EXPLAIN PLEASE - Mac Bump (trailer)

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rick retiree
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EXPLAIN PLEASE - Mac Bump (trailer)

Post by rick retiree » Tue Mar 28, 2006 12:34 am

Help' Can you good folks explain to me what is the "Mac Bump" I know its not a new dance step. And does it have to do with no matter how tight i winch her up onto the trailer the darn thing slides back 3 to 4 inches even with no ballast in her, ??????? Glad we're back on line. Thanks

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ALX357
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Post by ALX357 » Tue Mar 28, 2006 1:29 am

The MacBump is necessary to seat the Mac into the nose stop after on level ground.
When afloat, the boat is at a different angle to the trailer and no matter how tight the winch and nose against the stop, after the trailer is pulled out of the water, and the boat settles, the nose will move aft. Just a matter of geometry.
No problem. While afloat over the trailer, just winch it up on to the trailer stop until it contacts it, and pull the boat out. After it is on the level, away from the ramp, it will be aft a bit. IT IS BEST TO NOT WINCH IT TIGHTER, at this point, BUT LET A BIT OF SLACK INTO THE WINCH STRAP OR LINE . While the runners on the trailer are still wet, and after everything is stowed to keep the contents from sliding forward,
then drive forward SLOWLY until you are going about 10 miles an hour, on level ground, then put on the brakes a bit firmly ( but you don't need a panic stop or skidding tires ) - to get the boat to slide forward on the trailer - until you hear and feel a BUMP and the boat has moved into the nose stop. Then winch it tight.
IF you winch the boat tight before the bump, trying to pull it forward, INSTEAD it just pulls the bow down tight onto the nose roller, and makes it much harder to get the boat to slide and bump. This is critical, a real mistake that everyone seems to make until they get the method. Any complaints about how hard it is to accomplish the bump are caused by tight winching and the increased friction between the bow and the trailer.
You can't pull the boat forward with the winch, it just pulls the nose down. Leave it loose, and with the BUMP procedure, the boat readily slides forward into the stop. Then of course, winch it tight.

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Ric K
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Post by Ric K » Tue Mar 28, 2006 1:40 am

Hi Rick:
I have 2 Macs, an '88 26 D and an '02 26 X. I'll crank them up as tight as I can with the winch and they still " slide" back a few inches, I think it is the attitude of the boat when it is floating, it does not allow you to crank it at the proper angle. I dont fight it anymore, I just I just drive forward at about 5mph, hit the brakes gently, and the boat slides forward into position, I then crank up the boat.
I hope this helps! :D

Ric K

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Sloop John B
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Post by Sloop John B » Tue Mar 28, 2006 8:34 am

Even with a good solid bump and winching, my nose is a couple inches back by the time I arrive home. I'll try ALX's method of inducing a little slack before the bump.

LOUIS B HOLUB
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Post by LOUIS B HOLUB » Tue Mar 28, 2006 9:07 am

My 26-X slides aft as described by SloopJohn, also.
Thanks to ALX, I think I've found the solution too. It's interesting how little "tips" in sailing can help so much.
:macx:

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Idle Time
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Post by Idle Time » Tue Mar 28, 2006 9:37 am

I was making the mistake of winching tight as soon as I got to the top of the ramp. Then the "bump" didnt seem to move it much..but I would get out and take up the slack and try again.

The solution given is so simple my little mind didnt even think of it until I went out and looked at the angle of the line from the winch ....cant wait to give it a try with a bit of slack first. Thanks for the tip.

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jsserene
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Post by jsserene » Tue Mar 28, 2006 10:06 am

Be careful when you do the mac bump with the strap loose. I stopped too hard and slightly bent my ladder forward. Of course no bottom paint helps it slide easier. :o

Jeff

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Divecoz
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So Far I dont find this a problem

Post by Divecoz » Tue Mar 28, 2006 10:22 am

So Far I don't find this a problem.
Maybe its not a problem for the M? I have been able to so far , winch mine up to the nose roller and she sits right there . Have other M owners noticed this too? OR .. . .maybe the ramp I used was just right??

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Richard O'Brien
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Re: So Far I dont find this a problem

Post by Richard O'Brien » Tue Mar 28, 2006 11:23 am

Divecoz wrote:So Far I don't find this a problem.
Maybe its not a problem for the M? I have been able to so far , winch mine up to the nose roller and she sits right there . Have other M owners noticed this too? OR .. . .maybe the ramp I used was just right??
:? I need to do it. Like the man says "It's the geometry" . ALX b, Good suggestion about loosening it up a bit before you do the bump. I didn't realize that.

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Jeff
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Post by Jeff » Tue Mar 28, 2006 12:31 pm

I haven't had my new M in the water yet, but I did notice this in the M owners manual, under the Return the Boat to It's Trailer section:

"If you pull the boat out of the water and find that the nose of the boat is not quite in its rubber pad, drive the car and trailer forward at low speed and tap the brakes, the boat will easily slide into the rubber block. This saves having to overload the winch and line to move the boat".

The manual is dated July 14, 2004.

bobmonroe
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Post by bobmonroe » Tue Mar 28, 2006 6:34 pm

I tried it this afternoon, wet the beds down with the hose, loosen the winch strap and it worked perfectly with two try's, within about 100' in my backyard, I had never got that boat in the "V" before. Never thought to loosen the strap. Thanks ALX 357.

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DLT
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Post by DLT » Tue Mar 28, 2006 7:14 pm

Personally, I try to avoid wetting the bed...

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USAF M26X sailor
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Post by USAF M26X sailor » Tue Mar 28, 2006 7:40 pm

I've read a bead of dish detergent on the bunks before dunking the trailer to recover the Mac works. Also an interesting conversation piece of why the trailer produces some bubbles.... I didn't know of the loose strap trick. I thought my bottom coat was preventing the bump from working (prior to the soap attempt-works too).

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delevi
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Post by delevi » Tue Mar 28, 2006 8:59 pm

I thought I was the only one to have this problem. Yes it is so on the M. I actually bent my ladder in the first month of having the boat. Too ambitious of a bump. Learned my lesson.

Leon

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Dimitri-2000X-Tampa
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Post by Dimitri-2000X-Tampa » Tue Mar 28, 2006 10:35 pm

I used to be able to get my 26x to slide forward even with the winch tight, but that was when I kept it in the water for a while and it had slime on the bottom. Now that I repainted the bottom and don't keep it in the water much anymore, it doesn't slide...although I have to admit, I never thought about loosening the winch rope.

So I use the technique of pulling up the ramp 2-3 feet, stopping and rewinching, pulling up another 2-3 feet, stopping and rewinching, and then one last partial pull out (by this time, most of the boat is out of the water) and a rewinch. By winching in 3 increments like this, you can get the boat all the way into the V-snub without having to do the bump. My wife does not like the bump much so this is a more tame way of getting the boat all the way forward.

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