EXPLAIN PLEASE - Mac Bump (trailer)

A forum for discussing issues relating to trailers and towing MacGregor sailboats.

Moderators: Catigale, Paul S, Heath_Mod, beene, Hamin' X, kmclemore, tangentair

1st Sail
Captain
Posts: 563
Joined: Wed Dec 31, 2008 2:58 pm
Sailboat: MacGregor 26M
Location: Moline, IL '06M 50hp Etec
Contact:

Re: EXPLAIN PLEASE - Mac Bump (trailer)

Post by 1st Sail » Wed Jul 25, 2018 10:37 pm

There is a an old post where someone mounted a second winch above the current winch location. The strap was either threaded over the bow roller or he actually cut a slot in the channel where the oem winch is bolted. In any case I remember the strap angle was such that the boat is lifted while afloat a few inches. When the settled on the trailer the bow settled into the v bunk. Claimed the bump was eliminated. I spent $25 at the local farm store and mounted a second winch above the oem. I'LL keep you posted after the weekend when I pull it out of the marina for clean

I keep fresh carpet on all the bunks. Pull your boat out with it 12in from the bow rest and check your gelcoat where the rear bunks bump slide and the hull rests on the bunk pads. I'm putting money your gelcoat and color coat are toast. Mine is.

User avatar
Dimitri-2000X-Tampa
Admiral
Posts: 2007
Joined: Fri Jan 02, 2004 8:36 am
Location: Tampa, Florida 2000 Mercury BigFoot 50HP 4-Stroke on 26X hull# 3575.B000

Re: EXPLAIN PLEASE - Mac Bump (trailer)

Post by Dimitri-2000X-Tampa » Mon Jul 30, 2018 9:55 am

kmclemore wrote:The MAC BUMP is not just with Macs. I have a brand new Tahoe 550TF and it also needed the “bump” the other day when I hauled it out.
Like this boat?

Image
:wink:

User avatar
paula_ke
Chief Steward
Posts: 57
Joined: Tue Sep 26, 2017 3:16 pm
Sailboat: MacGregor 26M
Location: Earth

Re: EXPLAIN PLEASE - Mac Bump (trailer)

Post by paula_ke » Mon Jul 30, 2018 8:24 pm

Mac bump works better if you have put silicon on the friction areas of your bunks. It does not take much to move the boat forward. I have found that just slowing down going down hill will slide the boat forward.

I have also installed a strap roller above the winch where I feed the strap/hook then to the boat. This keeps the strap pulling up until the boat is seated. It also keeps the strap flat. This avoids the strap jam failure where the strap can end up slipping to the side inside the winch.

I also use a safety chain mounted low on the winch mount and a strap around the bow pylons to the bottom of the winch post around the trailer neck. This reduces any hobby horsing and keeps the boat from 'walking' back.

All learned from a 2,000 mile trip to/from Baja.

:macm:

confluence
Just Enlisted
Posts: 20
Joined: Sat Dec 19, 2015 2:10 pm
Sailboat: MacGregor 26M

Re: EXPLAIN PLEASE - Mac Bump (trailer)

Post by confluence » Sat Aug 18, 2018 6:20 pm

My trick was to pull my M out of the water all the way to top of the ramp, draining ballast on the way up then i used the stern lines to tie the boat to the trailer, backed the works back into the water(of course a less busy ramp is most friendly for this action) the boat floated the trailer, i tightened up on the winch and it snubbed up nicely.

User avatar
Chinook
Admiral
Posts: 1553
Joined: Sun Feb 26, 2006 10:20 pm
Location: LeavenworthWA 2002 26x, Suzuki DF60A

Re: EXPLAIN PLEASE - Mac Bump (trailer)

Post by Chinook » Sat Aug 18, 2018 6:59 pm

Keeping the brakes functional on my stock trailer has been a continuous struggle. Doing the Mac bump turns out to be a great way of confirming that the brakes are working. 10 mph or so is fast enough to snub the boat up if the brakes work. If the brakes have quit, I need go get going faster, and then the boat and trailer pushes the truck ahead. Feels quite different.

User avatar
NiceAft
Admiral
Posts: 4033
Joined: Tue Feb 01, 2005 10:28 pm
Sailboat: MacGregor 26M
Location: Upper Dublin,PA, USA: 2005M 50hp.Honda4strk.,1979 Phantom Sport Sailboat, 9'Achilles 6HP Merc 4strk

Re: EXPLAIN PLEASE - Mac Bump (trailer)

Post by NiceAft » Sat Aug 18, 2018 7:04 pm

confluence wrote:My trick was to pull my M out of the water all the way to top of the ramp, draining ballast on the way up then i used the stern lines to tie the boat to the trailer, backed the works back into the water(of course a less busy ramp is most friendly for this action) the boat floated the trailer, i tightened up on the winch and it snubbed up nicely.
Why not just empty the ballast before getting to the ramp, floating the boat onto the trailer, and then cranking up to the snub? Either way, when you pull forward, the strap is going to be pulled tight, and in spite of your efforts, the Mac will again be pulled back a few inches away from the snub. You then crank it forward some more. No stern lines involved, but no matter what you do, a Mac will not stay snug to the snub :wink: :)

In spite of all your efforts and techniques, you still need a good rachet strap around both the trailer and the boat’s stern. Just holding on st the bow will not take care of the boat bouncing off the trailer, or rolling off in an emergency swerve.

Ray

User avatar
Jimmyt
Captain
Posts: 722
Joined: Sat Jul 18, 2015 11:52 am
Sailboat: MacGregor 26M
Location: Mobile AL 2013 26M, 60 Etec

Re: EXPLAIN PLEASE - Mac Bump (trailer)

Post by Jimmyt » Sat Aug 18, 2018 9:21 pm

Apparently confluence had the nerve to try what I thought was a crazy idea to correct for the poor geometry that you get at the snubber and winch when the trailer is well below the boat when floating on at the ramp. I believe Tomfoolery has diagrammed the issue to clarify what causes the gap to develop even when you winch it tight to the snubber.

As confluence points out, tying the trailer to the boat, and backing into the water, will keep the boat tight to the trailer at the stern. This eliminates the geometry problem, allowing him to jamb the boat tight to the snubber while the bunks are tight to the boat. Although, he does risk incurring the wrath of other boaters for a "too much time on the ramp" penalty. Result is no need to do the Bump.

Well done...

User avatar
Tomfoolery
Admiral
Posts: 5198
Joined: Tue Jul 05, 2011 9:42 am
Sailboat: MacGregor 26X
Location: Rochester, NY '99X BF50 'Tomfoolery'

Re: EXPLAIN PLEASE - Mac Bump (trailer)

Post by Tomfoolery » Tue Sep 04, 2018 6:24 am

Jimmyt wrote:I believe Tomfoolery has diagrammed the issue to clarify what causes the gap to develop even when you winch it tight to the snubber.
Correctamundo. Cheesy sketch, but it illustrates what's happening.

Image

Post Reply