Keel Flats

The keel is 60 mm. thick, and sits on a flat planed into the bottom of the hull. The stem, on the other hand is only 25 mm. thick. So where it meets the keel there is a discrepancy of 35 mm. Should the keel, therefore, be tapered to 25 mm. in this vicinity, or should it meet the stem suddenly with a jump in thickness? If it is to be the latter, should the flat for the keel be stepped down to a different depth than the step for the stem, because the depth necessary to flatten out 60 mm, is considerably more than for 25.

Looking at pictures of the stem ends of traditional boats it seems inconceivable to me that there would be a step down from stem to keel, so, either there must be a taper or the stem is the same thickness as the keel. In this case, where the stem is stipulated to be 25 mm. there is going to have to be a taper. That also lessens concerns about planing too deeply into the hull near the bow end of the keel, because if it is not going to be 60 mm. thick up there, the depth of planing can be lessened.

Of course, being an epoxy ply construction, the boat could dispense with its stem altogether, as shown in this electric slipper launch, as could any hull made of GRP. The function of the stem in these vessels can only to be to protect a little against slight knocks. There is no rabbet and no planking to fit into it after all.

Electric slipper Sun Penny without any appreciable stem.

Traditionally built Jessica with a sizeable stem.

In the end the solution was the taper of the keel, combined with a little widening of the stem, as shown below.

Back to other Problems