Boat lift project...

[mrc]

I mentioned in another thread that I am contemplating a fairly major project in aluminum which is a boat lift for a 3500# boat. Shorestation, shore master, Daka make similar things for less than it will cost me to build it... but that's not as fun.

I'm in the mental design phase now and have a couple of questions for the group.

1) I've built several welding projects including a log splitter using a combination of low powered MIG (weldpac 100 + gas) and Stick welding(Miller M180 running 7018ac at 130amps). Nothing has fallen apart (yet). I'm more than willing to dedicate a good chunk of time to practicing before attempting actual construction of this project (~100 hours). I have been planning on purchasing 210 amp MIG unit for the job, but reading through posts on welding aluminum I noted that Dan said it perhaps takes more skill to mig weld < 1/4" aluminum than it takes to TIG weld it. I was leaning toward MIG because I figured the learning curve would be not quite as high as TIG'ing it. I am not all that concerned about impressing people with pretty welds as long as they are structurally sound. The aluminum tubing walls will certainly be less than 1/4" thick.... Pricewise it is relatively a wash TIG or MIG. (okay now for the question)... Which welding process would you recommend for me?

2) The DAKA lifts use a stackable (? not sure if that is the right term) aluminum square tubing which does not have flat sided walls... there is some structure to them which lends strength without using increased thickness (Think I beam or channel over flat stock) These tubes will stack inside each other nicely for telescoping sections (such as used to do individually extendable feet for leveling purposes). Do you guys have any source for this type of tubing? Quick search through internet metal supplies did not yield any results.

3) I was thinking that as a backup to my welding,I would add some internal solid square stock to the joints for peace of mind... opinions? Overbuilding or overspending?

4) There are two options for the lift mechanism hydraulic and winch+cable+pulleys. Cable and pulleys is the least expensive and is fairly straight forward as to how to prevent the lifting portion from racking due to the uneven load on all lifting corners. Hydraulic is more sexy, fun, expensive, and perhaps easy to build. However if I go with a cylinder on all four corners is there a way to insure that all for corners lift evenly (flow balancer?) I supose I could do some sort of hybrid with a single cylinder, lever arm and 4 cable/pulleys. Any suggestions on the raw mechanics of the lift?


Thanks in advance for your thoughts.

Regards,
Mike

[sd_sk]

You could always try to design your own hydraulic (as in water and air, not oil) hoist.

http://www.boatlift.com/

I've had one of these for my 28' Baja and they work great if you have power available to drive the lift mechanism which is a small vaccum cleaner motor that pushes out the water to lift the boat out of the water (took about 90 seconds to lift my boat completely out of the water, effortlessly. To lower it back down you open the valve to let the water back in and the boat slowly lowers back into the water.

I don't know how much the DAKA lifts cost but I believe the HydroHoist was around $4500 for a #5000 lift and since they dont wear out the resale value is about 80% of new if you ever want to sell it, which I did when I moved to a new marina. I'd be curious to know how much the DAKA cost for comparison.

Good luck,

Steve

[chris88]

Since my dad just moved down the shore on the water we have been contemplating puting a lift in for the bass boat. What I was thinking what might work, correct me if I'm wrong. Build your base and the poles up about 8 feet or so out of the water, run 2 I beams accross and get 2-4 hoists depending on size of boat/ budget and get some real heavy duty straps for under the boat and put some weights on em so they sink in the water. Then run your boat over the straps and lift the hoists until your boats out of the water. The only thing I was thinking about is the straps breaking down in the salt water and UV rays. Would this work?
Chris

[mrc]

Originally Posted by sd_sk

You could always try to design your own hydraulic (as in water and air, not oil) hoist.

http://www.boatlift.com/

I've had one of these for my 28' Baja and they work great if you have power available to drive the lift mechanism which is a small vaccum cleaner motor that pushes out the water to lift the boat out of the water (took about 90 seconds to lift my boat completely out of the water, effortlessly. To lower it back down you open the valve to let the water back in and the boat slowly lowers back into the water.

I don't know how much the DAKA lifts cost but I believe the HydroHoist was around $4500 for a #5000 lift and since they dont wear out the resale value is about 80% of new if you ever want to sell it, which I did when I moved to a new marina. I'd be curious to know how much the DAKA cost for comparison.

Good luck,

Steve

Thanks for the idea Steve,

My major problem with that approach is the water depth required. I live on a channel, and I'm going to have to dredge out and put in retaining wall to get the depth I need for even a drop carrage lift.

Mike

[mrc]

Originally Posted by chris88

Since my dad just moved down the shore on the water we have been contemplating puting a lift in for the bass boat. What I was thinking what might work, correct me if I'm wrong. Build your base and the poles up about 8 feet or so out of the water, run 2 I beams accross and get 2-4 hoists depending on size of boat/ budget and get some real heavy duty straps for under the boat and put some weights on em so they sink in the water. Then run your boat over the straps and lift the hoists until your boats out of the water. The only thing I was thinking about is the straps breaking down in the salt water and UV rays. Would this work?
Chris

It seems like it would work, only problem I see is that the straps need to be pulled up on both sides AND front and back evenly, other wise boat tilts.

Mike

[sd_sk]

Originally Posted by mrc

Thanks for the idea Steve,

My major problem with that approach is the water depth required. I live on a channel, and I'm going to have to dredge out and put in retaining wall to get the depth I need for even a drop carrage lift.

Mike

Mike,

That makes sense to me, those hoists need at least 4.5 feet of depth, which is a lot of dredging!

Another option, if you have a fairly gentle slope to the water and adequate space on shore, would be to build a track system for a trailer/carriage that you can put the boat on and then pull out of the water using an electric cable winch. Gravity should pull the trailer and boat down the slope using the winch in reverse to slow the descent in a controlled manner.

A family I knew back in Wisconsin had this setup at their house on the lake for thier MasterCraft which they didn't want to leave in the water all season long. They used the trailer that came with the boat. If you are really concerned about the trailer rusting, getting water in the bearings, etc., you can also pull it back out of the water while you are out boating.

Steve