Download it here. The app is searchable in the Google Play Store under Sailboat Owners.
Sorry iPhone/iPad users, we are still waiting on Apple. :(Click the X in the upper right corner to make this go away
Dave is right on with his answer. I use the topping lift to adjust the boom height to clear the bimini, so that the boom doesnt chafe the top of the bimini. It also needs to be adjusted so that there is adequate tension on mainsail leech, when the sail is unfurled. Once it has been set, I usuallly don't mess with it and use the vang accordingly.Sometime there might be an occasion to peak the boom up to get it out of the way.
Based on your statement I am left to guess that you have a "Rigid Boom Vang". The boom is supported (suspended in the air) by a spring and piston inside the Rigid Vang.Frankly the boom vang hardly moves.
It makes sense in the first two lines to a point. Your third is in error, methinks. /// On all 3 of the boats I've owned, I added a boom bail bolted through the aft boom-end fitting. Both the topping and mainsheet can attatch to the same point on the boom and not put opposing bending tension on the boom. /// They are sayng do not suspend the boom by the 2 ends, then pull down or up anywhere along the boom in between. That would be like pulling the string on a bow/arrow and curving the bow more away from being straght.For what it’s worth, US Spars says this about not using the vang to support the boom at rest - “When boat is at rest at its berth, attach the boom lift and release pressure from the vang.”
Earlier in the same owner’s manual they also say - “Do not tighten the boom topping lift by tightening the main sheet or you will risk damaging the boom outboard end, the rigid vang or rigid vang bracket on the mast.” //// So I guess when you’re not sailing you’re supposed to just let the boom hang and swing as the boat rolls. I’m not a big fan of that approach.