tube supports and use
sheet track slides and two short lengths of geoa track to make it quickly
detachable.
I did not really get how the track doesn't fall down when the traveller is
'dead' in the middle, tho - or is it just a question of 'snapping it over'
to regain stability.
--
Anders Svensson
----------------------------------------
Rodney Myrvaagnes
It was actually a Bierig (sp??) boom. Hoyt called for it in some of
the last Freedoms he was involved with. On the Freedom 32, it worked
as a self tailer, and adding sheet tension did flatten the sail.
It accomplished this by cranking the end of the boom, rotating its
curved shape mor nearly into the plane of the sail. It was in a wide
pocket that left room to rotate it flat.
Frankly with two people on the boat it is so easy to tack a blade
(about 310 ft**2 on our boat) that such an arrangement has no charm
for me. If we need a self tacker, I will try to make one like
Fishmeal's. It allows more control over the sail.
On 15 Apr 1998 02:44:31 GMT, "Charless Fowlkes" <cfow...@imt.net>
wrote:
>Does anyone have guidelines for the design of the HOYT, self tacking jib
>boom?
Rodney Myrvaagnes
On Wed, 15 Apr 1998 18:45:33 GMT, fish...@netcom.com (Paul Kamen)
wrote:
>
>windsurfer hardware), and it worked great. Note that if there is no
>longitudinal sheeting force to balance the boom thrust, this system *will*
>cause a kink in the forestay (like on the Freedom 30, the one with the
>half-wishbone in a sleeve in the sail) and the sail has to be cut with
>this dicontinuity in mind.
>
That half wishbone is the Bierig? thing I referred to in my previous
post. The Freedom 32 had it also.
Dave Forsman
Rodney Myrvaagnes wrote:
The Bierig Camberspar is what is being referred to above. It's a neat
arrangement where the a curved boom is actually in a pocket in the sail.
There is a roller at the luff which rides on the headstay. The sail is cut
to compensate for the fact that there is reverse headstay sag induced by the
boom.... the headstay is pushed forward when sailing on the wind. On a run,
it takes a little while to get used to seeing the headstay sag "on the wrong
side of the boat" so to speak.
I use this sail on my own boat (L.F.H. canoe yawl) and have a picture of the
sail at http://www.personal.psu.edu/faculty/d/r/drf6/gjoa.html If you pick
on the second and third picture you get an enlarged view and some discussion
relative to it. I find the sail to be perfect for my application. I should
mention that a number of years ago, I spent eight years working for Bierig,
four years part time, four years full time, although that had nothing to do
with my choice of the Camberspar. It's simply what made the most sense.
Every once in a while I still do some sail making, ( I did make my mizzen,
the sail covers and the winter cover) just to remind me why I got out of the
business.
--
Dave Forsman dr...@psu.edu
Penn State Erie, The Behrend College
Station Road, Erie, Pa. 16563 814-898-6469
http://www.personal.psu.edu/faculty/d/r/drf6
Terry Spragg
In article <01bd6819$0ec67480$6b3f0ecf@internet>,
"Charless Fowlkes" <cfow...@imt.net> wrote:
|Does anyone have guidelines for the design of the HOYT, self tacking jib
|boom?
|How do you determine the angle of the bearing?
|How far is the bearing set back from the tack of the jib?
|How stiff should the tube be?
|
|Has anybody made or used one of these willing to tell me how it worked?
|Thanks, Charless Fowlkes Bozeman, Montana
|
|
One lazy day, I decided to try a self tacking jib. I stuck the spinnaker pole
out through the pulpit, with a bight of line bittered to the mooring cleat,
passed through the pole eye forward and back to a cleat in the cockpit for an
outhaul. I tacked the storm jib to the headstay fitting, siezed the clew to
the inboard eye of the pole, led a sheet from the inboard pole eye back to a
cockpit winch through a mast base block, hoisted the jib, and voila! With a
good breeze, all I had to do was steer! Yeah, it was cheezy, and I looked
funny with 4 feet of spinnaker pole for a floppy bowsprit, but it worked. I
still use it on occaision, when beating alone on a windy day.
Dave Hord
Charless Fowlkes <cfow...@imt.net> wrote in article
<01bd6819$0ec67480$6b3f0ecf@internet>...
> Does anyone have guidelines for the design of the HOYT, self tacking jib
> boom?
> How do you determine the angle of the bearing?
> How far is the bearing set back from the tack of the jib?
> How stiff should the tube be?
>
> Has anybody made or used one of these willing to tell me how it worked?
> Thanks, Charless Fowlkes Bozeman, Montana.
Charles,
Jib booms are not a hard thing. They aren't very technical either. Set
the pivot point of the boom within a foot of the sail tack and you should
get the
required radius. Allow the clue to be adjustable where it attaches to the
boom,
for better settings. I used a small trailer hitch end welded to the boom,
and secured it to a trailer ball on the deck. This allowed for easy
removal
for cleaning and maintenance of the boom and the deck. It looks neater if
you're
going to be in port for a while, to remove the boom from the foredeck.
I painted mine flat black and it worked out well, and looked presentable.
On small boats, aluminum tubing works, or larger boats with larger jibs,
galvanized pipe works well. Size depends on sail area and stress.
Common sense and logic prevail, and it's best to go a little too large than
too small.
Good luck and good sailing.
Dave Hord
sv 'Christian Island'
a Spirit 23
motorcy...@aol.com
> Does anyone have guidelines for the design of the HOYT, self tacking jib
> boom?
> How do you determine the angle of the bearing?
> How far is the bearing set back from the tack of the jib?
> How stiff should the tube be?
>
> Has anybody made or used one of these willing to tell me how it worked?
> Thanks, Charless Fowlkes Bozeman, Montana
the bend is 59 degrees. the boom is designed to mount to a level deck at an anle of 29 degrees aft. so, if you have a more traditional sheer, and your deck is not flat, you nd to add whatever degree of angle needed to make the base angle of 29 degrees. for instance, if your deck is at 5 degrees, your mounting angle would have to be 34 degrees aft.
if you go to sites selling the hoyt jib boom, you can get tubing diameters recommended for jibs with a foot the equal of yours. i hope that helps.