My boat is an 85 Mac25. The current problem is an indentation in the hull where the rear, starboard bunk support is. As time passes, it seems to be getting worse. Inspecting the hull from the inside is difficult, but doable. Access is through the small removeable cover that lies below the rear cushion of the dinette area. There is a frame crossmember that lies below the front edge of the molded cockpit floor. The port side is good, but the starboard side has broken loose. It's a tight space to work in, but I can get to it to put in new glass reinforcement. The challenge is how to get the weight of the boat off of the rear of the bunk support so the frame member can settle back into place. I am miles away from water , so floating it isn't an option. I've spoken with a few marinas. Two say they don't do that type of repair. The third says that it would involve cutting through the cockpit floor and that the cost could run as much as several thousand. That's more than the boat is worth. Any suggestions how to get the weight off of the effected area will be appreciated. And if anyone else has ever had this problem, how was it repaired? Thanks for any ideas.
Hull structural problem
- Thread starter Tom7219
- Start date
You might consider building a frame over the boat that would support a ratcheting lifting strap that could be located to bring the hull into conformity with the interior member you need to reinforce.
Build the frame and then jack up the boat off the trailer a few inches right at the hull/transom intersect. Position and tighten the strap and lower the jack transferring the weight to the strap. Check you brace position and rejack and re-position the strap until the hull conforms to the brace. Glass and let set. Then you can dismantle the frame.
For the frame, I would suggest making an 8'x8'x8' box out of 2"x6's but using 2"x8's for the strap supports. Use2"x3's for some angle braces to make the box rigid. Use 3 inch deck screws to build the box.
Here is a pic
of the 10'x10' frame I am using to refurb my 1968 Venture 21. Your box would extend from a couple of feet behind the boat. That should allow you to position the strap where it needs to be.
Build the frame and then jack up the boat off the trailer a few inches right at the hull/transom intersect. Position and tighten the strap and lower the jack transferring the weight to the strap. Check you brace position and rejack and re-position the strap until the hull conforms to the brace. Glass and let set. Then you can dismantle the frame.
For the frame, I would suggest making an 8'x8'x8' box out of 2"x6's but using 2"x8's for the strap supports. Use2"x3's for some angle braces to make the box rigid. Use 3 inch deck screws to build the box.
Here is a pic
Build a platform to go under the transom...
Build it so that it fits under the transom with the tongue of the trailer on the ground. Then jack-up the tongue and the boat will be on the platform under the transom and forward on the trailer. It will be free of the bunk towards the stern.
You can do something similar on the other end if you want to remove the trailer.
More here...
http://purplesagetradingpost.com/sumner/macgregor/outside-3.html
Sumner
==================================================================
1300 miles to The Bahamas and Back in the Mac...
Endeavour 37 Mods...
MacGregor 26-S Mods...
Mac Trips to Utah, Idaho, Wyoming, Canada, Florida, Bahamas
Build it so that it fits under the transom with the tongue of the trailer on the ground. Then jack-up the tongue and the boat will be on the platform under the transom and forward on the trailer. It will be free of the bunk towards the stern.
You can do something similar on the other end if you want to remove the trailer.
More here...
http://purplesagetradingpost.com/sumner/macgregor/outside-3.html
Sumner
==================================================================
1300 miles to The Bahamas and Back in the Mac...
Endeavour 37 Mods...
MacGregor 26-S Mods...
Mac Trips to Utah, Idaho, Wyoming, Canada, Florida, Bahamas
Even with the weight on there should be little or no indentation. The liner should hold the shape. The factory tied the liner the the hull with one layer of sloppily applied glass and resin. Basically to keep them together. Not for stopping compression. There might be more going on. I replaced some of mine when I found them separated. Up by the v-berth and cabin seats. West System epoxy and glass cloth. Probably from pounding in our New England waters. It made a difference in stiffness when pounding in weather. The front edge of the bunks seems to push the hull in a little when on the trailer but not much. There is some flex in the hull. If you need to lift I did this(see pic) Less than $100 to make. Having a chain fall helps.
Attachments
I'd recommend building something similar to what Sumner built. Crank your trailer tongue all the way down, place stand underneath and then crank back up. The rear end will be lifted. Be sure to leave your bow eye connected so the trailer doesnt move. In most cases this will put weight on the front of the bunks.
To replace the bunks with longer ones you have a few options:
Every one of these options has different levels of risk involved. Use your own judgement
To replace the bunks with longer ones you have a few options:
- Use an automotive jack on the ground or trailer to support the boat while changing the bunk
- Use a heavy 2" ratchet strap around the boat and trailer. Make sure the ratchet is on the side that has the bunk that you DON'T want to change. The boat will be pulled to that side. Sounds more dangerous than it is
- As a safety, I've used 2x4's. One end goes under the hull/deck lip, the other touches the ground and a ratchet strap pulls it against the trailer frame to hold it in place. This isn't possible on all boats/trailers
- Or you could do what we did. Used a janky forklift that looks like it had been through two world wars...
Every one of these options has different levels of risk involved. Use your own judgement
Can you show all of us a few pictures. I think this problem might be able to be fix for very little money.
I don't have any pics. You have to take out the front flotation through the tiny access opening. The shelf that makes up the front of the vberth acts as a structural bulkhead and hull bracing. All of the glass that tied the hull to the liner was broken. I cleaned it up and laid two layers along the whole thing with West System epoxy. I took the time to thoroughly clean under there while everything was out. I also cleaned and disinfected the foam chunks at the same time. I found all of this when I was searching for a good spot to mount my Lowrance depth sounder transducer. This was a perfect spot for mounting. Hair dryer and toilet ring wax. I had mouse nests and everything else in there. It felt good to have it cleaned out and disinfected, bleach. Be careful. Nothing brings out the bad vernacular like reaching down and have 30 year old dirty fiberglass daggers stick into into your fingers.1/2" deep at least. Even better is when they break off! Seeing this I looked under the cabins seats and they were the same. I did the same thing there. The liner is glassed to the keel trunk under the sink side. That was intact.
I have more projects to complete before this season but it has been raining ever day for over a month.
. There is always something with these boats. I always sail with my tools and spare everything. I sail the ocean out here and our water can get pretty rotten when you least expect it. Every trip is an adventure.
I have more projects to complete before this season but it has been raining ever day for over a month.
. There is always something with these boats. I always sail with my tools and spare everything. I sail the ocean out here and our water can get pretty rotten when you least expect it. Every trip is an adventure.