The plate that hold the bottom of the boom vang to the mast has 4 holes on each side containing (or formerly containing) stainless 1/4 screws. Three of them have broken, sheared at the interface of the mast and the stainless vang plate. I assume that was due to corrosion of the screws. I tried backing out the broken pieces but they didn’t move. That leaves me the opportunity to drill them out and re-tap. Anyone have anything to share before I undertake this? Am I missing anything?
When replacing the screws I will use an anti-electrolysis material before inserting them (I bought the stuff from the UK but can’t remember what it is called at this sec).
Sounds like to me you’re on the right track. I can’t see that trying to back them out with an “EZ-Out” would work very well, but you might give it a try. Either way, a drill and some GOOD bits are going to be needed.
My booms are painted, and applying heat to try to “break the bond” by differential expansion of the dissimilar metals would be “out”…I assume you are in the same shape.
I’d suggest removing the boom and drilling/re-tapping on a drill press with sufficient stabilization of the boom while doing so. I think it would be worth the effort.
Trying to drill out a stainless steel screw that’s “welded” into an aluminum boom (with a hand-held drill) could result in a mess and more “oversizing” of the replacement screws than you had contemplated (or want).
Kroil works better even than PB Blaster on stainless bolts corroded to aluminum spars.
Nothing beats the “heat wrench”. If you still have a nub that you can grab with a vise-grip you can try pin-point heat on the bolt itself. I have o2/acet torch but I also have a little o2/map gas torch (available at the hardware store) that makes a great pin point flame for avoiding collateral heat damage and it’s very portable.
If you go the drill route, first file the threads flush with surrounding surface and use a center punch before drilling. It is very difficult to do so without damaging the original threads. Not to worry. Drill oversize and go back with helicoil thread inserts. The big advantage with this is that from now on you will have stainless on stainless so that next time you have to pull those bolts out they will come out… with a little help from step 4.
And last but not least. Be kind to the next guy even if you go with the thread inserts… use anti-seize. Furuno actually includes a little syringe of some stuff that works great but I’ve never found it on the open market. I just nurse the little I have from job to job but the Permatex product is great too.
I suppose you’re talking machine screws here. An EZ-out tool can work if the screws are thick enough to drill holes in the ends of them. If extracting seized screws from carbon, take care not to break a chunk out of the carbon. As suggested, make liberal use of releasing agents. A bit of heat fed into the screw with a soldering iron can have a healthy effect too.
When mounting new screws it does not hurt to use a larger gauge screw to maximize thread length 1/4" (6mm) screws are a bit thin for good holding, I feel. I always use 8mm minimum in my masts to get more thread. When tapping in carbon fibre, take care of the following: the stuff is very brittle, keep your drill and taps very still! And use a smaller drill then the tap-manufacturer suggests for metals. I had a lot of problems with oversized holes. Only use the first and second tap if you use a tap-set of three taps. The third tap makes the threads so deep the tops will break because of the brittleness (is that a word?). I’m now more and more going to use monel riv-nuts when mounting hardware, but in the beefed-up area for the vang collar they are no use, nor are normal rivets. Always use Locktite; moving screws in CF ruin the holes.
Good luck.
EDIT: I just now saw George’s post. Helicoils seem like a very good idea that I never thought of before for the mast, although my engine is full of them. In that case the 1/4" screws are fine.
Glad you posted behind me. Everything I said above concerns stainless screws in aluminum spars. I have absolutely ZERO experience with carbon fiber spars and I yield those with the greater experience here. Mia culpa.
Thank you, team. I am told that there is a plate inside of the carbon mast which is glassed in to which the vang screws. So I don’t think I would be really tapping the carbon fibre but the plate inside the mast. The Vang plate is (from memory) aluminum and the bolts are stainless. shame I can’t light the anchor light with the current produced.
Has anyone had constructed (instead of my bolt arrangement) a girdling band that went around the mast? Any success with this arrangement?
It’s my understanding that an external collar arrangement is what Garhauer uses with their rigid vangs, and that they have done many of these on Freedoms and have the templates etc so they can just “make one up”…seems I recall their prices for these collars were remarked on as being “VERY reasonable”.
I’ll bow to the experience of someone else…maybe we could make this a “New Topic” thread
The 1/2" curved aluminum plate is set with epoxy to the inside of the spar. The bolts for the external Hall Quick Vang bracket were to be tapped through the mast wall into this plate. Corrsosion of course has been a problem so pretty quickly Freedom stopped using the aluminum plate and went to an external stainless ring that is fit around the mast with flanges bolted that squeeze the mast bracket around the mast with high durometer rubber material between the stainless wall and mast wall. Paul Dennis at Warren River Boatworks in Warren RI makes these up all the time. 401-245-6949. Give him a shout.
Thanks, Mark. I had actually spoken to Paul Dennis about it (Dwight had also made that suggestion) but Paul thought that reusing the existing set up was preferred. I don’t recall his reasoning but I think from the pure engineering of it the wring is a better solution. If my tapping doesn’t work I will go with a ring but I do have a mast step at the same height as where the vang connects to the mast. Oh, well, nothing is simple.
A comment about the external stainless ring: I’ve heard of installations where the ring slid upwards over the mast. In one case I know someone used two rigging screws to attach the vang-ring to the deck collar to keep it from sliding up. I would say with the internal aluminum plate, you could just as well tap new oversized thread into the mast and the alu plate and use screws. You have ten more years before corrosion gets a problem. If you use an anti-seize agent, perhaps 15 years.
I was going to reply to this post before, but I went off looking for photos of the boom vang collar (which I didn’t find) and got sidetracked along the way. Anyhow, the 40/40 uses a collar, but I’ve had 2 problems with it.
First off, the collar consists of 2 semi-circular pieces of 1/8" stainless that’s about 6-8" wide. It end are bent at 90 degrees to form tabs to bolt the halves together. There’s a triangular piece of 1/4" stainless on a hinge that sticks out and the boom vang slides into it. Here’s a crappy picture of the attachment point for the vang.
Unfortunately the fabric mast collar is covering up most of what I wanted to show. Anyhow, the first problem was that the 1/8" stainless wasn’t up to the job and actually tore due to a lot of heavy down-wind sailing that I did. To solve this I had the tear welded and another 1/8" welded over the top of the other plate. This sufficiently distributed the loads away from the hinge tabs so that it has never torn again, and I’ve been in a lot more heavy down-wind situations since then (ever sailed the coast of Colombia? WOW!)
The next problem was something that Michel mentioned…the collar sliding up. This happened to me, and my first attempt at solving it used a stainless chain looped over the vang collar and attached to the mast ring. This worked OK, but wasn’t very pretty. I then made a plate out of 1/4" stainless which attached to the bottom of the vang hinge tabs, but as you can see from the photo below, it wasn’t up to the task.
I then re-made it using 1/2" stock and this baby works great. It keeps the vang collar in place hasn’t distorted.
– Geoff
Attached are photos of a complete, uninstalled ring. I plan to install it on my F36 after I figure out how to modify an F40 Quick Vang to go with it. I am going to incorporate your ring idea to keep the collar from sliding up when I am able to install it. First I need to modify a used F40 Quick Vang that I have.
There is a Loctite product available in Europe called “Schnell-Röstler”, catalogue nr 39160, also numbered 8040 on the can, which is said to freeze metal to -43º C. It is also a penetrating oil. Perhaps alternate use of this and some locally applied heat might loosen up the broken screws enough to remove them with a screw extractor? It has worked for me on aluminium/stainless, but I haven’t tried it on Carbon Fibre.
The stuff described by “Castaway” is available in the USA as: “Loctite Freeze and Release” Item # 996456 in 400 Mililiter cans. Given the description, this stuff should be very helpful in breaking things loose using “Differential Contraction”, for instnce the stainless machine screw that has welded itself to an aluminum part. Herm
