Anonymous wrote:

Len thanks,

and sorry for the misleading opening. I’m indeed adding a wider-than-keel itself endplate (not a ”wing” but a long one) to add the effectiveness of the shallow keel..

That makes much more sense then. The cove between the plate and the original keel should be generous and the layer count should be as well in that case. Rather than bolting the plate on, drill holes through the plate that continue the epoxy through from one side to the other. Make sure the bottom of the current keel is well "keyed" (lots of grooves). Maybe thicken the epoxy with chopped strand (for the part that goes through the holes in the plate. The FG cove along each side are like a long bolt or screw holding the plate to the keel. So it should be stronger than steel screws anyway. I wonder how other boats with an end plate were done. The Shoe String for example.

Anonymous wrote:Would it be sturdy enough if the plate was bonded with something other than drilling through the fiberglass and into the iron ballast?

Epoxy? Sikaflex? And encapsulating the plate with fiberglass (with large overlap to the keel)?

If you are encapsulating with fibreglass anyway, I would use epoxy all the way through. I would use epoxy to hold the plate on and fill any gaps between the two, as well as using epoxy as the resin in the fibreglass. Make sure that the original keel is free of paint and gel coat of course. I cannot give you a layup as that is beyond my education... however, the normal things apply: the glass threads should probably go in at least 4 directions (0, 90, 45 and 135) and the total layup should be at least as thick as the original hull but probably thicker as this is a place the boat will rest in the yard or if it bottoms.

So now the question becomes why? It seems you are not putting a wing on the bottom (plate is as wide as the keel) and the plate is not going to be used as a "scratch plate" because it will be encapsulated in FG that will fill that function. It does add some ballast but it also adds some buoyancy because it adds to the total volume of the hull. Will the added ballast and draft be worth the trouble? Will adding another sealed compartment cause trouble down the road if it leaks? What is the weight of the steel you are adding as a percentage of your current ballast? as a percentage of your current displacement? What will your ballast to displacement ratio be as compared to now? How far down will this move your centre of gravity?

Even if you already have the steel plate, the cost in time and materials to add it to the boat is considerable (add in yard rates, your time, the cost of repositioning, etc.) If you are going to re-glass the bottom of the keel anyway, maybe that is a different matter.

Len