Yew self-bow (not a war bow) in the cold?

[Lefty38-55]

Gents:

Used to hear the ‘old wives tale’ that said shooting a yew bow in the cold will break it. I live in the northeast US, where the temperature one night was 28-degrees F outside, or ~ -2C. My SUV had been used so was warmer than being cold. I headed out to my Archery Club’s indoor range that is 20-minutes away, but I did make one stop of no more than 5-10 minutes (car shut off).

Whilst driving, I put the yew ELB across the rear seat as I intentionally didn’t want the heater that blows out from the front seat to harm the bow. Whilst driving the car inside was warm, not below freezing. I took the bow right into the range & let it warm up some & even hand-runner it all over before stringing it, then did a series of 1/2-draws from my left (I’m lefty) and right sides, to warm me AND the bow up.

Used same arrows matched to the bow using the ‘shoot 3 fletched & 3 bare shaft’ method to ensure all arrows hit the same spot. They do, from ~5-yards out to 20 or more. But this night, I noticed a fishtail upon release that I had never seen before. I put the bow on the same scale it was initially tested on (43-pounds) and it now read 49-pounds, checking it 3 times.

The bow is OK, and I shot a 2nd bow ... “just because” ... but what are your thoughts or comments? Would a yew selfbow, even one nicely finished ... weigh or scale that much differently than whence 1st tested when it was likely 80-degrees F outside (~27-degrees C)? Note I have not shot nor tested it since.

Thoughts?

[Lefty38-55]

ADDED - I have recorded chronograph data from a Summer session, so can I re-run a
speed test using the same arrows.

[stuckinthemud]

I had heard that yew gets stronger in the cold.....

[Mikkolaht]

I think warmth has to do with it also humidity is important.
When it gets to below freezing, the humidity drops down.
Junipers become brittle when the air is dry, so do white woods.
When it is too humid, compression strenght becomes weaker.
Tensile strenght gets weaker with dry conditions, sometimes resulting in a breaking. This is more likely with new bows than older bows, because older bows have been used to stretching and have gained some stringfollow.
If the bow is properly sealed and stored in a more humid place there should be no issue.

Temperature also affects, I sont know if it makes bows weaker in tension etc. Only experience is that the warmer it gets the more pounds i lose.

Edit: On some warm summerdays my warbows have dropped even 10punds. One example was my ipe maple hickory 120lbs laminate. At the morning it was 120 and when sun showed up it got down to 110.

Also one wych bow lost like 15pounds but that was part of breaking in.

Just my bits of info what I have gathered.

[Lefty38-55]

I shot today when it was 40-degrees out, using the same chronograph, arrows and glove that I had shot through a chrono last Aug/Sept. At the same brace height I recorded 15 FPS faster today. Unfortunately I did not have access to a scale, but from this limited testing, I am seeing faster speeds in cold(er) temperatures.

[willie]

humidity is important.
When it gets to below freezing, the humidity drops down.
Junipers become brittle when the air is dry, so do white woods.

yes, and observing the draw weight increases can give you a heads up if a bow is  heading for an explosion. yew does not like being too dry on the back   caution is needed in winter, as would being in a desert


badger has worked quite a bit with the mass principle and could advise if the bow is too light or too heavy for the tiller and drawweight. this might make for an interesting topic in the general bow section

[bownarra]

Humidity combined with the temperature is the cause. The bow is drying out and becoming stiffer, this is what breaks bows.

[Bryce]

I’ve shot many a yew bow in below freezing and below 0 temps.. never seen one break. I’m sure it was just another excuse told by archers and bowyers to play off a poorly made bow

[Strelets]

Yew bows certainly gain weight in cold weather. The following measurements were all made on the same equipment, for a longbow of English yew (Taxus baccata) drawn to 27":

67 lb at 10 C
64 lb at 19 C
60 lb at 27 C.

The differences were not due to the bow becoming weaker with age; after a warm summer the bow went right back to its "winter weight" of  the previous year. I have two yew bows that I use regularly, a "summer bow" and "winter bow". The difference can also be measured with bows made of hardwoods, but is less than for yew.

[willie]

Yew bows certainly gain weight in cold weather. The following measurements were all made on the same equipment, for a longbow of English yew (Taxus baccata) drawn to 27":

67 lb at 10 C
64 lb at 19 C
60 lb at 27 C.

The differences were not due to the bow becoming weaker with age; after a warm summer the bow went right back to its "winter weight" of  the previous year. I have two yew bows that I use regularly, a "summer bow" and "winter bow". The difference can also be measured with bows made of hardwoods, but is less than for yew.

interesting data. How much time was there between measurements, and did you do the colder measurement first?

[Deerhunter21]

the colder something gets the stiffer it becomes. the warmer it gets the looser it becomes. thats with basically all things in the world. my guess is that yew is more sensitive to it than other woods.

[Strelets]

Willie asked "How much time was there between measurements, and did you do the colder measurement first?"

30 January 2018.  Temperature not recorded but probably about 5 to 10C. 67 lb at 27".
25 May 2018.   19C. 64 lb at 27".
15 July 2018.  27C. 60lb at 27".
20 December 2018.  10C.  67lb at 27".

Because of these results I now always record the temperature whenever I measure a bow's draw-weight.

27C (81F) used to count as "very hot" in southern England, but now is becoming much more frequent. Winters are becoming warmer, wetter and windier.

. 

[willie]

Strelets,

thats quite a spread in a half a year. would you be willing to comment on your type of finish and storage conditions? Do you think the bow could be taking up moisture and drying between the test intervals?

[Strelets]

The finish is several applications of beeswax polish.The bow was kept inside the house, typically at around 16 to 18C except when we had  hot spells in summer. The relative humidity was probably lower in winter when the house is heated. However, I now keep the bows in a dry but unheated outhouse. I haven't measured the draw-weight recently, but I can tell by the feel when I draw it that it is at its "winter weight". 
Perhaps I should start recording the mass of the bow as well as the draw-weight, to see whether it is gaining or losing moisture content.

I also have bows of ipe backed with ash. They typically have about 2 or 3lb difference between summer and winter  draw-weights.

[willie]

thanks for sharing your data. I find it interesting that yew is affected more than your other bows.