swing keel concerns

[watercolors]

More thoughts

Couple more thoughts about the 3 keel stories and the Catalina keel.The MacGreger, the keel was modified so that story doesn't count but, think about the other two stories. In both stories the weight of the keel wanted the keel to keep moving even though the boat was stopped. The Merit, the bow was stronger than the keel trunk and the keel has no extra support. The Balboa, the keel swings on a cable just like the Catalina, but swings up inside the hull. I failed to tell that the damage was done to the front of the keel trunk and not the back. No one knows how tight the keel cable was!Catalina keel thoughts,Keel swings on a rod attached to the boat with 4 bolts.90 percent of the keel size and weight is to the one side of this rod.What keeps the Catalina keel from swinging like a pendulum.The Catalina keel does not hang completely vertical when down.What holds this keel at about a 20 to 30 degree angle when the cable goes slack . . . ?The Balboa damage was cause by the keel riding up over the top of the stump and when it cleared the other side came slamming down like a gigantic lever. The top part of the keel, just like a CatalinaÕs, crushed the keelÕs forward stopping mechanism. The keel stop is just a keel trunk part that allows the top of the keel to rest against, thus holding the keel to its suggested design angle. A 900 to 1000 lb. 6 foot lever against a small 2 x 12 inch fiberglass keel trunk on the Balboa! On the Catalina, I believe, is the side of the front settee seat, Ô86 and newer, the raised side that the cushion doesnÕt cover. Upon repair of this keel stop, small pieces of regular sponges were found in the fiberglass. Mr. Hess designed this area for an impact.So, if the cable would of been tighter, not allowing the keel bottom to move forward like the Merit, would there of been less damage? If the cable is tight, not allowing the keel to swing further forward and the keel is dropped like the Balboa, would the cable stop it? Would the cable snap?Hum!

 

[Bilbo]

Good points Watercolors

I think that the 550lb SK on the Catalina hits the top back of the keel trunk when down all the way. (Which in't vertical as you mention) There is a locking bolt that extends from the side to the top of the keel BUT it isn't really all that good for much from what I understand as you can winch the keel up with the bolt tight and these bolts have bent from the keel and winch. For the one boat though, Merit 22. It may be that the keel trunk for this daggerboard style was not made substantial enough. It may be that as a racing type, they were conservative with fiberglass and weight. There could be a lot of prying action going on in that situation, opening up the front if the trunk like a can opener from bottom to top. Perhaps when down, the weight needs some support from the cable. The cable should be some what taught when it's down all the way. the Catalina Direct site recommends this. AS for hitting an object like a log, I'm not sure what will happen. FOr maximum damage to occur, you'd probably have to hit something that is at a depth that would cause the keel to swing up pretty much all the way. This is near to a water depth of about 2.5ft. I'm not sure if this can happen because the leverage would probably cause the boat to come to a complete stop before the keel slid over the object. If the boat stops, the first thing that I'd do is winch up the cable to free the boat. Now, I could see the keel sliding over an object that left a water depth of 4ft. At this point the keel would beging to go down again gradually becasue of the angle of the keel bottom. So the free-fall drop might be only about 6 inches. Where the swing keel can be a problem from what I've read is if the boat heels beyond 90 deg. the keel can swing up all the way and then if the boat rights, the keel will fall down and possibly break the hull. that is if the boat didn't sink already from the 90+ degrees of heeling action. No flotation being what it means. Some don't secure the seat lockers or the companionway, a ticket for quick sinking on a windy day in high seas. I know that theis happened to one C-22 in lake Michigan. "What keeps the Catalina keel from swinging like a pendulum?"The weight of the keel below and behind the pivot pin keeps some of the weight above the point of equilibrium and astern of it being a swinging pendulum. The keel trunk and top of the keel on it is the other end of the fulcrum. "So, if the cable would have been tighter, not allowing the keel bottom to move forward like the Merit, would there of been less damage? If the cable is tight, not allowing the keel to swing further forward and the keel is dropped like the Balboa, would the cable stop it? Would the cable snap?"Also add, would the winch come off?I think that with a lighter keel on the C-22, it may have a better chance to stop it. So, the fiberglass of the keel trunk stops the 550lb Catalina keel at the down position, The cable should be kept a bit tight to further aid in the distribution of weight/strain.This from CD:"Tips to prevent failure of the keel cable:1 Always lower the keel onto the trailer while trailering.2 Apply a bit of tension after lowering to set the winch's clutch and prevent a rats nest of cable as it unwinds.3 Never allow excess slack in the cable after lowering the keel. If the cable is loose, the cable will be "waving in the breeze" as the water flows past. The constant bending will work harden the cable at the top of the fork and it will fail."Another point of concern is if the cable fails when the keel is up, the keel will swing down hard. Since this almost happened to me last year, I tend to visually inspect the cable and the linkages often looking for meathooks (Shreded cable). When mine almost failed, I think that the cable was still holding the weight at three strands on a 1/4" Type 316 stainless steel cable.I think this that the fixed keel can be a problem too in certain situations. If you hit that stump or a rock and the keel stops but the boat keeps going, going down.... If you ground out, a swing keel can be a blessing. Winch up and drive on out of there. But if you drift backwards through a weed bed, you may be diving to unclog the weeds to raise the keel and get the drag off the cable. For sailing function, I think that a fixed, bulb-type keel as Aldo mentions would be the most effective. For trailering and getting into the shallows, the swing keel or a weighted dagger board make decent sense on a 22ft boat.