Bulb to Keel Attachment

[r2heisch]

Hoping to get some reassurance or advice regarding my bulb attachment. Regrettingly I did not take physics in high school because my father taught the class...

Background on my keel/bulb build: The keel is laminated vertical Douglas Fir wrapped with a few layers of carbon cloth. I also ran 4" wide vertical carbon tape on both sides for lateral strength. It weighs 20 lbs. I did a two-part bulb pour in order to sandwich the two halves around the bottom portion of the keel. I used positive molds inside the concrete bulb molds to create the gap for the keel foil. The bulb turned out very well but it was a bit light (130 lbs.) so I decided to space them 3/4" apart and poured lead shot/epoxy in the gap which increased my bulb weight to 149 lbs, putting my total keel/bulb weight at 169 lbs which I was very happy with. I sandwiched the bulb halves around the keel using (5) - 3/8" stainless bolts, (3) of which pass through the bulb AND keel. In order to help take some of the load off of the bolts, I drilled (3) shallow 3/8" angled holes into both sides my keel before attaching them, thinking this would give the lead shot slurry something extra to grab besides just the smooth surface of the keel.

So here is my concern... The (3) bolts that pass through the bottom of the keel are exactly 1-1/2" from the bottom edge of my keel. I am probably over-thinking this, but is that a concern to anybody? I REALLY would prefer to not lose my bulb....

Pic attached. I would appreciate your thoughts...

[monsters inc]

So the lead bulb halves, did you grind the glued faces and seal them immediately with epoxy, so they won't have oxidized? Any voids in the slurry? Did you seal the drilled holes on the fir keel with thickened epoxy? The three bolts will hold the bulb, if the wood stays sound. I figure the top of the fin that fits into my keel box is the week spot on my boat. I witnessed a Melges bulb and keel slam down into the keel box after the winch line failed. It didn't break the box or keel but is really loud and scary. Think of the worlds biggest slide hammer...

[admin]

Yours sounds almost exactly like mine (in terms of the way it was built-even down to the final weights!) So far, my bulb is still attached. I used just three lengths of threaded rod, I think, and they were thru the thickest parts of my laminate foil lay-up and maybe just a smidge higher than 1.5 inches up from the bottom. But not too much more.

I've abused the heck out of the bulb/keel combo and so far so good. I mean some (more like many) hard groundings, some violent episodes getting the boat out of the water and some truly dumbass machinations getting the stuck keel out of the boat. The bulb seems like it'll be stuck to the foil no matter what I do to it.

Hope it doesn't change its mind....

[r2heisch]

I did not seal the drilled holes as you suggest, wishing that I had now... There are no voids in the slurry that I can tell and the lead had not oxidized. So as long as I can keep water out and off of the fir, I will probably be OK? The boat will be trailered when not in the water so hopefully that will keep things a bit dryer. Guess I better make sure the outside of the bulb is sealed properly...

[ryderp]

I molded my keel bulb in one piece, but the bolts go through my foil in about the same place that yours does. I've hit a couple of rocks really hard with no noticeable damage to or cracking at the bulb-foil junction. I can't say the same for the front of the bulb or the trailing edge of where the foil exits the keel sleeve however. I had to repair both - twice.

Phil

[r2heisch]

Thanks everybody. I feel much better now about it, as long as I can keep water from seeping in and rotting the keel.

[jerome]

Your keel is just about exactly the same as mine. It is very sturdy the way you build it. No future worries
http://i550-hull270.blogspot.com/2011/0 ... rdeal.html