The J105 helm,
instrument remote and the propane bottle locker
The J-105 genoa
tracks and the triple cabin-top rope clutches
J/105 hydraulic backstay, the wheel, the traveler system with a double-ended
plate and the foot rest for the main trimmer
J105 cabin-top instrument cluster, starboard side
upgraded instrument cluster, port side
Larry is smiling at the helm and our mascot is flying; Screwpile 2003. Notice instrument remote on the wheel and the propane bottle locker
The mainsheet system
the history of the J105 production, there has been several variations and
improvements for the mainsheet system within the same basic parameters (6:1
gross trim and 4:1 fine trim giving a combined 24:1 trim). A few years back,
the double ended plate was introduced by Andy Skibo with the swivel for the gross trim at
one end and the one for the fine tune at the other end. A discussion on the
web forum (below) contributed in making the change class-legal and soon
thereafter, the newer J/105s adopted the design.
Some J/105s have set
up the gross trim aft to facilitate main trimming by the helmsman. On
Chantecler, I have set up the fine trim aft because that is the one I am
most likely to adjust when helming. Furthermore, when single handling
Chantecler, I can easily adjust the gross trim because of the wide rotation
angle of the forward swivel. Finally, when racing, the main trimmer should
be forward of the traveler and thus the forward position for the gross trim
is the most natural one.
Forum discussion; from:
|Nelson Weiderman Wickford RI
Posted on Wednesday, January 03, 2001 - 9:51 am:
Revise 5.3.6: A fine tune system for the mainsheet with a maximum 24:1
power ratio may be installed over the coarse tune block or on a bracket
mounted on the opposite side of the traveler at the same height as the
Discussion: The revision to the fine tune system was proposed as a
simply way to alter the existing system to minimize the problem of the
fine tune sheet getting tangled in the mainsheet.
|Marv Pozefsky - Bridgeport
Posted on Monday, March 26, 2001 - 6:07 pm:
tried, or planning to try the newly approved mainsheet-fine tune
|John Kircher, Annapolis
Posted on Monday, March 26, 2001 - 7:08 pm:
main on Bill Sutton's Blonde Attack several years ago both before and
after he 180-ed the mainsheet support plate. Not only does it reduce the
tendency for the two sheets to foul, it lets the main trimmer go forward
and to the rail with the coarse-tune, while leaving the fine-tune aft in
easy reach of the helmsman.
Funny you should ask now, since we just turned Jay Boat's mainsheeting
system around yesterday.
|Marv Pozefsky -Bridgeport
Posted on Tuesday, March 27, 2001 - 5:27 am:
John....Could you share your experience - what parts did you buy, where
did you get them, did you double support and etc. Thanks
|Nelson Weiderman KIMA Wickford RI
Posted on Tuesday, March 27, 2001 - 7:54 am:
here's my experience. I had a friend make up a single aluminum plate
with a mirror image on either side of the traveller. You can actually
work aluminum with woodworking tools. But later I noticed that Layline
carries a "swivel base flat bracket" that might work well in conjunction
with the existing platform. You would need longer bolts through the
traveller to attach both platforms. You would probably have to take off
the traveller, which could be a pain. The flat bracket is LL1005 on page
15 of the 2000 catalog and costs $30.
I bought two Harken bases for the fine tune and eventually sent them
both back. The 1573 fits the larger mid-range 1566 fiddle w/Hexaratchet,
not our smaller 060. The 010 ball and socket base works, but you need a
smaller clevis to fit the 060 and the working load is a little skimpy. I
ended up using a hefty Shaefer eyestrap with standup spring. Works
great. Use a padeye if you want even more heft.
For the main block, I'm sticking with the 170 Hexa-Cat base. The bracket
on top is no longer functional, but it shouldn't get in the way. I guess
you can hacksaw it off if you like or tape up the integral clevis on
top. If your mainsheet block needs to be replaced anyway, I think it is
the 009 Hexaratchet is what you would need.
Take this all with a grain of salt since it hasn't been tried out yet,
but you can do the job for under $50 with no new blocks to buy. Note
that I did not go with an additional support post and don't think one is
necessary. With the split system, you have equal and opposite forces
pulling up on either side of the traveller which lessens the need for a
second support post.
Jaffar Bentchikou - Annapolis
Posted on Tuesday, March 27, 2001 - 8:36 am:
|Marv, I am
John's partner on Jay Boat. The job was done by team member Paul
Hillier, who is a marine industry pro. He used screwdrivers, a socket
wrench, a caulk gun with Sikaflex, a big piece of wood and the knowledge
to apply force when needed and where needed. The V-shaped aluminum
support is bolted to the bottom of the traveler's track. The aluminum
pipe support is attached to it with one screw and to the cockpit floor
with another screw. The geometry is easy because everything is
symmetrical. You turn the plate around 180 degrees, make a new hole in
the cockpit's floor for the screw at the bottom of the pipe and plug the
old hole. The problem is that on our boat they did not come apart easily
because the aluminum support plate became welded to the track's alloy
due to the galvanic current between the two different metals. They
should have been electrically insolated, but were not. For the new
installation he used Sikaflex. So, he used the piece of wood first to
knock the pipe support sideways and then to separate the V-shaped plate
from the traveler's track, with the help of large flathead screwdriver
driving a wedge in between.
I know that properly plugging the hole left behind on the floor is
critical. Until we test on the water, we have temporarily used a flat
head machine screw with two washers and a good dose of Sikaflex.
|Doug Berman/San Francisco
Posted on Sunday, April 01, 2001 - 10:37 am:
|I just got
Out-of-Options back from Key West/Miami and had my boat yard move the
course tune forward of the traveler. I opted to have them move the metal
triangle base forward and not fabricate a new one.
I don’t know how difficult it was to remove, but the rigger did mention
the metal post on my boat needed to be shortened once forward of the
traveler.?. The other issue was the bottom bolt that holds the post to
the deck, seized. He needed to drill out the bolt and run new threads
(tap and dye). The filled the old hole (where the post was) with gelcoat
and painted to match. It took him half a day to do.
Yesterday, we participated in the Lightship, a 25-mile offshore regatta.
I’m very happy my main trimmer is no longer sitting right next to me and
is a good 3+ feet forward. He likes the arrangement as well, except when
is lost his footing on that 12’ wave and fell in the cockpit. Details,
I just have to mention this... When we finally rounded the weather mark,
it was blowing about 24 gusting to 33. We opted NOT to set the kite and
run back with main and jib alone. About a quarter of the way back… Down
a really big wave… With a really big gust… Boat speed was 23.5 knots!
YEHAAA! Unbelievable experience.
|Andy Skibo Plum Crazy Hull #90
Posted on Sunday, April 01, 2001 - 2:05 pm:
|To All: As
one of the originators of the now-allowed fine tune, Plum Crazy offers a
simplifying suggestion. If you are splitting the fine tune/coarse tune,
you don't even need the post that holds the plate. Plum removed it four
years ago, w/o a problem, and Plum certainly is a hard used boat. With
the new arrangement, the load on the new plate under the traveler is
balanced. You have one mainsheet fall to the swivel on one end, (four
falls to the fiddle block on the traveler itself) and one fall going
through the fine tune to the other end of the plate. In the old
arrangement, you had two falls going to one end of the plate, resulting
in a torque load trying to twist the traveler channel. The post was put
there by factory to support this unbalanced load. Not true any longer,
with split system. (And for reference, since we couldn't find our old
post, we sailed all of 2000 with the unbalanced arrangement w/o the post
with no problems.)
So installation is really trivial. Just get a mirror-image plate made up
(cut out of aluminum stock with hand tools), put a small bail on the
end. Drill hole pattern to fit current swivel on other end. Disconnect
fine tune from top of swivel/coarse tune assembly, complete with its
spring, and just re-shackle to the small bail on other end of plate.
Attach coarse tune swivel to the other end.
Once you have the aluminum plate and the small bail, this takes less
than 10 minutes to do.
Patch hole in bottom of cockpit floor by using a large ss backing
plate/washer, drilled for same bolt pattern that held post in place.
Seal everything up with sealant, bolt down, and presto, you're done. (We
left a bail there, so that when the J/35 fine tune to cockpit floor,
double ended arrangement, is eventually approved, we can hook it back up
If you've got the aluminum stock available, and you cut it yourself,
this whole thing costs less than $10 to do.
We've installed it/removed it several times as rules have come/gone/come
(locally/nationally) allowing use of this arrangement. It's not hard,
it's cheap, and the improvement in tangle free use of fine tune is
|Tom Rolfes/Cincinnati-Southwest Harbor/ME
Posted on Sunday, April 01, 2001 - 11:00 pm:
As my boat is still 1150 miles away in Maine, I'll not get a chance to
work on this aspect for a number of weeks yet. So, to get materials
ready, do you have an idea of how thick an aluminum plate we will need?
Has anyone a full sized sketch that could be downloaded or faxed?
Tom Rolfes/Sidewinder #161
Posted on Monday, April 02, 2001 - 9:08 pm:
I have taken the existing plate off my boat and have brought it to a
machine shop. They will send me the blueprint for the new part, the
material list and etc. I will post them on the web for all to have! If
you will not have the time or energy to make your own part, E mail me so
I can direct you to the machine shop.
|Jaffar Bentchikou - Annapolis
Posted on Tuesday, April 03, 2001 - 9:15 pm:
could very well believe that splitting the fine tune aft and the coarse
tune fore of the traveler reduces dramatically mainsheet tangles. But
why the new aluminum plate? Could you put the small bail for the fine
tune directly on the floor, using for that purpose the hole that the old
post is leaving aft of the traveler? Is this basically what you describe
as the 'J35 fine tune to the floor' (without the double-ended
arrangement)? To be legal, the fine-tune system should be 'at the same
height as the traveler' but this can be solved with a piece of cable
between the bail and the fine-tune swivel.
Andy Skibo Plum Crazy Hull #90
Posted on Wednesday, April 04, 2001 - 8:16 am:
We did indeed use a small bail on the floor for what everyone calls the
"J/35" arrangement. The problem with using a wire or line to get the
bottom of the fine tune at the same height of the traveler is two fold.
First, (and biggest) limitation is that the bottom of the fine tune
arrangement is the swivel block with cam cleat. That block/cam cleat
arrangement requires a relatively solid mounting to work. Otherwise, it
will be a PITA to get the line uncleated. Second, (and lesser
consideration) is fact that if it isn't mounted to a plate (or bracket)
under the traveler, you've got the possibility of fudging on just how
high is the fine tune block off the floor. I wouldn't worry about it
personally, but we're still dealing with a fleet that has some folks
concerned about whether removing the old snuffer control line cam cleats
on the side of the cabin (which haven't been used in OD racing for seven
years) is legal or not. So don't assume that tying the line to the bail
on the cockpit floor "same height as traveler" or not will be accepted
as kosher by everyone.
The more compelling argument for the plate (or bracket) is fact that you
probably need it to make the setup work.
Forum discussion from:
|David Frizell-Perth Amboy,NJ
Posted on Friday, April 20, 2001 - 11:46 am:
come up with a source for the aluminum piece needed to retrofit the fine
|Marv Pozefsky/Bridgeport, CT
Posted on Saturday, April 21, 2001 - 9:31 am:
The first plate is almost done. After it is installed and tested, you
will be contacted and can then place on order. I am forwarding inquiries
directly to the machine shop.
Posted on Tuesday, May 01, 2001 - 5:21 pm:
installed and tested the first plate. Works like a charm. Those who
contacted me will get an E mail from the machine shop. The price will be
$ 82.00 plus shipping. To order the fore and aft tuning plate Email
'Slingshot31998 at aol dot com' or Fax (203)878-4232
Dawid Manufacturing Inc.
185 Research Drive
Milford, CT 06460
|guy ballou/#164, Dark Star, Annapolis
Posted on Wednesday, May 02, 2001 - 10:27 am:
change you could take a picture and put up on the webpage. guy
|Nelson Weiderman KIMA Wickford RI
Posted on Tuesday, May 08, 2001 - 10:36 am:
photo of the modified fine tune from a boat that has the modification
installed (not KIMA). Note that the coarse tune block is the same as the
original, but with the "ears" clipped off. I did this on KIMA with a
hack saw and a file, so the only parts I bought were the eyestrap and
the spring, and the new aluminum (3/8") plate. Note also that this
installation does not use a support post. I recommend that you leave the
one that's there, but don't bother with a second support.
|Stuart Burnett/Richmond, VA #198 Legacy
Posted on Wednesday, May 09, 2001 - 10:28 pm:
trying to visualize how you do this and still get a fair lead using the
existing blocks...so far with no success. Is it possible to set this up
without having crossed lines going to the block on the traveler? Can
someone explain or post a diagram? Thanks!
Nelson Weiderman KIMA Wickford RI
Posted on Thursday, May 10, 2001 - 7:07 am:
to the Fleet #5 site and click on "Alternate Fine Tune Installation".
The diagram there shows how it is done without having crossed lines..
|Stuart Burnett/Richmond, VA #198 Legacy
Posted on Thursday, May 10, 2001 - 1:53 pm:
sailed with this configuration extensively and what has been your
experience. I can see the benefit of allowing the main trimmer to sit
further forward (especially since mine weighs 240+), but what effect
does it have on cockpit space? Now there's a pretty big projection
forward into what used to be wide open cockpit. Also, has anyone sailed
short-handed with this configuration? We have a fair amount of trouble
with the traveler-mounted block twisting on jibes and occasional with
the fine-trim block getting wrapped up in the course-trim cleat, is this
configuration less susceptible to that or more?
|Andy Skibo Plum Crazy Hull #90
Posted on Thursday, May 10, 2001 - 2:42 pm:
The picture posted by Nelson is from Plum. We've been sailing with that
setup for two years (except for a few races starting with last years'
NAs through KW, when the system was temporarily not allowed), both in
races as well as with two person deliveries. And before that, we sailed
with essentially same set up, except fine tune falls run to small blocks
directly on cockpit floor, for two preceding years. (You can still see
eye strap for that in picture.)
It's primary advantage, whether you have 6 people on the boat or 1, is
fact that you never get the usual tangles, overlaps, rat's nest, between
fine tune and coarse that you used to get with the factory setup.
Especially on gybes.
As far as the slight extra protrusion of one extra end of the plate,
you'll never notice it. On a tiller boat, that slight protrusion sticks
into the space the helmsman moves around in on tacks, etc. I had your
same worry before we first installed it. Never noticed it. Never hit my
shins on it. You'll find that you just don't put your body that close to
the mainsheet falls/fine tune fall anyway, so you just don't get near
And setup will not change the position of where your main trimmer sits,
unless you choose to. Both lines still run to his hands together, as
they did before. They just don't get tangled.
Trust me, all you'll get is a heck of a lot easier handling of
mainsheet/fine tune, with no observable difference in cockpit space.
|Cedric Lewis MIRAGE HULL#328
Posted on Friday, May 11, 2001 - 1:38 pm:
We have had our boat for exactly one year. We quickly discovered what a
nightmare the main sheet/traveler can be. In light air it was a nuisance
but in heavy air it can be down rite dangerous. We followed Andy's lead
and split the fine tune and main sheet and had a custom plate fabricated
to replace the existing plate. I took the existing plate, scored it
along the traveler. I then removed the plate, traced it and then flipped
it around (180 degrees) and traced it again making sure that the bottom
line and the scored line matched. The end result is a diamond shaped
plate that protrudes on either side of the traveler in a mirror image. I
also traced the mounting holes and the post hole. There is no need for a
second post as long as you use 3/8" stock for the plate. The whole mod
cost me ~ $75. The only thing I had to buy in addition to the plate was
the strap and the hardware to mount it to the plate.
In addition to the easy of use it allows us to get the sails set after a
tack and get the main trimmer on the rail. Now the helmsman (or driver
as I guess they are now called) can make the final adjustments with the
|Bill Hunt/Rhapsody 487/Boothbay Harbor, ME
Posted on Friday, May 11, 2001 - 2:21 pm:
plate that Dawid Mfg is offering match the one Andy has on Plum Crazy?
(i.e. same kind of nice finished curves, etc.) I have a 4 year old so I
am concerned that it not have sharp corners or edges (actually even w/o
the 4 yr old I'd have the same concern).
|Jonathan Udell NJ
Posted on Friday, May 11, 2001 - 4:43 pm:
Andy's plate for him, so thanks for the nice comments. I also have in my
hands five of Dawid Mfg's new plates, just arrived today. They are quite
nicely made; predrilled and anodized. I think you will be very happy
with their work.
|Bill Hunt/Rhapsody #487/Boothbay Harbor, ME
Posted on Friday, May 18, 2001 - 9:25 pm:
|Here is a
picture of the Fine Tune double ended plate from Dawid Mfg. (see above).
|Andy Skibo Plum Crazy Hull #90
Posted on Tuesday, May 22, 2001 - 8:27 pm:
|To Tom and
others: I'm not sure why the David plate has swivel hole pattern in both
ends but worrying about a second swivel is unnecessarily complex (let
alone illegal). The fine tune block swivels around it's own post--just
as it does on the standard fine tune setup.
The plate we used (and plate which I understand Layline will sell,
complete with bail already attached) just had two holes drilled on the
fine tune end for a bail. These plates are aluminum--a household drill
bit and electric drill will go through them like butter.
Once you have bail mounted, all you have to do is take standard fine
tune block, and use small D shackle to pin it through the bail. Stand-up
spring will hold it up, and will easily fit over the D shackle. You
don't need a stand up post mounted to the plate. The bail works just
PS: You don't want to lose any of the throw available on this fine tune
setup by using 10 inches of the vertical clearance for a swivel arm
anyway--even if it were legal.
|John Sullivan / San Francisco / Hull 181
Posted on Tuesday, June 26, 2001 - 12:07 am:
anyone, including the TC, come up with a totally legal split mainsheet
system diagram? I want to try it but want it to be legal.
|Jim Snair/Andrea5 of Sunnybrook/#506/Halifax, NS
Posted on Tuesday, August 28, 2001 - 11:50 pm:
Owners who are reviewing this thread...The fine tune/racing mainsheet
available as a factory option. Its being
installed on at least three boats in the 501-506
|Nelson Weiderman #300 KIMA
Posted on Tuesday, October 02, 2001 - 5:23 pm:
diagram of how to rig the alternate fine tune system, courtesy of George
Petkovic of Fleet #5.
|Perry Moy / Hull #39 / Synergy
Posted on Friday, November 30, 2001 - 6:08 am:
in removing the old plate. I have hull #39 and I removed the four(4)
bolts under the plate and the support post. The plate does not move. TPI
suggests that I drill out the bolts; can not see that. So any suggestion
will be a great help.
|Nelson Weiderman / Hull #300 / Kima
Posted on Friday, November 30, 2001 - 8:11 am:
of years ago, I removed the plate on #37 to turn it around. I had the
same problem as you have. As I recall, I just had the courage to use
more and more "persuasion". I'm not sure whether it was in the form of a
small sledge or in the form of a wedge between the plate and the
traveller. The two obviously weld together from galvanic action, but the
"weld" is not as strong as the plate or the traveller and you are going
to break the weld before you break either the two pieces being held
together. No guarantees, mind you, but drilling out the bolts seems much
harder in my mind and does not break the weld anyway. You might also try
softening it up with Liquid Wrench before applying the extra force. Let
us know what finally works.
|Jaffar Bentchikou / Hulls #208 & 536 / Annapolis
Posted on Friday, November 30, 2001 - 9:30 pm:
|I have had
the same problem and it was solved by my team member
Paul Hillier. Click on the link to find the post. He used a large
screwdriver, a big piece of wood, a big blow and the knowledge to mix
them together properly. However, on your hull the galvanic current has
worked over a longer period and may have produced a stronger natural
weld. I agree with Nelson that drilling may not be the proper solution,
as you have already removed the four bolts and the natural weld is
between the traveler and the plate. If you do not want to try a big
blow, my son Chafik, who is a mechanical engineer, advises to try to
heat the plate. As the two metals are different, they will expand at a
different rate and thus apply stress on the natural weld.
|John Sullivan / Hull 181 / Wianno / San Francisco
Posted on Friday, November 30, 2001 - 10:37 pm:
|I used the
heat method and after about 4 cycles a little leverage with a big wrench
removed the plate. It took some time but eventually it came off!!!
Pulling the J105 mast forward on a run
Forum discussion from:
|Rich Levitt Hull 203 Maccabee
Posted on Thursday, August 26, 1999 - 6:27 pm:
care to comment on the techique of pulling the mast forward when on a
run? I know that it is fast. Boats equipted for PHRF racing often have a
spare jib halyard which can be lead to the stem and used to pull the
mast forward when using the spinnaker. The standard J-105 in one design
mode does not have a second jib halyard as standard equiptment. Would it
be class legal to to use or add a second jib halyard for this purpose?
|John Driver Tech Comm Annapolis
Posted on Thursday, August 26, 1999 - 7:04 pm:
second jib halyard is not standard equipment for OOD racing and
therefore it would NOT be considered class legal to pull your mast
forward in this manner.
|Alex Baluta 72-Highlander - Toronto
Posted on Friday, August 27, 1999 - 2:54 pm:
the question of legality, can you explain in a bit more detail how and
why this works? thanks.
Posted on Sunday, August 29, 1999 - 12:49 pm:
hear from the rest of the tech committee on this subject? I cannot
fathom how this technique, standard practice in every form of racing
there is, could be considered illegal.
|Stuart Burnett - Richmond VA - 198 Legacy
Posted on Monday, August 30, 1999 - 12:28 pm:
not on the technical committee, I support John's position that
installing and using a 2nd jib halyard for the purpose of adjusting mast
rake in One Design races would not be consistent with the class rules.
Besides, with raked spreaders and fairly tight rig tuning, how much can
you move the mast forward anyway? Certainly you could not move the mast
to a vertical position, which would require inverted bend which I think
would risk a mast failure.
Posted on Tuesday, August 31, 1999 - 7:26 am:
point of moving the mast forward downwind is simply to help hold the
main boom and mainsail out. Imagine your boat drifting in no wind.
Imagine your mast raked way aft. If you were to push the boom and
mainsail all the way out and then let go the boom and mainsail would
want to fall towards centerline. Now imagine the mast raked forward so
that it extended out over the bow. If your sail and boom were on
centerline they would want to fall all the way out. Every little bit you
can pull the mast forward while sailing downwind in light air means that
the wind will have an easier time inflating your mainsail. In heavy air
it serves almost no benefit.
Most race boats drop their jibs downwind so if it is legal in their
class they use the jib halyard to pull the mast forward. The J/105 does
not allow for a second jib halyard, but the existing halyard is still
attached to the bow of the boat of the boat through the luff of the
rolled jib. You could pull the halyard up to accomplish the same thing.
Be careful that you don’t damage the lighter material in the front of
your jib! A little extra tension will be amplified when you pump up the
back stay and pull the mast aft with mainsheet after you turn the
leeward mark. It is common to ruin the shape of a new sail by over
tensioning the luff.
New J/105 partner (March delivery)
Shore Sails Ltd.
Posted on Tuesday, August 31, 1999 - 3:34 pm:
at least one J105 that has (in the past) used this technique downwind.
When we sailed on a J29 we always put the old jib halyard on the tack
shackle in the bow and cranked the mast forward. It is VERY important
(IMHO as just a crew member) that is issue be addressed by the technical
committee ASAP. The boat that has (in the past) used this technique is
very fast down wind. There may be other factors other than the halyard,
however, if this procedure/set up is deemed 'OK' we would be trying to
get a rig set up to do this before CBYRA RW.
Please do not ask me what boat it was (not really important), it is more
important to decide if it will be 'officially' considered legal.
|Stuart Burnett - Richmond VA - 198 LEGACY
Posted on Tuesday, September 07, 1999 - 11:41 am:
referred this thread to the full J/105 Technical Committee and asked
them for an expedited ruling.
Posted on Tuesday, September 07, 1999 - 10:57 pm:
First, welcome to the fleet, Geoff. I used to enjoy your regular e-mails
on tuning and sails and look forward to more posts now that you are an
owner. You certainly educated me on why masts are moved forward
downwind; I had assumed that it was to move the center of effort forward
and/or to enlarge the slot.
I've been thinking about your suggestion on how to bring the mast
forward using the halyard of the furled jib and, to be honest, I'm
having trouble imagining how it would work. Here's why:
I think of the roller furling system as essentially being equivalent to
a piece of rod rigging. The length of the rod is fixed, so the only way
to change the distance between the ends of the rod is to bend or
straighten the rod.
If the goal downwind is to shorten the headstay length, then a second
halyard does this by becoming the shorter of two headstays and inducing
bend in the (longer) roller furling unit. But if the halyard of the
furled jib is tightened in an attempt to bring the mast forward, doesn't
the now-tight luff of the jib serve to keep the roller furler straight?
In other words, does the tight luff become a shorter headstay than the
roller furler, or does it actually reinforce the furler against lateral
I hope others will chime in on this issue as the correct answer would
also influence upwind trim, that is, the relationship between jib
halyard tension and headstay tension in a boat without runners.
|Jaffar Bentchikou - Jay Boat 208 - Annapolis
Posted on Thursday, September 09, 1999 - 5:37 pm:
to Stuart Walker (a manual of sail trim, p88) quote 'forward rake
counteracts the windward yawing moment created by the offset mainsail
and the offset spinnaker. It determines the angle of incidence of the
head - the relationship between the horizontal surfaces of the spinnaker
and the air flowing above them. .. it separates the spinnaker from the
mainsail, greatly improving the efficiency of the partially blanketed
spinnaker. The aerodynamic lift created by the air flowing above the
spinnaker, the angle of incidence and the lift are increased by forward
Thus, it seems to me that raking the mast forward would not benefit a
J105 with a class asymetric spinnaker on a sprit as much as boats with
symetrical spinnakers running deeper angles and subject to rocking and
unstable oscillations of the chute in heavy air.
So my vote goes in favor of NOT allowing in the class any additional
halyard or mast raking.
Somebody said in the discussion on 'Jib Tracks' that we needed to 'keep
the boat simple'. I believe that this apply perfectly to mast raking
with only minor benefits for us.
We need however to draw the line higher on the benefit scale and keep
looking for low cost hardware improvements which would have a greater
impact on the quality of our racing and the speed of our learning. There
is one device out there that fits that definition perfectly: 'jib lead
cars that are adjustable under load'. All indicators point in the same
direction: Jeff Johnstone in the other discussion was open to the idea
'if it improved class racing'. Most people who contributed to that
discussion were in favor of it as well as many J105 owners I have talked
So, please, please, Chris, get the issue of adjustable jib cars on the
agenda of the technical committee.
|Andy Skibo Plum Crazy Hull 90
Posted on Saturday, September 25, 1999 - 5:48 pm:
the reason you pull the mast forward. You are basically trying to get
increased separation of kite and main when running deeper angles in
light air. As air gets heavier, advantage disappears for a J/105. Chris
asked if there was a way of using the single jib halyard in use for jib
to do this. I haven't figured that one out. There is a way of achieving
same result, without using second halyard (we've used this when too lazy
to pull second halyard down, or when second halyard is stripped out of
mast, with only messenger line in place.) And Chris came close to
hitting the answer when he said only choice was to either "shorten the
rod" or "bend the rod". Choice #2 is the answer. Just leave roller
furler control line cleated (jib is furled, with a couple of turns of
the jib sheets around the furled sail/forestay) and crank back a bit on
both jib sheets. That pulls middle of forestay back, pulling masthead
forward. And you don't have to move the forestay aft a lot, to move
masthead foreward enough to achieve desired affect, due to geometry of
angle of attack. A little more rigorous on furled jib. Makes no
difference to forestay, since it has to deflect same amount regardless
of whether you're pulling on it using jib sheets, or whether it is
simply falling out of way, because you've pulled masthead forward with
second halyard. This variant uses installed, class legal equipment only,
and is trivial, takes seconds, to do. A standard racing technique. Hard
to see how you'd define this variant as not acceptable. Either variant
works equally well. And, with newer kites which run much deeper downwind
than original designs, the technique is more effective now (in light
air) than it would have been for older design kite. Neither technique is
necessary in heavy or even medium air.
|Nelson Weiderman Wickford RI
Posted on Tuesday, April 18, 2000 - 10:48 am:
close out this thread with some definitive information, the ruling from
the TC on using a jib halyard to rake the mast forward was NO, it is NOT
allowed. The reason was that most boats don't have 2nd halyards; and in
order to take advantage you'd probably have to have an illegally long
backstay throw on the cylinder.
|Jonathan Udell NJ
Posted on Tuesday, April 18, 2000 - 12:31 pm:
I've just reviewed the Technical Committee rulings as presented in the
J105 Class website and there is nothing whatsoever with regard to
halyards pulling rigs forward. Please clarify where this exists per your
|Nelson Weiderman Wickford RI
Posted on Tuesday, April 18, 2000 - 4:33 pm:
you're right. It's not there. When I created the new page on
interpretations, I recalled this discussion about raking the mast and
could not find an interpretation. When I asked, I learned that there are
some questions that are answered by the TC directly and never reach the
level of a formal Rule Interpretation that is circulated to the
Executive Committee. I posted it here because I thought people would
look here for an answer to the question that was raised in this thread.
Now that I've done so, I'm sure that some people will suggest that it
deserves the status of a formal interpretation. I guess I would tend to
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features of J105 hull #536|
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launch of my J-105 in Baltimore, from shrink wrap and cradle to the
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