toby:
I flipped my DS last year, using a hoist and some slings (ratchet straps). Some tips, for what they're worth:
-I ran a line around the middle of the boat, as close to the back lip of the cuddy as I could get. The line went thru a single block that I attached to the chain hoist, in a continuous loop.
-Flipping the boat was "simple" ..use the hoist to get her off the trailer, pull the trailer out from underneath, flip it in the air , and then set her down on haybales. I did it with one very strong helper to flip, by my (weak) self to unflip once I knew how easy it was.
-Obviously, I had to preplan where I put the knot in the line, so it wouldn't jam in the block as I rolled the boat. Also, I had to retie the loop a few times, to account for stretch in the line. No way to do it except trial and error. Also - at least on my trailer - the midpoint of the boat is sitting on the trailer bunkers, so I had to have a friend lift the oat a bit on each side, so I could get the line under. No big deal, although I feared for my fingers! IN retrospect, I could have down this with my ratchet straps.
-You need a sling forward and aft on the boat to keep it from tipping and then slipping out of the loop. As I lifted then lowered the boat, I tightened and loosed the ratchets accordingly. But they're just a safety measure, the action is in the loop. You could do the same thing with two helpful friends, one at each end of boat. Would make flipping easier too!
-Flipping it is not as hard as it looks, the trick is to keep it even on it's axis (first try, she started moving diagonally in the loop, no good) and on an even keel. The weight is really not so bad, all of it is held by the slings, you are just overcoming rotational inertia. You can do it alone, lifting at the midpoint of the gunwale. I'd guesstimate that I was exerting about 100-150lbs of force as I flipped her, remember to bend your knees, spread your feet, straighten your back, and lift from your quads - just like lifting any other heavy object. With friends, put them at the bow and stern and have them flip, just like flipping a mattress.
-The "crux" is when the boat is halfway over - you need to run over to the other side while she's balanced on her side and let her down! Use the fore and aft straps as "brakes" - loose enough that the boat will turn but tight enough that there is some friction. This photo is from when I unflipped the boat, you can see my loop and pulley, as well as how the straps are both holding and "braking" the boat. I was turning her from star to port, clockwise, so I'm not actually at the crucial halfway point yet. Just testing to make sure my slings were properly holding her.
- Crunchtime
- IMG_20190323_185551.jpg (171.15 KiB) Viewed 4467 times
-Again, friends are very helpful, but you can do this alone if you have to.
-Suggestion, if you can't work on her right under the sling and have to move her somewhere else to work - put two or three 2x4's sideways across the bunkers of your trailer and set your boat down on that. Upside down on the trailer. Then move her off to your workspace.
-Lastly, be careful and move slowly. The DS is a 550-lb unwieldy lump, when you're flipping it in the air like this bad things can happen quickly. You need to pre-plan each move, think of what can go wrong and prevent it. Most important part is to keep everything lined up, including how you use your body. Fingers and feet can get crushed, your back can get wrenched. Slow and steady is the way to go, if it feels wrong then STOP! If you are used to heavy physical work (construction, etc), then this is a cinch. Otherwise, especially if you are a desk jockey like me, then be aware of your limitations. Either way, use your brains, not your back! Sorry of belaboring the obvious, but be safe. And wear boots, use gloves.
Good luck and I'm happy to answer any questions. Somebody actually did all this using an engine chain hoist (like the kind from Harbor Freight aka Northern Tools). As long as the arm is rated for 1000lbs or so (plenty of safety margin), why not?
Tom