Composite Construction Tips.

Hi so i've been running around the forums just out of curiosity would there be any benefit to this?
for example. strip planking over plywood? what forms are practical? just curious thanks.

 

I'm not sure your question is entirely clear. You mean strip planking in preference to plywood, or...…..?

 

we'll i have heard some things about composite construction like strip planking layered over plywood(honestly does'nt make sense to me) and i was wondering if it's practical for certain scenario's like a sailing haul for blue water or for motorized racer etc, what are the benefits? would'nt maintenance become a nightmare? etc.

 

Strip planking is usually associated with hull shapes that would be impossible with sheets of ply, I don't know why it would be an idea to combine them.

 

my thoughts exactly. but i was wondering what are some forms of composite construction? what would there benefit be? i have seen some designs where there were two layers of planking or there steel hauls with wooden stringers (this is a bad idea as rust is encouraged).

 

Well, obviously the fibreglass boat industry has forever been using composite construction, with timber and ply combined with the laminate, and also other plastics like various sandwich materials. Most of this is because of the flexibility of glass laminates being an issue. Clearly you don't want a metal hull in intimate contact with support structures of a flammable kind, when welding repairs are called for, so that is an obvious contra-indication for mixing build materials.

 

so glass on it's own needs reinforcement itself?

 

Depends on shapes, but the laminates are more flexible than other common boatbuilding materials. But you can use the same material, GRP, to make stiffening elements. Sandwich construction is largely a way of eliminating the restrictions imposed by that flexibility, by making the shell an "I" beam, of sorts.

 

noted. i'll check it out

 

Composite construction just means that there are at least two materials involved and as such has changed its common language meaning over the years.
1. Steel framing with wooden skin (usually carvel). The "original" composite in the time of wooden ships.
2. GRP = polyester + glass fiber. What we now usually call single skin fiberglass.
3. Cored panels of all types. What most people mean by it now in a way or another.

Without specifics "composite" can mean a lot of things. Ferrocement is a composite for example. Sheated ply is a matter of interpretation as are some forms of strip planking.

 

Even the old copper sheathed carvel sailing ships

 

So it's a very broad term then. like epoxy and wood is considered composite construction. i'm assuming there's pro's and con's with each form as with every choice you make in a design. So figuring out the best one for my current design will be carefully considered.

glass and wood = rot city/prolongs an already damaged boat and if thick enough blocks wood boring organisms
wood and steel = rust city / greater strength for less material used while to providing the wooden boat look .

although i'm assuming if the steel and wood are properly insulated from each other it would still be a good choice.

 

Not seeing much scope for combined steel and timber, really. How would you make a weld repair without risking a fire ?

 

When this combination was invented welding still involved the use of a hammer. Normal procedure to this day is to remove for repair.

There are benefits to it for larger vessels, the metal framework will weigh less and be less intrusive than double sawn frames and floors. Metal floors are still used to this day on yachts for this reason, and not only in carvel construction or other traditional types. The french RM range wich are plywood multichine and Perry's Sliver Class wich is woodcore epoxy have shallow bilges with heavy bulb keels and use metal floors for support.
It is not imperative to use iron alloys, bronze and even aluminium have been used for frames and floors. One could use titanium if cost is no issue.
The fetish of no maintenance/100 years lifespan is a modern invention. Normally a wooden boats life expectancy would not go over 25 years before it became uneconomical to repair. The fact that the framework eventually rusted out was outweight by the benefits. In the begining wrought iron was used wich rusts less then steel, later hot dip galvanizing was invented and became standard, today a lot of restaurations involve stainless. Cast bronze floors were also common on yachts.
There are disadvantages of course like different thermal expansion, etc. Some boats it pays to use metal, some don't. Compromises as usual.