lifting boat with a floor jack?

[bparker]

I'm getting set for a total bottom paint re-do and wish to support my 18' Continental from underneath with minimal blocking at the corners and keel. It's currently on a trailer which I hope to pull out of the way.
I don't have a gantry crane to lift from above, so would there be any harm in using an automotive floor jack fixed with a big pad to provide lift one corner at a time?
I don't think I need to lift it much, or for very long, just enough to clear the trailer bunks and get a support under there. Anyone?
Thanks in advance, BP

[Don Ayers]

I would make sure you are under a major frame section and also use a board to spread the force from the jack. The more you spread the weight the less the impact in a particular spot.

[mfine]

Pictures of the trailer would help, but if possible I would lift under the engine stringers or keel and not from the rear corners. If lifting from the corners, I would do both at once to avoid twisting forces on the transom and last frame.

If you can slide the boat back so the rearmost 6" over hangs the trailer and then jack it up with boards spreading the weight across major frame members that would be better.

Another better option would be to jack up the trailer and attack the lifting rings to beams above (assuming in a garage) and then lower the trailer. Again, depending on the trailer, you may be able to jack the trailer up and add your supports from below and then drop the trailer. Either way, the weight stays spread out on the trailer bunks, and not at a single jack point.

[bparker]

Good points. The boat/trailer is outside with nothing overhead. I had thought of using the tongue jack and the "teeter totter" effect of the single axle trailer to do the job. Nose down, the aft end is up in the air about four inches above level. In theory, I could put supports under the rear corners that way, then jack the front way up and block the keel. Lowering the trailer to level would then enable me to pull it out, stopping a couple times to reposition the keel block for the axle and cross bars. Yes? Do you think that would work?

[Bill Basler]

You have to be pretty careful of the area towards the bow where the forefoot meets the keel. There is a joint there, and you need to watch how much of the boat weight is carried at this point. If I was trying this, I would make some sort of cradle shape block out of plywood, blocks and carpet. Big enough to carry the weight through the keel, and spread over the garboard planks and beyond, making sure to span at least one set of bottom frames. Jack it up just long enough to get the trailer out from under, then lower it down on a full set of supports. I would opt for more than just one support forward and two aft. The down side is that you will have to jack, and move supports. Let paint dry, then jack again and move supports again. Better than doing damage.

[mfine]

The boat/trailer is outside with nothing overhead.

Here is what I would do.

1) Buy some lumber and build a 2 or 3 overhead arches. One for each lifting ring and maybe a third for extra support on the engine.

2) Use the tongue jack method or chainfalls/winches to get the boat supported by the lifting rings, off the trailer.

3) Build some wide, strong "safety" supports to go underneath, but make them about 1/2" too short so they don't touch the paint and you can move them around.

If you are brave you can skip step 3 and paint. If you are worried about a boat falling on your head, build the supports first.

[57 chris]

Before I built my A-frame shelter for lifting the boats I used bottle jacks and heavy blocks to lift my boats off of their trailers. Like you my boats are small so I felt that this was acceptable, I don't think I'd try it with a larger boat.

Craig

[gbraker]

Honestly, I think the boats are a lot stronger than you think. I have seen boats supported incorrectly that hog and go out of shape but it takes a long time for that to happen.

Lets face it the bow area has a very lot of strength. It takes the force of waves hitting it. I agree that whatever you do, make sure there are equal forces on each side, and support it from the engine stringers, but as far as the bow you could just support that with a block of Styrofoam or block up under the bow area. Just don't leave it that way for weeks at a time.

[parroteyes]

An engine hoist is pretty cheap ($120) and should work.

The stern should not be a problem. set the tongue of the trailer on the ground, block under the now elevated stern and lift the trailer tongue back onto the hitch.

Lift the bow clear of the trailer with the engine hoist using the lifting ring. Pull the trailer fore ward until the wheels are to the engine hoist. Block under the keel as far fore ward as you can (aft of the axle). Pull the trailer on out as far as you can.

You may have to reposition the hoist and relocate the keel block several times to get past the trailer cross structure. I would use a jack stand under the keel to make adjustments easy, but a floor jack could be used, 'cept it might move.

You may need two jack stands if the trailer has a member running under the keel, one to port and one starboard with a plank between them to support the keel.

The plus of the engine hoist is you can easily lift the boat one end at a time once it is off the trailer, to relocate your supports as you paint. Or just lift it by the stern lifting ring paint the stern area let it dry and then lower it. Just be sure to retain some safety blocking a couple of inches below the boat that will catch it when the hoist fails.

Speaking of safety, leaving the hoist attached to the lifting eye with the slack taken up is a back-up for the blocking at that end of the boat.

[Bill Foley]

I use a couple of engine hoist to roll over 16 footers and other jobs when working on boat, but the thing they won't do is reach the bow ring and still clear the trailer wheels. On full extention of the hoist you are limited to about 500 pounds and the legs interfear with pulling the trailer free. When I retired (sold my company) I bought a used forklift-I was in the warehousing busines-which has been invaluable in prusuing my newest hobby.

Bill Foley - Olympia

[parroteyes]

Bill is right. The hoist will not clear the wheels at all. The trailer must be pulled forward 'til the wheels are against the hoist frame, then get the boat blocked up and the hoist removed. Then move the trailer to the blocks, then, with the hoist behind the wheels, lift the boat off the trailer.

Depending on the trailer set up, this may not work. You have to look at where the hoist, the blocking and the trailer will be at each stage.

I was able to get mine off with a hoist as described -- single axle trailer, smaller boat.

[Mark Campbell]

I wasn't going to chime in here...but why not. I can not count the amount of times I have seen and or jacked a boat (Chris Craft) with bottle jacks and wood blocks from the rear corners and center bow area. Triangle will not rock or tip. Under 20 foot there is no problem at all. The corners are not weak spots. They are a location that transfers the stacked and mounted frame energy, lifting, as well as the bottom. Short term for painting the bottom or varnishing is perfect this way. I "respectfully" consider concerns here of damage to the boat by this method as unusual to me. It is the only safe and widest tripod support that can be applied to each boat. Only the bow could be pushed off support... "could"...Regular auto support can be adjust as temporary supports.

There is a strategy of jack placement and relocation around trailer frame at a time as the boat remains and the trailer is moved out from under the boat.

This I speak from experience many many times..

A hoist makes this a breeze. put supports under the rear corners with the tongue down (this brings the rear higher) and hoist from the bow lift ring. As the lift begins the rear sinks onto the rear corner supports
...the front continues to lift and now you remove the trailer by hand or mower or vehicle and put a support block or foam towards the front forward , windsheild like area .

EDIT: Corners should be supported at a 45 degree angle with a piece of wood to support rear edge and side edge. This angle flat piece of wood transfers support and stability as well.