Pontoon Boat & Deck Boat Forum

My big SouthBay (sort of) has grown in weight with the wheelhouse, furniture, air systems, water systems, stereo, power ladder, and just plain heavy wiring. My trailer is new, but I am close to the weight rating on the twin axles. My brother was driving behind me and said he could see them bow just a bit as I hit bumps. Plus the fenders are very close to the tires.

Would the easiest and cheapest way to mitigate this be to install a THIRD axle with springs?
I wouldn't need brakes as they are already on the other two axles.
OR could I just add overload springs?
Any advice is much appreciated as I just don't know that much about trailers.

i know nothing about trailers, either... it seems, though, adding a 3rd axle would be the toughest task. 1 inch out of alignment, and you'll be going thru tires like crazy...

consider buying a 3 axel trailer, and selling the dual?

I'm thinking I'd at least would go with the route of least resistance. In your case it appears your axles and likely springs aren't up to the task or should I say load. The easiest way to go would be change out your existing axles for beefier ones. Your existing brake hardware and tires most likely bolt right back up and you should again ready for the road in exchange for a few hours work. Pretty good list of available axles here.

AWESOME link, Bambi! Much knowledge to be gained there.
Doc, it would be tough to sell and buy a trailer up in the bush where I am.
I need to gather all my specs together (including tire ratings etc...) and give this a good thought.

If your axles are visibly bowing, your axles need upgraded with an appropriate upgrade on the tires as well.

For example, if your current axles are 3500 lb capacity that's 7000 total.

You can upgrade to 5000 pound axles so that the axles combined capacity is 10,000.

But then you have to upgrade the tires as well as upgrading the axles but exceeding the tire weight does you no good.

Around here, the Co-Ops have scales and it's easy to run across them and get a trailer weight.

Axle position also makes a difference, influencing both axle and tongue weight.

Adding a third axle can be easily done by a competent machine shop or alignment shop. Key word is "Competent".

I know of two locally.

You probably already know all this, and if so, I apologize for repeating what you already know.

Before I did any changing of axles, I would be calling the manufacturer to see if that frame would be still rated for the extra load. The trailer is a complete system. Just changing the axles doesn't mean the trailer would be rated at the higher load.

I'm thinking like Babock. Pontoon trailers are typically very light trailers for their length and width. The toons sitting in their V brackets are actually adding structure to the trailer.

I've seen tri-axle trailers for Suntracker's houseboat and 31' hull, but I've never seen 5,000 pound axles which would require 6 bolt wheels and 15" tires. The pontoon boat frames are just not that strong.

I agree about running your trailer across a scale to see where you're at vs. specifications on the plate. Unless your trailer is a cheap, lighter than normal trailer, you're probably doing about as well as you can. If you already have 4 wheel brakes, your trailer is probably of adequate quality for any boat that's not a lead weight.

Well maybe we've not yet seen everything?
Boat is 35' in length, the trailer weighs 4,600 lbs. empty, the wheels are 15" with 6 bolt rims. The trailer handles the boat OK but as you can see the bunking system for the boat on this trailer sucks. The bunk boards are currently removed and I've been searching for replacements for the support system everywhere without much success. Tried to buy these from a PS affiliate trailersforpontoons which I know would work for my needs but I've received no cooperation from them as to actually getting my hands on them and the manufacture won't deal with individuals like me themselves, must go through a vender.



Anyway it can be done, and I'm betting my boat is heaver than tuned is.

I gotta grab trailer specs, but I know trailer is about 1500# and boat is about 5600# with full fuel.

How far do you trailer? maybe a set of 5000# torsion axles? I would have to think your toon is heavier than that, I think mine is 5000, and dont have the cab. but then again, I been wrong alot lately, lol, good luck Todd. JT

pond tuuunes wrote:How far do you trailer? maybe a set of 5000# torsion axles? I would have to think your toon is heavier than that, I think mine is 5000, and dont have the cab. but then again, I been wrong alot lately, lol, good luck Todd. JT

I don't normally go more than 20 miles, and usually once each way/year at that. I sure would hate to wreck a new trailer. I would like to be able to run up to two hours tho. A number of cool lakes within that radius, including down to Vermillion area to have a beer with the Fox and Rancher Lee.
That is a pretty true weight (right off the truck scale). The shack is built pretty light duty, plus most of my furniture is plastic lawn chairs. I did forget to add about a 100# for my new rear sundeck build, so 5700# fully loaded.
Once I FINALLY get launched (maybe a week) I'll be able to get a good look at the trailer. I'll give the builder (over by Ty) a call as well and see what he has to say.

I wouldn't worry about the axles bowing a bit, it's actually quite common with the wide axles used on trailers, especially those with round tube construction. I've got 55" perch to perch 2200# axles under mine and those deflect a bit with only 1500# each on them. My car trailer with a pair of 3500# axles deflect quite a bit also when loaded to max, and I bet the really deflect when I hit bumps in the road (glad the roads are so smooth in northern MN)

rancherlee wrote: (glad the roads are so smooth in northern MN)

They are great as you well know. The logging and mining trucks tend to smooth them out