Scott Dufour wrote:

For the mast step, I'm going to use Arne's technique of laying in built up layers of plywood until I've spread the load over a large hull area.  I think that I'll add fiberglass that extends off the surface of each layer of ply onto the hull.  This is because the build up technique using ply means that the majority of hull-to-ply bond will be in the endgrain of the ply. The glass tape will connect the flat grain of the ply to the GRP hull.  Probably overkill, but it will help me sleep better.

As far at as the partners...  I'm not sure what to do there.  The mast is actually going up through thin air at the moment - it's a hatch.    I'm stripping out the liner and bulkhead entirely so that I can add back in structural elements I need.  It's going to be a lot of serious beefing up that I'm sure will be over engineered.

Hi Scott--Yes, multiple layers of ply/epoxy overlayered with fiberglass is what I did to reinforce the deck.

From pics I see you've torn out the furniture in head area...fwd berth too(?) so you've got lots of room and can give the mast installation priority. I was not keen on tearing out furniture else I might have gone with a larger diam (8" OD x 1/4" wall) aluminum light pole mast and placed it fwd 2-3 ft up aganist the fwd hatch or maybe in it like you plan to do. I weighted access to and space in, the head and fwd berth compartment so went with a 6" OD mast as per dimensions close to Needlespar/Hawk Marine masts supplyed by Robin Blain/Sunbird marine.

The lead was effected. The bermuda geometric lead is 18% LWL. The junkrig geometric lead is 11-12%. The junkrig's actual lead as per Arne's cambered-sail-5%-LWL correction puts the lead at 15-16%. In actual sailing no difference in balance and weather helm betwn junkrig and bermuda. Because of the hull's underwater shape, weather helm increases around 15 deg of heel and it is time to reef, which can be done on a tack from the cockpit.

Not having placed the rig 2-3 foot more forward means that I have more space on the bow. You'll back into the sail bundle a few times before muscle memory remembers it is there.

If you have not finalized your sail take a look at Sesi's split rig:

http://www.junkrigassociation.org/general_forum/3712908?mlpg=3

I liked the outline shape and the fact that it has a total of six panels, not 7 like mine, yours and Poppys but retains the Arne-style 6-point sheeting, which means that all the battens have a sheetlet connection. More control? Unforseen problems? The pics don't show any obvious issues.

Scott Dufour wrote:

Robert - I don't know how I missed it before, but it appears that I'm doing nearly the same conversion you did, and you're here in the USA! A mere 3000 miles away.  Our boats' stats are quite similar (12,000 lbs, 33 feet).  I may get annoying picking your brain.

Yes, the Pearson 10m and Roberts 34 are same '70s vintage IOR-like designs. Not that I'm that fond of IOR types but often takers can't be choosers. There is a big difference in the hull specs. For example the Pearson should be alot quicker boat (tacking, accelerating out of a tack, etc.)  with a D/L of 223 vs the Robert's D/L of 374. 

How do you feel about your rig design now that you've used it a bit more?  Is it a scaled version of the Poppy rig, or did you make more significant changes?  Your photos are very helpful, though the scantlings of your mast partner is intimidating: it looks like it could survive a nuclear war. Is there somewhere I can read more about your design choices?  I really haven't a clue on what constitutes "strong enough".

I'm happy with the conversion and my choice of split rig. Pretty much all the rig-descriptive info in Slieve's writeups I have found to be true. I've mostly done winter and summer day sailing in protected waters north of Puget Sound. Max winds encountered were F6. The shape of my sail is only slightly different from Slieve's with more area in the upper panels and lower AR and 33% balance vs his 30%.

Re: the mast partner (and) step scantlings it is only at the end when you cut the deck hole that you find out how thick the reinforcement actually is. I underestimated the thickness of original foam-core deck and added a few more layers of epoxy-glued 1/4" ply reinforcement because it was a foam-core deck. I think one of my pics shows total thickness of the deck partner. What you see is only 3 ply layers outside and 4 inside with the equivalent of 4oz glass between layers.

Re: "strong enough". Your boat's structure in vicinity of the mast position (your pic showing the mast mimic cement form) is quite open, U-ish hull and one full bulkhead aft...very different from my setup. My mast is right up aganist a full 5/8" ply bulkhead aft and another full 5/8" ply bulkhead 18" in front so I'm fairly sure the 10,000 ft-lb load gets spread out and transmited to the hull...that's the hope anyway. I'm not at all sure how I'd do your step, except to try and spread the load to a large area. How large an area? Add partial floors to the hull? Worst case, the adhesive/epoxy bond between the hull and your step structure breaks loose in a seaway. I'll leave the solution to a more experienced seat-of-the-pants engineer than I.

Scott Dufour wrote:

Do those spanned downhaul parrels require 1 per 2 battons, so on my seven panels, I would need three, maybe four lines running to the cockpit?   Or can they be daisy-chained to reduce it all to one line running aft?

I ended up using very short, fixed batten parrels on my 7-panel split rig

http://www.junkrigassociation.org/Sys/Profile/PhotoGallery/36138566/0/55147679?memberId=3252499&dh=0&cppr=3

and 3 dedicated downhauls (not the combo parrel/downhaul) that span 2 battens each

http://www.junkrigassociation.org/Sys/Profile/PhotoGallery/36138566/0/55147682?memberId=3252499&dh=0&cppr=3

and lead back to the cockpit.

http://www.junkrigassociation.org/Sys/Profile/PhotoGallery/36138566/0/55147685?memberId=3252499&dh=0&cppr=3

Ah.  So the whole diagonal-stabilizing element in PJR becomes moot.  That now jives with what Arne mentions in his article, Batten stagger in a junk rig with cambered panels.  Arne uses Hong Kong parrels to handle the loss of diagonal stabilization, and Slieve is using the handy gap in the split.

 

Do those spanned downhaul parrels require 1 per 2 battons, so on my seven panels, I would need three, maybe four lines running to the cockpit?   Or can they be daisy-chained to reduce it all to one line running aft?

 

 

 

 

 

I've seen a few passing references to the split rig not needing stagger in order to sit in the reefed bundle correctly.  How does that happen, exactly?  I'm trying to picture it, and keep coming up short.