[Public-list] Chainplate knees and mast pad

[Alfredo]

The knees were redone on Free Spirit last spring due to some separation
between the knees to the hull. They were removed and replaced with
teak, covered with altering fiberglass roven mat and cloth. The bolt
size was increased to 5/16 and oversized washers used to act as back
plates. The repairs were thoroughly tested out at sea under strenuous
conditions. The mast still stands today.

Alfredo

--- George Dinwiddie <gdinwiddie at alberg30.org> wrote:

> Eliminating the knees seems an overreaction, to me.  Using plywood,
> even
> marine grade, for an area where you plan to through-bolt to the
> outside
> (particularly in a place that will, at time, be underwater), seems
> risky, also.  It also sounds difficult, as there are bulkheads in the
> way.
> 
> Typical chainplate knee jobs involve
> 
>  * Filling any space between the knee and the deck.  On some boats,
>    Whitby didn't fit these very well.  Leverage against the deck adds
>    a lot of strength.
> 
>  * Extending the length of the knees to provide a more secure
> attachment
>    to the hull.  Some people remove the knees and replace them with
> new
>    ones, but if the originals are in good shape, I like Towney's
>    solution of adding additional knees below the originals and
>    connecting them with straps.
> 
>   - George
> 
> 
> On Thu, Jul 29, 2004 at 05:42:17PM +0100, Peter Amos wrote:
> > Also I have always been concerned about the chainplate
> knees.Compared
> > to those I have seen on other boats of a similar size they appear
> > lightweight and not well finished.Although I have never heard of
> them
> > being a problem,except the 1/4 bolts,while the mast is down it
> would be
> > a good opportunity to do something about them.I have in mind to
> remove
> > them,and after preparation add a couple of layers of heavy mat to
> the
> > hull along the length between the lowers.Then add three strips of
> 1/4"
> > marine ply over the same area so there is a thickness of
> 3/4".Finish up
> > by fixing new sturdier chainplates inside bolted through the hull
> from
> > the outside with 5/16" bolts.
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