Keel Bolts

[Willallison]

in an FRP yacht, where the ballast is located within the FRP keel, how is the lead put in? And then how are the keel bolts secured to the lead?

[dougfrolich]

In the oldendaze ie the 60's big fat ugly keels were laid up some how, as part of the hull, then lead,slag, and all sorts of other stuff was thrown in the void, then a bog of goo was poured over the entire mess to keep it in place, not too cool.
Now that things are more civilized, molten lead is poured into a cast with the bolts jiged into place, some times the bolts are long and "j" shaped to "hold on", sometimes they are part of an internal framework, and sometimes the bolts are tapped into a steel flange at the root of the keel. Then the entire assembly is attatched to the hull/internal structure. somtimes a flange and fin are machined from steel and a weighty lead bulb is fastened to the tip. check out www.Marsmetal.com for the latest tech.

[CDBarry]

It is not unknown to use what are essentially big lag bolts that are tapped into the keel, just like wood screws.

[Eric Sponberg]

Coming up in a few months in the June/July issue of Professional Boatbuilder magazine are two articles on keel and rudder design and engineering. David Vacanti is supposed to have a piece on keel and rudder design, talking about hydrodynamics, lift and drag, design ratios. The second article is one that I wrote as a companion piece that describes the engineering and construction details of different kinds of keels and rudders. Kevin Milne, President of Mars Metal, has a sidebar in my article about some of the techniques that they use to cast and fabricate keels.

We three participated in a session on Keel and Rudder Design at last October's IBEX conference in Miami Beach, and these articles are a summation of the material we presented at that time.

Eric

[Willallison]

Thanks guys - Eric, I'll look forward to seeing the PBB articles.

[nemo]

This maybe a little OT, but still...
I made some structural analysys on a canting keel structure, as shown in this picture and here at http://digilander.libero.it/delledesign/keel2.htm
Now my question is how to fix it to the hull (a mini650)? I was thinking about putting the shaft through two tranverse carbon sandwitch stringers, with a reinforced core.

[chandler]

Eric,
Thanks for the ref. on carbon fibre mast manuf.
Looking forward to the article in prof. boatbuilder.