Bow Prod

So I got it in my head that I could fabricate my own bow prod out of carbon fiber sleeves.   As described below, I previously built a carbon fiber tube to use as the well for a crane to lift up the keel.  This was quite a bit larger undertaking.  The "mold" for the prod was a section of 2" PVC pipe from Home Depot.  This pipe has an outside dimension of 2 3/8".  I sprayed the length of tube with plain old Lemon Pledge furniture polishing wax.  and then wrapped the pipe with polyethylene sheet prior to pulling on the carbon fiber sleeve.  I didn't have the courage to try this without the plastic sheet, but I think that it would be possible to just mold the tube over the PVC pipe directly.  Lemon Pledge actually works pretty well as a release agent.  Some time in the future I might experiment a bit with this.  


Pulling on the first layer of CF sleeve is pretty easy.    This stuff works just like the finger traps that you buy in Chinatown however and will bind if you pull too hard on it - you almost have to push it on.  I then just painted the entire length of the sleeve with epoxy. 

 For subsequent layers, it is best if you roll up the ends axially (like you would a sock) and then push them together to form a very wide pipe.  It is pretty easy to slide this wider "pipe" over the previous layers, and then expand it outward from the middle.  For each layer, I then painted on the epoxy.  


I used three layers of heavy 3" carbon fiber sleeves and (more for aesthetics than anything else) an outside layer of a Kevlar Carbon fiber weave.  I then vacuum bagged the whole thing.  

I hadn't done a vacuum bag on something this large.  It came out pretty well.  The surface under the top of the bag is absolutely beautiful.  The bottom collected some excess epoxy which I had to remove with a Stanley Sureform and some sand paper.  If I had it to do over again, I think that I definitely would have used release cloth between the bag and the tube.  

In any case the tube came out pretty well.  The whole thing weighs less than four pounds  and it is incredibly rigid.  The tube is very round except for the last few inches near the ends.  I'll just trim both ends.  This will leave the tube a bit short, but I'm going to put a tapered tip on the outside end anyway, so I'll just make this tip a couple inches longer than I was going to.


If I had it to do over again I would not have used the Kevlar composite on the outside layer.  Carbon fiber sands very easily whereas Kevlar does not.  Also, Kevlar is less UV resistant.  I don't view that as a big deal however since the pole will be retracted most of the time.  Finally, in retrospect, I think that I could have gotten a very nice tube without the bagging by bunching the four sleeves together at one end and then tying a string to them, hanging the whole thing from the ceiling, then tying a weight to the other end, and then wrapping the whole thing in release fabric.  I say this because the tube looked really nice before I even put it in the bag.  


Next up is to fabricate the receiver tube.  Of course I'm going to use the prod as the mold for the receiver.  I don't think that I'll vacuum bag the receiver.


Finally, I don't have an exact cost on the tube since I bought more sleeve material than I needed.  But roughly the prod and receiver are going to end up costing me about  $300.  This would have been a bit less if I had just used carbon fiber.