TOPIC: Metal stringers??

would it be possible to use formed aluminum channel for the stringers on a fiberglass boat? i've got access to lots of sheet metal at cheap/free prices as well as all of the equipment to form it. after reading many threads on here, it seems to me that the general consensus is that the fiberglass that goes over under and around traditional wood stringers is what gives the boat its strength and that a few boat manufacturers didn't put any wood in the stringers anyway. with, say, 1/8" aluminum formed into channels, i would never need to worry about rot and will probably save some weight too.

just wondering out loud... thoughts?

-Chris

Are you building a boat or fixing a boat? The Aluminum won't flex as much as the wood so you might get more stress cracking at the ends of the stringers.

It would be interesting to see how it works.

i am just anticipating fixing my current (or future) projects. being a sheet metal worker by trade, i always look for ways to incorporate what i do into what i'm doing =). especially if it works out to be easier/cheaper for me without sacrificing function.

as far as flex goes, i can always make them from thinner aluminum to make them a tad more flexible, if that is of concern.

several years ago we fileted a lone star flamingo, about a 1960....it had aluminum stringers....john

rice,
are you still planning on glassing the alluminum channels to the hull? Cause if i remember correctly, aluminum can still corrode from minerals and salt in the water. I'm sure that you have probably already thought about this.

Every boat, you will have to make a judgement call at the time.
For me after doing one floor, I would never put anything back, wood or metal.
If the original form of the glass over the stringer is intact, get the wood out, and double up the fiberglass.
That is what I did on my 68' Starcraft. The wood was there to make a form for the fiberglass in construction. In some cases it isn't needed after that. It is just there to rot, soak up water, and block bilge channels.

docstark wrote:

rice,
are you still planning on glassing the alluminum channels to the hull? Cause if i remember correctly, aluminum can still corrode from minerals and salt in the water.

my intended use for the boat is freshwater only. i'm a ways from any salt water and am not planning any trips to the coast. if i ever did manage to make it that far, i'd be REAL seldom.

i was anticipating glassing the channels to the boat though. if corrosion is still likely, i can always use stainless steel. a bit more weight, but i can probably get away with relatively thin stuff that way.

jim18611865 wrote:

For me after doing one floor, I would never put anything back, wood or metal.

i hadn't really considered this. i'll have to see once i get around to getting everything apart. that's a ways away, so i've got time to think about it. thanks for the input!

jepstr67 wrote:

Are you building a boat or fixing a boat? The Aluminum won't flex as much as the wood so you might get more stress cracking at the ends of the stringers.

It would be interesting to see how it works.

The inability to flex is an issue- I have a '60 Speed Queen with aluminum stringers and the ends of the stringers have separated from the floor.

You may be able to get more flex by drilling/sawing large round holes in the channel. I've seen that done in I beams to save weight. It really doesn't effect strength much.

Of course aluminum boats all have aluminum stringers.....that seems to work just fine. Maybe copy what they do there.

Aluminum stringers could work fine . As pointed out, aluminum boats use aluminum stringers. Wood is usually used as the core for stringers because it can easily be shaped, tapered, and bent as necessary to fit the boat hull, keel, and/or double bottom. Once covered with an adequate thickness of fiberglass, they become durable and strong. If you taper and shape your aluminum stringers as necessary, and lay them into a bed of resin and glass cloth, they should work .

Pipestone Sales' early fiberglass boats used aluminum keel and stringers. I know a guy that was working at a marine dealer selling those boats. He bought one in the 1950s for his personal use. He said the aluminum would flex and bend upwards creating a hog. He'd jump down off the seat to "pop" it back into the proper shape!

Didn't Herters also use aluminum keel and stringers in ther 1950s fiberglass boats?

Andreas

I'm no structural engineer but one thing I do know is that when flexible meets not flexible and it is not secured good enough, something will give. I'm not saying it would be bad because I've seen metal in versions of my MFG and they seemed fine. If that is what you have a mind to try I say Good Luck and I hope all turns out fine. Lets see what your doing because "We like pics".