Keel Fin and Keel (fishing lead sinker) attachment? - RC Groups
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Aug 24, 2009, 09:12 AM
Registered User

Keel Fin and Keel (fishing lead sinker) attachment?

Dear all,

I am in the process of scratch building a 65 cm sail boat (RG65) and let me start by stating that I am a complete beginner.

I am done with the hull and the keel fin and some of the boat structure.

I am now trying to attached the 500g weight (keel) to the keel fin. The keel is made from a lead fishing sinker (hammered and file to hydro-shape). The keel fin is made out of 2 layers of plywood epoxied together, covered with fiberglass and sanded to shape.

I initially inserted a bolt at the bottom of the keel fin. The idea was to drill thru the lead to screw the sinker to the fin. I came to realize last night that drilling thru lead is not that easy. I also realizedthat i should also carve into the lead so the fin will be tighlty inserted.

So my problem is this: drilling thru lead and carving the fin tip into the lead.

Any advice or technics I should consider.

Also I am sure some of you have come up with a much more clever idea, (or just not as dumb as mine) to attached the fin to the lead. Please feel free to pass any helpfull comment.

I also thought of melting the lead down and reshaping it with a mold but that would involve a whole new project.

as always thanks for your help.


If i am not clear enough in my explanation let me know and I will post some pics.
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Aug 24, 2009, 10:06 AM
Registered User
thorsail's Avatar
Hey Xman
Have you tried to contact Earl Boebert and ask him how to attach the
lead weight to the fin ? you can get an Email addy through the AMYA
I have A) never built a boat and B) dont know anything about the RG65s
BUT I have seen many dire warnings on this and other chat forums about
working with lead - the idea seems to be DON"T unless previous experience
and you have all the proper equipment - and specifically SAFETY gear .
I guess it's pretty nasty stuff to mess with and probably not worth any
possible health issue's due to melting/molding the stuff......
my 2 cents.
If the class recommends using the lead weight they must hace some
clever way to attach it - fiberglass cloth over and around the bottom of the
fin maybe ? dunno.....

Aug 24, 2009, 11:11 AM
Registered User
I have heard that using cooking oil as a lubricant will help with the drilling of lead. Have not tried it. Also have heard that freezing the lead before drilling helps as well.

For a pocket I use a chisel and cut the lead. Not perfect, but was able to cut a big enough pocket into my star bulb to get it mounted.

Aug 25, 2009, 05:43 AM
Registered User
Lube well and drill slowly, a little bit at a time with a nice new bit. Anything else, the lead melts due to friction and tries to weld the bit to the workpiece. The chisel idea works well, but use a freshly sharpened cheap one, not your prized wood-shaving one. Using the drill to make a string of holes will probably help.
Aug 25, 2009, 06:15 AM
Useful Idiot
B*****r the drill. get a good iron masonry (steel nails tend to bend) nail and hammer it through the lead. Much easier than drilling. If you cut a slight curve into the bottom of the fin to match the curvature of the bulb, when you tighten the ballast with the bolt, it should be fastened solid. Just to make sure, smear a bit of epoxy on the bottom of the fin before tightening.
Aug 25, 2009, 08:18 PM
Registered User
Easiest and least messy way I found was to put the lead bulb in the freezer .... then drill your holes while the bulb is still cold. Drills easily without the bit binding and you don't end up with messy liquid lub everywhere. You might need to freeze the lead several times as it does heat up whislst you are drilling the holes.

As mentioned before, you can drill a series of holes for the slot ... then chisel off the bits in between. To get a smug fit between fin and bulb in the slot, I used some slow cure epoxy and just dripped it into the gap between the two. If you need the bulb to be removable from the fin, coat the fin with a debonding agent first before you add the epoxy.
Aug 25, 2009, 09:02 PM
Last edited by Trakka; May 28, 2011 at 05:13 AM.
Aug 25, 2009, 09:54 PM
Registered User
Dick L.'s Avatar
As noted - a hammer and old screw driver works just fine. Draw a line, place screwdriver tip (or cold chisel) on line and give it a "wack" with hammer. Continue length of keel blade. Wedge keel blade in and assure alignment, fill with thick epoxy. If you are concerned you can always wrap a layer of glass cloth from one side of keel, down, under bulb and back up to other side of keel. Then just fair in and sand epoxy fairing filler. Mine were 1 lb. /500 gr fishing sinkers and keel blade was 1/8 inch thick basswood. (Eventually covered by layer of glass as sandwich composite.)
Aug 26, 2009, 02:21 AM
Registered User
tbarjohn's Avatar
I have found that a couple of drops of Tap Magic and lead will drill like butter.
John R.
Aug 26, 2009, 08:14 AM
Registered User
Wow, again so many great reply from you guys... Thanks

I have reviewed all of them and am still undecided as to how am I going to try this. For now the simplest technic to try seems like the good old "wack" with a hammer. I think I am going to start with that and if unsuccessfull will move to the more advance, i.e. drilling with freezing and/or lubing with oil.

I am gonna try this tonight so I will report with the result tomorrow and maybe some pics if I can get a round twit ;-).

thanks again to all......

My next step will be starting to rig up, and am I sure i will have many question about it. I should receive today the material I ordered from the goodwinds kiteshop. yohoooo!

I'll keep posting.



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