Floating trailer II

[REW]

Eric, from Co. has posted recently about his tandem wheel trailer which floats if backed into the water too farm.

He indicated that his trailer was manufactured by Marine Master who also manufactures the Triton line of boats.


Last month we had a new couple move in next to us. One of the last things that the neighbor moved in was a nice Triton deep V boat on a Marine Master trailer which appears to be identical to the picture that Eric had posted about his problem.

So, tonight, I was chatting with the neighbor and asked him if he ever had issues with the trailer floating.

Much to my surprise, he said Yes.
He said that every time that he would back the trailer in so that every tire was submerged, the trailer would begin to float.

His opinion was that the floating was simply caused by the 4 inflated tires lifting the weight of the unloaded trailer off the bottom of the launch.

So, it doesn't sound like Eric is the only one who has seen this situation with a tandem axle trailer.

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So, lets see if we can figure out how much upward force is on the trailer by the submerged tires.

From Fluids - the buoyant force of an object fully submerged in water is equal to the weight of the water that is displaced by the object.

So, we need to figure out how much water, each tire displaces.

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For assumptions, lets assume that the trailer has a 15 inch tire on it with a typical diameter of 30 inches.
This means that the outer circumference of the tire is 94 inches.
The inner diameter of the tire is 15 inches with a circumference of 47 inches.
The average circumference is then 70.5 inches.
The area of the tire will be the radius of the tire cross section squared times pie or 64 sq inches.
Then the volume of the air in the tire will be the average circumference times the cross sectional area or 4512 cu inches.
The volume of a cu foot in inches is 12 cubed or 1728.
Then the cu feet of air in the tire is 2.6 cu feet.
One cu foot of water weighs 62 lbs. So each tire will displace at least 160 lbs.

Then, if you multiply the weight displaced by the number of tires you have a displacement value of 160 X 4 = 640 lbs.

However, you now also have the wheels themselves and the frame and other trailer parts displacing water.

For every additional cubic foot of water that is displaced by the trailer frame and wheels, there will be an additional 62 lbs of lifting force on the trailer.

So, for the trailer in question, it would be quite reasonable to expect a lifting force on the trailer of around 800 lbs.

If the trailer is near that weight, one can easily visualize that the trailer might have floating issues- especially under wind and current conditions.

--
Eric - if you have a trailer only weight ( let us know what that is.)

So based on the previous calculations, it is quite reasonable to expect that a 4- wheel boat trailer could float if all of the trailer was submerged displacing that volume of water which is causing the trailer to lift from the water.

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Think back to the time that you were a child floating on an inner tube.
Sure, we sometimes used car or truck tires for floating, but under most circumstances, the typical adult would not sink a typical inflated auto tire tube.

Take care
REW

[ffishman]

Do these trailers have sealed tubes for the frame? My EZ Loader had box tubing with drain holes in it. Never had a problem.

[dkooser]

REW - thats a lot of effort to help Eric out. Much appreciated. He is on the water now in NE and probably wont be back reading all this until Sunday night or Monday.

My question is do others with dual axels have similar issues? I have not heard of any. I suspect it is air being trapped in the fenders. I backed in his trailer a few times when we fished a tournament recently and could see lots of air escaping out the front of the fenders (via the side view mirrors). I tried to back slowly and let the air escape but the trailer still floated.

I hope Eric is playing with this issue this weekend so he can come back with more information.

[perchjerker]

Originally Posted by dkooser

REW - thats a lot of effort to help Eric out. Much appreciated. He is on the water now in NE and probably wont be back reading all this until Sunday night or Monday.

My question is do others with dual axels have similar issues? I have not heard of any. I suspect it is air being trapped in the fenders. I backed in his trailer a few times when we fished a tournament recently and could see lots of air escaping out the front of the fenders (via the side view mirrors). I tried to back slowly and let the air escape but the trailer still floated.

I hope Eric is playing with this issue this weekend so he can come back with more information.

looks like the way his fenders are designed they are big air traps. I have never seen a trailer designed like that

thats why I told him a few times to call the company but he's too busy to do that I guess...

My tandem trailer sinks like a rock. But it doesnt have all that plastic on it either.

[REW]

Perch,
I sent an e-mail to the company for him.
Their reply was that it was an 1100 lb trailer and had never had anyone comment about the trailer floating.

I replied that I had two examples of their trailer floating and if possible - could they take one of their new trailers and fully submerge it to see if would float or sink.

I do agree that the large fenders with the air space - in addition to the floatation provided by the 4 tires could very well be enough to float the trailer.

REW

[ffishman]

My trailer is a tandem axle, and I've never had a floating problem. I wonder if the trailer is made from cheaper lighter material.

[REW]

FF,
As others have voiced:
These marine master trailers have a very unique fender setup.
The fenders are between 5-6 feet long and about 2 feet high. They are not just a little fender over the top of each tire.

I calculate that the lift generated from these unique set of fenders is about 300-400 lbs of lift.

Furthermore, I calculate that the lift from the 4 tires is about 800 lbs.

So, the 800 + the 300 = the 1100 lbs of actual trailer weight.

These are extremely well made and robust trailers. But, I expect that the combination of the 4 tires, and the two very large fenders trapping air are sufficient to float the trailers a bit.

REW

[4JawChuck]

Not too much work to drill a 1/4" hole in the top of a fender...heck an 1/8" hole would work too.

[Eric_CO]

The efforts are certainly appreciated.

Perchjerker - I guess I knew what the response of the manufacturer might be based on how these things usually go with manufacturers of all the products I use.

The ramp at Big Mac this past weekend was very very shallow so I wasn't really able to make any progress. To back it in far enough to get it to float would have had me submerging the rear differential on my truck which I don't like doing. We really had to power load it to get it on right but they don't mind that at Big Mac.

I did notice that alot of air was escaping from the frame as it sat there.

[Tim Ellis]

Originally Posted by 4JawChuck

Not too much work to drill a 1/4" hole in the top of a fender...heck an 1/8" hole would work too.

Exactly