Planking Lower Decks

[Bill Jackson]

According to John J. Flynn in Ship Modeler's Shop Notes, page 109.

"The lower planking should be laid at a 45 degree angle to the center of the ship".

My question is WHY? What purpose did that serve? This is the first time I have heard of this.

Stay Safe

Bill

[Jaager]

This was from vol. 3?   There is an "IF" phrase in your quoted phrase.   I was not able to find the original article on the CD.  Thus, I am not able to discover the context.

He is describing a way to build a strong deck on some model by laying it in two layers.  The under layer being laid at 45 degrees.  I am guessing that the beams are spaced too far apart to provide 90 degree strength.

 

There are some examples that I have seen in Paris? or similar with diagonal planking that was an attempt to resist hogging or sagging.   I read that one of the innovations with the original version of Constitution was a series of substantial riders that were diagonal and chevron in pattern.

[Dr PR]

Some wooden minesweeper hulls were planked in two layers. The inner layer was at 45 degrees to the horizontal/vertical and the outer layer was a more normal parallel to the horizontal. The frames were typical wooden ship design. I don't know if the deck planking was in two layers (I don't recall spending much time looking at the overhead), but the top layer was normal longitudinal planking.

[Mark P]

Good Morning Everyone;

 

I can understand the reason for making the lower planking diagonal in a model for strength, if this layer is then covered by a more normally-oriented set of planking.

 

Re full size practice, when Robert Seppings became Surveyor of the Navy in the early 1800s, one of the reforms which he introduced was diagonal deck planking, and diagonal riders. The riders were successful, but the deck planking was dropped after a few years, if I remember correctly. 

 

See below part of a plate from John Fincham's works, showing some ways in which this was done.

 

Diagonal ledges seems to run counter to one of his guiding principles though, which were to reduce timber consumption, as well as to add strength. 

 

All the best,

 

Mark P

 

Edited February 26, 2021 by Mark P

[Bill Jackson]

Thank you guys for your comments. I believe I should have mentioned that the galleon in question is San Marcos from 1580.  John Flynn did not identify what ship he was talking about in his article. My quote is exactly as printed.

Stay Safe everyone

Bill

[Kevin]

i try to learn something new everyday, shame i missed the idea for 60 years of my life

 

i have never heard of the diagonal  under decking

[kurtvd19]

Below is the entire bit in the original Shop Notes that was initially referenced.  Below that is the original published in the Secretaries Newsletter Vol 3 - pg 25.  It is an exact copy of the referenced text that I found in the #3 SNL file on the CD.  It was a shop note in the SNL - no other related info.

 

Kurt

 

PLANKED DECKS by John J. Flynn (3-2)
If one is at all apprehensive about an individually laid planked
deck opening up, make allowances for a double deck. The lower planking
should be laid at a 45 degree angle to the center of the ship.
In the past I used blackened glue to indicate seams between
deck planks, but no longer do so. I feel the seams and butts are prominent
enough with just a glue line.
I put in enough nails to hold each plank until the glue underneath
it has dried. The nails are left slightly above the deck surface so
they can be easily drawn. Sanding fills these nail holes and is just suggestive
enough of actual wooden plugs put over the counter sunk nail
holes in a full sized vessel.