How to properly block up a 20' boat to fix the trailer.

[tedstruk]

I need to fix my trailer. It is falling apart. I have to block my boat up so I can pull the trailer out from under it.!

 

[Chris1956]

Cement blocks are the cheapest blocks of sufficient strength. You want blocks under the rear cornet of the hull and under the keel, where the vee flattens.

I drop the nose of the trailer as far as possible. Then I use 2 8" blocks on the ground under each corner. The second layer is a single 12" block on each side. Then a single 8" block on top of that. Then fit wood between the block and hull.

Now jack up the trailer tongue until all the weight is on the rear blocks. Now block up the keel in the same manner.

Important: Rock the boat side to side to make sure she is solidly blocked.

Now the PIA part...lower the trailer tongue a bit and pull out the trailer until the first cross piece hits the front block. Now you need to use a bottle jack and a piece of wood, blocks etc, to lift the keel and remove the block to pull the trailer forward to clear the cross piece. Now reblock the keel and pull the trailer forward to the next cross piece. Repeat process for all cross pieces.

Anyone got a better plan that doesn't involve a forklift?

 

[dingbat]

When I rebuilt my tandem trailer a couple of years back, I thought about removing the boat from the trailer but decided too many things could go wrong. Decided to try leaving the boat on the trailer and support the weight of the boat on a where needed basis.

To start, I lowered the coupler to the ground (raised rear of boat) then used 4" x 6" and 6"x 6" to build a support under the keel at the transom.

Then, used the tongue jack to raise the front of the boat which lowered the transom on the stack of blocks taking the load off the rear half of the trailer.

Changed out all frame and support hardware, the rollers on the last two bunks and both sets of springs. Then reversed the process, raise the tongue with the tongue jack and built a support under the keel at the bowl. Lowered the bow down on the stack which took the load off the from of the trailer.

Note: A 4" grinder with a cutting wheel is a god send. Made quick work of the old 1/2" galvanized hardware and u-bolts holding the frame and support members together. Worked a lot better and quicker than the impact wrench

 

[kcassells]

Yea why not leave it on the trailer...raised to perform tasks. I've been thinking about that approach
lately. Actually think its safer and definitely tighter to perform the tasks.
Cool!

 

[JASinIL2006]

I personally don't have a lot of faith in cement/cinder blocks, particularly the hollow ones when the weight is not evenly distributed across the entire surface of the block. Depending on the weight of the boat, concrete blocks may be fine, but I don't trust them and I would never get underneath anything supported by them.

When I rehabbed my trailer, I used hydraulic bottle jacks under wood blocks about 12" long that ran parallel with the trailer bunks, with a third jack (and block) nearest the bow, directly under the keel. The boat was supported at three points, two at the stern and one under the keel closer to the bow.

I jacked up the boat off the trailer, pulled the trailer forward until trailer cross-members were close to the jacks, then I lowered the boat a bit onto jack stands (and blocking, of course) that were placed behind the trailer cross members, and moved the trailer forward again as far as I could. I did this, alternating supporting the trailer with jacks and jackstands, until the trailer was free. I then lowered the bow onto a v-shaped support made of 2x4s, to support the bow section. The stern was supported by two jackstands and blocking. I was very deliberate, but the entire process took less than an hour. The boat was very stable supported in this fashion.

Putting the boat back on the trailer was the simple the reverse. A number of folks here on iboats advocated just pulling the boat off the trailer onto old tires, but I was concerned about being able to get it back on. It's hard to winch it up the bunks sometimes, and pulling the boat onto the entire length of the trailer was not something I wanted to try.

Good luck with your trailer work?

 

[Chris1956]

Working on the trailer, while it was still under the boat will be a real PIA, in my opinion. If you have a simple repair like axle or spring replacement, it can work.

Cement blocks should be used web side up, as they have incredible strength that way. Much much more than you will ever need. Everyone has seen 3 and 4 story houses built on 8" cement blocks.

Just make sure the blocks are level and stacked so the webs are in contact as much as possible. Use wood across the webs to support the hull.

 

[JASinIL2006]

Cinderblocks can support a great deal of weight if it is evenly distributed, as when they are used in a wall. When you use them to support things, as if they were jackstands, the load is not evenly distributed and that is when there are problems.

 

[Scott Danforth]

hoist from above using the eye hooks at the bow and transom

 

[PC on the Bayou]

When I replaced my bunk boards, I simply took my boat to the public launch and replaced them in the parking lot. Of course I pre-cut the bunks before hand.