Are these lifts correct?

[Louie da fly]

Here's a picture from 1457. It's from  "Hesperis" - a fantastical biography of the Italian nobleman Sigismond Malatesta.

 

The mainyard has been lowered. I had a look at the lifts; this is one of the few contemporary pictures that shows them in any detail. At first glance it looks very good. The lift goes from the outer end of the yard to a double-sheaved block (sister block) hanging from the masthead, and back down to the yardarm, plus the upper sheave has a rope passing from the masthead and back up again. But though I'm no rigging expert (that's for sure!) it seems to me that the artist has got it wrong - surely it can't work like that. The rope passing through the lower sheave doesn't seem to do anything - it's got no "fall" - nothing to pull on to adjust it. And the same applies to the rope going through the upper sheave - where are the "falls"? I suppose they might be among those vertical ropes coming down from the masthead.

 

But why have lower sheave in the sister block, with two fixing points on the yardarm? To reduce the forces involved, or possibly even them out? I dunno.

 

Any advice or explanation would be greatly appreciated.

 

Steven

 

Edited April 12, 2023 by Louie da fly

[Louie da fly]

OTOH, this detail from the Tavola Strozzi of 1465 shows lifts which seem to have a similar arrangement (if that's a rope going through a lower sheave - I can definitely see two lines there).

 

[Jim Lad]

I can't really see the advantage of using a sister blocvk in that situation, but the confirmation of your second illustration seems to confirm the practice.

 

John

[Jaager]

I have zero knowledge about the rigging of the yard, but there is a notable presentation in the picture in post #2.   I am not sure if the picture is not the first one from the time that I have seen where the forecastle has a deck that is horizontal enough for a human (and not a chameleon) to stand on and do something other than hold on for dear life. 

The camber in those old pictures is usually absurd. 

 

For the rigging, perhaps you could do a mock up using the components  shown and see if there is a way to lead the lines to actually raise and lower the yard.

Edited April 13, 2023 by Jaager

[Louie da fly]

Yes, I agree that artists probably exaggerate the angle of the forecastle in many depictions. But the more reliable ones (Carpaccio, Master WA, Bonfigli and others) show it as quite reasonable.

 

 

 

I don't have any doubt that the arrangement would work to raise and lower the yard if I'm correct in thinking the falls/downhauls are among the vertical ropes coming down next to the mast - I just can't figure out why they'd have the lower sheave. It doesn't seem necessary.

 

Steven

[Jaager]

Steven,

I have given this some thought. 

How I think I would rig this:

 

The rope at the end of the yard would be a loop.   The inner end fixed to the yard.  The outer end a deadeye that slips over the end of the yardarm.  The opening above the block sheave that it reeves thru would be large enough to admit the deadeye.  To stow the yard, all that need be done is slide the loop back over the end of the yard and back thru the block.

When raising and lowering the yard, the friction/pressure point on the loop would change as the angle to the raised position becomes more horizontal.  If the rope is less than perfect quality = a longer working life.

 

The upper block - if I remember the physics correctly - twice the length of rope must be pulled as is the distance that the yard moves - the work is half.

I would lead the line over to a double block fixed at the mast - just under the top.   The line from each end would go thru this same block and then go down fife rail.  Being in parallel, one man could handle the yard - or a group working together.

I would try a deadeye at the end of each lift lead that was just below the mast top block.  A hook would tie each line to a single down haul line.  When the hook was pulled to deck level the yard would be about half way up.  That would be about the optimal height for the sail to be reefed or have another band of canvas added.  Storm or light winds.   The line with the hook could be separated and stowed at the fife rail and the two lifts pulled and tied off when the yard is fully raised.   This reduced the length that a single line must be.  There may be some economic or equipment maintenance  advantage to that.

Edited April 13, 2023 by Jaager

[Mark P]

Good Evening Steven;

 

An interesting question; I see no problem with accepting that your second picture corroborates the first. 

 

Re the loop of rope used to attach to the yardarm, if one accepts that two anchorage points is better than one, because the load on each leg is much reduced if there are two, then one must conisder how this would work as the yard rises, and the angle  of the two legs relative to the yard changes. When the yard is fully lowered, the legs will be at their closest point to being equal, although the inboard one will always be shorter. As the yard is raised, the angle of the lift becomes much closer to the horizontal, and the difference between the leg lengths changes significantly. If the main lift block was simply seized to a bight in the rope at the yard-arm, then, as the yard rises, the inner leg would slacken, and all the stress would be on the outer leg only. By allowing the bight of the rope to move through the sheave of the lower end of a sister block, the stress remains equally distributed through both legs, regardless of how much their lengths change relative to each other.

 

All the best,

 

Mark P

[Snug Harbor Johnny]

21 hours ago, Louie da fly said:

Here's a picture from 1457. It's from  "Hesperis" - a fantastical biography of the Italian nobleman Sigismond Malatesta.

 

The mainyard has been lowered. I had a look at the lifts; this is one of the few contemporary pictures that shows them in any detail. At first glance it looks very good. The lift goes from the outer end of the yard to a double-sheaved block (sister block) hanging from the masthead, and back down to the yardarm, plus the upper sheave has a rope passing from the masthead and back up again. But though I'm no rigging expert (that's for sure!) it seems to me that the artist has got it wrong - surely it can't work like that. The rope passing through the lower sheave doesn't seem to do anything - it's got no "fall" - nothing to pull on to adjust it. And the same applies to the rope going through the upper sheave - where are the "falls"? I suppose they might be among those vertical ropes coming down from the masthead.

 

But why have lower sheave in the sister block, with two fixing points on the yardarm? To reduce the forces involved, or possibly even them out? I dunno.

 

Any advice or explanation would be greatly appreciated.

 

Steven

 

  Steven,  'Looks to me like the 'block' at the yard ends are similar to a 'violin' block.  There is a single lower sheave and a single upper sheave.  As the yard is raised, the angle of the lift changes - so the lower sheave permits a single rope with both ends fastened to the yard to automatically re-adjust so the tension remains even.  A line starts at the top end of the block shown (method of attachment not detailed, but could be a becket), goes up to the first sheave of a double block below the top (out of the picture), comes down and passes through the single upper sheave of the yardarm 'violin', back up to the second sheave of the double block under the top, then down to a rail (or other attachment point) at deck level.

[popeye2sea]

This is also the period when riggers went crazy with crows feet everywhere: braces, backstays, lifts, bowlines, martinets. 

 Your conjecture fits right in.

 

Regards,

Henry

[mtaylor]

13 minutes ago, popeye2sea said:

This is also the period when riggers went crazy with crows feet everywhere: braces, backstays, lifts, bowlines, martinets. 

 Your conjecture fits right in.

 

Regards,

Henry

I suspect that they were in the "more is better" mode then with over-engineering being an art form.

[Louie da fly]

Lots of food for thought here. Thanks everybody for your input.

 

As I mentioned above, I am no sort of expert on rigging - in fact it generally makes my brain hurt - so now I'll have to sit and think about it. Fortunately it's not something that vitally affects any aspect f a model in progress - it was mainly curiosity, wondering what it could possibly be for when I couldn't see a reason for doing it that way. I certainly understand rigging far better having spent some months applying Anderson's The Rigging of Ships in the Days of the Spritsail Topmast to my Great Harry, but I'm still just working through it, trying to get my head around it all.

 

4 hours ago, Snug Harbor Johnny said:

Steven,  'Looks to me like the 'block' at the yard ends are similar to a 'violin' block.

Yes, I agree. I've also seen them called fiddle blocks and Anderson calls them sister blocks - as far as I can see, all the same thing - a block with two sheaves, one above the other instead of side by side. Your explanation makes sense, particularly as I've seen a similar function carried out by a fiddle block on the martnets of the Great Harry.

 

Anyway, thanks again, everybody. I appreciate your help.

 

Steven

[Louie da fly]

5 hours ago, Mark P said:

By allowing the bight of the rope to move through the sheave of the lower end of a sister block, the stress remains equally distributed through both legs, regardless of how much their lengths change relative to each other.

 

From what I can make out, you and Snug Harbor Johnny are making pretty much the same point, and it makes a lot of sense to me.

 

Steven