Thursday, April 3, 2008

Far Out Dude!

At long last I'll start on the account of the passage. I left Port Canaveral around noon on Wednesday. The wind and waves were from the east as I motored out past the Cape Canaveral Shoals. It was a slow motor into the wind with some bridge slap onto the waves. Once past, I turned NE and set sail.

One of the things I learned on the trip was that my boat will pretty much sail itself. Until the last day, I seldom touched the helm. The boat likes a beam reach, wind pretty much perpendicular to the boat (60-100 degrees off the wind).

The boat will sail itself for hours at a time. It will wander 10-20 degrees around a compass heading, especially if the wind shifts. But it won't go into irons or tack. And I can adjust the point of sail with the rudders and sail trim.

I was never able to do this with my old boat. Of course, time aboard could be part of the reason. The old Pearson monohull I day sailed and did weekend trips. After six months aboard Split Decision, I should have some more familiarity with its performance. But I also think there is a difference between monohulls and catamarans.

I've been trying to think of some sort of physics explanation for this. I think a monohull wants to be in irons (pointed directly into the wind). That is its most stable position. To take it out of irons, some force has to act on it. A back winded jib, motor or wave. Under sail, there is a balance of forces which keep it moving forward through the wind. The wind pushes the sails, the keel keeps the boat relatively level and the rudder keeps the boat pointed.

My catamaran seems to want to sail. Its most stable position seems to be perpendicular to the wind. I think that this is because there is no keel and it doesn't heel. The force on the sails is dissipated throughout the boat in contact with the water. It's a simpler physics system than a monohull.

Anyway, my plan had been to get far enough out so that I could hove to (stick the bow into the wind and stop forward progress) to get some sleep. This turned out to be unnecessary. Unfortunately, when I awoke around midnight, the boat had decided to sail not only north, but quite far east and out into the ocean.

4 comments:

Ross said...

I think that a boats tendency toward being 'balanced' when under sail results from a complicated relationship amoung variables such as the shape of the hull, keel and rudder (longer is more stable)and how this relates to the sail plan. I've never been lucky enough to have a vessel with a helm that is as nicely balanced as yours.

I'm curious why you didn't have your autopilot engaged. ?

Rose said...

Did the head gaskets come today and do you have electricity yet?

Rose said...

Also, Fred tried to call you about half hour ago, but no go on your cell phone.

NautiG said...

Electricity on. Boatcam on. Phone on.

Rose, I ran out of minutes on my phone. Fred must have used them all up calling you when he was on the boat ;)

Ross, I'm sure you know why I didn't have my autopilot engaged: Because it's broken. I have a fix for it, but I've been procrastinating about it. I know most cruisers consider an autopilot essential. But I've never had one, so I don't know what I'm missing. I think it's lucky that the autopilot is broken. I don't think I would have discovered how well balanced the boat is, if I had one.