We have sailed our C-22 without a boom vang for long time, and my son sailed on another C-22 this past summer and recommended that we add one soon. I have several questions: 1. What should the mechanical advantage be for a C-22 boom vang? I'm guessing 4? 2. What line diameter should be used? I'm guessing 1/4 inch. Does the line lead back to the cockpit? 3. How far up from the base of the mast, and how far back on the boom does it go? It suppose that the angles should be about 45 degrees. 4. What does the fitting that goes onto the mast at the bottom of the boom vang look like? 5. Does the boom vang interfere with the pop top at all? If so, is it removed when not being used, or is there another place that the bottom shackle is snapped, when the pop-top is up? I know that these questions must sound very basic, but I usually used a preventer when we were running, especially if we were cruising. I added a bail to the boom, and then ran a line through one of the jib sheet turning blocks and ran it back to the jib sheet winch that wasn't being used, and pulled the boom down that way. This also prevented accidental jibes. I'm not really intrested in spending the money for a boom-kicker. I have never had any topping lift problems. I simply have a very small line, about 1/8 inch diameter, that goes from the mast head (where the back stay attaches), to the fairlead on the end of the boom, and then onto a little cleat that I have mounted about a foot from the end of the boom. This has work fine for me. (I, of course, use the shackle on the backstay when the sail is furled on the boom). Thanks, Aldo
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Boom Vang questions/answers
1. 3:1 for cruising, 4:1 for racing. 2. 5/16" with cam cleats vs. jam or v cleats. You do not need to lead to cockpit, you can put cleat end on boom and cleat it standing in the companionway. 3. As near to the base as possible. If you have a ring at the base of the mast aft, use it. If not, a deck ring screwed into the base of the mast slot will work. Be careful here because if you step the mast without a hold-up device on the transom, the ring will punch through the deck. There is a folding padeye version that works well here just remember to tape it flat before you lower the mast. 45 degrees approx. is fine, don't get too hung up on this part. Look at the Catalina 22 national sailing site and look in technical section for further placement advice. 4. Use a boom bail or a hound fitting, make sure that your fitting on the boom vang fit through the attachment whatever it is you choose. Use machine screws or through bolt. #10 is fine. 5. The poptop should not be up in the raised position when sailing. The mast can flex and the little plastic nut holding it onto the mast can split or fail. Either way the force of a falling pop-top is significant and possibly very dangerous. (think fingers resting on cabin top or small child sitting with legs hanging into the cabin area). Last but not least. The line in the setup needs to be 30'-40' depending on 3:1 or 4:1, this will allow you to remove from mast base and place on lifeline base for a quick preventer for those nice long cruising downwind legs. Good Luck
1. 3:1 for cruising, 4:1 for racing. 2. 5/16" with cam cleats vs. jam or v cleats. You do not need to lead to cockpit, you can put cleat end on boom and cleat it standing in the companionway. 3. As near to the base as possible. If you have a ring at the base of the mast aft, use it. If not, a deck ring screwed into the base of the mast slot will work. Be careful here because if you step the mast without a hold-up device on the transom, the ring will punch through the deck. There is a folding padeye version that works well here just remember to tape it flat before you lower the mast. 45 degrees approx. is fine, don't get too hung up on this part. Look at the Catalina 22 national sailing site and look in technical section for further placement advice. 4. Use a boom bail or a hound fitting, make sure that your fitting on the boom vang fit through the attachment whatever it is you choose. Use machine screws or through bolt. #10 is fine. 5. The poptop should not be up in the raised position when sailing. The mast can flex and the little plastic nut holding it onto the mast can split or fail. Either way the force of a falling pop-top is significant and possibly very dangerous. (think fingers resting on cabin top or small child sitting with legs hanging into the cabin area). Last but not least. The line in the setup needs to be 30'-40' depending on 3:1 or 4:1, this will allow you to remove from mast base and place on lifeline base for a quick preventer for those nice long cruising downwind legs. Good Luck
Boom Vang
Hi Aldo! Check my entry in the "small boats" forum for pictures of the boom vang that you can build yourself for under $50. I think there are also pictures of the bale that is used on the mast. A similar one is on the boom. You do want a 4:1 and the vang pictured has that. It uses 1/4" line. You also want the vang mounted at 45 degrees and with the pull line at the lower end so you can pull toward the stern to tighten it. Do your measuring and mounting with the pop top up so there is no interference with it. Ideally, the bales would be about 2 ft out on the boom and the same distance down on the mast from the goose neck when the boom is in position. I haven't mounted one yet on the Catalina and it may not be possible to get the 2 ft spacings with the pop top up. The vang comes into play with a little heaver air so you may be able to do with the pop top closed during those times that you need the vang. Your boom topping lift is the same as what I am installing presently. Works great on my precision and will also on the Catalina. I have a quick release clamp on the lower end and when not in use, I hook it to a cleat on the mast. I can send photos if you would like. Bob
Hi Aldo! Check my entry in the "small boats" forum for pictures of the boom vang that you can build yourself for under $50. I think there are also pictures of the bale that is used on the mast. A similar one is on the boom. You do want a 4:1 and the vang pictured has that. It uses 1/4" line. You also want the vang mounted at 45 degrees and with the pull line at the lower end so you can pull toward the stern to tighten it. Do your measuring and mounting with the pop top up so there is no interference with it. Ideally, the bales would be about 2 ft out on the boom and the same distance down on the mast from the goose neck when the boom is in position. I haven't mounted one yet on the Catalina and it may not be possible to get the 2 ft spacings with the pop top up. The vang comes into play with a little heaver air so you may be able to do with the pop top closed during those times that you need the vang. Your boom topping lift is the same as what I am installing presently. Works great on my precision and will also on the Catalina. I have a quick release clamp on the lower end and when not in use, I hook it to a cleat on the mast. I can send photos if you would like. Bob
Differing Opinion
Aldo: I would use bales on both mast and boom through-bolted with a compression tube. You do not want to bend the spars when tightening the bolts; this will greatly weaken them. Also, the farther aft on the boom you place the bale, the more mechanical advantage you will have. Mine is closer to 60 degrees. Check with a rigger or look it up in a book if there is any doubt. You can buy a good boom vang from Garhauer Marine for $70-$80. 3-1 will be fine if you place the boom bale in the right place. Good Luck. Mike.
Aldo: I would use bales on both mast and boom through-bolted with a compression tube. You do not want to bend the spars when tightening the bolts; this will greatly weaken them. Also, the farther aft on the boom you place the bale, the more mechanical advantage you will have. Mine is closer to 60 degrees. Check with a rigger or look it up in a book if there is any doubt. You can buy a good boom vang from Garhauer Marine for $70-$80. 3-1 will be fine if you place the boom bale in the right place. Good Luck. Mike.
Boom Vang leverage
Mike, I respectfully disagree with you on the leverage. The vang pulls downward and forward at an angle. This force can be broken down into two component forces, one verticle downward and one horizontal toward the mast. The further out you place the bail on the boom, the longer you are making that (horizontal)component as compared to the verticle component. The verticle component is the one that is tending to pull the boom down and tighten the sail. The horizontal component is wasted effort because it is trying to compress the boom toward the mast. Your mechanical advantage is actually increased by placing the attachment point on the boom closer to the mast end of the boom. The 45 degree angle gets it out far enough to give leverage and still retains your mechanical advantage. As for attaching the bails, I used 4 No. 10 stainless sheet metal screws on each one and there is no compression on the boom or mast. These screws are holding in the shear mode and not stressing either the boom or mast. If you choose to attach some type of loop on the deck just aft of the mast attachment, then those fastenings would be in tension and pulling against deck surface. Through bolts on the mast and boom would be nice, but I can't see how you would get inside to place the compression tube.
Mike, I respectfully disagree with you on the leverage. The vang pulls downward and forward at an angle. This force can be broken down into two component forces, one verticle downward and one horizontal toward the mast. The further out you place the bail on the boom, the longer you are making that (horizontal)component as compared to the verticle component. The verticle component is the one that is tending to pull the boom down and tighten the sail. The horizontal component is wasted effort because it is trying to compress the boom toward the mast. Your mechanical advantage is actually increased by placing the attachment point on the boom closer to the mast end of the boom. The 45 degree angle gets it out far enough to give leverage and still retains your mechanical advantage. As for attaching the bails, I used 4 No. 10 stainless sheet metal screws on each one and there is no compression on the boom or mast. These screws are holding in the shear mode and not stressing either the boom or mast. If you choose to attach some type of loop on the deck just aft of the mast attachment, then those fastenings would be in tension and pulling against deck surface. Through bolts on the mast and boom would be nice, but I can't see how you would get inside to place the compression tube.
Bob F:
What you say about leverage is simply not true. The farther out you attach the vang, the lower the load is. Try it out with a similar condition like a tree branch. It takes more force to pull down the branch the closer you are to the tree. Its basic physics. I can point you to a set of equations if you like. As far as the connecting the hardware, what I suggested is, from what I understand, standard in the rigging industry and is the correct method. You drill the hole to fit the compression tube; cut the tubing so that the ends of the tube are flush with the boom; insert the bolt in the tube and (with the bale in place) place the assembly through both of the holes in the boom and bolt into place. I would also install some plastic washers between the bale and boom to eliminate damage to the boom. Your method has problems in that the dis-similar metals will cause corrosion in the aluminum boom and eventually the hole will become bigger and the screw will come loose. Also you are relying solely on the strength of the screw. There is a lot of load on the boom vang. MJ
What you say about leverage is simply not true. The farther out you attach the vang, the lower the load is. Try it out with a similar condition like a tree branch. It takes more force to pull down the branch the closer you are to the tree. Its basic physics. I can point you to a set of equations if you like. As far as the connecting the hardware, what I suggested is, from what I understand, standard in the rigging industry and is the correct method. You drill the hole to fit the compression tube; cut the tubing so that the ends of the tube are flush with the boom; insert the bolt in the tube and (with the bale in place) place the assembly through both of the holes in the boom and bolt into place. I would also install some plastic washers between the bale and boom to eliminate damage to the boom. Your method has problems in that the dis-similar metals will cause corrosion in the aluminum boom and eventually the hole will become bigger and the screw will come loose. Also you are relying solely on the strength of the screw. There is a lot of load on the boom vang. MJ
Boom Vang calculations
M.J. You are right! There is more to the calculations than just the vector diagram portion. You have to introduce the torque portion which I was not doing. Moving the attachment point on the boom further out will give more leverage. Bob
M.J. You are right! There is more to the calculations than just the vector diagram portion. You have to introduce the torque portion which I was not doing. Moving the attachment point on the boom further out will give more leverage. Bob
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