MARINE TIMBER   Home   Menu 

COPYRIGHT Tim Lovett June 2004 

.

.

.

 

There are many factors governing the choice of timber for use in a marine environment.  

Strength. The mechanical properties need to be suitable for the task, things like strength, stiffness and toughness. This is important if the timber is to be used in the frames, keel or stern post. But more complex than outright MOR (modulus of rupture - a bending related strength property), the timber is most likely to fail at a joint. The joint performance such as nail holding ability becomes paramount. The sheer size of the ark and the fact that it must ride the open sea makes a high strength timber a logical choice.

Decay Resistance. Marine timbers are selected with superior resistance to decay. Obviously external timber gets wet often, so timber for the decking and planking must be carefully selected. Most often it is not the timber underwater that has trouble, but the timber higher up that gets a constant dousing with cycles of wet and dry. Another troublesome are is the internal timber - particularly low down near the keel. Ventilation is often inadequate and the high moisture levels can set up decay from the inside out. The short length of the Ark voyage (less than 5 months) makes these issues insignificant, especially since the higher strength timbers are usually more rot resistant anyway.

Shrinkage and Swell. All timbers swell as moisture content increases, demonstrated by the familiar 'stiff door' during periods of wet weather. For marine use a minimal change is desired - or at least a consistent and predictable degree of swell when it's in the water. Some hull planking methods actually rely on the expansion of wet timber to seal the hull, much like the staves of a timber wine barrel. The standard method for the timber sailing ship was the carvel hull, where a caulking material is rammed between planking. This reduces the reliance on precise fit and is relatively simple to repair (Provided it is accessible - which it probably isn't). 

Size. For Noah's Ark, it would be advantageous to make some structural members in one piece. This of course requires a big enough tree, with a suitably long and straight bole (main trunk). Timbers such as Douglas Fir, many Eucalypts and rainforest species such as Teak grow in a suitable form for producing very long logs. The most famous tall trees being the Redwoods approaching 120m, but Douglas Fir is almost the same at 115m, and not far behind is the Tasmanian Eucalypt approaching 100m. It seems unlikely that a pre-flood tree would could have a bole long enough to match the ark length of 150m. Not only that, the log would weigh hundreds of tonnes. (400 tonne TT85 Tasmanian, or the enormous 3200 tonne Lindsey Creek tree (GBR), a coast redwood Sequoia sempervirens that blew over in 1906 - almost enough wood to build the entire ark). 

Workability. The timber must be easy to work. This is related to hardness and also to the grain pattern. Some timbers are easily milled in the green state but more difficult when dry. Many high strength timber are prone to split when nailed, and may have poor nail holding ability. Some very hard timbers are simply too difficult to process in the dry state. In the case of the Ark, it would be reasonable to assume the timber was not troublesome to work with, since a slightly weaker timber could be accommodated by using larger sections. 

Seasoning. The drying of timbers is especially difficult in large sections, because it takes longer for the moisture to escape. This can cause differential shrinkage rates which give rise to flaws such as checking (cracks) and distortion. Generally speaking, a slow steady drying process is the safest way to season timber. The difficulties in seasoning can vary considerably, but generally softwoods are easier than dense hardwoods. As moisture content is reduced from the green state, the strength can increase by several orders of magnitude. However, it is not possible (nor desirable) to keep the wood totally dry, so a moisture content of 12% is "dry". Larger timber sections are more difficult than thin sections because it takes longer for the moisture to escape, and it tends to be wet on the inside and dry on the outside.

Availability. A big concern for the modern shipbuilder is timber availability.  The fossil record points to a more lush climate before the flood, so timber was unlikely to be a limited resource in Noah's day.  

 

Species

Density masts,
spars
planking,
bulkhead
sheathing
steam
bent
decking deck
frames
bulkhead
frames
keel,
stern
posts
stringers

Cedar, red

420   Y            

Spruce, Sitka

430 Y       Y     Y

Beech, white

500   Y   Y        

Quandong, silver

500 Y   Y          

Fir, Douglas

530 Y Y     Y Y   Y

Pine, hoop

530 Y Y   Y        

Maple, Qld

600 Y Y            

Ash, silver

620 Y   Y   Y     Y

Pine, celery top

650   Y Y Y        

Teak

670   Y   Y        

Meranti, dark

700   Y            

Jarrah

820       Y   Y Y  

Oak, tulip

830     Y          

Stringybark (Yellow)

870 Y Y   Y Y     Y

Blackbutt

900   Y     Y Y Y Y

Gum, Red river

900             Y  

Karri

900           Y Y  

Gum, Spotted

950 Y Y Y Y Y Y Y  

Tallowwood

990   Y   Y Y     Y

Mahogany, white

1000             Y  

Messmate

1000   Y       Y    

Tuart

1030     Y          

Gum, grey

1080           Y Y  

Wandoo

1100       Y Y      

Box, grey

1120           Y Y  

Ironbarks

1120           Y Y  

 

 

 

 

 

 


References and Resources

Timber Resources

Ministry of Defense Std 02-188 (NES 188) April 2000 Requirements for the Procurement Storage and USe of Timber http://www.dstan.mod.uk/data/02/188/00000100.pdf . General terms and definitions, seasoning, timber flaws, storage, timber properties for 41 common marine timbers, design data. Good general resource for timber design and properties.

Forest Products Laboratory. 1999. Wood handbook--Wood as an engineering material. Gen. Tech. Rep. FPL-GTR-113. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 463 pages. http://www.fpl.fs.fed.us/documnts/FPLGTR/fplgtr113/fplgtr113.htm

Woods of the World CD http://www.forestworld.com/wow.cfm

AS 1738: Timber for Marine Construction. Australian Standards

Characteristics, properties and uses of timbers: Vol 1 South-east Asia, Northern Aust and Pacific. W.G.Keating, CSIRO 1982

Tall trees

Tall trees in Tasmania. (>90m)  http://www.forestrytas.com.au/forestrytas/pages/giant_table1.html

Tallest Living Tree Guiness Book of Records. The world's tallest living tree is the Stratosphere Giant measuring 112.6 m (369 ft 4.8 in) as of 2002. This coast redwood (Sequoia sempervirens) was discovered by Chris Atkins (USA) in August 2000 in the Rockefeller Forest of the Humboldt Redwoods State Park, California, USA.

A limit to tree height. 420 feet for Redwood? Water flow, leaf density, photosynthesis and carbon dioxide concentration all appear to converge at their minimum levels of efficiency at the heights reached by the California redwoods.  http://www.usatoday.com/news/science/2004-04-21-tallest-trees_x.htm

Tallest tree Douglas Fir 115m  http://www.cfl.scf.rncan.gc.ca/imfoc-idwcf/hosttrees/conifers/douglas_e.html

Most Massive Tree Ever Guiness Book of Records. The world's most massive tree ever (by trunk-size) was the Lindsey Creek tree, a coast redwood (Sequoia sempervirens) in California, USA. It had a total trunk volume of 2,549 cubic meters (90,000 cubic ft) and a mass of 3,300 tonnes (3,248 tons). The tree blew over in a storm in 1905. The name is widely thought to honor Sequoyah, also known as George Guess, inventor and publisher of the Cherokee alphabet. (Note. The mass is higher than the volume which implies a very high density. Since Redwood is not a heavy timber, the mass must include branches and foliage, so a trunk mass would be more like .)

Boat hulls

A strip planked timber boat. http://www.selway-fisher.com/Stripplank.htm

Boat planking methods. http://www.gartsideboats.com/faq2.php

Glossary of Timber Ship building terms. http://www.bruzelius.info/Nautica/Etymology/English/Murray(1765).html

Planking methods for small timber boats http://www.gartsideboats.com/faq2.php

Strip planked small boat http://www.selway-fisher.com/Stripplank.htm

How barrels are made. http://www.mastergardenproducts.com/barrelsmade.htm

Boat building methods http://www.marinetimbers.com.au/boatbuildingmethods.html

Edge Fastened planking

Lake Champlain Maritime Museum: Archeological projects: Missisquoi Bay Barges http://www.lcmm.org/site/index/framesets/mri_framesets/frameset_mri.html A flat bottomed timber barge utilizing the "edge-fastening technique". The primary characteristics of an edge-fastened vessel are the vertical sides of the hull connected by through or drift bolts driven down into the edges of the planking. In this technique the side planks are so thoroughly locked together that they act as a single timber, thereby lending significant longitudinal strength to the hull. This technique was used extensively in the latter half of the nineteenth century for building any type of vessel that had vertical sides. Effectively mimicking the effect of mortise and tenon planking of the Greek trireme more than 2000 years earlier.