What is our hull speed?

12 nautical miles

The wind started off light, so we motored round to the north side of the harbour, anchored and made coffee. Tim took a swim... well... not a voluntary swim, he wanted to remove the growth from the outboard motor. We had sprayed it with anti fouling, but we are still seeing growth - mainly see grass - and he rubbed this away with a soft brush.

The forecast said winds of between 12 and 17 knots (Bft 4-5) from about mid-day. So we sailed off towards Cape Pila. One thing we wanted to do was rewire the windlass control box, but I didn't really want to do that while at anchor since if anything went wrong the windlass would not work. So... we had a few hours sail and then turned for home.

On the way back the wind picked up as per forecast and we were touching 5 knots with just main and genoa. At one point Tim started the outboard to see if we could get the yacht up to hull speed. The formula is 1.34 x square root of length of waterline. The waterline of a Nicholson 39 is 30 feet, so the square root is 5.47 and multiplied by 1.34 it is 7.34, ie the maximum speed we can expect out of King Malu is 7.34 knots. 

Adding the outboard added about a knot, so we got up to about 6 knots but no faster. I think we have had about 7 knots at one stage in the past, but it was interesting to see. King Malu seems to cruise happily between 4.5 and 6 knots from what we have so far seen. But we have only been sailing her 5 months now - seems a lot longer - so still trimming the sails and experimenting. Certainly today the tell tails were flying straight and true.

When we got back we did re-wire the windlass and it all looks a lot neater now.