Aluminum boat building

[salter]

Do any of you have any experience or know someone who has experience in aluminum boat building. To give you some idea of what I am wanting to do. I am wanting to build a boat to run shallow in the river. Flat bottom, wide (8') and somewhat long but less than 20 feet. The bottom is going to be built out of 1/8 material so that it can handle being drug across the bottom etc. My questions are this:

What is the best series of aluminum to build with?

Is it advantagous to have the ridges built into the bottom and sides with a press or will it be fine to either rivit or weld strenthening ridges into these places?

How high does the transom need to be to handle "normal outboards"?

These are just a few, as I am sure there will be more. Thanks for everything.

[Speargun]

Don't rivet. Weld.
If you rivet it, it's gonna leak eventually.
Unless you have experience in fabrication and welding, I would recommend finding someone who has due to structural concerns and you don't want welds that are going to leak or break.
Another option is to find an old airboat hull and use that. It would probably be cheaper in the long run. Besides, all of the engineering and construction is already there.

When choosing aluminum, the higher the number, the more brittle and less flexable it becomes. Aluminum in the 3000 range is soft and flexible where the 7000 range doesn't bend well and will tend to crack. Your best bet is something in the 5000 to 6000 range, like 5053 or maybe 6061.

To determine your transom hieght, decide which engine you are going to use. I think 15", 20", and 25" shaft lengths are pretty much standard. Since you are wanting to run the flats, you will want the prop or jet foot in the water below the hull, but as shallow as possible to keep it off the bottom. I would ask someone in the boat business about how to set this up.

Good luck!

[Spear One]

Those guys in Louisiana are experts at building Aluminum boats. I'm sure they can tighten you up on whatever you need to know, or build it for ya!

[NOLA Hunter]

There is a company in Morgan City, Louisiana called Hanko Boats. They will build any boat you want.
Clint

[Spear One]

There ya go! Spearboard rules.

[FredT]

If it's going to see mostly salt water go with 5086 alloy. 508* alloys also bend fairly easily without cracking.

11 gauge (1/8") may be a bit heavy but it will ease the welding issues. Reinforce corners AFTER the primary welding, or weld with a gap to the reinforcing member, then stitch the member inboard.

Avoid sharp square corners as they are bad stress risers.

FT

[salter]

This will be a fresh water boat only. Its primary (and possibly only) purpose will be a dive platform.

[swimndive]

You might want to check out some of the PNW whitewater jet boats as well.