Axle Placement on Trailer

[MCNPathfinder]

Hey all, I know I post in here a lot about my boat and trailer. What it comes down to is I need more tongue weight. I can move my boat about 3 inches forward, but that will only get me about another 40 pounds of weight on my hitch. What I did figure out this past weekend is that I can move my double axles back as they are not welded to the trailer like I originally thought! I can move them back about 11 inches. I'm wondering if you guys see any problems with this? My biggest concern is that the wheels will be that much further back. I'm worried about falling off the boat launch. It's amateur hour 24/7 on the lake I frequent so power loading is common practice, I'm sure the washout is just horrible. Luckily our water is high right now. Typically though, how far can I expect the ramp to go back into the water? It's not paved all the way down, they put big cement blocks in kind of like longer railroad ties if you know what I mean.
Has anyone attempted to do this with the boat on the trailer? My plan is to drop the boat in the lake, go home where I can get access to air tools and drills if need be and go back. There's just too much that could go wrong if I do this with a 4,000 pound boat on it's trailer.

 

[H20Rat]

Re: Axle Placement on Trailer

pics? How do you know you will only gain 40 pounds? Usually it doesn't take much movement at all to gain quite a bit of weight. Moving an axle 11 inches is massive...

 

[roscoe]

Re: Axle Placement on Trailer

No problem doing it with the boat on the trailer.

You are going to have to get the trailer off the ground and onto jack stands with or without the boat on it.

Leave it attached to the tow vehicle, jack it up and put 4 jack stands under the frame.
Then you can loosen the spring mounts and move the axle with ease.

 

[MH Hawker]

Re: Axle Placement on Trailer

Axle adjustments are done inches at a time 2 to 3 at most.

 

[Silvertip]

Re: Axle Placement on Trailer

The reason the sub-frame is NOT welded to the trailer is it CAN be adjusted to accommodate the tongue weight adjustments. Agree that you don't need to splash the boat. Block the trailer wheels, mark the current sub-frame position, loosen the u-bolts and then give a gentle tug with the tow vehicle to reposition the sub-frame. Note the GENTLE TUG - not a dash into the next county.

 

[Thalasso]

Re: Axle Placement on Trailer

pics? How do you know you will only gain 40 pounds? Usually it doesn't take much movement at all to gain quite a bit of weight. Moving an axle 11 inches is massive...

Thats exactly my thought. Before i would be going thru all the hassle of moving the axle's i would move the boat first.

 

[MCNPathfinder]

Re: Axle Placement on Trailer

We figured the math on it. It's a long story... LOL! The boat weighs about 4,000 pounds, we figured the center of gravity was right in between the two wheels. I'm looking for roughly 400 pounds of tongue weight. From a previous forum discussion, I was told that I should be able to stand on the back swim platform and not have the front of the trailer come up off the ground. I weigh about 165 pounds, and the front of the trailer comes up off the ground before I even put my full weight on the swim platform. I would guess that I have less than 100 pounds of tongue weight which causes the trailer to pull the back of my truck up and start swinging. If we move the boat back on the trailer about 12 inches, I should get somewhere around 400 pounds of weight. My trailer already has holes to move the axles back 11 inches. So I'll do that and get just shy of 400 pounds. The way we figured it if I move the boat forward, I'm only getting about 60 pounds if I move it the 3 or 4 inches.
The trailer wasn't designed for this boat. Long story short, the trailer for this boat was in an accident, and this one went to he PO's other boat which he sold without trailer. I think this trailer belonged to a 19' or 20' open bow. This trailer fits this boat pretty well, with the exception of the weight distribution problem.
To be honest, it'd be easier to move the axles back rather than the boat forward. The boat lines up with the bunks and rollers right now pretty nicely.

 

[hungupthespikes]

Re: Axle Placement on Trailer

Here you go. Just take your time and read. It takes a little time to get the numbers right, but works like a charm.

http://www.continuouswave.com/whaler/reference/trailering/trailerCalculations.html

Moving the axles is not near as hard as you think. Moving them several times to get the weight right, is.

Moving the boat is easier, but how does the boat set now? Would moving the boat expose the tabs, transducers, speedo to damage from the bunks?

good luck
huts

 

[H20Rat]

Re: Axle Placement on Trailer

You can do both... I'd move the boat as far forward as you can as a first step, and see where you are at that point. That will also reduce how far you have to move the axle, and reduce the ramp complications. As the post above mentioned, the back of your boat might limit you. You don't want to hit anything on the bunks, nor do you want the edge of the boat getting in front of the last bunk support. (ie, if your bunk broke, you don't want the boat unsupported. It should still have the bracket and whatever wood is left supporting you.)

 

[MCNPathfinder]

Re: Axle Placement on Trailer

Thank you for the advice. The last little bit (~3 feet) of my trailer are rollers, and right now the back of the boat rests on the last set of rollers. If I move it too far forward, there won't be anything supporting probably a whole 12 inches of the boat (it won't be resting on the roller anymore). Also, yes my transducer and broken speedo fin is back there. Although the depth finder and speedo don't work anyway. I skimmed over the website you provided and a lot of the calculations look like what we did last weekend. My Dad is an engineer, and pretty much did all the calculating and handed me my notebook and was like here... Move the axle back to the last "notch" and you should get pretty close to the tongue weight you need. I guess I could give it a shot, if it doesn't work then move it back. There's already predrilled holes for all the hardware it looks like.
Thanks again for the help.

 

[digler]

Re: Axle Placement on Trailer

I moved my duals on my pontoon trailer in about 10 min. Break the u-bolts loose, mark the frame where the
axel cradle sits chock the wheels and pull fwd EASY . Measure new position to marks and adjust with block of
wood and sledge hammer to make both sides even tighten u-bolts
You need the boat on the trailer so the chocks will hold it and not let trailer ride up over them
its easy........good luck

 

[Josh P]

Re: Axle Placement on Trailer

if you do move the axle, make sure you measure from a fixed point on the axle that would be the same on both sides to the hitch ball to make sure your axle is square and the trailer wont dog track.. most mfgs say a maximum of 1/16 of an inch difference.

 

[MCNPathfinder]

Re: Axle Placement on Trailer

I did it last Saturday with my brother right in the trailer parking. We took the boat off, jacked up the trailer frame and moved it back. It took all of 15 minutes with hand tools and half of the time was my brother taking "breaks" to get another cigarette and the cops stopping to chat with us. The boat tows MUCH better, and the tongue weight is where it should be now. I was getting about 150 pounds before, and now I'm guessing I have at least double that. Although I think now I need to beef up the rear suspension on my truck... LOL! Can't win...