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Strength of mild steel square tubing?

by hanksvilleman
Tags: mild, square, steel, strength, tubing
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hanksvilleman
#1
Aug30-10, 09:33 AM
P: 1
Hi all, My project that I am working on is a pontoon boat trailer but here is my problem. When I have launched the boat before, it was is shallow water and we had to back in so far that we ended up getting water into the fuel tanks. So, I fugure that I would moke an extendable tongue.

My wife says to just use square tubing and put a ball on the end and use that as an extension. Basically, unhook fron the trailer, slide this 10' extension into the hitch on the truck and hook it to the trailer. I think that this method would put too much strain on the receiver hitch on the truck and I don't think that this 2" x 2" x 1/4" square tubing would support that much weight over the 10' span.

My idea is to make an extendable tongue on the trailer. The trailer has a main beam that goes from the hitch to approximately 9 feet back under the boat. This beam is 2.5" x 4.5" I.D. and my design would use 2 of the square tubings stated above and weld them together and then weld shims to the tubing to take up the extra spacing that would be left. I would then have to make pins to secure the tongue in place.

The way I see it, both ways have their drawbacks. We are on limited budget and I just would like to find out if my wifes idea would be enough to handle the launch and removal from the water.

I know the other factor is the weight of the boat. It is a 24' pontoon boat. There are 3 pontoon under it and they are all made of steel and not aluminum. The decking also has a metal floor under the carpet. To get a better idea of weight, here is some info. The 2 outer pontoons are 19" diameter and the middle toon is 21" diameter. When the boat is in the water (with our gear) the outside pontoons are 1/2 in the water and the inner toon is a little under 2/3 in the water (middle toon sits a little lower than the outers). Yes, it is a heavy boat and the toon are not home made. It does ride like a Cadillac in the water.:

If anyone can give me some suggestions, that would be great.
Thanks, Dave
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