Hemlock offers lighter weight Sitka Spruce rails as an option. Other than extra cost and lighter weight,what would the advantages and disadvantages to this material be?
thanks,Turtle
high strength to weight ratio and
and resliience among other properties
http://www.coastforest.org/species_pdf/sitka_spruce.pdf
Highly desireable wood
As previous poster says, strong but light, and it also resists rot and is easily worked. Or so I hear, I have never seen a piece, that I know of. That stuff is highly sought after. Airplane builders love it. How much does it add to the cost of the boat?
~~Chip
Wenonah Comp Canoes
use spruce for the gunwales and most only get inwales.It conforms better than ash to the tight curves of the competition canoes.
I had sitka spruce gunwales on a
Mad River Compatriot. They were stiffer than the usual ash rails, though Jim Henry warned that they would not be as tough, more likely to split under extreme stress.
Also, sitka spruce is NOT especially rot resistant. Sitka spruce gunwales must be kept varnished, and probably should be unscrewed to oil the inside surfaces. I did have some dry rot occuring due to water sneaking in between the wood and the hull.
This will not be true. The spruce is
– Last Updated: Apr-04-09 1:13 PM EST –
stiffer than ash, and will not conform to unusual curves as easily. The only way one could get the impression that sitka conformed better would be if one was using such a small cross section of spruce that it was pushing the limits of stability.
Probably the reason they use Sitka is that it is stiffer than an equal cross section of ash, as well as lighter. Thin competition canoes often require edge stiffening to perform properly.
I have a bunch of sitka, given to me by a guy who made his own biplane. The reason sitka is approved by the FAA for home-built planes is that it is STIFF.
Sitka spruce is the carbon fiber of the wood world.
Ash is the Kevlar.
Their own tables don’t support their
statements about “resilience.” Compared to ash gunwales, sitka spruce gunwales of similar cross section are stiffer but much less resilient.
as an opt. to what other wood ??
… also , what grade of Sitka ??
lighter weight, period
At least where gunwales are concerned, the only benefit you are going to see is lighter weight. It’ll dent easier than Ash, which is a consideration when you’re talking outwales, especially. And it’s not, IMHO, even as rot resistant as Ash.
Personally I’d rather have Walnut or Cherry if I was going to spring for a premium wood gunwales.
More on Sitka spruce
here is a canoe made with it and cedar…dont know what the rails are made of. Nor anything about the maker.
http://cgi.ebay.com/17-Wood-Strip-Canoe-1974-Wilderness-canoe_W0QQitemZ140312154652QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item140312154652&_trksid=p3286.c0.m14&_trkparms=72%3A570%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1307%7C301%3A1%7C293%3A1%7C294%3A50
BTW I havent had any rot problem with a double paddle cored with Sitka
In turtles case the best bet would to have a discussion with LDC… and he will be at the Solo Canoe Rendezvous.
The weight
factor is pretty big, ash is heavy. Spruce is strong but as discussed, dents pretty easy. I have restored many wooden canoes, there is a reason the old time builders used spruce so much. I have also seen many 80 + year old canoes with the spruce gunwales still very much still intact.
Sitka spruce, or other varieties?
Sure, I have a close-grained
length of sitka that would make an excellent Greenland paddle. I make sitka spruce thwarts to replace ash thwarts and save weight.
But I have to coat each sitka thwart with epoxy, reinforce the screw contact area with little slips of glass, and even epoxy a plastic straw tube in the screw hole to prevent rot. Then I paint the thwart with UV resistant varnish to protect the epoxy. All this because when I disassembled my old MR canoe, I saw what any entry path for water had done to the spruce. Jim Henry had told me that sitka would require more ongoing care than ash, and he was right.
If a hull design and layup promotes stiffness on its own, then ash gunwales will be plenty stiff enough, and substituting sitka will contribute nothing useful to additional stiffness. But it will save a few pounds.
sitka spruce
"The reason sitka is approved by the FAA for home-built planes is that it is STIFF."
The FAA does not approve woods for homebuilt aircraft. And the reason sitka spruce is used for aircraft is it’s light weight and relatively strong for it’s weight.
Strong = stiff, and strong in
compression and extension. There is an approval agency for construction of personal design aircraft. I am not aware that they approve woods other than sitka, but other violin-soundboard-quality woods would do the job. European firs. Sitka is relatively cheaper and more available. I have seen select close grain douglas fir that would do as well, and doug wood has been offered for harpsichord soundboards. There were few takers.
Why would one not see ash used for similar aircraft applications, even if it were as light?