Old drawing abbreviation mystery

[fosterbill]

I have a set of professional drawings for a 1938 boat. The bottom frames show the dimensions as: SID. 7/8”, MLD. 1 1/2”
It’s pretty clear that they refer to thickness and height, but what do those abbreviations stand for?
Thanks
Bill Foster

[MAGIC's Craig]

perhaps "sided" and "molded" which would indicate direction of measurement.

[John Meachen]

Sided and moulded.For example, a frame might be 1 1/2" sided and 1 3/4" moulded which means that the parallel faces are 1 1/2" apart and the curved (or moulded) faces are 1 3/4" apart.

[Peerie Maa]

^or to put it another way, sided is the thickness of the slab that you saw the frames from.
Or the width of the lamination that you stack up to laminate a frame, seven 1/4'' lams giving 1 3/4 moulding.

[Thad]

Definitely "sided" and "molded", but if those numbers are correct the designations are reversed unless the frames are sawn from grown stock. It would be practically impossible to bend 7/8 x 1 1/2 stock against the 1 1/2 dimension against the hull or ribband. 7/8 x 1 1/2 stock is not unusual 7/8 bent against the hull form, molded, 1 1/2 the fore and aft dimension, holding it's siding. My take.

[Peerie Maa]

Definitely "sided" and "molded", but if those numbers are correct the designations are reversed unless the frames are sawn from grown stock. It would be practically impossible to bend 7/8 x 1 1/2 stock against the 1 1/2 dimension against the hull or ribband. 7/8 x 1 1/2 stock is not unusual 7/8 bent against the hull form, molded, 1 1/2 the fore and aft dimension, holding it's siding. My take.

If they are the ''bottom frames'' they may be the floors linking steamed timbers.

[J.Madison]

Atkin boat by chance? I believe he commonly used sided to mean the slab planed thickness and molded to mean the curved or other dimension, rather than the convention regarding tangent vs normal to the hull. Don't have any drawings near me to confirm.

Edit- you reference bottom frames, is this a hard chine or flat bottom boat? Dimensions would make sense.

[Peerie Maa]

Atkin boat by chance? I believe he commonly used sided to mean the slab planed thickness and molded to mean the curved or other dimension, rather than the convention regarding tangent vs normal to the hull. Don't have any drawings near me to confirm.

Edit- you reference bottom frames, is this a hard chine or flat bottom boat? Dimensions would make sense.

That won't work, and I don't believe it is conventional. That would mean that every frame would have to be sawn out of differing thickness stock. If the boat is round bowed or in a fantail counter, you use cant frames to prevent the frame section becoming to extreme.

[fosterbill]

Thanks to everyone for the helpful replies. Using your suggestions I was able to find a number of historical references to both “siding” and “mould” dimensions, specifically in reference to boat frames. Siding is clearly the fore/aft dimension and Mould(ing) refers to the tangential perpendicular to the arc of the hull) dimension.
The drawings are for the early Lightning (Sparkman & Stevens). The dimensions I gave are correct for the bottom frames of that boat which are sawn or, more recently, laminated.

Thanks again.

[Thad]

Thanks for the clarification. Not surprised that Olin was correct.