how do I crane launch a 25 Mac

[augustasail]

I have a 1984 Mac 25 at Charleston Yacht Club. Everyone uses the crane to launch the J 24 boats. Has anyone every used straps to launch a Mac.. any info would be appreciated.

[kmclemore]

I don't know of anyone specifically using straps, but there's certainly nothing about the Mac 25 that would prevent it. Most folks just use a ramp and let 'em slide off the trailer though - it's loads cheaper!

[fishheadbarandgrill]

You mean you can't get the Mac to float in the pluff mud.... Have you tried the ramp at the CYC... as you know it only has water at high tide which is why I had the Mac group launch at Remley Point for the Holy City Mac Roundup in October. We did have on of the folks with an launch and recover at the ramp there at the CYC... at high tide of course.

Bob

[augustasail]

Thanks Bob, trying to keep truck and trailer out of salt water with the boat ramp. I have had the boat there three months working on it. Its ready to splash. Do you know anyone that could give some direction? How often do the mac guys get together? I would like to join.

[THE CUSCUS]

Just make sure the straps are fore and aft of the keel.

[Tomfoolery]

Assuming you're using two slings (which you should be), the hoist line needs to be directly over the center of gravity of the boat, or it'll hang crooked until it is over the CG. Looking at it on the trailer, assuming you have somewhere near normal tongue weight, the CG of the boat will be a foot or two forward of the axle, which will give you an idea of how to space the slings.

The one-designs I see launched with a free-standing jib crane have a lifting eye somewhere in the cockpit, so no slings are needed, and the hoist line is always correctly placed for level lifting. Doesn't mean you can't do it with your boat, but you might need to experiment a little to get it to hang level.

[fishheadbarandgrill]

Augustasail,
PM me with your phone number and I'll give you shout on sailing in Charleston and other Mac events I usually participate in up in NC. Why don't you join the sail up in Wilmington mid-June? Here's the post. http://www.macgregorsailors.com/forum/v ... =4&t=21904

Bob

[augustasail]

yes two four inch slings . all going to the center of gravity point... would this put too much pressure on the sides. i don't have a spreader bar. I am sure its been done.. hope to find someone with exp.

[Catigale]

Try to avoid this

http://www.youtube.com/watch?v=JX9AvH-_wS0

[Boblee]

You shouldn't have any trouble I lifted our off the trailer a couple of weeks ago and sat it on the ground and will be putting it back on the trailer tomorrow so will try and take a picture but only used two snatch straps hooked up to an endless chain.

[Boblee]

G'day Augusta sail
Sorry couldn't remember which topic this was on but got your email (no PM yet) and went looking I did post a picture on the Aust section under " new trailer just about finished" http://macgregorsailors.com/forum/viewt ... 19&t=22006
If you want more let me know but we will probably be out of internet after next Wed so let me know asap, the straps in the picture are just snatch straps which have a bit of flex and the front one is a bit longer even doubled but at that position around the staunchions it was fairly stable even with me on top working the endless chain and then going off out the stern a couple of times to line it up but it did go a bit sideways when I put it back on the trailer so hopefully it will right itself on the road.

[augustasail]

Thanks but I could not open the link. Trying to crane lift at the dock. Single point of center of gravity?

[Tomfoolery]

Trying to crane lift at the dock. Single point of center of gravity?

I'm not sure what you're saying. The center of gravity (center of mass, really ) IS a single point, fore-aft, port-starboard, up-down. The crane hoist line will be directly over that CG no matter how you sling it, the difference being, if you sling it way off, the boat will rotate until the CG is under the hoist line, and if it's badly off, it can slide right out of the slings.

Unless you have a single eye in the middle of the boat that's right over, and higher than, the CG (like the one-designs near my slip, which are made for that), you need to use two slings, spaced about equally in front of and behind the CG. Test lift only a little, and if it's heavy on one end or the other, move the slings until it hangs level. When fully supported by the crane's hoist line, with no other outside influence (wind, you pushing), the CG will ALWAYS be directly under that hoist line, no matter what contortions the boat has to do to make it that way. What you don't want it the boat doing contortions to make it so - you want it hanging nice and level, with (hopefully) roughly equal loading on the two slings.

Do NOT flare the slings so far forward and aft such that they're likely to slip towards each other - if one slips, the boat can tilt, possibly causing the boat to teeter on the one sling, and slip right out. Plenty of videos on youtube of this happening.

Edit: I should add that this is different from a Travel lift in that the TL uses 2 (or 4) independent winches, so the fore and aft slings are independently controlled, and can have different loading on them but still hold the boat level. They can also slide those slings fore and aft on the pipes to set them in the desired locations on the hull. Lifting with a single line, without a spreader frame, is a much different animal. Be careful.