Main Discussion Area > HowTo's and Build-a-longs
Mary Rose Replica Bow Build-Along--An Entrance into the World of War Bows
duffontap:
Jaro,
Thanks for the pics--the tiller of that bow impresses me every time I see it. I asked Steve about those experiments a while ago and he said he never did do any. Pip seems to imply that he has worked with Steve Stratton on those tests. I think he talks about working with Mark more. I'll ask Pip.
I agree that the laminated stave is not preferable, but I didn't want my personal preference for self bows to exclude others who would like to try a war bow style but don't have a chain saw and a Yew permit.
I would love to buy one of Steve's Italian Yew bows, but my truck didn't even cost that much. I think they're priced fairly--I was surprised at how low--but I'll never have that kind of money. The most interesting thing that they show is that bows cannot be made to MR dimensions out of Alpine Italian Yew without hitting 120-160#. It's some of the most valuable research done to date.
J. D. Duff
duffontap:
Hey everyone,
Note that the pics that Matti posted show Yew bows with both heart and sapwood.
Here are Jaro's pics if you haven't seen them yet:
[attachment deleted by admin]
Kviljo:
The experimental data is quite convincing, but I think the properties of the wood varies quite a lot, and does disturb the data quite much.
If the 80" 96# bow Jaro mentioned was cut down to 74", and was gaining 4# for each inch, it would draw 120#. I guess it couldn't be thicker than 30mm if it is 30mm wide. My first and only self yew is 33mm wide and 30mm thick, and only 70 1/2" long, it has a quite squarish cross section, and it bends perhaps a bit much in the handle. All this leads us to believe it should be over 120#. In fact it is 40 punds lighter, being only around 80# (@28"). A variable of 40 to perhaps as much as 60# is quite a lot!
Now, my bow is made from pacific yew, which could account for some of the difference, but it sure does tell me that these experimental data is quite unreliable.
Using the correct species with the correct density, right amount of sapwood, and making them from exect measures could lead to some rough approximates.
I haven't gone through much litterature, and I don't know if the 150#+ or 100#- guesswork is supported by reliable experiments, but it seems like the disagreement suggests that they aren't.
And this of course leads to: Where can one get hold of some exact measures of different Mary Rose bows? Millimeter-measures for at least each 20cm would be preferable. Have anyone been in contact with the museum regarding this?
Jaro:
"Now, my bow is made from pacific yew, which could account for some of the difference, but it sure does tell me that these experimental data is quite unreliable."
- That is complete quatch my friend.
Pacific yew being entirelly different species is much more elastic than european yew. But we have now opportunity to work with the same yew which was used for Mary Rose bows and its harvested from the same plantage where it was 400 yrs ago. Pretty convincing results actually. Bows from Italian yew also shoot better and further than best Pacific yew.
Even working with not so dense european yew, you will hit 100+ at width 32-34 mm and the biggest problem is to get actually the thing to bend.
I just made 34 mm wide 78´´ english yew bow and it came out pretty flat to actually hit the target weight as the guy cannot pull more than 85#. It was hovever 110x when I braced it and that was pretty much tilered bow.
I will post pictures later, no hornnocks, but if youd throw it amongst MR bows, only bad wood quality would distinguish it from them. This is wood which has only about 40 rings per inch.
I m having some Czech yew, which in mediaval literature is described "as bad quality" and it still better than the piece I just worked on.
Even that one is still not longshot to that Italian yew.
(Actually I have some czech yew which might be the same density, but its not seasoned.)
Jaro
Jaro:
".... but I think the properties of the wood varies quite a lot, and does disturb the data quite much."
- Yes the properties of individual pieces of wood do varies a lot, but tell me then, why should they use bad quality wood for warbows? (Means low stiffnes per mass) Particulary if we know that the quality of wood on MR Bows is outstanding....
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