American designer Bob Perry on seaworthiness

[geem]

Sorry but I don’t agree. By physics a boat going upwind in 20 knots TWS under full sail must be massively under canvassed for sailing in 5 knots TWS.
Also on a properly set up boat putting in first reef upwind should be less than 2 minutes work without leaving the cockpit, and less effort than tacking most genoas. Shaking out may take a few seconds longer. Reefing is just like shifting gear, not a big deal.
PS. We also have a substantial lead keel, but a big mast above it.

Yep, us to. 41% ballast ratio and generous sail area. 20kts over the deck to windward is are limit of our 130% genoa. We would already have a reef in the main. At 20kts over the deck up wind we change down to the working jib as well. We would point higher and not lose any speed?

 

[38mess]

I haven't had time to listen yet but I remember a rule of thumb for a cruising boat from an American designer, possibly Chuck Paine, that a cruising yacht should be able to sail to windward under full sail in twenty knots of wind at no more than 20 degrees of heel. This is quite a tall order for a small boat and mine just about makes it.

Yes the 20/20 rule of thumb, a nic 32 springs to mind

 

[Laminar Flow]

At angles of heel up to 20 degr. form stability and displacement play a much greater roll than ballast ratio or CoG.

Meteorologically speaking, wind speeds are given at a height of 33' (10m) over ground. At the height of CE of the sail it is likely to be 10% less, due to gradient.

20kts of wind is near the top of a F5; wind pressure would be about 2 lbs/sqr ft.

At 20degr heel the exposed area of the sail would be reduced by the cos value of the angle, which is about 10%; at 30 degr by about 15%.

Calculation of wind pressure on rigs is done with the unrealistic assumption that the sails are hauled flat amidships.

When I redesigned the rig on our tubby ketch, I used the above data to pre-determine that I would be able to carry a much increased SA to about 22kts wind speed before having to reef.
This has subsequently proven to be the case. In practical terms in 18 to 20 kts we heel about 10 degr on a reach (90 degr); this increases to 20-25 degr close hauled. Due to her hull shape at the stern this is about as far over as is useful. We have a SA/Displ. ratio of close to 18.

What is not discussed much, is that at the top of a F5 and in open water, wave height is likely to be about 2m. This will impede a small boat's progress considerably and cause a significant reduction in VMG.