Fir vs Pine : Which one to use for keel /stringers ?

[Bhatla]

Hi ..

Need some advice :

Can pine ( see below) be used instead of fir ??


Douglas Fir, Oregon
460 - 560 kg/m3 ( Moisture content 12%)
Shrinkage Tangential 5.0%
Shrinkage Radial 3.0%


Preservative treated
Radiata Pine /Monterey Pine

460 - 560 kg/m3
4.7%
2.2%


The timber will be epoxy coated after the build.

Any other characteristic to look for ??

If you have chosen pine over fir, to build the keel /gunwale/stringers your experience will be much appreciated.

I ask above as I have a useable quantity of good dry machine finished pine.

Regards

Bhatla

[CHarris]

I used lodgepole pine 2X6's for the stringers on the OD18 that I'm building. I had to pick through the stack but eventually found two that were free of knots and perfectly straight. I have not had a problem with them yet , but I'm still in the middle of the building process.

Chris

[JerryF]

Generally the pine we get here in the western USA is much softer and lighter than Douglas Fir and would not be suitable for structural components IMHO. However, when I was building my GV11, I bought some wood labeled as New Zealand Pine at Home Depot that was as hard as DF and would have been fine for that use (again IMHO). That wood was clear, straight grain, kiln dried and a bit lighter than clear dry DF but heavier than typical Western Pine. It was being sold not as dimensional lumber but in moulding along with western pine. I made gratings for the sole out of it and they are light but easily hold my weight.

You quote similar densities for the 2 woods. Similar density at the same moisture content does suggest similar strength but that is not a certainty. Perhaps the preservative in the pine adds to the weight. Our western pine is 1/3 less dense than DF.

You could run a simple test for relative strength or maybe another NZ or Aussie builder will chime in with a direct answer.

Jerry

[Rick]

Generally the pine we get here in the western USA is much softer and lighter than Douglas Fir and would not be suitable for structural components IMHO.

A lot of the tree farm quality pine has wide growth rings and is, as Jerry says, not great for structural purposes. Douglas-fir, by the way, varies widely in strength from tree to tree, and is not necessarily stronger than some pines. As with any lumber, choosing wood with tighter growth rings will usually give you stronger sticks.

I cannot recommend the US Forest Products Laboratory highly enough. From their Web site at http://www.fpl.fs.fed.us/documnts/FPLGT ... 3/CH01.pdf:

"Pine, Radiata
Radiata pine (Pinus radiata), also known as Monterey pine,
is planted extensively in the southern hemisphere, mainly in
Chile, New Zealand, Australia, and South Africa. Plantationgrown
trees may reach a height of 26 to 30 m (80 to 90 ft) in
20 years.
The heartwood from plantation-grown trees is light brown to
pinkish brown and is distinct from the paler cream-colored
sapwood. Growth rings are primarily wide and distinct.
False rings may be common. The texture is moderately even
and fine, and the grain is not interlocked. Plantation-grown
radiata pine averages about 480 kg/m3 (30 lb/ft3) at 12%
moisture content. Its strength is comparable with that of red
pine (P. resinosa), although location and growth rate may
cause considerable variation in strength properties. The wood
air or kiln dries rapidly with little degrade. The wood machines
easily although the grain tends to tear around large
knots. Radiata pine nails and glues easily, and it takes paint
and finishes well. The sapwood is prone to attack by stain
fungi and vulnerable to boring insects. However, plantationgrown
stock is mostly sapwood, which treats readily with
preservatives. The heartwood is rated as durable above
ground and is moderately resistant to preservative treatment.
Radiata pine can be used for the same purposes as are the
other pines grown in the United States. These uses include
veneer, plywood, pulp, fiberboard, construction, boxes, and
millwork."

[LIVEWIRE]

you probally dont have access to southern yellow pine.........its a very good structural wood. i had a shelter on a barn supported by heart pine posts , they had only been holding this shelter up since 1947. this years ice storm took the shelter out. the posts outlasted the galvanized tin on the shelter and they were direct buried.