Pontoon Questions: Jacking it up while on trailer? & What's this called?

[ChazzL]

I'm wanting to jack the trailer up a few inches so I can work on the bunks. The bunks are longer than the back of the tubes so I cant brace up and jack the bottoms of the tubes. So my questions are:
1) Is the welded box at the end of the tubes (for mounting transducers, etc.) strong enough to put a jack under? (#1b in photo).
2) What is this called and is it strong enough to put a jack under? (#2 in pic).
3) What about putting a 2X6 across these 3 of joists on each side to use as a base for lifting?
Thanks for any help. Would like to hear opinions.

 

[jlh3rd]

1. - no, you'll bend it.
2. - that's the bottom of your motor pod. It is not structural...you'll most likely collapse it.
3. - yes..that can work. The ribs (C channels) are a good support structure.
And the 2x6 spreads the load.
Furthermore:
the toons are normally built in welded sections. Each section is water tight which means there is a bulkhead at that seam. Another good structural point. Be careful lifting/supporting between these sections, or you'll end up like the picture.

 

[ChazzL]

1. - no, you'll bend it.
2. - that's the bottom of your motor pod. It is not structural...you'll most likely collapse it.
3. - yes..that can work. The ribs (C channels) are a good support structure.
And the 2x6 spreads the load.
Furthermore:
the toons are normally built in welded sections. Each section is water tight which means there is a bulkhead at that seam. Another good structural point. Be careful lifting/supporting between these sections, or you'll end up like the picture.

Thanks. Those pics don't look good. If I cut a foot off the back of the bunks is it structurally strong enough to jack the boat of at the rear end of the tubes?
(I'm going to go with the #2 option, but curious if I can use the rear of the tubes).

 

[Scott Danforth]

Jack it up from the deck, not the tubes

Your bunk trailer only works because it supports the whole tube

 

[flashback]

why not launch the boat and tie up on a pier, then do the trailer work.

 

[ChazzL]

why not launch the boat and tie up on a pier, then do the trailer work.

That is certainly an option, but the ramp is some distance and I'll have to haul all my tools. Plus I don't know hpw long it will take. Just much easier in my back yard.

 

[jlh3rd]

Thanks. Those pics don't look good. If I cut a foot off the back of the bunks is it structurally strong enough to jack the boat of at the rear end of the tubes?
(I'm going to go with the #2 option, but curious if I can use the rear of the tubes).

I would not jack it anything beyond what it takes to raise it and place a support.
I can't tell how high you can jack the rear of a pontoon using that end bulkhead before something "gives "
there is longitudinal support from the toon itself and from the decking but what the bend point is is unknown....maybe a pontoon can be totally lifted at the end with no issue...dunno.
I consider the bulkheads and ribs more of support points than jacking points.
they lift my pontoon at the marina by that "belt" lift machine with the belts positioned on the seams.

 

[jimmbo]

Exactly what work do you need to do on the Bunks?

 

[Jeff J]

This is something I have done a few times to repair trailers and/or give the welder access for repairs on the tubes. I was brought one boat where the majority of the bunk was pushed out at an angle from the tube. Only the front lag bolt was holding it.

As stated by others, stay on the seams if jacking on the tube. Cover as much area as possible to spread the load. Tubes on properly fitted bunks don’t give much access, if any, to jack on the bottom of the tube. Better to use the deck structure but rigging that safely can be a problem given the height along with having a trailer in the way. Lifting one side of a boat to repair a bunk will easily exceed 1,000 pounds.

Lift slowly and no higher than absolutely necessary while watching for problems. It worries me every time I do it.