Aluminum Boat - Foam Floatation - Cleaning - Corrosion

[Lawfin]

For all of those decked aluminum boat owners - I have an aluminum boat. This is the typical NW deep-v welded aluminum boat with vinyl decking, full windshield/steering wheel, vinyl top, etc. Because the boat is under 20 feet, it must float level when filled with water per coast guard regs. To achieve this, the manufacturer used expanding foam to fill portions of the hull under the deck. Last year, I discovered pitting through the hull. The pitting was fixed by the manufacturer at minimal cost, and the hull was re-foamed. My rookie research leads me to believe the pitting was caused by poor draining, which allowed the foam to stay wet, which in turn created an acidic environment.

Recently, I returned from a four-day at Sekiu (by the way, fishing was decent - not great). While there I ran the bilge after running the boat fast and at the end of each day. When I returned, I cleaned my boat in accordance with the manufacturer's recommendations. I then put the tongue on jacks an drained the boat for a few days . . . even vacuumed the drain hole to get the last remaining drips. Last night, I decided to pull a floor panel to ensure the area was dry, and to my dismay, I found water in the area of the new foam on the outer sides of the boat. It appears this area will not drain. I am, of course, paranoid that my boat may pit-out again.

Soooo - I have some questions. Has anyone experienced this problem on an aluminum boat (wet foam, or pitting), and if so, what did you do to solve it? And, more basically, how do you wash the interior of your boat after having it in the salt (What cleaner do you use? Do you hose it down or simply wipe it down? Out of the box solutions for draining?). Any thoughts you wish to share?

Thanks for your input. With the exception of this issue, I love this boat, and I take great care of it. I hope to be able to pass it along to my son when my boating days are over.

Happy Fishing!

[4n6fisher]

First you need to find out how the water is getting into the foam. Is there a leak around a seam, fish box or another location? Is the foam sealed in or just open to the bilge (which in my opinion would be a major deign flaw)?
I would also question manufacturer, since they fixed it the first time maybe there is something else wrong with the installation that they can fix (and are obviously aware that that has happened before). If this was happening on all their boats they would quickly be out of business.
There is a whole class of corrosion termed corrosion under insulation, not only on boats. If the foam continues to get wet there will continue to be pitting issues does not even necessarily have to be salt water, but salt will make it corrode faster.
The other concern would be that they fixed some areas, but what about the areas that had not corroded all the way through, there could be some thin spots.

Keeping water out will be the only real way to prevent that from reoccurring.

[The Quadfather]

Sounds like you got some solid advice to start with.
I was going to mention you shoukd check out these guys.
https://www.tinboats.net/forum/
They have a pretty deep well of knowledge from a lot of guys who have torn their own boats down, and up again.

[Bodofish]

Food for thought.

If your boat is over 20' it doesn't need to have foam floatation from the mfg. Many people prefer not to have the foam which will soak up water over time. Even so called closed cell foam soaks up water. Air bladders do not soak up water but you will still need to put some sort of floor in under them that will allow water to drain out. That said most of the high end Alu boats are painted on the in side with a sound abatement paint. Almost anything that keeps the water and air from the aluminum keeps the oxidation at bay. Quiet Car is the brand you can get is small amounts. Marine quantities are sold by the 55 gal drum. Think painting the inside of the ferry. As always you need a Zinc chromate primer to bond paint to aluminum. Etch and paint or sand and paint, the aluminum needs to be free of all oxidation or the pain will not stick and the Alu will oxidize under the paint.

PS: Boats under 19', the Coast Guard requires all boats to have flotation when they leave the mfg.. It doesn't mean you have to maintain it after the initial purchase.
Boats over 19' Some mfg do and some don't. Pros and cons to either way.