Cant frame R+S

[Don Case]

Steel says my Discovery1789 has an R+S of 28". Do I keep the same spacing with the cant frames? Some of the pictures/drawings I've seen look like they're spaced a little wider but that could be the camera.

[allanyed]

Don,

The 28 inch room and space only applies to main frames for your ship.  From Goodwin, page 23, "The 'room and space' was reduced in the vicinity of the cants, so that the angle could be decreased in the run forward or aft."

Allan

[Don Case]

I just thought of something. Does the R+S only mean on the keel? I was thinking about the spacing out where the planks go whatever that's called.

[allanyed]

?????  Not sure what you mean where the planks go??   

 

[Don Case]

On the outside of the frames.

[Jaager]

This is limited to English shipyard practice.  A chronic shortage of timber required ( or at least was the excuse for) labor intensive methods, not replicated in countries with abundant timber.

 

A close look at Steel shows that the sided dimension of frames was not uniform over the whole of the hull for even the square frames.

The sided dimension of the floors was allowed to be reduced towards the ends.  As the identity number was higher the sided dimension of each futtock was allowed to be reduced.

What I mean is that F1 was not as wide as the floor. F2 was not as wide as F1.  F3 was not as wide as F2 etc. 

The factor that changed was how much of the planking surface was space.

 

R&S - room and space  - room plus space -  was defined by the Stations.  R&S is some interval of the number of bends.  (I have only observed one example of the Station interval not following its set Station intervals - Saint Philippe.)   In the RN plans, the numbering of the Stations indicates the number of bends each defines.  Things were often a bit different at "0".  The bends were all identical here and the number could be increased at the last minute if a longer hull as ordered.  The gap between 0 and A is often greater.   Once the real numbering or lettering began, the pattern was there to follow.  For example where it is D then H , 4 then 8  - the number of bends is "4" -  The midline of D,  then E, then F, then G, then the midline of H.   The RN tended to use a fixed two bend interval for Stations. So it is B, D, F, H, J,  ( It may be K.  Some naval architects omitted "I" and "O" .Maybe they had had a problem with dyslexic yard workers?)  There were often ( usually), for the RN usually more frames in the interval than just bends.  There were singleton filling frames.   At times, more filling frames than bends.  These frames seemed to have no identity.  On some framing plans, the actual bends may be difficult to tease out if the the bends were made with a significant air gap in the middle. There would have been a lot of ugly, irregularly shaped chocks in the gap.  Every trunnel or bolt connecting the halves of a bend would go thru its own chock.  The chocks would not be as wide as the full moulded dimension.  Air communication along the whole length was important.  There were also a lot of chocks connecting the filling frames to their next door bend or next door filling frame.  An actual framed hull would not be all that attractive or as regular as the models that are supposed to represent one.

 

My theory on cant framing:

All bets were off where the cants were.  The general sided dimension for the floors was used there, but the space was wedge shaped.  The heels would touch  and the intervening space would be whatever was needed to get the outside face as parallel with the run of the planking was possible.  This way, the beveling on the face was greatly reduced.  The beveling at the heel required much precision work to get the angle correct.

Edited March 7, 2021 by Jaager

[allanyed]

Hi Jaager,

To add to your comment about the R&S not always being related to the stations, in addition to Saint Phillippe,  Litchfield 1695 frame locations and R&S  for one more example have no relation to the station lines.   I have seen others as well where R&S does not necessarily have any relationship to the  distance or location between the station lines.   

 

You are of course right about there being reduced siding on the frames parts but I wonder if it really had anything to do with lack of lumber?    I don't have any idea  when the timber shortage became an issue but reduced siding dimensions are shown long before Steel, going back to the 1719  Establishment and even further.  Looking at several contemporary contracts, including Lark 1702,   Romney 1693,  Severn and Burlington 1695,  and  James Galley 1676 they specify siding dimensions of the floors, futtocks, and top timbers and they are reduced even more than shown in Steel and the Establishments.   

 

Allan       

[Jaager]

Allan,

 

I was being a bit snarky there.  I suspect that there was a weight reduction factor involved as well as economy and conservation.  Unless someone from the time wrote an explanation , we can probably only speculate about their reasoning.  Today, it would make for a paper or series of papers in a professional journal. 

 

It is not that S-Philippe has no no correlation between Station position and R&S.  It does.  The complicating factor is that there are 4 different sets of intervals.  The R&S matches each of the intervals.  There are just 4 different sets of R&S,  There are 4 different stocks thicknesses of framing timbers required.  It is a complicating factor for anyone building this ship POF.

 

I am perplexed about Litchfield.  Unlike how we modelers traditionally loft frames on a drawing board by measuring waterlines and buttock lines to plot the shape for every bevel of every frame, an actual mould loft only expanded the Stations to full size on the floor make make the patterns.  Richard Endsor goes into detail in Master Shipwright's Secrets - although I am still not sure the patterns they made also had the sirmarks for the frames between the stations.  The guys with the adz could have faked it using the ribbands.  Perhaps it was done both ways depending of the yard doing it.

 

At the beginning of my framing method research, I was using Marquardt's HMS Beagle monograph.  I messed with designing for futtock sided reduction and filling frames. I figured out an idiot proof way to do it.  But, most of the reduction is above the main wale and the extra attention and time was just not worth it.  I also go with square frames all the way - no cants.  At the bow, I come in perpendicular - parallel with the stem.  Aft, I do square up to the fashion timber.  I do not bother with: sided reduction either fore and aft or towards the top timbers.  The framing above the main wale looks more like house carpentry to me, with no real curves,  so I hide it under the planking.  Because I hide it, I do something even worse and make it a solid wall above the main wale with no spaces.  It really fixes the frames in place, I also make the deadwood go from keel to keelson in the spaces.  This locks the bottom.  I see indications that at least some actual ships did this part way.  They left a gap at the bottom for bilge water flow, but that only needed a few inches.  Display models do not have to worry about bilge water, so I go all the way with wood.   

[Don Case]

I think I just learned a few things. Thanks to both of you. All I have to do is remember it. I will check my station spacing. I did notice that it was close(ish) to matching the frame spacing. That's good to know that most ships followed this. I thought there was no relationship.

 

I checked by plans and it looks like my R&S is 25.5".  

[Jaager]

OK, beam 28'     SR has floors sided 11"    Meade  about 100 years later also has ~11" for a ship of this size.

25.5 - 22 =  3.5"  of space.   A bend would be a pair of 11" frames.   

Prediction:

If filling frames are present and the stations at 51"  The stations would be the midline of a bend. There would be 7" of space  and two filling frames with 3 space gaps.  The spaces would be 2.33" each.   If the stations are at 3 R&S intervals - 76.5" intervals, the mix of bends and filling frames can be a bit more creative.

Most RN plans would have the stations at 51" intervals.  With an American ship the plans would have a high probability of the middle 1/3 of the hull having  with stations at 102" intervals with that changing to 51" intervals as the slope of the bevel becomes greater at each end. 

 

I suggest that with this being your first effort at POF, go simple.  Just frame using all bends. 

 

Even more approachable would be Hahn style -  make the frames sided 12.75"  use all bends and omit every other bend.  This has a more interesting visual presentation.  Framing it per scantlings would only have ~14% as space.  Close to being a wall of wood.  The Hahn style saves time and wood.  --  I am not suggesting that you use his upside down fabrication method. 

[Don Case]

What, exactly, is a bend? I know it's a combination of frames of some sort but I'm having trouble thinking beyond that. My glossary doesn't list "bend" and Googles gets me nowhere.

[Jaager]

To just use the term frame for everything there can get a bit convoluted.

Frame is a series of timbers that are all in the same plane. 

It may be Floor + futtock 2 (F2) on either side + f4 on either side + a half top on either side  ( multi deck ship )

It may be  a half floor or cross piece or cross chock  +  F1 on eiyher side  + F3 on either side  + a top timber on either side

Both are frames. Where the floor butts against F2 is in the middle of F1.

 

A bend is one of each of these frames, joined side to side (the original meaning of scarph) - The butts of each frame has an overlap support from the partner.

 

Bend is not a universal term, but it easier to type than 'paired frames'.

 

These are the parts of a bend:

 

Edited March 7, 2021 by Jaager

[Don Case]

Got it🙂 All the plugs I built for moulding FG hulls for IOM's I built upside down. I'm struggling with rightside up. I'm used to looking down on a model to see if it's fair. Bending over and looking up ain't easy for an old fart.

[Jaager]

There is nothing wrong with upside down.  I framed Kate Cory using that method. The experience gave me a compulsion to find an easier way to loft and build a POF hull.   I was just suggesting his framing convention without meaning to endorse  the whole of his method.  The all bend,  room = space convention was also from Davis, so it predated Hahn by decades.  As near as I can tell, the more authentic framing started with our exposure to Model Shipwright and soon after, Boudriot's ground breaking books about the building of a Sane designed 74 gun warship.  It only took them about 40 years to offer the unbound plans for sale.  Those books are still the deep way to understand wooden ship building.  I think that the build logs here showing a complete POF replication of various ANCRE monographs or the Swan series may be offering a distorted view of how complicated a proper POF hull needs to be.

[Roger Pellett]

Charles Davis got his experience working as a draftsman in the WW I shipyards building wooden ships for the Emergency Shipbuilding Program.  In  1917 American shipyards built large wooden ships with regularly spaced sistered frames (two layers of timber with segments butted together and joints staggered).  This reflected how large wooden Schooners had been recently built.

 

When he got interested in ship model building he published The Built Up Ship Model purporting to be a guide to building the Revolutionary War brig Lexington “using methods just like those for building real ships”.  Never mind that the plans that he provided are for a brig built for the Royal Navy years after Lexington sailed, and Revolutionary War era shipbuilding practices were not the same as those used in 1917.  

 

His book was apparently widely read and Harold Hahn used Davis’ regularly spaced double sistered frames when he built his beautiful colonial shipyard diorama in the mid 1970’s.  He adapted Davis’ writings to include his “upside down” method as a means to ensure proper alignment of frames.  His method per se does not prevent varying framing to more closely represent actual practice.  In fact, for his model of the 74 Alfred he included two different sided frame dimensions - heavy bents, and thinner fillers in between.

 

I personally like Hahn’s upside down method, as it provides a foolproof system for accurately aligning frames.

 

Roger