I've seen posts where people describe various ways to remove a boat from a trailer for hull repair / repaint. A year ago I removed our 2000' Four Winns / 5.0L from the trailer and repainted both. I used the following jack made out of lumber, steel, and a $10 bottle jack from your local hardware store. This process is quite safe and stable if you approach this with caution, some abstract thinking, and patience.
You just slide the jack under the boat, lift it up, and then pull the trailer out from under it. Obviously, you need some jack stands and enough jacks to juggle when pulling the trailer out. The trailer frame crossmember will hit a jack or stand at some point and you need to juggle that jack stand to just-behind the crossmember.
Anyway, this is really cheap and easy to do. You will want to shape the 4x4 coming out of the top of the jack for a "V" shape or a slight slant, depending on where you are going to use THAT particular jack. I guess what I wanted to show here is that you can take a very small bottle jack and using dimensional lumber, make a tall & sturdy lifting apparatus. Hope this is helpful.
You just slide the jack under the boat, lift it up, and then pull the trailer out from under it. Obviously, you need some jack stands and enough jacks to juggle when pulling the trailer out. The trailer frame crossmember will hit a jack or stand at some point and you need to juggle that jack stand to just-behind the crossmember.
Anyway, this is really cheap and easy to do. You will want to shape the 4x4 coming out of the top of the jack for a "V" shape or a slight slant, depending on where you are going to use THAT particular jack. I guess what I wanted to show here is that you can take a very small bottle jack and using dimensional lumber, make a tall & sturdy lifting apparatus. Hope this is helpful.