Rigging for a symmetrical spinnaker

[Mert Gollaher]

I certainly apologize for any potential disservice.  I actually thought it might help future readers if I raised my questions about rigging for symmetrical spinnakers on this thread, given the title and the helpful comments from last year.  I guess my follow-up question on the tack pennant strayed a bit.

References to my current A-spinnaker rigging were only meant to describe how I hope to do double duty with my A-sail tack line as the S-spinnaker foreguy, and to see if there are strong preferences as to attachment points and methods for aft turning blocks for spin sheets. 

I'm also interested in whether those who fly S-spinnakers find that they need (or prefer) both sheets and afterguys attached to each clew along with midship afterguy attachment points or whether a reasonable level of performance and control can be had with one line on each clew.  I've sailed other boats with S-spinnakers rigged both ways, but I have limited experience with symmetrical spinnakers on a C34.  I expect I'll wait to decide on midship afterguy attachment points until our crew gets more experience with the S-spinnaker.

Thanks for the help.

[pablosgirl]

This is on my project list as well.  I did not see a reference to the pole diameter in this thread.  Would 2.5" be adequate or is 3" the preferred size?  Also, I have the factory installed Genoa toe rail tracks.  Are they strong enough to mount the guy blocks to at the forward end of the track?  What type of spinnaker halyard block did you mount to the bail at the mast head?  Do you launch the spinnaker from the forward hatch or a bag launch from the lee rail forward of the stays?

Good discussion so far on this topic.

[Ron Hill]

Paul : I'm not in that business anymore, but I had a 2.5" pole for my 26' boat!  
Don't think you should consider anything less than a 3" diameter pole for a C34.  Tall rig you may want to think bigger!   My thoughts

[pablosgirl]

Ron: I found a 3.5" 15' pole on eBay and I will need to shorten it.  Earlier in this post I say reference to the maximum length being equal to the J measurement  which was stated at being 13'.  Applying the age old wisdom of measure twice and cut once, I consulted the MK I manual on this site and found the J measurement to be 13.5' for both the standard and tall rigs (I have the tall).  So which is it 13' or 13.5'??  Anyone out there have an "official" racing rule book for the C34 class to get an answer and how do I get a copy?

Also, I am still trying to determine if the factory installed toe rail jib track is sufficiently strong to use for the Guy blocks.  Any wisdom would be greatly appreciated.

[Ron Hill]

Paul : All of my data on the MKI and MKII for both the standard and tall rigs, show a J measurement as 13.5 ft.
I believe that the "Genoa rail" on the top of the gunwale/toerail is held on with screw - there is no backing plate.  This should be sufficient to hold your guy blocks. 
Maybe some of the racers like Dave Davis could confirm this?    Hope this helps

[Miles Henderson]

Guy blocks should be placed at the widest part of the boat.  The working guy is the line which goes through the block, then through the end of the pole and attaching to the leading clew of the spinnacker.  The working guy carries a HUGE load under at 15 knots (you don't fly it at 20 knots as it is too easy to broche).  The guy blocks are placed amid ship, because if they are placed too far aft, the working guy will bend the stanchions when the pole is forward.

I would urge any C34 owner interested in converting their rigging to accomodate a symmetrical spinnacker to first crew on a racing boat flying a symmetrical spinncker to see what your getting yourself into.  It takes a six person crew to safely jibe the spinnacker while racing. 

It's worth it!  I converted my boat to fly a symmetrical spinnacker three years ago so I could participate in our local club's beer can races.  It's a good time.  Get out there and have fun!

Miles H
Kumatage #1204

[Mert Gollaher]

Miles,

I noticed in your comments in the early part of this thread and in the lower center of your 24:1 mainsheet picture (another project added to my list) that you have u-bolts at the rail amidships for your afterguy.  I like that approach, but after staring at the inside of the hull-deck joint, I'm not sure how to best fit backing plates, nuts, etc inside the hull.  Did you have to angle the u-bolts inboard to provide clearance from the hull under the deck for backing plates?  Also, any recommendations on the size/strength of the u-bolts?  Any suggestions you have would be greatly appreciated.

Thanks,
Mert

[Miles Henderson]

Hi Mert,

I have an extra U-bolt here at home.  Not sure why I had an extra??  I pretty much took the approach that you can't be too big to carry the amount of pressure a spinnacker will put on the U-bolt when the pole is forward in decent wind (we're talking broach here).  I got a U-bolt with bolts 2 inches apart on center.  The diameter of each bolt is 1/2 inch (or a sixteenth less than that).  The length of bolt has 3.5 inches of thread.  I don't recall if I used all 3.5 inches or if I ended-up shortening each bolt by cutting it with a grinder.

The U-bolt came with a backing plate (it covers both bolts).  Above the thread, each bolt has a small ring (about the size of a small washer) which was forged into the U-bolt which I used to backstop a washer on top of the rail.

I don't recall if I had to angle the drill hole in order to come out in the proper place below.  I do remember that I used a drill bit guide (normally used for drilling dowel holes) and that I started with a large size bit.  That was a mistake.  The large bit cut into the fiberglass rail and started throwing chunks of figerglass here and there.  I immediately stopped and started the hole with smaller bits and worked my way up to the 1/2 inch bit I ultimately needed.  I do remember it was unnerving trying to get both drilled holes perfectly parallel even with the help of the drill bit guide.

I would start with a small, but long, bit and angle the drill bit as you deem appropriate and then see where it comes out on the inside.  You will need a good rachet set with a long socket to fit around the bolt as you tighten the nut.   

Good luck,
Miles H

[Mert Gollaher]

Thanks, Miles.  Starting with a small bit should give me a little room to align the hole to an appropriate position inside.  I'll try a guide too.  I'm hoping I can get a reasonable assessment of clearance by measuring off nearby stanchion bolts.

Thanks again,
Mert