> The trouble with a very strong keel trunk is that when the keel hits a rock
> if the trunk is rigin the force is transmitted to the bottom of the hull.
> It that is strong enough then no harm done, but I would rather have a
> wooden or nylon
> pin break and even some damage at the top of the trunk than
> risk damage at the deepest part of the boat.
>
>
> Regards,
> Keith Sisterson
> P-19 #460 <TBN>
>
Hi Keith,
That's a valid concern that you've brought up. I haven't ever done a
modification of this magniture, but I think it can be done just fine.
It's critical to distribute the force of having the trunk flexing (and any
impact) over a large area of the bottom of the hull. If you "tab in" the
keel trunk using narrow layers of glass that all stop at the same place, the
hull will flex sharply along the edge where the tabs meet the hull. That
could cause stress cracks and possible failure of the hull along the edge of
the glass tabbing.
The right way (I think) to do the job is to use many layers of cloth to tab
the trunk to the hull, each one extending slightly further outboard than the
last. The longest tab might extend along the hull bottom perhaps 12" wide,
while the shortest might extends only 2" on the hull bottom. With a
"bevelled" tab system like this, the hull flexes smoothly over the whole area
of the tabbing, distributing the force of any keeltrunk flexing or strong
impact over a large area.
I know that's the way correct way to install or repair a loose stringer, to
avoid stress cracks in the hull at the seam bewteen the stringer and the hull
itself. I think that's the way to do a keel trunk do, but, just to be sure,
I'm going to get tons of professional help from Svendsen's Boatyard on this
project. They are really good at what they do. I'm fortunate to have them
so close by me.
Fortunately, my insurance is paying for "repair" part of the project..
Allstate accepted Svendsens bid with a smile and a promise of a check
immediately. I'm going to pay for the differenc in cost between repairing
the trunk and improving it. I'm going to have Svendsen's do most of the
work, including re-epxoying the monster 400 pound keel. I'll do the
functional design specification using the type glass they recommend and
incorporating any good suggestions they have, and probably fabricate a
mahogany keel cap myself (cheaper and handsomer than having them fabricate a
new fiberglass one)
One of the beauties of working with fiberglass is that you can make any
repair just as strong as original construction. If we design the project
right, the end product will be as strong or stronger than new.
Fair winds,
Judy