Free: Contests & Raffles.
I don't see a problem with adding them. My recurve is the exact same noise level as my compounds, but I put little stock in bow noise. We'll never get them as quiet as we want, and we'll never outsmart a buck's ears.
I'm guessing you already messed with the brace height. I can't tell what kind of bow that is, it looks to be some sort of Bear, but in general a longbow should likely be between 6.5-7.5" on brace height and a recurve between 7.5-8.5", again, just in general. It should be relatively easy to find on the manufacturers page to find out exactly what range you should be within. Sometimes it can be arrow related as well, either spine issues bouncing the shaft off of the riser, or nock height issues bouncing the shaft off the shelf. If non of that worked, I'd try heavier shafts. All bows, compounds included, are more efficient when shooting heavier arrows. The stored energy in the limbs is used to propel the string forward, powering the arrow with it. Some of that energy is lost as drag when the string cuts through the air, some is wasted as vibration or noise, the rest goes into the arrow. Heavier arrows take more of the stored energy to move, and leave less of it to be wasted as noise or vibration. Wool puffs and the like slow the string down a bit and cut down on that noise.I don't know if you shoot a compound as well as traditional stuff, but I did some testing a few years ago shooting heavy and light arrows out of my bow. The heavy were 650 grains, the light were 400 grains, both out of a 60# bow. While the lights obviously went faster, the heavy were more efficient when turning up the poundage of the bow and were significantly quieter. When I turned the poundage up 5#, the lighter arrows got about 5fps faster, the heavy got 12fps faster. The heavier arrows more efficiently got energy from the limbs. What I lost as sound with the heavier arrows, I gained as more speed and efficiency, at any given poundage. I always hear people talking about KE as it relates to bows, but that is a completely useless metric to use in relation to bows and arrows. Arrows don't kill though kinetic energy transfer like a gun does, arrows kill by cutting. In a perfect world a firearm would transfer all of it's KE into the target with just enough left over to make it 1" out the far side and fall to the ground. That's what hollow point are for. Transferring kinetic energy. And arrow is the exact opposite. You want it to go through, and thus cut as much as possible before it stops or slows down. That's why people want the sharpest broadheads, the smallest diameter shafts, and fastest most powerful bows. No bow in the world shoots anywhere near supersonic, so KE is pointless. Momentum is everything for an arrow. I want it to stop for nothing until it's in the ground on the far side. To that end I shoot heavy arrows, within reason. I find that around 10 grains per pound work out perfectly for me, in both compounds and traditional gear. They are quieter, they stop for nothing, it's relatively easy for me to make them from readily available supplies, and they aren't unduly slow. I'll take a 650gr arrow at 220fps over a 400gr arrow at 270fps every day of the week. KE wise, it's a wash, momentum wise, the heavier one has 35% more.
Bear suggests a brace height of 8-9" for that, but you should be fine where you're at. I take it the bow is marked 55#. Which arrows are you using? You can add footers and insert or point weigh to get the weight up. At your draw length, you'd likely have to add both, because there isn't a whole lot of manipulating you can do to the arrow with a 31.5" draw, as far as shaft length and the like. I understand not wanting to get a hole new batch of arrows or mess around having to bare shaft and stuff all over again, but there are some things you can try if you wanna add some weight. Adding weigh to the point will lower the dynamic spine, but adding a footer will bring it back up, and both will add weight fairly quickly. A 4" footer will add ~50 grains and about 10lbs of spine, depending on the shaft you use. Adding another 50 gr to your point will bring those 10 lbs of spine back down and leave you about where you started, except 100gr heavier. The points would be cheap enough for target points or what have you, and half a dozen aluminum shafts can be had for $30 or less, and that'd be enough to foot about 4 dozen arrows. You could mess with adding insert weight too, depending on the inserts you have now, though it's harder to do, because you'd have to deconstruct your arrows. There are ways of doing that relatively easily as well if you're interested.
Without knowing anything about your arrows, I assumed you had the standard 11.4gr aluminum insert, and left the shafts at 32".Gold Tip Trad 400 (55/75) at 32" with 3 - 4" feathers, 15gr nock, 125gr point, 11.4gr insert, and a 5.5" footer at 13.8gr per inch (75.9gr) comes out at a dynamic spine of 76.9#Bear Super Kodiak @ 55# drawn to 31.5" with a 16 strand fastflight string comes out to a dynamic spine of 76.8#Total arrow weight then would be ~530gr. I've got some 175gr field points I could probably give you if you're near Seattle, got some shafts you could use for footers on those arrows too. Those points with a 6 3/4" footer would spine within 1/2# of the bow and the total weight would be right around 600gr.
From all of the above posts you are pointed in the right direction. My biggest impact on noise has been arrow wieght. You are on the edge of being too light for your draw weight that you could cause damage to your bow. The point where I see the most noise reduction is around 11 grains per pound of draw weight, that puts you at 693 total. There are lots of options to get where you need for arrow weight. Let me know if you want more advise on this. The second piece of advice is that the spine calculator on 3rivers website does not work for me. I have a long draw length too at 31", and have talked to a few people with longer draws that say it does not work for them either. I shoot MFX 340s out of my 66lb longbow, but that is with 250 grain point weight. I can shoot the MFX 400s with 125 grain points, but they are a lot more noisy because they are lighter.I have also found that by using one silencer at the 1/3 point of the total string length from the bottom and the 1/4 point from the top gets a lot of the harmonic hum out of the string.Final thought is that a 60" recurve may be on the short side for your long draw length and that may be causing some noise issues as you could be overstressing the limbs at full draw. I hope some of this may help. -Clayton
