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@stricklandmma. It's great to have you join us.
Your question is a very common question for new sailors. In general, it is pretty hard to sink a sailboat and flipping one over is not easy, even for a dinghy, that is a small, unbalasted one or two person boat. A larger boat, such as a McGregor 26 will usually be able to lay right over on her side and still come back up if the sail isn't under water.
A strong wind will not make it capsize. A strong wind will round up the boat, it will spill the wind and straighten up.
Joe is referring to turning into the wind when he says "round up" And, "spill the wind" means that, as the sail leans over more and more, the wind doesn't push as hard on the sail or pull on the other side. Usually, once the angle gets too low, the hull interrupts the airflow and lift is harder to maintain. The angle of the wind on the sail changes from coming perpendicular to the mast across the sail to an angle more from below and the airfoil shape becomes less effective. Air essentially "spills" out of the sail's concave profile leaving your boat able to swing back up.
A keel boat will 'round up' because as she heels, her keel swings to windward (towards the side the wind is coming from) and cause an asymmetrical drag on the boat. The curve of the hull digging into the water on the leeward side (the side away from the wind) and the shift in the driving force of the sail to the extreme outboard leeward side combine to work the boat towards the wind around the dragging keel.
Wave action can interfere or help at random times and breaking waves over the boat are dangerous, but those are very large and you are unlikely to see such waves as a new sailor who stays close to the harbor while they are learning.
While sailing, adjust the sheet or the traveller (I don't know if the Mac has a traveller) by letting the sails out just until you see that beautiful tight wing shaped curve in the sail "luff" a tiny amount. "Luffing" means the sail next to the mast looses that smooth airflow across it and starts to curve the wrong way. After you see the sail just begin to luff, tighten the sail back in so it just loses its luff and is a nice tight wing shape again. This insures you haven't pulled the sail in too tight, using the wind more to heel than to drive the boat.
Also, don't fight the tiller. If you are pulling hard on the tiller to keep the boat from rounding up, you may be sailing to close to the wind, fall off a little and adjust the sails out as described above. Sailing too close to the wind (towards the wind) and having to fight the tiller can cause the boat to slow down as the rudder drags at an angle through the water and that angle will also encourage the keel to surf towards the surface (more heeling).
8+ knots is an impressive speed in any sailboat. It must have been a very fun day. Sorry I wasn't there with you.
Exciting times ahead, keep us posted.
-Will