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Dick
Hi Dick
I’m back on the forum from my home computer.
Thanks for doing whatever you did to ‘fix it’
Phil
Just changed your IP address in your data profile,
Glad I could help.
Dick
Update to a previous thread about a bulb…
I finally broke down and purchased a small digital scale. I must be the only person who never had one - always running to post office or UPS store to get weights.
Anyway - as I suggested, I purchased a replacement keel and bulb for my nARROW and tonight weighed both. -----
Keel and bulb attached = 677 grams
Hull only - 100 grams (this is epoxy coated, balsa strip, all internal templates removed - but no decking yet.)
Hope this helps for comparison.
Dick
That is incredibly close to the plans. I must look for a local distributor
I attempted a clever way of doing a keelfin.
It was atrocious lol. So I’ll do the fin and rudder as per the ModelYachting RG65 article me thinks.
I have started sanding the deck line on the hull to accept the flatboats for the mould, so things are happening but quite slowly. So far the only issue has been that I didn’t epoxy the inside with enough around the frames. The sanding shook one loose on the side so I’ll re-epoxy with 5min 2part to make it a good solid attachment 
Believe it or not I am making progress - very slowly.
Here is a pic of the hull with lots of sanding done and the beginnings of a deck.
Looking pretty good. Keep on working toward the finish.
Dick
“THIS WAS A DISASTER - DON’T USE THESE LINES. I’ll post up correct ones when I get it correct”
So people don’t waste their time on these.
The bulb…
I kept whacking numbers into the bulb calculator and came up with this shape.
It gave the lowest wetted surface which is what I thought I was aiming for.
But I have since read some threads (RCGroups IOM or Marblehead IIRC) where guys mentioned that although you want it to have a low wetted area, you also want a streamlined shape as opposed to a wider, blunt shape.
So I’m just running with this for now. I was hoping to build 2 boats, so If the mood moves me I’ll try build a different shaped bulb for that one and have a drag race (Get it… drag race…drag… I know, it was bad)
Bulb PDF for printout and the settings I whacked into the calculator.
If you use this PDF double check the scale when printing it out. For some reason it kept printing out too big so I had to adjust the scale.
The balsa bits…
I cut them from 2mm balsa which should be too thick, but i figured that it will be easier to grind off extra weight rather than add it.
By preference I would like to do what I’ve seen in Claudio’s build and cut lead sheets and glue the bits together, but I can’t get lead sheet easily, so I would have to pour my own - which defeats the point of trying to avoid molten lead.
So what I might try is this:
I used a rasp to remove lead from a sinker on the Apsara I built. These lead shavings work out WAY cheaper than any leadshot I can find (sinker is R70 so that works out to $4.50 for 600g). So once I shape and build a plaster mold I’ll try use those shavings and epoxy to build a bulb. I’ll just need to be aware of spreading the shavings equally in the mould.
If that fails, I’ll have the 2 part mold to pour the molten lead anyway. I have done it once so I reckon I can avoid killing myself.
Any input on any of this will be greatly appreciated.
If you have any firearm/hunting stores where you are … ask if they have any #9 lead shot (used to reload shotgun cartridges) for shooting “clays” (clay pigeons/disks thrown into the air) This is fine enough you can use epoxy to hold it all together. Around here a 25 lb bag goes for about $45.00 at a local outdoor shop.
Dick
Just another example of how much help this forum can be!
I have wanted to build a design that called for a 3.1-3.2 kg. bulb. Claudio’s idea for making a bulb with lead tape or foil sounded good, but I couldn’t find any lead tape available. I thought about making a mold and pouring a lead bulb but the thought of molten lead was less than appealing to my senses. In trying to buy a ready made bulb, the only one that was even close in weight was from a company in Europe. Not only was it a little over the required weight (requiring drilling holes or shaving off some weight with a rasp) but the cost for the shipping was more than the cost of the bulb.
It never occurred to me to use lead shot with epoxy resin holding it together. It’s kind of ironic sense I do reload ammo for rifles and handguns. (Not for shotguns, though)
I will give your idea a try and perhaps attempt building another, heretofore out of reach, larger sailboat.
Thanks,
Clark
Good luck Clark.
You know - with adequate lubrication, You can craft the bulb size needed from wood. (use a lathe if you have access to one) and than cover the wood bulb with multiple layers of fiberglass cloth. Be sure to coat the wood bulb with plastic tape, multiple layers of wax, etc. Once the bulb covering cures, you can cut the bulb lengthwise and peel the fiberglass off the wooden bulb. Support the fiberglass, and add some non-stick into the inside of the glass “half-bulb”. Fill with very fine lead shot, tamp it down and add thinned epoxy. Keep building it up until you reach the top. Might want to add plastic tape around the open perimeter so you can overfill (slightly) the fiberglass mold. When cured, the epoxy/lead should be able to be removed from the inside of the half fiberglass mold. Use a coarse rasp, a belt sander or ??? to flatten the lead bulb. (use lead safety precautions) and when done, you can mix up some thickened epoxy (peanut butter consistency) and spread on the flat sides of each half. Place together and clamp or tape to avoid movement. Once cured, remove tape and finish sand.
Hang onto the half fiberglass “molds” so you can cast more bulb and vary the fill to get weight needed. Because you are releasing the lead without needing to melt it first, the fiberglass casts seldom are damaged.
Let me know if I lost you on this suggestion. I can add a drawing to help explain.
Dick
No need for a drawing, Dick, it makes perfect sense to me.
Thanks,
Clark
Hello gents.
Thanks for the info Dick, there’s a great ammo shop right near me. I’ll swing by and ask them
Clark, glad you got an idea to try out. I have done the molten lead but would prefer not to do it again lol.
Thanks Dick!!
I can’t get no9 anywhere but I can get no7 which is pretty close according to here:
http://www.shotgunworld.com/amm.html
Which works out to $1.94 for the bulb!!!
Scary thing is there was a 35% difference in price between two shops.
Two possibilities when asking a friend who shoots skeet here …
Higher price = a shop that has a lot of reloading customers. Must keep stock on hand, and can get a premium if he is the stocking dealer of preference.
Lower price = dealer bought with expected order and the purchase by shooter/loader fell through. Can put a lot of cartridge ammo in same space as a bag of shot. Clearance ???
In either case, I would go with it - do a fiberglass mold for bulb, add non-stick surface and lay up the shot plus epoxy and retain bulb and glass mold for future bulbs.
Hmmmm - maybe time to dust off the lathe (wood) and make up some wood bulbs for molds. :rolleyes: Once garage is warmer, I will pull it out, get some dimensions and make a couple to see if any interest.
I once read about, but never actually tried, making a wooden bulb out of (I’m pretty sure) red cedar. Apparently, the red cedar is 1/16 the density of lead. Therefore, the weight of the wooden bulb in ounces should be the weight of the lead bulb in pounds.
Now you can craft whatever shape you want and have a good approximation of the finished weight.
I also remember hearing that the optimal bulb shape should similar to a great white shark’s body; kind of short and stubby. The theory being that the sharks are verrrry efficient swimmers.
Remember when you use the lead shot and epoxy method that the result is less dense than solid lead…the bulb will have to be bigger to get the needed weight.
Thanks for the heads up.
I’ll make a plaster mold then and if the weight is considerably out, I can use that to pour the lead.
Well, after work etc. I had very little time to do anything.
But this weekend I finally felt confidant enough to throw on primer to see how well all my sanding had gone. It was horrific with big wood grain holes visible. I was rather bleak and went over the steps of doing this in everyone’s build and realized that I’ve been a complete moron. I meant to sand the balsa, put on some filler to get the rough shape and then do the glass/epoxy. Because it’s been so long I forgot to glass/epoxy - dumbass 
So I’ve hopefully remedied the problem and its curing outside now.
Bulb plug will hopefully have made a successful mold when I try remove it tomorrow.
I figured I can then get an idea of how many grams it will weight using the lead shot and make a call from there.
I’ll post pics of the stuff up once I re-size them later
Hello all.
It’s been a bittersweet week for the yacht.
The good…
-
I finally had a legitimate excuse to dress like a supervillian.
-
I went from pieces of paper to a lead bulb making a mold/cast.