A liitle Feedback with respect to the MAC Bump

[Paul S]

I did a Google on "Proper Lubrication" and came up with Lifestyle Condoms as the second entry .......

Glenn

Maybe good enough for the small vbunk on the M trailer.. but the mid and rear bunk boards may need Magnums

[March]

My personal advice--don't do it

[Russ]

Wow!!! What's the story behind that?

[March]

When pulling out of the water, I had cranked the boat all the way to the plastic roller. The boat settled back, the band stretched, leaving about 4-5 inches between the nose of the boat and the roller. I tried the MacBump in the parking lot: driving carefully and slamming the brakes. First time, nothing happened. Second time, I drove a little faster (but not too fast--I was still in the parking lot) and slammed again. The boat slid all the way forward, dislodging the vertical post, slammed into the end of the vehicle denting it badly and settled with the nose off the trailer.

It was a nightmare: a charitable soul pulled the boat back in place with a rope around the engine and a sturdy truck--but the base of the trailer was twisted out of shape. . had to find a welder to weld back the post in place (it was aluminum). Towing insurance would not help--the trailer and boat were too long and nobody wanted to assume responsibility. The trailer was brand new: the company manufacturing it in Florida refused to touch it, even though the welder insisted that the original welding was faulty. Be it as we may--we drove back from Florida to Iowa with a twisted trailer, at 40 m/h. I had to buy the longitudinal beams and have someone bring them from Florida, I changed them myself, reinforced the post, and now the trailer is better than it had ever been before.

The other lesson is--forget about the MacBump. Now we take an extra 10 minutes, take the boat out of the water, empty the ballast tank, relaunch it, crank it up again and repeat. The boat sits well on the trailer

PS--as noted on a different tread, the problem is the geometry between the front roller and the band with the hook: once the boat is out of the water and it settles on the trailer, everything changes, no matter what. The MacBump maybe a quick-and-dirty solution, but it's like playing Russian Roulette.

Thank you, but no, thank you for me

[Russ]

Wow! Just .......Wow.

[Jimmyt]

My personal advice--don't do it

Yikes! Sorry you had that happen. Sounds like you recovered well, though.

Thanks for posting this. Never tried the Mac bump for exactly this reason. Once you get enough force to break the static friction, and sliding begins, you've got a lot of mass in motion that something has to stop. I wondered how long it would be before someone had this happen. I absolutely agree with your Russian roulette comment.

If I need to get it close to the v-block, I put on the stern strap, just snug, and back it (boat strapped to trailer) into the water. This will keep the geometry closer to correct; and get the boat closer to the v-block after grinding the winch. Someone else posted this procedure awhile back and I thought it was worth a try. Best to do this on a day when the ramp is not busy though...

Glad it wasn't any worse (although, I'm sure it was bad enough).

[pitchpolehobie]

Sorry that happened thanks for sharing. I think Im done with the bump as well. I believe a more practical solution is to put another strap over the bow thru the pulpit down around the frame of the trailer. I always backup my winch with a double eye dyneema towline rated for like 20k lbs. Even with refloating my boat I havent had good luck getting it back seated in the front of the trailer, Ive suspected due to the steep incline of the ramps Ive used to pull from water.

At the start of summer I did an aggressive Mac bump on gravel and blew my front brake line. I had to rent a truck for the trip I was about to take. An 800$ repair... Done w the macbump.

[Piddle and Futz]

Just a quick follow up.

After replacing my bunks (wood was rotten, so I rebuilt them with PT 2x4s, bunk carpet from West Marine, and stainless steel staples and bolts) I sprayed on Liquid Rollers and was able to do my bump at just ~5 mph last weekend. Don't know how often we will need to spray, but delighted with that initial result. Feels much safer.

https://www.crcindustries.com/products/ ... wt-oz.html

Although, I suppose, theoretically, that making the bunks slippery would also allow the boat to slide off more easily. Happy to have a new winch, safety cable, and a big strap across the top.

[kingtoros]

Your story is tragic and I am super glad nobody got hurt and only some equipment damage, but you are still afloat.

The other lesson is--forget about the MacBump. Now we take an extra 10 minutes, take the boat out of the water, empty the ballast tank, relaunch it, crank it up again and repeat. The boat sits well on the trailer

I respectfully disagree, because I think this is an edge case, an exception, and not the rule. The Mac bump, though so coined for our boats, is one I have done with every sailboat I have owned. Torquing down on the winch will simply tear the bow eye out of the boat, fiberglass will weaken and become brittle over time.

I agree with caution, and exploring alternative methods, but sometimes the pitch of the ramp means I can barely pull out with all that weight going on a steep incline held by one rope and friction...