possibilities of plastic panels 4 yacht construction?

[Peter Duck]

I'm a newbie to these forums so excuse me if there are threads existing on this topic.

I have been wondering for some time about the feasibility and cost of using some type of strong plastic panels or similar that can be joined to construct a cruising yacht. Looking at yard funiture, water tanks etc it seems plastic of some types, if designed with the right bracing may be strong enough, has anyone heard of anything like this or have any ideas if it could work?

[bistros]

Originally Posted by Peter Duck

I'm a newbie to these forums so excuse me if there are threads existing on this topic.

I have been wondering for some time about the feasibility and cost of using some type of strong plastic panels or similar that can be joined to construct a cruising yacht. Looking at yard funiture, water tanks etc it seems plastic of some types, if designed with the right bracing may be strong enough, has anyone heard of anything like this or have any ideas if it could work?

Anything can be done, and just about everything has been tried.

The fastest growing segment of small dinghy sales is rotomolded and thermoplastic hulled boats. These hulls are practically tough and durable, able to withstand a lot of abuse. The two main plastic construction methods are injection thermomold and rotomolding.

Downside is that repairs are tough if major damage is done - plastic "welding" isn't as simple, reliable and strong as the original surface. Plastic hulls are much heavier than most other materials if built to the same strength. Plastics don't like long term UV exposure - degradation in strength happens pretty fast.

I own and paddle a Perception thermoplastic whitewater kayak (pretty much all whitewater boats are plastic). We don't leave them out in direct sunlight longer than necessary.

Larger scale boats may not be as advantageous in plastic, as the larger the unsupported surface span, the more likely oil-canning (cyclical plastic deformation due to varied surface pressures) will occur. Soft hulls are slow hulls, therefore the stiffer the surface, the faster and better performing the boat. I think weight would quickly become a factor in larger boats as well. More ambient heat equals more flexing as well.

Wood boat folks said fiberglass would never catch on, and fiberglass people said composites were too expensive for mass markets. Who knows, maybe Tupperware larger boats will become a reality.

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Bill

[Munter]

My experience with plastic boats is the "Topper" dinghy we used as a sail trainer at my old club. They were heavy, slow and indestructible which made them perfect for beginner sailors. It didn't take long before most were looking for something lighter and faster. I'm told there are newer designs out there in plastic that perform much better but can't imagine that they come close to a good foam sandwich boat.
If the properties of the plastic suit your application then they might be a good idea but I can't see a large vessel being constructed this way due to the issues listed by Bill above.

[Peter Duck]

The thinking is that there may be a way to take the current $30K/ft yacht to $1k/ft by using plastic panels and ribs & epoxy joined. A sort of flat pack Lego/ikea boat that might sacrifice 20% performance by using composit rigging, plastic tarp like material for sails etc not costing $1-2M for 60ft but cost $60K and be affordable to people like sea scouts or outward bound, yet still able to cross oceans safely ( if a little slower )