combunation materials

[ted655]

Has anyone ever designed a sailboat rhat used aluminium for a bottom & hard chine to waterline, then used ply sheets for the rest of the sides, deck & superstructure?
I have a local guy who won't take on a solid aluminium boat, (nor can I afford total aluminium). He is willing to build the bottom and frames. Yes I have thought about the difference in expansion, crawl, working/movement of fasyeners, etc..
I'm wondering if strap bracing, modern adhesives, etc., could make it possible. Any thoughts? Thanks

[D'ARTOIS]

I cannot resist to answer your query. To use an aluminium bottom in combination with plywood topsides is one of the weirdest combinations I ever came across.
And that for costsaving reasons only.
Of course it can be done. But for what? It definately leads to an unsaleable and disastreous construction that won't last very long due to the big differences in material, the difficulty to bond aluminium and plywood in such a way that the plywood cannot delaminate in years to come; and what are the advantages?

Make the boat entirely out of plywood and you have avoided the dramatic bonding problems of those two materials.

Making a costanalysis of a boat you will discover that the hull is only around 20% of the total costprice of the boat.
Constructing a boat in this way is provoking future problems.

[ted655]

Monster as you describe, maybe. I;n sure rhose building pky boats don't share the propkescy of doom you predict. I'm sure they have expectations of a longer vessal life. I see no reason ply/epoxy should have the brief life you predoct.
The keel, floor & ribs are much easier in metal. The cost between sheets (and that is the bulk of materials above waterline), of alum-ply is greater than just a few dollors.
While I can build in wood, I can't weld. There I save more. Then there is the matter of positive flotation. Metal boats are finished inside with wood. I've seen many plans where the topsides were prescribed for wood.The ratio of hull cost to finished cost is noted, another reson to save a buck, IF it does not rob the final results.
I'm glad you were so aghast at this question as to respond. I enjoy good debate, thats hoe mistakes are avoided & new ground is broken. Repulsive as the idea may be to a tradisionalist, No physical reasons have been presented... YET.
It may not be Yar to some but is it sound design?