E32 Mainsheet Refit, 4:1 or 5:1? or...

vanilladuck

E32-3 / San Francisco
Blogs Author
My 1985 Ericson 32-3 has a 3:1 mainsheet which runs under the boom and down/back through the deck organizer to a winch on the starboard cabintop -- pretty standard I think.

2021-01-25 16.53.40.jpg2021-01-25 16.53.49.jpg

I'm interested in converting this into a 4:1 or 5:1. Thanks to @gfilipi, who directed me to Harken's mainsheet system site, I have a clear picture of what a 4:1 would look like. I can actually accomplish this without buying anything new and just swapping the aft block w/becket and the next-forward block under the boom.

1611795605816.png
I'm curious if anyone's attempted a 5:1 on this boat? There are only two block lugs under the boom in effective positions for the mainsheet instead of the three depicted on Harken's site -- makes sense as it's not boat specific. I was thinking of using another fiddle block instead of the aft two singles pictured below. Or even use two side-by-side double blocks.

Screen Shot 2021-01-27 at 5.16.59 PM.png

And, heck, why stop there? I could achieve a 6:1 or better using triples. Any science? or rules of thumb around sheeting systems to think about?

For reference, here's a thread I found that shows the E32-3 4:1
 
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Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Our boat has a 6 to 1 Harken tackle, located back a bit further on the boom, to connect to our bridge deck traveler. The extra parts should reduce the effort for you, if you change to all ball bearing sheaves. In multiple part tackles, friction can become a real problem.
 
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Kenneth K

Contributing Partner
Blogs Author
If Harken is correct in calling that first depiction a 4:1, then what you show in your photo should be called 4:1 as well. Both show 3 lengths that connect the boom to block B, plus a 4th length that carries the line forward to the gooseneck. However, in Harken's diagram, two lengths run between A and B and another two between C and B. In your photo, 3 lengths run between A and B and one between C and B. Since block A is farther aft than block C (and creates a greater moment arm on the boom than block C), I think your current setup is providing more leverage than the Harken setup would, because it moves the forces further aft.

My mainsheet is rigged as you show in your photo. I've thought about adding another block, but that just means a longer sheet, more line to haul in and let out, and a bigger coil of rope in the cockpit most of the time. I've learned to live with the setup you show since it's manageable.
 
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oldfauser

Member III
We have been using the 4 to 1 as you pointed out by just moving the swapping the blocks, never had a problem. I would worry about maybe bending the boom with a 5 to 1 with a winch!

our biggest issue is moving the traveler under load, but that's another topic :egrin:
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Referencing the first picture in the first post in this thread, if you drop the boom block (where the sheet makes the 180 degree turn) down about a foot or a bit more using a pennant, you get rid of twice that in sheet length.

This idea works better with a longer distance, such as the bridge deck traveler on some Ericson's and the Olson's, but it might help when jibing.
I added over 2 feet of pennant length right after we bought our boat, and cut off quite a long-ish piece of mainsheet. Of course our 6 to 1 sheeting makes this idea more productive, admittedly.
(Prior boat had a cockpit-spanning traveler and I had done the same mod on it.)

And if you have more parts to the purchase making that 180 deg. turn like the other Harken illustration, more line can be eliminated.
 
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nquigley

Sustaining Member
Maybe I'm missing something, but can't you increase you current purchase by just adding a double fiddle block with becket like this one:
or like this one:
... putting it on the traveler and moving your current no-becket double fiddle block up to the boom in place of the single block-with-becket?
As Loren said, you might be able to avoid buying a longer mainsheet by adding a pennant that drops the upper fiddle block down, almost to the bottom one when fully sheeted in.
 
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vanilladuck

E32-3 / San Francisco
Blogs Author
Ah, these photos and suggestions are making sense with the dual fiddle blocks. Thanks all!

If you're interested in getting into the weeds of block and tackle systems, keep reading ;-)

@Kenneth K, until you mentioned it I didn't realize... Rumour's current rig is the same as the Harken 4:1 depiction. What I'm still on the fence about is whether it's 3:1 or 4:1. I was reading https://en.wikipedia.org/wiki/Block_and_tackle and discovered a term which is new to me: rove to [dis]advantage.

Screen Shot 2021-01-28 at 11.57.07 AM.png

Focusing on the "V" shaped lengths of line and ignoring the rest that runs forward and through the deck organizer, there are four lengths. This makes the last leg of the "V" the hauling end. As the hauling end is pulled away it moves the load (the boom with a sail) the opposite direction, which makes this block and tackle configuration 'rove to disadvantage' and we ignore that last length of line (aka the last leg of the "V"). This applies to both the photo of Rumour and the Harken 4:1. And I believe this would make the contraption 3:1.

Now, let's consider the remainder of the system -- the block at the gooseneck and the deck organizer. Does this apparatus add to the mechanical advantage of the system? My theory is no, since the extra turns are attached to blocks which don't multiply force to the movement of the load.

Ken, you also make a good point about moment arm. Configuring turning blocks with multiplying force in two places on the boom seems like it would create a shorter effective moment arm. Where as having all the turns between the aft most lug and the cabin top would create the longer moment arm (short of moving the point of attachment aft on the boom). Is this how you think about this as well?
 

vanilladuck

E32-3 / San Francisco
Blogs Author
@Geoff W. - based on the block and tackle description above, this looks like it's rove to disadvantage with 4:1 purchase. I fiddled with your diagram a bit:

1611866462676.png

I think this is what Christian had on his E32-3 and @nquigley described as well
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
I just put 7/16ths Regatta braid on the E381, but I'm sure it was smaller on the 32, probably 3/8ths.. (I'm really enjoying Regatta braid as a mainsheet.)
 

Kenneth K

Contributing Partner
Blogs Author
Focusing on the "V" shaped lengths of line and ignoring the rest that runs forward and through the deck organizer, there are four lengths. This makes the last leg of the "V" the hauling end. As the hauling end is pulled away it moves the load (the boom with a sail) the opposite direction, which makes this block and tackle configuration 'rove to disadvantage' and we ignore that last length of line (aka the last leg of the "V"). This applies to both the photo of Rumour and the Harken 4:1. And I believe this would make the contraption 3:1.

Now, let's consider the remainder of the system -- the block at the gooseneck and the deck organizer. Does this apparatus add to the mechanical advantage of the system? My theory is no, since the extra turns are attached to blocks which don't multiply force to the movement of the load.

Yeah, I would agree with all that, and I see it as this:
tackle.png
The three strands that add mechanical advantage have the yellow arrows, the fourth strand is the "rove to disadvantage." But if you run the "rove" line back down to the deck (as shown in the progression from 1 thru 4 below) this system does seem to become a 4:1.

tackle2.png

So, what it is at position 3, where I have seen some boats run their mainsheets? A 3-1/2:1? I don't really know???
Configuring turning blocks with multiplying force in two places on the boom seems like it would create a shorter effective moment arm. Where as having all the turns between the aft most lug and the cabin top would create the longer moment arm (short of moving the point of attachment aft on the boom). Is this how you think about this as well?
Yes, that's how I see it. But, as you move the blocks farther and farther aft (or forward), a portion of the advantage is lost as the tension vector becomes more horizontal (simply compressing the boom) rather than vertical (pulling the boom in or down).

tackle3.1.png

At least some of that lost advantage is regained when the block is moved aft, because the tension then acts at a greater moment arm (e.g. farther away from the pivot point at the mast). As you move the blocks further forward, however, both the vector and the reduced moment are working against you.
tackle4.png
I,e., you could haul the boom in from a single line located at A or B, but you couldn't from C.

A further thing to consider is that running the lines in a "V," such as the Harken diagram, at least loads up the gooseneck more evenly (3 lines pull the boom forward toward the gooseneck, one line pulls it aft, away from the gooseneck). In your current setup (and mine), all the forces cause the boom to be pulled forward or compressed into the gooseneck. That may be something worthy of consideration when going to 5:1 or 6:1 systems or more.

It's all a little more complicated than it looks at first glance.
 
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goldenstate

Sustaining Member
Blogs Author
This is my inherited set-up:
IMG_9053.JPG

I don't know if the middle bail was an after-market add-on, but I imagine it distributes the "instant load" of a gybe swing on the boom more evenly than if absent.

It does take some work to torque down the main amidships. I'm gradually getting better at using my traveler for tuning situations where the main sheet becomes unpleasant to tighten up.
 

Christian Williams

E381 - Los Angeles
Senior Moderator
Blogs Author
As a random note, we are certainly free to experiment with reducing the purchase of the mainsheet. The fewer blocks the better. Friction of old blocks is fairly high, and it's just a trade off between how easily the main goes out vs. effort to trim it. As a practical matter, the effort can be the same in heavy air or light, because the sail is typically reefed. I can haul in the main on my boat without a winch in 30 knots, simply because the third reef is in.

Similarly, the line size and characteristics. Stiff line adds friction to the mainsheet, and I am finding single-braid (not shown) reduces it. The best thing I did when revising my traveler was to go down a size for the control line, which is now better behaved and more responsive in all respects.

old traveler .JPG...new traveler.JPG

Old traveler control line at left.
 

clayton

Member III
I inherited the same original setup as Tom. First replacement was a double fiddle block attached to traveler car and 2 double blocks above leading forward to single then down to mast base and then aft. Blocks were Garhauer, smooth running and reasonable $. Wound up eliminating the double fiddle block, stayed with 2 doubles, and downsized sheet. Much easier to work with, only need the winch to fine tune above about 12 knots. The forward of mid boom sheeting position on my 32-200 necessitates this.
Clayton
 

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vanilladuck

E32-3 / San Francisco
Blogs Author
Update from the deck of Rumour:
Was about to pull the trigger on Harken Midrange Classic fiddle blocks which are probably identical to Christian's E32-3 setup. But, then I dropped by a local marine store and found some Garhauer fiddle blocks for much less ($60 for fiddle, $70 for fiddle w/becket). Load ratings are just as high at around 2800lbs and they have ball-bearing sheaves.

Am still waiting for delivery of the NE Sta Set 7/16" line which I have on order. In the meantime I rigged the old fuzzy-salty-worn-cover mainsheet and went for a sail today. Definitely reduced a lot of friction in the system and it's a bit easier to sheet in. I'm considering running the line diagonally to the block at the base of the mast to avoid rubbing on the rigid vang.

PXL_20210130_231802958.jpg
 
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