Lifting a boat off a trailer ... not floating if off.
- Thread starter McMXi
- Start date
I stopped by the boat storage unit yesterday and took some measurements and it occurred to me that I don't really need to lift the boat as such, simply support it on one side at a time so that I can remove the existing bunk on the side being lifted. With the bunk removed I could clean the hull, polish the gelcoat and replace with a new bunk. I would jack up one side just enough that the hull is off the bunk.
I think a pair of jacks like the one shown below could work well. They're rated to lift 3,000 lb but hold 15,000 lb. The lift rating is probably due to the friction on the threads more than anything. I measured 30" from the underside of the chine near the transom to the concrete, and 33" at a suitable lifting point further forward. A couple of stands made from pipe or h-beams (I have both) to make up the difference between the 9.5" minimum height of the jack screw, along with some way to prevent them from moving as the load is taken up and I should have what I need. I have very hard rubber pads to place on the hull, and could cut some wood blocks to match the angle of the chine relative to the ground.
This jack is $179 so a pair would not be too much of an investment. They could both live in the toolbox on the Kaufman gooseneck trailer along with suitable blocks of wood so that I could use them to help with changing out a wheel if necessary.
I think a pair of jacks like the one shown below could work well. They're rated to lift 3,000 lb but hold 15,000 lb. The lift rating is probably due to the friction on the threads more than anything. I measured 30" from the underside of the chine near the transom to the concrete, and 33" at a suitable lifting point further forward. A couple of stands made from pipe or h-beams (I have both) to make up the difference between the 9.5" minimum height of the jack screw, along with some way to prevent them from moving as the load is taken up and I should have what I need. I have very hard rubber pads to place on the hull, and could cut some wood blocks to match the angle of the chine relative to the ground.
This jack is $179 so a pair would not be too much of an investment. They could both live in the toolbox on the Kaufman gooseneck trailer along with suitable blocks of wood so that I could use them to help with changing out a wheel if necessary.
No doubt a car lift could be made to work but I don't have one. I can't say that I've seen a boat lifted with a car lift but no doubt someone has done it. The hydraulic systems that I posted a link to are basically mobile car lifts and they're used by boat yards who can justify the expense. I'm trying to achieve what I need while being safe and investing as little money as necessary.
I joined that forum a few years ago when I bought the boat but it's nothing like this forum so I don't spend any time on it.
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@JasonW, thanks for this suggestion. I've been thinking about your idea a lot over the weekend and it's a good way to proceed. A quality bottle jack sitting on a steel base with decent blocks will work. I won't leave the boat supported by the jacks, but rather just to get the boat off one bunk and back onto blocking.
Other than the factory bottle jacks that come in some trucks and cars, I've never owned a good one. I have two floor jacks, a 2 ton and 3 ton that work well but they're not as practical to haul around in the bed of a truck. I could have used a pair of bottle jacks when I flipped the rear wheels around on the M6060 a few years ago. The other problem this solves is having a way to raise a trailer with a load on it and change a tire while on a trip. I have more than a few trailers so a bottle jack or two would be good to have, one for each truck is my current thinking.
I'm looking at a pair of 12 ton "hi-range" bottle jacks from U.S. Jack. I like that they're made in the US, that they have repair kits and that they appear to be well designed and well made.
Thanks for all the suggestions and I'll post some photos in a week or two once I've got the boat up.
option 'j'.... buy, rent,borrow or make a 'gantry crane' with chain hoist and sling. You can easily lift one end of the boat up with one crane. Do the cleaning/painting, lower,reposition the crane, then do the other end.
Made my own 25 years ago to split a D-14 for clutch install.
Made my own 25 years ago to split a D-14 for clutch install.
Thanks for the suggestion, but since I could really use a pair of quality bottle jacks I think I'll start out with the approach suggested by @JasonW. I might find that I have what I need to inspect, clean, polish or paint the hull each year in addition to having the equipment needed to handle a lot of other tractor, trailer and truck projects or issues. Worst case, I have two really good bottle jacks.
A search on Amazon is kind of shocking. 12 ton jacks for under $50. Hmmm .... I have no desire to risk my life or expensive equipment with a $50 VEVOR jack. What I've found is that you typically get what you pay for with hydraulics, engineering and manufacturing.
Rather than lifting the boat off the trailer, why not lower the trailer from the boat?
With the boat on the trailer, back the trailer up or pull the trailer forward onto ramps made from staggered/stacked 2x12's. Make some cribbing to hold the boat where it is, put a jack under the trailer axle, pull the ramps out from under the tires and lower the trailer.
With the boat on the trailer, back the trailer up or pull the trailer forward onto ramps made from staggered/stacked 2x12's. Make some cribbing to hold the boat where it is, put a jack under the trailer axle, pull the ramps out from under the tires and lower the trailer.
Just looked at the US Jacks, those look nice a little bit it sticker shock though. I agree you get what you pay for but $400 for a 12 ton bottle jack. But I’m not working under hydraulics anyway.
I have a few Harbor Freight bottle jacks. 8,12, and 20 ton jacks. I use the 20 ton with my gooseneck for changing tires. I use the same jack when I went through the bearings and I just blocked it up under the spring pad mount with some 8x8’s.
I have a few Harbor Freight bottle jacks. 8,12, and 20 ton jacks. I use the 20 ton with my gooseneck for changing tires. I use the same jack when I went through the bearings and I just blocked it up under the spring pad mount with some 8x8’s.
You only use the jack to lift the boat NOT support it ! You use SOLID wooden blocks or safety stands to support the boat. I have used several 'offshore' jacks to raise stuff up and none have failed,but always support the load with 'stands' of some kind.
Also do NOT use 'cinder blocks' or hollow concrete blocks, as they WILL fail...
Also do NOT use 'cinder blocks' or hollow concrete blocks, as they WILL fail...
This is in line with what I was thinking, drop the trailer, not raise the boat. Or raise the boat while on the trailer, then cribbage below and drop the trailer to do your work.
I called US Jack this morning and spoke with a nice and very knowledgeable customer service rep who it turns out was about to call me. I had selected red as the color with black and green being the other two options, but it turns out I can have any color I want as long as it's green!
Yes, they're pricey, but given the cost of what they'll be lifting I think that this is a good investment. I have a lot of stuff that I can use them with so that makes a difference. One of the things I've noticed with cheap hydraulic tools is that they come with cheap valves that don't have enough control on the valve when releasing pressure, almost a fully closed or fully open situation. That kind of thing can be catastrophic depending on what's being lifted or lowered. Other aspects of poor quality show up in the form of leaks, not meeting claimed specs, etc. US Jack products have black nitride on the ram and pump piston, the bearing surfaces are machined flat to distribute the load evenly etc. Also, I like supporting US workers when possible, and US Jack builds most products on site and the company supports 15 families. That's all a plus in my book.
When I sold the M-1078 we experienced a catastrophic tire failure during the test drive. I tried raising the front of the truck with the MX, then the M, then a floor jack but no go. Luckily, the guy buying the truck had a huge bottle jack with him and he was able to get the front right wheel off the ground and we got the damaged wheel/tire off and one of the spares on. It was a little embarrassing that I didn't have the equipment to change a wheel/tire and I drove that thing 600 miles from Tacoma, WA back home. He bought the truck and I made a lot of money from the sale so not a big deal to roll a bit if that into a really useful pair of bottle jacks.
HA! Just got a shipping confirmation from US Jack. I like that they sell rebuild kits for their products and provide actual customer support. Shipping weight is 60lb. 
Looking forward to getting the bunks swapped out, the hull cleaned and then polished. Bet the boat will be 10mph faster now!
Interesting information on the invoice.
Looking forward to getting the bunks swapped out, the hull cleaned and then polished. Bet the boat will be 10mph faster now!
Interesting information on the invoice.
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Runs With Scissors
Well-known member
Equipment
L2501 TLB , Grappel, Brush Hog, Box Blade, Ballast box, Forks, Tiller, PH digger
My buddy uses “mostly” wood blocks at his marina, but I have never actually watched him block a boat, so I can’t help there.
But I put these “teflon” things on my bunks and have been pleased with them.
https://www.amazon.com/dp/B077H64JRD?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1&th=1
But I put these “teflon” things on my bunks and have been pleased with them.
https://www.amazon.com/dp/B077H64JRD?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1&th=1
The jacks showed up yesterday afternoon/evening and I bought a couple of 2"x6"x12' for the new bunks so should be able to get this job checked off over the weekend.
I sure could have used these jacks when I changed the spacing of the rear wheels on the M6060. There isn't a lot of room for jacks under the rear end, and automotive style floor jacks aren't optimal for this kind of work given the height of the axle relative to the ground.
I sure could have used these jacks when I changed the spacing of the rear wheels on the M6060. There isn't a lot of room for jacks under the rear end, and automotive style floor jacks aren't optimal for this kind of work given the height of the axle relative to the ground.
I cut up an old 8"x8" into 2ft long pieces this afternoon to sit the bottle jacks on when raising the boat. They'll be useful for positioning the jacks under tractors and trailers as well. I also cut up a 4"x4" and made some hard rubber pads. A test fit/run of everything this afternoon/evening indicates that the jacks will lift the boat like it's a sheet of paper!
I need to make up a couple more pieces of 4"x4" and some more pads and all being well will get the bunks off, the hull cleaned and polished where it currently contacts the bunks, and the new bunks installed. As I mentioned, I'm not trying or wanting to get the trailer out from under the boat, just to support it so that I can replace the bunks.
I need to make up a couple more pieces of 4"x4" and some more pads and all being well will get the bunks off, the hull cleaned and polished where it currently contacts the bunks, and the new bunks installed. As I mentioned, I'm not trying or wanting to get the trailer out from under the boat, just to support it so that I can replace the bunks.
Thanks for sharing! I need to do this also. So I will be watching your progress!I cut up an old 8"x8" into 2ft long pieces this afternoon to sit the bottle jacks on when raising the boat. They'll be useful for positioning the jacks under tractors and trailers as well. I also cut up a 4"x4" and made some hard rubber pads. A test fit/run of everything this afternoon/evening indicates that the jacks will lift the boat like it's a sheet of paper!
I need to make up a couple more pieces of 4"x4" and some more pads and all being well will get the bunks off, the hull cleaned and polished where it currently contacts the bunks, and the new bunks installed. As I mentioned, I'm not trying or wanting to get the trailer out from under the boat, just to support it so that I can replace the bunks.
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Ron
Hopefully this thread will give you some ideas on how to achieve what you need.
I stopped by the boat storage unit yesterday with some steel tubing that I'd found in my scrap pile. I decided that the angle on the underside of the chine needs to be replicated in some wood to distribute the load evenly. The underside of the chine isn't parallel to the ground (has a negative taper) which is part of the reason why the boat has such a dry ride. The water is directed downward rather than up and over the gunnels.
I used my table saw this afternoon to rip a 4"x4" to the proper angle and now have two pieces of wood that can sit on the steel tubing on each jack. The underside of the wood is parallel to the floor and the top side is parallel to the underside of the chine. I cut more rubber pads too and now have everything I need to complete this job.
I'll update with photos in a day or two.
A quick test this afternoon proved successful and I was able to get the starboard side of the boat off the bunk by 1/2" or so without any horrible noises or indications of imminent failure. The wood blocks that I cut to match the chine angle work well, and so I should have no trouble removing the bunks, cleaning the hull and replacing the bunks with the new ones.
Once this job is done I'll think about making up some steel supports that have a section of pipe on the underside to locate on the jack, and something on the top side to keep the wood blocks in place. Since I plan on at least inspecting under the bunks each year it'd be good to have a kit that I can roll out when needed.
Once I get the old bunk off I can see how much thought went into it. I'm not sure if it's shaped to the hull from the get go or simply got shaped over years of supporting the boat. I'm hoping that I'll only need to cut the 2"x6"x12' pieces down a little and then cover with the new bunk material.
Once this job is done I'll think about making up some steel supports that have a section of pipe on the underside to locate on the jack, and something on the top side to keep the wood blocks in place. Since I plan on at least inspecting under the bunks each year it'd be good to have a kit that I can roll out when needed.
Once I get the old bunk off I can see how much thought went into it. I'm not sure if it's shaped to the hull from the get go or simply got shaped over years of supporting the boat. I'm hoping that I'll only need to cut the 2"x6"x12' pieces down a little and then cover with the new bunk material.