Casting the bulb

[i550sailor@aol.com]

Looking at Loh's mold above, am I seeing this right,,,, a approximately 1 1/2" hole to pour thru for a 1 piece pour?. I am sure this has been posted before, do I need a breather hole also, or just one, large hole to pour thru?. also what was the preferred casting material, concrete or plaster?.

Thanks,
Mark

[micah202]

lohwaikin wrote:The bulb weighs 80kg (176 lb), or at least that's what I've been charged on the receipt...

.micah...''..ummm,isn't the whole keel meant to be 150 to 185lbs?..or did you intend a heavier keel?? ''

My keel strut came in around 10#, so he's right on track. He'll lose a couple pounds with the routing and drilling. If OD is ever an issue, it's lots easier to make a heavy keel lighter than to make a light one heavier...

uhhhn,,,one of my 'not-having-built-from-scratch' deficits coming through!
....I recently just got my keel de-installed,,ready for a re-shape,,fairing ,tweeking,,,finishing........
............somehow I had the impression that the lead was ~80lbs--thilly!!..........my bad!!..................no wonder my back's sore!!!

.

[lohwaikin]

The pour hole is produced from an inverted taper paper cup about 1-3/4" at the base and 2-1/4 at the brim. Then there are 2 "breather sprues" fashioned from roughly-rounded 1/2" square battens, each located 4" from the nose and tail.
My mold parting was left-right with the pour and breather holes on starboard side.
If I were to do it again, I'll build the mold parting top-bottom with pour holes on the top.
This way lateral symmetry is preserved should anything "untowards" occurred during the pour...

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[lohwaikin]

Mating of the keel foil and bulb...
I use stainless M12 X 140 hex bolts.
The nuts were mild steel 32mm bar-stock, cut to 19mm thick and threaded M12 thru'.

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[Tim Ford]

Massively informational, Loh! Thanks a million --TF

[lohwaikin]

Progress is slow, but we're getting there...

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I've been reading this thread since purchasing the plans in DEC 2011.
And thanks to Chad I've learnt a lot from mold-making to lead-casting.
It's been a meaningful 2+ years of boat-building (though on the same boat!).
I guess the only way to repay kindness is to post more pictures...

Cheers,

[i550sailor@aol.com]

Looking really good Loh, you will be sailing soon from the looks of things.

[Tim Ford]

Did The Pour on Saturday. Things went OK. No one had to go to the ER. That said, I learned a lot. Bottom line: this is a very do-able project and with a modicum of safety and health precautions, no one should stress over doing this. It's actually kind of fun once you get the drill down, so to speak. What I learned:

1) read this entire thread again before proceeding
2) cast iron is the ticket. It disperses the heat more evenly and doesn't set up hot spots/cold spots in the vessel you are using to melt the Ledd. Steel does set up hot/cold spots. Cast iron retains heat longer and more evenly
3) heat from above will speed things up like crazy. I did not realize/do this until well on into the process. But just sitting there applying a propane torch to the top while the gunk starts to liquidify on the bottom really helps, cuts the melt time in half if not less.
4) pour straight from the cast iron pan, don't even bother with the ladle (assuming you can lift it, the handle is HOT!)
5) just before each new pour, on top of an existing layer that has cooled back into a solid, hit it with the torch a few seconds before the next pour.
6) let it cool overnight and the bulb should drop right out of the mold once it is inverted.
7) use dry wall compound to smooth/fair the inside of the mold if it is crumbly or has gaps from cement pieces that did not cure perfectly.

Set-upLeadPour.jpg

[ryderp]

Congratulations Tim on a major step forward.

Phil

[jray]

Very nice Tim! Another step crossed off the list, and a big one. Getting closer to splash time.

[i550sailor@aol.com]

Keep it up Tim, you will be splashing soon.

I was going to post this for those of us working in enclosed spaces, pouring bulbs (i did mine outside), sanding, painting, etc, Is to use carpet fans to aid with ventilation, you can buy plastic (sheeting) air ducts from any water restoration supply company, tape it to the end of the snout and it will exhaust high quantities of air to the outside. It also works great to bring fresh air into a shop.

For final paint and some 6 mil plastic walls around the boat, you can use it to create a negative air environment.

[admin]

Jon, my bulb initially came in at 140#, but I added weight when I poured between the two halves and ended up with 172#. My foil was the surprise, it came in at a whopping 18#, putting me over the limit until I drilled and countersunk for the bolts to hold it all together. Right now I think my bathroom scale puts me right at 185#, but I'm going to drill out a little more lead to put me a pound or two under the limit, and fill the holes, just in case my scale isn't accurate!

OK, nuther set of questions. Both my halves came in at 70 pounds. No problem, I'm having an issue carving out the cavity where the keel slots in, so I am going to bolt the thing together and pour lead back in to fill the gap, See accompanying crude diagram.

TheGap.jpg

I have two questions:

1) what should I use to fill in the bottom so that the lead doesn't drip out? (I thought about using joint compound mud)
2) I'm going to be pouring 600+ degree lead in against my keel which has an e-glass skin and then some fairing pox and then some paint on top of that. What will the 600 degree lead do to the keel skin and could it also compromise the laminate structure of my keel foil? (white oak laminate)

thanks!

[ryderp]

Tim,

If you are at weight, why not just fill the gap with fairing compound?

Phil

[Tim Ford]

That's a good question and thanks for asking, Phil. Thing is: I am not at weight. I had to sheer off 14 pounds of lead to create the cavity (and it looks like hell). So my lead is down to 126 and my keel foil weighs 28 pounds....that's 154 total. Kind of on the light side.

I thought about making up an expoy/lead shot slurry to pour into the gap. What do y'all think of that? My only worry is that it will be less sound structurally with the lead shot slurry. Or is it Slurpee®?

[ryderp]

OK, I see the issue. I'd recommend keeping the lead away from the wood/composite foil. How about adding hot lead to the ends? I filled in some gaps in my bulb with lead after I took it out of the mold. If you pour it slowly, it pretty much sets up right away due to the difference in temperature of the liquid and the cooled bulb. You could then use your "slurry closer to the foil.

Phil

[jray]

Might just be me, but I wouldn't pour hot lead around your strut. I used the epoxy shot method to join the two halves, and it worked just fine. If you are concerned about them separating put two more cross bolts, forward and aft of the strut.

[i550sailor@aol.com]

If your bulb is standard (non beaver tail) you could sit your bulb on edge with the keel sticking straight up and down,,,, in the mould (the mould will cradle the bulb). I would create a dam to keep the lead away from the keel blade itself, then just fill it solid.

[Tim Ford]

Mark, one mold got tossed in a dumpster and the other one cracked when I dumped the cast bulb out of it. So that's out.

Jray and Phil, thanks, I think you guys nailed it. I'll put some lead back where it is needed and use the slurry method. That seems pretty sound structurally and should be pretty heavy. Jray, is there anyway to qualify what your slurry consistency was like? Did you add anything in to the mix? My recollection of shot and neat epoxy mix is: it is runny and the shot separates easily into a different layer. DId you add a filler? Like 405 or 406?

Thanks again, fellows, I think I can resurrect this effin mess....I sure as heck do not want to start over.

[jray]

Yes add a filler with the epoxy. I did not use West System so am unfamiliar with what 405 or 406 is. I used SystemThree products. Colloidal silica and milled glass as fillers for thickening the mix before adding the shot. I didn't want to use any wood flour or porous material for fillers on the bulb. Get the smallest shot available, 7.5's or smaller. Sometimes local trap clubs have deals on reclaimed shot at half the cost of new stuff. Reclaimed can be a mix of sizes, and will still work great.

Use the slowest hardener to give extra time to double check that everything is right. I used duct tape to seal the seams, worked just fine. Tap/burnish it down as it is pressure activated.

Found by volume, not by weight, a ratio of 70/30 shot to epoxy left extra epoxy after it all settled in. Don't over thicken the epoxy to much before adding the shot, you want it all the shot wet. You can add more fillers after the shot is mixed in if nessary.

[Tim Ford]

Excellent, thanks a million Jray. That is exactly the info I wanted/needed.

Once again, this board kicks tail.

[micah202]

That's a good question and thanks for asking, Phil. Thing is: I am not at weight. I had to sheer off 14 pounds of lead to create the cavity (and it looks like hell). So my lead is down to 126 and my keel foil weighs 28 pounds....that's 154 total. Kind of on the light side.

I thought about making up an expoy/lead shot slurry to pour into the gap. What do y'all think of that? My only worry is that it will be less sound structurally with the lead shot slurry. Or is it Slurpee®?

...''light side' isn't bad at all...the boats are very stable,,,and if/when they get tossed,,they stop at the side-panels

[Tim Ford]

That's interesting, micah202. I will race this at one of the breezier spots on the Chesapeake. We get a lot of late afternoon/evening thermal breezes into the mid 20's there. So I'm going for a bit more beef.

Jray and others, one more question (probably already posted somewhere else, but….):

what diameter bolts did you use through your keel? I bought some 5/8th inch boats that are 6 inches long, but they look a little too big for this application now that I have them here at home. They looked fine in the hardware store….

thanks!

[jray]

I used regular 3/8 bolts, thought about stainless but heard that SS doesn't like to be encapsulated. Drilled out 5/8, filled with thickened epoxy then re-drilled to 3/8 because I was drilling through the strut, and set them in with epoxy. So far so good.

[micah202]

That's interesting, micah202. I will race this at one of the breezier spots on the Chesapeake. We get a lot of late afternoon/evening thermal breezes into the mid 20's there. So I'm going for a bit more beef.

.......I from what I've seen sailing the boats,,,the extra weight doesn't seem necessary. At the last event I was sailing with a none-too-heavy 14y.o.crew,,and we had some breeze-on conditions...we had some issues with sail-flattening controls which definitely caused some issues for upwind speed,,but once sorted,there was no problem...whatever keel-weight you carry doesn't do much at all until the boat's substantially healed,,,but then the big wide side-panels do the work,,with something of an assist from the keel-weight.
...in fact my keel blade is 4-5''short for adding a higher keel-trunk when I renovated...I don't see a point to 'fix' it

...one thing to consider is 'pitch-inertia'...builders generally do their best to centralize weight as best possible --keeping the end's light. I know starboats went this way with keel-weight too!........When I was involved with Rocket22's,,I noticed something I didn't like at all when hiking on a deep-bulbed lightweight boat --the boat hits a wave and slows down,,but the keel's weight continues forwards in a way that seemed to magnify the effect of a wave's -ve effect,,as well as transfer a nasty-feeling torque up my spine!...Rockets solved the issue by installing hiking-restrictors as other sport-boats do.

...time will tell!

.

[Tim Ford]

Good stuff and thanks for the intell, Michael. As for "hiking-restrictors," do you mean something like the granny bars on a Laser SB3?