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Old 27-07-2020, 01:04   #1
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How to set up turning blocks for aft controls?

I have a bristol 30 that I'm spending more and more time single-handing, so I really, really want to set up lines aft. Plan was to have 2 reef lines, halyard, outhaul, and vang run to the cockpit. Maybe even a mainsail downhaul.



My mast is deck stepped. I've been exploring options to set up turning blocks at the base. I really don't want to get a mast plate that fits under the mast, and even if I did, I'm not sure if I have enough room for it.

My mast sits on this weird box, which is probably cored with plywood to distribute the load of the mast.

1. My first thought was to through-bolt the sides of this box and mount these plates like this--
On each side of that box.

Problem: I am thinking drilling through the core will compromise the integrity of the material inside. Furthermore, if it ever leaks (since it will flex a lot), it'll rot the wood inside.

2. My 2nd thought is to mount the same plates onto the deck, with backing plates.

Problem: There is a bulkhead underneath the mast step. It will probably be in the way.
Problem 2: the further away it is from the base of the mast, the more geometry problems I will have -- the length of the lines will change on each tack.

3. My 3rd thought is to mount the plates right onto the mast with through bolts.

Problem: I already have a boom vang mounted right where I'd want to put these plates. Any higher and the angles to the deck organizer will be really weird, though that can always be solved by adding more blocks.
Problem 2: I feel *very * uncomfortable drilling 4 holes in a row into the mast.

I'm thinking the best compromise is to mount those plates onto the deck. Any other ideas? Would appreciate some help. I already bought the plates, winches, blocks, and clutches, but I can still return some of the items. I've been wrestling with how to set this up for quite some time now.
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Old 27-07-2020, 02:52   #2
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Re: How to set up turning blocks for aft controls?

I would rather mount eyes on the mast and use dyneema loops and low friction rings to pull back. I am in the process of doing that to my Leopard 40 cat.
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Old 27-07-2020, 06:32   #3
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Re: How to set up turning blocks for aft controls?

Personally I would go with a mast plate, the strongest solution.

You would need access to through bolt it, and as you say, make absolutely sure that you seal any plywood/wood that you might drill through.



I believe that various mast plates can be sourced on line.
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Old 27-07-2020, 07:25   #4
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Re: How to set up turning blocks for aft controls?

If you want to mount the plates on the deck beside the mast, consider using a "L" bracket as the backing plate below deck, with the L plate also bolted through the bulkhead. That would transfer the lifting force on the blocks to the bulkhead rather than to the not so strong deck. Good luck with it.
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Old 27-07-2020, 09:34   #5
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Re: How to set up turning blocks for aft controls?

I would also go mast plate for a deck stepped mast. If a stainless one electrically isolate it from the mast. If thick aluminum no problem and you can always cut the mast if the plate makes your rigging too short. If you do plates beside the mast you probably should probably tie the two plates with an L or T under the mast area. If you are going to rely on the bulkhead make sure it is tabbed to the hull and deck. But your load on the plates will up upwards and should be in compression with the mast. If you penetrate the core, drill it oversize, fill the hole with epoxy thickened with a structural filler and then drill the bolt hole in the epoxy. So a 3/4" in hole filled with epoxy paste for a 1/4" bolt.

I lead all the lines back to the cockpit and did single line reefing on my 32 footer. Works fine but check for chafe. Takes a while to get it all tweaked perfect.
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Old 27-07-2020, 11:15   #6
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Re: How to set up turning blocks for aft controls?

In the last two years I've run all my lines back to the cockpit for the same reason, more single handing. My mast is keel stepped. I too already had added a boom vang. However, I did that by drilling through the mast and running bolt from one side to the other. That bolt holds a boom bail to which I connected my vang. I didn't want to drill any more holes in my desk than absolutely necessary. In any case the point is, the bail now also holds two sets of turning blocks that redirect lines to my deck organizers which send the lines to two sets of clutches on both sides of the companionway. Because all the blocks are "loose" on the bail they can slide a bit depending on what lines are taught. They self-align and it works really well. You might consider moving your boom vang to this position then you should be able to accommodate all the blocks. The result is I have all lines in the cockpit, two lines for my deep reef, my out haul, Cunningham, main halyard, and boom vang. Good luck.
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Old 27-07-2020, 12:01   #7
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Re: How to set up turning blocks for aft controls?

Stainless u bolts through the mast works well for for attaching blocks at the base. The mast step projects roughly an inch above the base inside the mast. The "bump" that the mast step is mounted to is actually a metal fabrication that is fiberglassed over. This straddles the doorway to the head to form a structure to transfer the compression load to the bulkheads forming the head compartment. I found it impossible to drill through trying to replace the original mast wiring.
Beautiful boat, I seen your picture and thought it was my old boat. I lived and sailed on a 1973 Bristol 30 for thirteen years before i purchased my current boat.
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Old 27-07-2020, 12:37   #8
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Re: How to set up turning blocks for aft controls?

Quote:
Originally Posted by billdre View Post
In the last two years I've run all my lines back to the cockpit for the same reason, more single handing. My mast is keel stepped. I too already had added a boom vang. However, I did that by drilling through the mast and running bolt from one side to the other. That bolt holds a boom bail to which I connected my vang. I didn't want to drill any more holes in my desk than absolutely necessary. In any case the point is, the bail now also holds two sets of turning blocks that redirect lines to my deck organizers which send the lines to two sets of clutches on both sides of the companionway. Because all the blocks are "loose" on the bail they can slide a bit depending on what lines are taught. They self-align and it works really well. You might consider moving your boom vang to this position then you should be able to accommodate all the blocks. The result is I have all lines in the cockpit, two lines for my deep reef, my out haul, Cunningham, main halyard, and boom vang. Good luck.
My boom bail is also through-bolted. Its supposed to be incredibly strong, so I might go for that. Did you put the blocks on the bail itself? Or on the bolt? Any photos? Thanks much.
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Old 27-07-2020, 12:43   #9
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Re: How to set up turning blocks for aft controls?

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Stainless u bolts through the mast works well for for attaching blocks at the base. The mast step projects roughly an inch above the base inside the mast. The "bump" that the mast step is mounted to is actually a metal fabrication that is fiberglassed over. This straddles the doorway to the head to form a structure to transfer the compression load to the bulkheads forming the head compartment. I found it impossible to drill through trying to replace the original mast wiring.
Beautiful boat, I seen your picture and thought it was my old boat. I lived and sailed on a 1973 Bristol 30 for thirteen years before i purchased my current boat.
thanks! I had no idea what was in that box. I guess my pilot hole merely drilled into a thick layer of FG.

So mount 2 U bolts, slightly staggered, through bolted through the mast? 8 holes right? same number of holes, but at least that solves the 'vang bail interfering with the blocks' problem, since its smaller. Do you think my fears of drilling all those holes are unfounded? Is this a better alternative to drilling holes on the deck?

thank you for the compliments. I actually really like my boat. A bit cramped inside, but its the only boat I can think of that is reasonably fast, yet heavy duty enough to be forgiving in bad conditions.
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Old 27-07-2020, 12:50   #10
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Re: How to set up turning blocks for aft controls?

The PO on my newest boat used mostly Schaefer 78-01 Pad eyes drilled and tapped at the bottom of the mast to fit the needed blocks. https://www.defender.com/product.jsp?id=116770 They have worked fine except one that had the bottom fastener tapped at the very base of the mast. Apparently the mast base trapped water behind the fastener and it corroded the threads in the aluminum. I turned that pad eye 180 degrees and tapped the now top fastener and all was fine. I've got all mainsail control lines, 2 double reef line reefs, outhaul, topping lift, Cunningham, Main halyard, as well as two jib halyards, spinnaker halyard, and pole lift pad eyes tapped into the base of the mast. Don't know how long the boat has been set up this way but I'd say way over a decade and could have been 35 years with only that one glitch.

On my other boat didn't want to pull the mast to put a base plate under it which was dumb. Instead mounted stand up blocks through bolted on the deck. They've worked fine but by the time I bought the expensive standup blocks, drilled the holes, routed out the core, filled with thickened epoxy, redrilled the holes, made a rather involved backup plate that wrapped around the mast for 7 blocks, would have been way better off installing a base plate.
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Old 27-07-2020, 12:56   #11
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Re: How to set up turning blocks for aft controls?

Sorry I don't have any pictures. I won't be down there until Thursday. The blocks are attached to the bail. Which forms a nice arch around the mast that keeps everything spaced out. If you still want pictures I'll be happy to take one so you can see it.
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Old 27-07-2020, 14:11   #12
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Re: How to set up turning blocks for aft controls?

Billdre and roverhi, thanks for the ideas. And I think I'm good with the photos. Basically attach shackled blocks right onto the bail.

Using the boom vang bail and pad eyes/u bolts seems more feasible. I can live with 4 holes (instead of 8) and the geometry shouldn't be that bad. Obviously the vang bail is the quickest solution, but It does make me worried. I imagine there is some tremendous load on the bail since its specified to use a 1/2" line when all my other lines are 3/8". Then add a 1-2000 more with halyards and reefing lines. The bolt probably has a shear strength of 6-7k lbs, which is pretty strong.

But it looks like there is an answer somewhere out there! Thank you. If anyone else has any more suggestions please let me know.
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Old 27-07-2020, 14:34   #13
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Re: How to set up turning blocks for aft controls?

Quote:
Originally Posted by roverhi View Post
>>>>>>>>>>>>
2 double reef line reefs
>>>>>>>>>>>>>>>>

>>>>>>>>>>>>>>>

Regardless of how you do it, this^^^ is something you should seriously consider and implement. I singlehand all the time, and double line reefing is worth whatever extra blocks and sheestoppers it costs. I've always considered it a premium safety aspect. My two prior boats (18 years) had double line reefing OEM, which is what almost all 1980s boats came with: separate clew and tack lines, usually on the boom and at the mast. My PO on this boat (23 years now!) had double line reefing, which is exactly the same thing and far superior to single line reefing.
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Old 28-07-2020, 13:23   #14
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Re: How to set up turning blocks for aft controls?

Thank you everyone. I am also thinking I have overesitmated the forces on the lines. All the turning blocks are doing are resisting the tendency for the lines to want to return straight under tension. Though this means I should not mess around with the terminal hardware (clutch, winch, and after a 90 degree downturn at the cockpit bulkhead, a cleat)
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Old 28-07-2020, 20:01   #15
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Re: How to set up turning blocks for aft controls?

On a 30' boat the loads just aren't that great and the fasteners in shear for pad eyes are at their strongest for the force on the blocks to turn the line. Halyards are normally sized for hand comfort not the actual load. 3/8" dacron would be more than adequate for halyard and reef lines. I've gone 5/16" exotic cored line on my S28 and would've gone 1/4" if my hands could handle it.
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