Strange way to swap out my center log?

[RonKMiller]

I've decided to replace my existing 20 ft, 21" partial center log with a 25 ft. 24" U shaped log. According to my calculations this will give me an additional 1800 lbs. of buoyancy and most importantly keep the front of my boat from "submarining" during quick stops and hopefully allow it to ride wakes without taking a bath every time. My outboard logs are 28 ft, 21".

As I explored different ways to achieve this they have all led to hiring a crane for a few hours and building some sort of cradle that I would rest the outboard logs on while doing the swap - while worrying about bending them if the cradles weren't perfectly level. Then I would have to rehire the crane. This is all some serious $$$$.

Then it came to me: Why not just unbolt the center stanchion winch "tower" on the tongue, cut the base of the existing supports for the bunks off the trailer with a plasma cutter, unbolt the old log - slide it out the nose - then slide the new one in and bolt it on. The only thing left to do at the point would be to re-cut/re-weld the bunk supports to accommodate the larger diameter of the new log - which would have to have been done anyway. Rebolt the tower back on and I'm done! (I would probably be wise to support the entire center section of the boat with some jacks to keep it from sagging once the center toon is removed)

The only downside I can think of is that it is going to be rather cramped working in the limited space under the trailer, but I think it's doable especially if I only work bolting it up for 30 minutes or so at a time, then take a break. I'll need an experienced welder to fare the new log to the transom, but this is just a matter of welding some sheet aluminum in place with some aluminum angle to transfer the thrust loading to the new log...

What am I missing here guys?

(The reason I decided on a center U log is to keep the two wakes generated from the outboard logs from washing over the top of the center log and effectively adding a heck of a lot of extra weight while under way)

[jimrs]

(I would probably be wise to support the entire center section of the boat with some jacks to keep it from sagging once the center toon is removed)

How wide is your boat? Regular toons only have two outside toons and they don't sag in the middle. There are people who trailer tri toons without a center toon support.


(The reason I decided on a center U log is to keep the two wakes generated from the outboard logs from washing over the top of the center log and effectively adding a heck of a lot of extra weight while under way)

The center log is bigger and should not have that problem even if round. Most manufactures don't use two kinds of logs when building their toons.

You might be over thinking this.

[RonKMiller]

Much appreciated, and your comment about over thinking is indeed a good one - I tend to do that a lot!

The reason I'll need to support the center is that I've got just a wee bit more weight on my boat than typical. It's well distributed over several stringers under the wheels where 90% of the weight resides - and over two stringers under the tongue. http://www.youtube.com/watch?v=c0IwHewPvEg

I'm still pretty sold on the idea of a center U-log to also help create a better "slip stream" for the two wakes to wash off the vertical walls instead of lapping on to the top of a round tube. It will also provide a better way to fare the new log to the existing transom since it is also U shaped. No need to transition from circular to vertical which would take some fancy sheet metal bending. Besides that I found a used one for $500.00, and it's local!

Finding exactly what I need in the middle of the steenking desert? Priceless!

toon at reflection canyon.jpg (465.74 KiB) Viewed 1916 times

[woolznaz]

Ron, I assume you would have the camper off the pontoon while you are doing the swap, right? If so, I don't think you need to worry about support/bending/stress on the outer logs while you are doing the swap. I would think your boat would be lighter than most when doing that, so supporting the center may not be required.

[Bryden24shp]

Last winter we yanked my neighbors pontoon off his trailer by using 4 Hyd engine hoists (Cherry pickers) one on each bow eye and one on the eyes of the back of the pontoons. Drove his old trailer out and his new trailer under in about an hour. Simple solution was to wait for the river to thaw, but no, he had to do it in January....
Just an idea for ya!

[tuned]

Last winter we yanked my neighbors pontoon off his trailer by using 4 Hyd engine hoists (Cherry pickers) one on each bow eye and one on the eyes of the back of the pontoons.

Good idea Brian. I just did it a different way on my SouthBay project. I lifted my boat using four 'chain falls' hung from the rafters of my pole shed. As I had a lot of work to do underneath (skinning), it was a blessing to be able to walk right in. I also used 2 large ratchet straps and four posts as safeties. It still moved a little so I belayed the four corners of the boat at angles with cinch ropes. It was rock solid then.