Bronze floor style

[stromborg]

I've been thinking about floors lately (the current project in my house-building adventure is installing tongue and groove planks to the ceiling of the covered porch, not particularly mentally taxing) and I'm feeling uncertain as to the benefits of a couple of approaches. There is "Tally Ho"and "Arabella" style with their floors laying on the sided face of the frames, bolted to the keel timber with fasteners running through the planking, frame and floor. Then there is the "Larry Pardey/Taliesin" method with the wings bolted through the molded face.

What are the benefits of one over the other? "Arabella" style puts fewer holes in the frames, probably a good thing but then I haven't heard of "Taliesin" breaking any frames either.

Sorry for the lack of pictures, my google-fu was weak this morning, "bronze floors Taliesin" turns of pictures of some old house in Wisconsin.

[cstevens]

Do you have Bud McIntosh's book "How to Build a Wooden Boat"? It has a really good section on floors including a discussion both metal and wood types and with or without wings. That seems like a good place to start.

[Peerie Maa]

You have your sided and mounded arse about face. Sided is the dimension between the parallel side surfaces. Moulded is the curvy thickness that may be bevvelled or other wise moulded to shape.
Sawn floors used to be an integral part of a frame assembly. The first futtocks often crossed the keel to butt on the centre line, so the floors, first and second futtocks and top timbers created a complete uniform frame assembly. They are easier for a shipwright to make and install, not requiring a smith or foundry.
Bronze or wrought iron floors take up much less volume in the bilge, a real advantage on a boat whose keel is deep enough to not need a keelson. However, they have to be bolted to the inner face of the frame to avoid the complexity of twisting the arms to allow them to be bolted to the side of the frames.

[stromborg]

"You have your sided and mounded arse about face."
Good point. I always have to think about my reference point for those terms. Even after thinking twice before typing I managed to get it wrong. I might lay off the power tools for the day. Sawn frames having their faces square to centerline making it easier to cast a floor makes sense. Thanks

I have Bud's book, he outlines a number of different floors doesn't directly talk about the types I was asking about. I've got a scheme to build a boat with steam-bent oak frames at some point down the road. Potential solutions to problems I don't have yet are sort of burbling about in my head.

[Peerie Maa]

"You have your sided and mounded arse about face."
Good point. I always have to think about my reference point for those terms. Even after thinking twice before typing I managed to get it wrong. I might lay off the power tools for the day. Sawn frames having their faces square to centerline making it easier to cast a floor makes sense. Thanks

I have Bud's book, he outlines a number of different floors doesn't directly talk about the types I was asking about. I've got a scheme to build a boat with steam-bent oak frames at some point down the road. Potential solutions to problems I don't have yet are sort of burbling about in my head.

Do not attach the floors to steam bent timbers, there is not enough wood in the steamed timber to take the size of fastening that you need for floors. Fit your floors between the timbers with arms long enough to span three strakes of planking.

If she is clinker built with flat floors you can use steamed floors of greater siding than the timbers, and for best quality build joggle them over the laps.

[stromborg]

The size of the frames is one of the things that had me thinking about the floor engineering. 1 1/8"x 1 3/8" oak with 7/8" carvel planks is what the designer called for back in 1932. I've been using Gerr's book as a reference for scantlings and the design follow his general recommendations fairly closely. I could end up building laminated floors too.

The whole project is a carrot dangling out there to help me finish off the list of partially completed ones I'm slowly chewing through.

[Andrew Donald]

Pardeys book has a bit of discussion, but only on his metal style v timber. Off the top of my head I reckon Arabellas would take a little more room in the bilge, with the web. Also their bolt is offset from aligning with wings.
I would think material would be same price (?) so if you can weld the Arabella ones could work out cheaper.

[stromborg]

I like the idea of metal floors a lot. The method Steve and Alex used to build them worked out better than I thought it would, probably have to upgrade my welder

[Tom Blake Surfboard]

I like the idea of metal floors a lot. The method Steve and Alex used to build them worked out better than I thought it would, probably have to upgrade my welder

Just a word of caution. The modulus of elasticity, ultimate tensile strength of those welded floors are going to be a function of the temper of the bronze material in flats near to and in the welds.

That temper will be just about uncontrollable in welding.

Meaning that: yes you have bronze floors but no, you have no way to calculate the stress that floor can take. That also assumes you have beautiful welds. Imperfect welds are filled with stress concentrators.

Will they be stronger than wood floors? Dunno, how will you calculate it?

Brad

[Canoeyawl]

I always just looked up the alloy in Mark's and calculated assuming it is in the "soft" or annealed state, then overbuild...
A little extra weight down low in a boat is generally a good thing.

[Tom Blake Surfboard]

I always just looked up the alloy in Mark's and calculated assuming it is in the "soft" or annealed state, then overbuild...
A little extra weight down low in a boat is generally a good thing.

That is a reasonable answer, yet I would still be extremely careful about discontinuities at the weld itself, as this is the area of greatest stress concentrations and least user control.

Permit me a moment to discuss John Roebling. Who was he? For those that don't know, he was Lead Engineer for the Brooklyn Bridge, built in the late 1800s. Suspension bridges were fraught with failure. It wasn't that we didn't understand the engineering, it was the control of the metallurgy that caused bridge after bridge to collapse and kill people. So why did Roebling succeed? The Brooklyn Bridge still is standing more than a century later.

Roebling succeeded because it was his own factory that made the wire. He controlled the metallurgy. When he was forced to use wire manufactured by others, he insisted on testing. When testing revealed deficiency due to fraud and corruption, he overbuilt the bridge to account for the deficiency.

It would be worth while for anyone considering welded metal floors, to consult with someone who can perform the stress/strain calculations and determine if the design is sound.

At the risk of sounding like a PITA, it can be dangerous to guess when catastrophic failure could be the result.


Sorry to be that pedantic twit, but someone had to say it.

[Canoeyawl]

A weld should always be stronger than the parent metal, i.e. a failure will not be in the weld or the heat effected zone. Sort of the first rule of welding, and any welder worth his salt will have tested representative samples of the work.
(Silicon bronze welds beautifully. I have done quite a bit of it with different processes and tested it to destruction. Typically welding bronze requires processes and skills that precludes amateurs.)

[Andrew Donald]

Canoe, you say s.bronze is above amateurs. I once bought an oxy-acetylene kit with thoughts of making some fittings. At first I thought it must be like welding mild steel but since it has become obvious that I’m dreaming.
Can you tell me if oxy-Acetylene is an easy to learn way with SB. I also have a MIG welder, would that be easier to learn?
would you rate it as doubly difficult over mild Steel or harder?
thanks

[Peerie Maa]

A little extra weight down low in a boat is generally a good thing.

Yes, I remember reading about a class of yacht with a class limit on ballast weight. So one designer specifies massively oversize bronze floors for "Hull" weight low down.

[wizbang 13]

Beneft?
a zillion hours of time and a bunch of expensive metal is a benefit?
A book tells us they are better....
I say hogwash.
The twists and turns taken by the two example builds to avoid using a few gallons of epoxy blow my mind.

[Peerie Maa]

Beneft?
a zillion hours of time and a bunch of expensive metal is a benefit?
A book tells us they are better....
I say hogwash.
The twists and turns taken by the two example builds to avoid using a few gallons of epoxy blow my mind.

Chill, Bruce, chill.

The size of the frames is one of the things that had me thinking about the floor engineering. 1 1/8"x 1 3/8" oak with 7/8" carvel planks is what the designer called for back in 1932. I've been using Gerr's book as a reference for scantlings and the design follow his general recommendations fairly closely. I could end up building laminated floors too.

The whole project is a carrot dangling out there to help me finish off the list of partially completed ones I'm slowly chewing through.

[Rumars]

Bruce, you get so excited about metal floors, you really need to watch this series. Just don't scream at the screen, he can't hear you, better write here about it.

[Canoeyawl]

Canoe, you say s.bronze is above amateurs. I once bought an oxy-acetylene kit with thoughts of making some fittings. At first I thought it must be like welding mild steel but since it has become obvious that I’m dreaming.
Can you tell me if oxy-Acetylene is an easy to learn way with SB. I also have a MIG welder, would that be easier to learn?
would you rate it as doubly difficult over mild Steel or harder?
thanks

Welding bronze is, well, different. None of it is difficult, it just takes time to sort out and test the process.
You can't "weld" it with an oxy-acetylene torch. You can braze it or silver solder it which is mostly fine for small boat bits, but not the same as welding.
Mig or tig welding copper alloys requires shield gas and preheat. (There are coated sticks for welding silicon bronze, but they are frightfully expensive. I have never used them) I have had good results with both both tig and mig but for any significant amount of work mig was the way to go. Bronze (Copper) takes a lot of heat and welding over 1/4" or 3/8" material I had the best results using a spray-arc process, which takes a large welding machine and a fixture to hold the work in position. (Noting the digital meter on the machine it was constantly varying between 300-330 amps) Short-arc is fine and can be done with a smaller machine. Tig is pretty sweet for smaller parts. Using a smaller mig machine will work with adequate preheat. For best results will need to get some temp sticks or a pyrometer. Wiki has a pretty good page on mig welding, although not specific to copper alloys

[wizbang 13]

plastic frames and fiberglass floors....oooookay
I know there are a hundred ways to do things right.
I can't watch Louis for more than a few minutes without throwing stuff at the screen

[Peerie Maa]

Welding bronze is, well, different. None of it is difficult, it just takes time to sort out and test the process.
You can't "weld" it with an oxy-acetylene torch. You can braze it or silver solder it which is mostly fine for small boat bits, but not the same as welding.
Mig or tig welding copper alloys requires shield gas and preheat. (There are coated sticks for welding silicon bronze, but they are frightfully expensive. I have never used them) I have had good results with both both tig and mig but for any significant amount of work mig was the way to go. Bronze (Copper) takes a lot of heat and welding over 1/4" or 3/8" material I had the best results using a spray-arc process, which takes a large welding machine and a fixture to hold the work in position. (Noting the digital meter on the machine it was constantly varying between 300-330 amps) Short-arc is fine and can be done with a smaller machine. Tig is pretty sweet for smaller parts. Using a smaller mig machine will work with adequate preheat. For best results will need to get some temp sticks or a pyrometer. Wiki has a pretty good page on mig welding, although not specific to copper alloys

14 minutes in.

[stromborg]

The build of Evelyn is going to twist a few panties.

I like building stuff. I like woodworking. I like metal working. I even like working with epoxy. I spent the first part of my working life figuring out how to transform lovely drawings from scenic designers into reality, and those guys are trained to pretty much ignore structural issues in pursuit of the art, most of them just let the technical director figure that part out. I'll use whatever materials and/or techniques make the most sense.

Right now I'm just trying to wrap my head around the benefits or drawbacks of what I'll call vertical-vs-horizontal metal floors. What I think I know is that one can do better than simply shoving a big plank-on-edge down into the bilge to keep the keel assembly attached to the rest of the boat. Floors of course don't exist by themselves. Sawn or steam bent frames? Are the frames notched into the keel, sit on top or stop short? One of the things I like about a metal (or laminated) floor is the ability to extend the "wings" up higher in the hull, capturing more planks without losing a lot of space inside. I'd rather put the sole where I want it than be constrained by the height of the floors.

The amount of work Larry Pardey put into those cast floors is daunting. Not just the in the pattern-making but the actual casting process had to suck up a lot of time. I've done just enough smaller scale casting to know those long thin pours don't always turn out the way you want, if I read correctly the "wings" of those floors are only 1/4" thick.

The floors Steve and Alix put in Arabella are fiddly in their own their way too. I suspect matching the curves of those steamed bent frames took a lot longer than the YouTube videos indicated. But it also allows for the builder to go back in and weld on more bits, like anchor points for the engine beds and mast step. Yes, one can argue the finer points of stress risers and the effects of heat on the underlying metal...but remember the original design was for a big piece of wood with a few bolts.

Speaking of wood, a nicely glued up winged floor isn't out of the question (Leo did a video on this while he was working on (I think) Curlew a couple of years ago. Wood on wood, you can run them pretty far up the hull to capture lots of planks. No sparks in the woodshop, always a plus.

Lots of options, and opinions...

I've stalled long enough this morning, the rain isn't going to let up and it isn't going to get any warmer out there, at least I'm working under a covered porch.

[wizbang 13]

Spring leaf lammed AYC floors

[Rumars]

The build of Evelyn is going to twist a few panties.

Right now I'm just trying to wrap my head around the benefits or drawbacks of what I'll call vertical-vs-horizontal metal floors.

There is not much to the vertical-vs-horizontal thing. Floors have two functions, keeping the keel attached and the hull sides from folding in. If you do a strap on the frame there must be enough metal in the arms at the bend point so as they don't fold in. A plate floor achieves the same by geometry with less metal, it acts as a bracket (knee). If you have sawn frames you can use a plate floor since the frames are oversized anyway, you just bolt on a knee. If the frames are steamed you need reinforcement so you double them with metal straps. If there are no frames or the geometry does not allow thick enough straps, or you are weight conscious, you use thin straps with a plate bracket, creating a C section. An ideal design would be a box floor, closed on all sides, but it's not practical.
I'll try to find you some pictures of composite boats with steel frames to illustrate.

The Evelyn build is a perfect example of what happens when someone does not understand that stiffness rules over strenght.