Pontoon Aluminum Weld

Well, a couple of scrap car tyres and a length of string would be an easier solution, Murphy.

crabby, what's the string for?

To tie the car tyres on where the impact damage is taking place, as a cheap and cheerful fender. Obviously!

They would be robust...... the down side. if you hit the angle hard, you may damage where they are welded on the pontoons....... what is the wall thickness anyways on the pontoons?

.090 inch (2.2mm) This seems to be a little thicker than some, but thinner than those that are listed as HD.

I'd worry about ripping holes at the spot welds.

What about using 5200 marine adhesive to glue on 1" aluminum square tube?

You could cut the front and back ends at an angle and weld on caps. That would make them look better.

I'd use something like this and "glue" it on. No stress concentration and easily replaceable.

Taylor Made Products 2014 Product Catalog

Nothing you attach to the pontoon would be as strong as the pontoon itself. In other words, as soon as you hit ANY dock, the stand-offs of your armour plate will drive into the pontoon. If you are just re-enforcing the pontoon, you will presumably make it stronger, however, it has been my experience that you cannot stiffen treacle with marbles...there will always be something which will give, and now you have denied access to any damage.

Old Salt has the answer. Thar ain't anythin he aint a seen before.

The angle will need to be seal welded along it's entire length and the ends closed or you will cause a galvanic cell to form and cause acellerated corrosion leading to a hole in your pontoon.

no you won't.

if you know anything about galvanic corrosion, you will note that you need dissimilar metals. By welding Al to Al you will not create any current.

And to address the others relating to strength and stiffness, the guy does not want the angle iron to stiffen the pontoons nor is he looking to cushion a blow to the dock, he wants to create some distance from the bolts so they dont scrape against his bladders. The angle iron will give the needed safety.

the galvanic cell will be formed by differential activity of the aluminum surface, combined with biologic contamination of the crevice. I think I know quite a bit about corrosion in such situations as I have worked in the offshore industry for many years.

Thanks all, There are a whole lot of aluminum welded components on the pontoons, so I'm not sure why the galvanic corrosion issue would be different. I have none now, that I've seen, just the aluminum oxide film that seems to form on anything aluminum in the weather. The boat is freshwater/ not offshore, I'm sure that is a different animal. The death ring bolts are sticking out of posts, threaded into nuts on the outside (I didn't build it this way, some other numbskull did, it's at a public marina, to boot)

I just want a light, permanent spacer. I do use cushions, but I would need about 60 on each side to cover the pontoons length, because they slip around a post. It's not like a long dock board at the water line. What I currently do, which is try to drive, keep my pontoons off the dock, and get out. Too much going on for one guy.

The angle CAN be welded to the pontoon material, but..............chances are good that they will be different grades, tempers, etc. and the welding characteristics will be different. Al doesn't get red when hot, so burning through is a real problem, especially at .090 inch.

So, unless you are really good with a welder, you may want to have a boat shop do the welding.

Thanks Lyn, I'm not good enough, and I will get the right person to do it. I will do some research on grades/alloys, make sue I'm sticking an apple to an apple.

the issue is the crevices, not the welding. dirt, salt, bacteria and god only knows what else will collect in the crevices and the trapped area will create a galvanic cell in the crevice. and since the area is "protected' and doesn't have circulation through it the ions build up in the crevice and drive the corrosion at a much higher rate than if it were in open air/water. aluminum is an active/passive metal, which means if the AlO2 oxide layer is ever breached and prevented from reforming due to an active corrosion cell then it can form a pit quite fast and drive the pit very deep.

http://en.wikipedia.org/wiki/Crevice_corrosion

Thanks Ror, making sure there are no holding crevices, check!

You haven't mentioned it but what is the length, width and draft of this pontoon boat? Some solutions that might work on a small boat might not work on a larger boat and vice versa.

There are numerous fenders in different sizes and configurations. Usually when there is a problem with a vertical obstacle cylinder shaped fenders are use and connected end to end . This assembly is then hung from the deck or fender cleats in a horizontal position similar to a rope hanging horizontally from near the bow to near the stern. It can also be hung in only the trouble locations. With a pontoon they would be of a large enough diameter and placed on the widest part of the boat where the troubles are.

In general, and certainly not always, if the hazard is of a vertical configuration such as a pole or piling the fenders are hung horizontally. If the hazard is of a horizontal configuration such as a dock or floating dock the fenders are hung vertically. For a flat surface such as a bulkhead the fenders are placed either way or a combination of both ways. Another style available for the bulkheads or rafting-up is the large "ball" shape.

There are a multitude of ways the fenders can be configured and used. It is only limited by the imagination. At least with them you know that the solution does not become more of a problem than the original problem. Besides when you raft-up with other boats for a cold one there will not be any danger of damaging the other boats tied up along side you.

Refer to http://www.westmarine.com/boat-fenders?page=1&q=

Good Luck, Old Salt