Lift/Drag/Stall of hull/keel/rudder combo

[Jamie Kennedy 108]

I’m curious about best ways to construct a lift/drag curve of a sailboat at high angles of attack, like when “forereaching” in strong winds and waves. Any good resources out there comparing a folkboat type hull/keel/rudder to a soling type hull/keel/rudder?

I’m particularly interested in strong gale conditions where you can no longer sail close hauled but still want to hold your own comfortably. By sailing at high angles of attack the hull can still be pointing 40-45 degrees or so to the wind and waves even though the boat is making progress say 70-80 degrees off the wind and waves.

This has the advantage of:
1. Less windage on hull.
2. Less vulnerable to breaking seas.
3. Sails can still be at low camber and low angle of attack without having to have boom and jib leads outboard.

For a folkboat type hull the stall point at high angles of leeway is not so dramatic and its behaviour in such conditions is well understood. For a sailboat like a Soling or Yngling you will be definitely be beyond the stall point of the keel, but I’m curious what hydrodynamic lift remains to be worked with. The spade rudder can still be set to match the angle of leeway plus or minus. What lift does the hull provide? Where is the centre of lateral effort. Can you sail the boat comfortably through waves in this “controlled stall” type scenario like fighter planes performing at air shows?

 

[philSweet]

Can you sail the boat comfortably through waves in this “controlled stall” type scenario like fighter planes performing at air shows?

Nope.

 

[gonzo]

You can heave to.

 

[Jamie Kennedy 108]

I’m going to play around with it this summer after I finally get the boat back in the water. I’ll stick with the river for the most part. The Kennebecasis Bay can get a fairly decent fetch in an SSW so fairly decent waves off Ministers Face and again down towards the Gondola Point Ferry. Much safer and warmer than the Bay of Fundy.

The Yngling does well upwind and broad reaching and running, but is known to be prone to broaching on a beam reach at least with the chute up. Much of that is because it was designed for the old Olympic Course, triangle WLW.

I was looking at my boat again today, parked on the side of my house. The Jib lead tracks are quite far inboard and opposite to the Soling you sail it with a flatter main and fuller jib. There is a tweeker to pull the sheet forward and outboard, and back at the shrouds there is a clip for the spinnaker guy that might also be used somehow. Point I’m trying to get to is in extreme overpowered and shorthanded scenario I can drop the main and let the boat heal more than usual to compensate for the lee helm caused by sailing with just the jib. If waves are too big to keep going to windward I can crack off some and still keep the jib flat but twisted by having a more outboard jib lead. I think in this mode it would be considered fore reaching.

One downside of jib only is I probably won’t be able to heave to. I’ll definitely practice heaving to with main and jib.

Boat was used for racing by someone back in the day as it came with 4 mainsails and 4 jibs, all in fairly decent shape. I will take one of the older but heavier mainsails and add some reefing points and use it as my cruising sail. I like the idea of reefing the main in such a way that it also raises the boom as well. With the main reefed in this way I should be able to fore reach with a more balanced helm and also be able to heave to.

I might also make a storm jib out of one of the jibs. Not so much a storm jib as a short-handed cruising jib. Still fairly big but with a raised clew. It’s not much of a foredeck to play on sailing solo, so it would be nice to have the jib a little smaller but not so small that I won’t want to use it until it’s too rough to choose it.

cheers