Yacht Keels

[Ian Rob]

I have been building an Infanta design 'cousin' to Sopranino and Trekka [all designed by Jack Laurent Giles] but instead of the fixed fin keels of these 2 my design has a fixed hollow fin with a swing down centre-board.
The dimensions of Infanta are - loa: 20'1" lwl:17'6" beam: 6'3" draft 2'6" & 5'6" with the plate down, ballast: 1000lbs in the fin.
I have built the fin of sheet steel and have developed the fin in such a way that I can detatch it [with a bit of bother] to inspect it if necasary.
However I am becoming concerned about the on-going maintenance of a centre board with marine growth etc getting into the C/B slot and wondered if there is any alternative out there in keel development that gives you shallow draft with windward efficiency - wings on the keel? etc ??

[Skippy]

You could try twin keels.

[mattotoole]

I don't know how they compare to modern winged designs, but Scheel keels can perform pretty well for shoal draft applications.

[Skippy]

Looks like a well-integrated bulb keel with the bulb shape acting as an end cap.

[tspeer]

Unfortunately the physics of keels says their drag due to lift is inversely proportional to draft-squared. So while you can perhaps make some minor improvements, shallow draft is going to impact windward ability.

[FAST FRED]

The great Herrishof figured that a 7-1 ratio between LWL and draft would work in all cruisers going to windward.

So a 28 ft waterline would have about 4 ft of draft.

No in calm water she wont point as high as a "race" boat sailing on the Keel , just dragging the hull along, but in the ocean where some HP is required to advance into seas , the combo of hull and 1/7 draft keel works just fine.
And is BETTER in light airs with less wetted surface than the lead mine.

Going around the buoys or the world , ???

FAST FRED