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Hull plank length


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Hi Guys

 

I saw the topic about deck plank length.

 

But I need to know where to find the length of a plank on the hull (of the French Gabare Les Gros Ventre).

 

I have not found in Delacroix's monograph or in Boudriot's books.

Could anyone help me?
 

Thank you in advance.

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This is American from 1826 - HASN   - General Instructions for building a Sloop of War

 

No length specified,  but " No plank to be more than 12" wide at midships."  I would think this would hold generally as a width max for any ship.

 

Deck plank   Heart Pine "no more than 10" in width"  "Average length to be 40'."

 

We had a lot more trees  than France - and most were 1st growth.  The pine was probably from the southeast US and the trees were 80-120 feet tall - mostly straight - and free of branches until near the top. 

The White Oak could also be 80' tall - so long plank "could" be had - the wood is much heavier the effort in manipulating the logs probably constrained how long they cut the logs.   Unlike deck planks, hull planks have curves and sometimes recurves.  The spilling required with an especially long hull plank would probably involve more wasted wood than most builders would tolerate.

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Hello,


 


The length of the hull and deck planking on French ship must be between 22 and 50 (french) feet either from 7.15 to 16.25 m. This is explained by the supply of ports, it is more of an observation than a rule: the planks are 10 to 13 inches (27 to 35 cm) wide which requires trees of big size to debit if we take into account the removal of the sapwood.

For the sake of economy, it operates the maximum usable length in the trees also available strakes have very varying lengths but still nearby the recited values. Near the hull ends, strakes are shorter because they are cut in wood twisted to adapt to the curvature of constraints; on the sides, they are the longest length available in the timber yard.

Typically, the plank lengths on the plans are indicative, you have the freedom to place your differences, you only have to stick to the lengths detailed above, but mainly to avoid having two successive scarph on the same frame at least four or five strakes above or below.

 

For Le Gros-ventre,  indicative lengths are drawn on the plates No. 21, 22 and 25.

 

Regards,

Gérard Delacroix

 

(Message send in MP to Mau)

Edited by G. Delacroix
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  • 7 months later...

A little late but thanks for that, Gerard! Another important data point for French ships to go along with your information on French deck planking practices (and plank length) in Mark's Licorne project thread.

 

Chuck or someone else knowledgeable, what were the RN hull plank length constraints in the Napoleonic period? As below I am building the "Lady Nelson" cutter, so I was hoping to find information in Chuck's Cheerful instructions since he uses planks that look like maybe 15'-20', but there wasn't any discussion of the rules that I saw, just tells the modeler to cut the planks according to the plan. I'll assume Chuck's skip order is correct. But instead of just copying his lengths, I'd like to know what the constraints and considerations were and if there were practices like Gerard mentions with shorter planks at the bow and stern and long planks midships.

 

Also it is interesting that besides having uniform plank lengths on Cheerful vs. French practice, they also all seem to be below the minimum length acceptable for French ships.

Edited by vossiewulf
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Hi Vossiewulf;

 

In the decades just before the French Revolution in 1789,  Royal Navy contracts with merchant builders (ie not Royal Dockyards) specified a minimum plank length of 24 - 25 feet for hull planking on large vessels,  sometimes stating that no plank should be wider than 12".  I am not sure how much this latter point would be applied to un-rated vessels such as cutters,  though. 

 

One reason for a maximum width could be that if they were wider,  they would not fit well around the curves of the frames,  unless the inside face was hollowed.  Which would be a lot of extra work.  Another could be that unless very well-seasoned,  all planks shrink across their width;  and the wider the plank,  the greater the distance it will reduce itself by as it dries out.

 

Under the demands of war-time needs,  with greatly increased workloads,  the proper seasoning of timber probably became less important than getting the ship off the ways and into the water as quickly as possible.  A similar thing happened with the 30 ships programme in the late 17th century:  many of these rotted rapidly at their moorings,  needing major re-builds within a year or two of launching.  This was widely attributed to the use of un-seasoned timber,  made necessary by the sudden increase in demand for seasoned wood,  which rapidly exhausted available stocks (although it was also found to be due to those supposedly taking care of the vessels not actually living aboard,  with the result that the gun-ports were not opened as they should have been,  to allow air to circulate)

 

I would not use planks any larger than the 12" width given above for the bottom planking,  or shorter than the length given. 

 

However,  on the upperworks some planks were wider:  the sheer strake,  for example,  being specified as 15" wide,  or 'as wide as may be got';  so around 15" was probably the maximum available most of the time. 

 

All the best,

 

Mark P

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Thanks Mark! I am confused by the first paragraph- did you mean that only the 13" width wouldn't be closely adhered to in unrated ships, or that both the length and width would vary more? Unless I'm well off, 24' seems longer than Chuck is using and I trust he has extremely good reasons for using those lengths.

 

I'd always wondered about those 30 ships as I'd read it being attributed to using green wood and that made little sense to me- I'd think that would result in all sorts of internal stresses and poor-fitting joints but not full-out rotting. Thanks for explaining.

Edited by vossiewulf
feet, inches, details details
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Both English and Americans really didn't adhere to the "regulations" on deck planking.  Come to think of, same for hull planking.  When push came to shove, they used what they had.

 

As for rotting, the Confederacy when captured (and she wasn't all that old at the time) was loaded with rot from green timber being used.  It wasn't uncommon as one would think.  They found in the British yards, the incoming bulks were dumped on a pile.  Shipwrights being human, often grabbed the easiest timber which was on top.  The seasoned stuff was on the bottom.   Anecdotely, some of the longest lasting ships sat in the stocks for a couple of years before launching.  

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From what I understand, they went for a ship pattern.  As for length... if the designer said (I'm going to be arbitrary) 30' long, and the yard only had 25-footers, that's what they used.  The other thing is beams don't seem to be evenly spaced so the plank length would vary some.   The problem was that at certain times, most notably the late 1780's and 90's on, the English were importing the wood for decks due to shortages.

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Mark - you were commenting on the importing of wood for decks, I'm wondering about minimum lengths of planking for hulls. With something like a 50ft cutter trying to get a good shift pattern on the hull would be quite hard without using lengths down to 10ft (5ft would be nice but I'd think not particularly effective). 

 

Rick

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That's a good question,  Rick, for which I don't have a good answer.  I do believe that the shipwrights would use what they had or could get at the time as they were, if nothing else, practical.  If we look at photographs of such ships a Victory, Wasa, Constitution, etc. it sometimes seems like the hull planking is all over the map.  We should take those photos with a grain of salt though, as except for Wasa (way earlier than we're talking about), the others have been replanked more a few times.

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Some of the 30 ships' program, after completion, Lenox, for example, were moored in places where they could ground by a few feet at each low tide.  This resulted in a band of plank that was constantly being dried, then wet, then dry, then wet.  Rot of that band of plank was the result.  They didn't indeed receive the care they should have, both because of the neglect of their caretaker crews and the lack of funds to effect appropriate repairs.  Indeed some of the repairs that were done did nothing to help, but encased the rot so it could flourish.  There is a book on Lenox, 'Restoration Warship', by Richard Ensor, that goes into this at fair length.

As to plank length, Vasa, in her lower deck plank is nothing if not expedient.  There are various lengths and widths, even small 'plugs' inset.  I have not seen a hull plank plan, I don't think it has been published yet, but all of the remaining decking is shown on the plans included with the first volume of the official publication.

The big thing with plank length, as somebody has mentioned, is that the butts must be on frames or beams, so the length will have to be adjusted somewhat to match that spacing.  In other words, '25 feet' is a guide, and probably more of a lower limit than an absolute figure.

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We are actually fortunate to have many planking expansions for royal navy ships.   The original drafts of such inboard and outboard expansions are available and have much of the info you need.   For Cheerful in particular,   both the inboard and outboard expansions exist showing the width, thickness and length of every strake.   The plans I developed for Cheerful are an exact match using that info.  Its one of the reasons I chose Cheerful,  the original documentation is so complete.

 

Here is the outboard hull beneath the wales for Cheerful as an example.  Finding the measurements is a snap.  The length varies from 23 - 25 feet mid ship.  There are however a few when needed that are longer but its an exception.

 

planking.jpg

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