Mystery Block

[Reid Smythe]

Had my Viper for about a month and a half now and I have a mystery block at the base of the mast I'm trying to figure out.  I was hoping to catch up with the west coast fleet at KHYC and get the question answered, but work is getting in the way.  The boat sails fine without using the block, I'm just curious what it would be used for.  I've tried a few experiments, but nothing really fits.

[Peter Beardsley]

Reid,

How is your vang rigged currently?  Usually that double will take the vang from the bullet under the boom and deflect it out to the rails.  In fact, if you wanted to do something similar with the cunningham, that is why there is a second eyestrap on the cockpit floor just to the left of the mystery block.  I will take a photo of my setup over the weekend and post it, but at minimum, your vang should go there.

PB

[Darren Gilbert]

Is it the Jib fine tune?

[Peter Beardsley]

From the photos it looks like this is on the starboard side of the boat, aft of the mast -- it's the vang double.   Jib fine tune on a Mark IV Rondar is on the port side and is much farther forward. 

[Reid Smythe]

Reid,

How is your vang rigged currently?  Usually that double will take the vang from the bullet under the boom and deflect it out to the rails.  In fact, if you wanted to do something similar with the cunningham, that is why there is a second eyestrap on the cockpit floor just to the left of the mystery block.  I will take a photo of my setup over the weekend and post it, but at minimum, your vang should go there.

PB

Let's see if I can do this from memory...

Going for bitter end to bitter end of the GNAV control line: Through a cam cleat by the driver on the port side, through two turning blocks along the base tanks near the deck, then I believe another block prior to going up to a floating block above the spin hal cam that adjusts the car.  It then mirrors that path along the starboard side.  This forms an inverted V above the spin halyard cam along that to swivel.  There is just enough length in the line for this setup, I've been thinking about replacing it as there is almost no tail after the stopper knots to grab on to.  But if that block is used for that system, I should probably plan on adding a few feet rather than inches.

[Peter Beardsley]

I think we solved it -- it definitely shouldn't look like an inverted V.   While not everything in the APS rigging photos is class legal and it's from a Mark II Rondar, it should look closer to something like this:

http://apsltd.smugmug.com/One-Design-Photos/Viper-640/Viper-640-73/i-HLS3vL9/0/M/IMG_0980-M.jpg (vang is orange) -- they have also led the cunningham down in these photos, but then led it aft to the skipper, which is not legal. 

http://apsltd.smugmug.com/One-Design-Photos/Viper-640/Viper-640-73/i-22qzwzd/0/M/IMG_0976-M.jpg

http://apsltd.smugmug.com/One-Design-Photos/Viper-640/Viper-640-73/i-ckj5QH3/0/M/IMG_0983-M.jpg

[Reid Smythe]

Makes sense, although I am having a little trouble seeing how the double block will work like that.  The only way I see is it is something like this (or I just get a second one and put it on the port side of the mast), but I'm not sure there's enough clearance to prevent rubbing.

[Peter Beardsley]

There's no criss-cross in the middle -- it goes down from the bullet in a reverse U.  One tail goes into the port side of the double bullet, exits starboard, and continues along the starboard tank.  The other tail enters starboard side of double bullet, exits port, and continues on port tank.  I'll try to get photos of mine this weekend if you're still having issues. 

[Reid Smythe]

Yeah, I see that now, I think my brain was fried this afternoon.  The current line is way too short for that, I measured the distance at ~12 ft from the cam cleat to the floating block w/ ~6 in of tail, so I figure 24' should cover it...maybe I'll get 25' just to be safe.

[Drew Harper]

Yeah, I see that now, I think my brain was fried this afternoon.  The current line is way too short for that, I measured the distance at ~12 ft from the cam cleat to the floating block w/ ~6 in of tail, so I figure 24' should cover it...maybe I'll get 25' just to be safe.

I've delivered 4 boats since yours Reid, but i think it was a long red line. Should be 28'  Just a suggestion. If you're looking for more purchase on your GNAV, before you go get more line, think about buying a triple block, replace the double with the triple, install the double on the bottom of your boom and Voila....you've doubled your GNAV. As of next week we'll offer this as an upgrade on new boats for $95. Block is roughly $40 and I'm trying to get the correct length for you.

[Reid Smythe]

Currently the thick red line runs as I described it, with the inverted V over the spin-hal and the unused double-block per the picture.  There is no tail on the stopper knots on the aft cam cleats for the line, so there is no extra length to lead it directly down from the floating block to the block on the deck and then out.  I haven't measured out the current line, but the extra distance required from not following the hypotenuse should be pretty significant.  I haven't looked into buying things yet, still measuring and going over things in my head.

This is not taking into account adding extra purchase to the system, just system geometry.  I'll look into the triple block, but that would obviously make the current length problem worse!

[Reid Smythe]

Just got back from the boat.  Measured my GNAV line, it was ~19.5', so it looks like that was the problem.  Are you talking about replacing the floating single block with a floating double block?  I've been scratching my head over it for a while and that's the only thing that makes sense.  So for line length in that system I get ~31 ft: 1' from the bitter end of the tail to the cam cleat to the deck block, 6' forward, ~2.5' to the base of the mast, ~3' from the deck to the floating block (x4), then another 2.5'+6'+1' along the other side.  Then add in a couple of feet of line just to be safe.

[Jonathan Nye]

Here's what I've got. Three singles are shackled to the floor at the base of the mast. All three are oriented with their sheaves opening thwartships. Then there's a double that floats off a pennant that travels through the boom to a set of two cascading 2:1 systems. This produces 4:1 below the boom and 4:1 above in compliance with class rules. And all the loads are in line so no torquing of the blocks. The below deck arrangement is attached.

Should be easy to measure the length needed - 4x the distance from the floor to the gooseneck + 2x distance from mast base to side tanks + 2x distance from forward block on side tanks to aft block on side tanks + 2x distance from aft block on side tanks to cleat +/- based on personal preference.

[Reid Smythe]

With some people using a triple in lieu of three singles at the bottom.  Seeing it helps a lot, thanks!  I had to make a mockup of the spinnaker using a paper towel, some small stuff, dowling rod and duct tape to convince myself I had my lines run correctly.

[Reid Smythe]

Here's what I've got. Three singles are shackled to the floor at the base of the mast. All three are oriented with their sheaves opening thwartships. Then there's a double that floats off a pennant that travels through the boom to a set of two cascading 2:1 systems. This produces 4:1 below the boom and 4:1 above in compliance with class rules. And all the loads are in line so no torquing of the blocks. The below deck arrangement is attached.

Tossed on that setup and it runs great, thanks for the help.  Helps that area look a little cleaner now too.