Trailer Bunks

[dontpanic]

My Magic Tilt trailer for my Com-Pac 16 has bunks on the outside of each side of trailer.  These bunks are made of 2.4 lumber that are bent to fit the curve of the hull.  These bunks (and the supporting hardware) are in poor condition and I would like to replace them.

Question 1 is how do you get the boat off the trailer or at least support it while you replace the bunks.  I can think of several ways to accomplish this one.

Question 2 is how do you get the curve in the bunks?  I suppose you could use straight lumber and then lower the boat on to the trailer which would ? force the curve into the 2x4.  However, I am afraid that would put a lot of stress on the hull. I guess you could use the old ones and laminate a new bunk by using epoxy and very thin strips.  This one sounds like a lot of trouble for a trailer bunk.

Help Please!

Thanks

Don't Panic

[nies]

The curve comes naturally over time.........choose a straight 2x4 and cover with carpet with the end grain curving toward hull ....the bunkes are for stability and a small amount of hull support.....the hull should be almost entirely on the keel......over time raise the bunks to match the hull....nies

[skip1930]

" how do you get the boat off the trailer or at least support it while you replace the bunks."

Buy a small bottle jack with at least a 6 inch stroke from your favorite gip joint. K-Mart, Wal-Mart, Target ...
Keep the boat on the trailer.
Park the trailer on flat pavement. Not on a crowned spot on the side of the road near the curb. Flat drive way? Parking lot?
Jack up the trailer just a little bit and put a jack stand under each back corner. You don't need to lift the tires or go crazy-high.
Now everything is solid on three points. Trailer jack and two jack stands.

Use your bottle jack on some blocking to take a strain under one square steel vertical holding the 2x4 up under the hull.
[Jack out about 5 inches and take some weight on the jack. There are three verticals to a side.]
Use your 3/4 inch socket to loosen one set screw at a time. Start at the one closest to the bow. [You might want to Neversease the threads for the next time.]
Let that square steal vertical drop down by s l o w l y releasing the jack from under the hull ... about an inch or so.
Your looking for day light under the whole 2x4 bunk and the hull. Do the other two on the same side. Well not really. As the boat starts to lean the day light will disappear. That just means the boat is leaning over.

O.K. now the boat has a slight lean of an inch or so toward these three lowered square steel tubes and remains supported by the old and lowered bunk.  
Grab a dock line and from the high side stern cleat to the trailer, tie off the boat. Just as a safety. Heck. Run a dock line both sides.
Actually if the trailer is dead flat the whole boat will balance on it's keel with out any hull bunks touching the hull. Just FYI.

Now on the other side, drop all three square steal supports as far down as they will go.
Unbolt/unscrew the lag bolts from the old 2x4 wood bunks. Remove the hull bunk.

*Cut new bunks, carpet them if you want to and lag bolt on the new bunk board to the square steal vertical supports. Start on the center support.

**Jack up the new board by jacking up the square steal supports under the hull. Start with the center one. Any end one and finally the last end one.

The new wood will follow the curve of the hull. There should be zero day light between the hull and the bunk boards.
Push the board up into the curve of the hull using the bottle jack to push the verticals up and lock down the 3/4 inch bolts.

Note: The hull and hull bunk boards pushed up create a cradle in which the hull sits in. This is why the boat won't slide off the trailer. It has to float off the trailer.

I put a single layer of a rag between the hull and the bunk board when jacking these up to the hull.
If I can not pull the rag out from under the hull bunk board in all three spots then the board is too tight to the hull and lifting the boat off the bottom rollers or bottom board.
If the rag almost falls out then the hull bunk is not tight enough.

Now do the same thing to the other side. Jack-tilt over-tie off-lower-replace board-jack back up.

It almost takes less time to do the job then it took me to type and edit and reedit this ... about 1 hr. and 4 minutes. Figure about 90 minutes for the job.

* ** It might be easier to jack the new board to the hull curve in the center AND THEN lag bolt the new wood to the support. Putting the squeeze to her before putting the screws to her. Working your way to the ends.

skip.

[nies]

Of course if you find somewhere to leave the boat tied up in the water over night or for the day you can take trailer home and replace bunk boards, just be sure to measure all heights and replace approx. same distances, then fine tune when you get the boat back on the tralier with the " Skip bottle jack"........nies

[Pacman]

There is a much easier way:

First, I used pressure treated 1x4 lumber.  It supports the boat nicely because it bends to conform to the hull shape so it spreads the load over greater surface.  2x4s are fine for larger boats but they are just too stiff for this little boat.

To install them the easy way, park your trailer, chock one wheel and the trailer jack.  Jack up the other wheel about 6" and put a block under it so the trailer will tilt away from the blocked side.  Tie a line from the stern cleat to the trailer on the "low" side to add a measure of safety.

Now you can remove and replace the bunk on the "high" side because the boat will lean toward the "low" side.

Remove the existing bunk.

Screw one end of the 1x4 to the "L" bracket.

Then you can push the 1x4 against the hull to induce the desired bend and slide it into place before fastening the other end.

Repeat for the other side.

[dontpanic]

Pacman. Sheer genius. Everything in your method makes a world of sense. I am going to try it.

At least I will after I manage to get the rusted  vertical support clamps off!

Don't panic