Help with king plank

[captainbob]

Among the drawings of the schooner Lettie G. Howard there is this one drawing of a typical frame.  In the middle of the deck is shown the king plank, which in this case are several narrow planks.  It also shows the king plank raised above the deck level.  This frame is in the area where the deck is lower.  The question is, would this same arrangement of the raised king plank also be on the raised portion of the deck?

 

Bob

 

[dgbot]

I believe the king plank served the purpose of strengthening and reinforcing the main deck.  The upper deck did not need this and did not have one.

David B

[garyshipwright]

Hi Guys.

Have to agree with you on what the purpose of the king plank was for, but only one thing comes to mind about it. If the deck has hatches down the middle of the deck and the king plank is cut up by these, where is the strength of the king plank. Wouldn't thicker planks on either side of the hatches , recessed in to the beams and not being cut in two have more strength, then a king plank cut up in to short pieces in the middle of the deck? Just a thought on it.

Gary

[mtaylor]

Gary,

 

I tend to agree with you but that method seems to be for English ships...  ???? Maybe not???  Some of the French ships have it the way Bob shows with the gratings flush to the king planks.  Thus, it might have served a dual purpose, strength (marginally) and also as a coaming.  The weird part is that some French ships had their coamings above the king plank level.  The Licorne has them for most of the main deck, stopping short of the great cabin and on the quarter deck but not the forecastle.  I think there had to be some pupose other than decorative. 

[jud]

The deck beam shown is arched, when loaded the decking would be in compression and strengthen the deck beam, the king planks being thicker would provide greater compression strength where the forces would be greatest across the span. Doubt that the internal divisions were designed to be structural members of the ship. Only my opinion based on the above drawing.

jud

[allanyed]

Bob,

The drawing of the Ernestina shows what appears to be a king plank on the raised portion, but none forward.  Different vessel, different designer, so maybe one of those "either/or" situations.  Photos of her deck indicate a king plank aft, as well.

Allan

[thomaslambo]

Hi Guys.

Have to agree with you on what the purpose of the king plank was for, but only one thing comes to mind about it. If the deck has hatches down the middle of the deck and the king plank is cut up by these, where is the strength of the king plank. Wouldn't thicker planks on either side of the hatches , recessed in to the beams and not being cut in two have more strength, then a king plank cut up in to short pieces in the middle of the deck? Just a thought on it.

Gary

This may help; I found the following information in the book "China Tea Clippers" by George F. Campbell.  

 

I believe the planks/strake you describe above is called a Binding Strake and they run on the outside of the hatches from bow to stern.  They were wider and thicker than the standard planks.  They were also notched or grooved as to be interlocked with the cross frames.  In some cases the standard butted edges (tree nailed) were replaced with Scarph joints.  Other opening/pierces (like bilge pipes, etc) were avoided.  

 

These strakes/planks along with the margin strake/planks (also interlocked with the cross frames) provided longitudinal strength to resist Hogging or Sagging of the hull/keel.  

 

Campbell also states that the center planks were not so important from a strength standpoint because they consisted of many short lengths.

 

Here is a link to the definition of Hogging: https://en.wikipedia.org/wiki/Hogging_and_sagging