Why an old plastic boat makes sense…

The other day while I was comparing various “classic plastic” designs I had a bit of a eureka moment…

Most of these boats are built like frelling tanks!
In the various boats I was looking at, almost none of the interior structure was actually… well, the best word to describe it, would be, structural. Or, in other words, 97% of the interior is just furniture. Think about that for a moment.

Having worked on quite a few classic plastic boats over the years, I was actually aware of this situation on a practical level but had never really thought about it past the point of “Sure you can pull out and replace that bulkhead without worrying about the boat taking on the shape of a banana in the process”.

Of course, these days folks build boats differently because it’s cheaper to make boats in a monocoque structure with all of the interior parts sharing the load. Which I’m not knocking in theory and I strongly believe that a monocoque structure is the only way to go when constructing a boat but, with that being said, you can take it too far… Something you’ll understand in a hurry when you go to replace a galley in a modern boat afloat and once you’ve removed a cabinet find the hull oil-canning inward once the support of said cabinet is no longer in place.
Now, our CAL 34 is a good example of a boat where the interior structure in the boat is doing pretty much zip in support of the hull and deck and, providing the mast/rig is not up, you can pretty much rip out the interior to your hearts content while afloat and the hull will remain the shape Bill Lapworth intended throughout the process.
But, back to that eureka moment…
When you replace the interior it makes all kinds of sense to rebuild as a monocoque structure because it won’t cost anymore to speak of (a 6″ roll of biaxial tape and a gallon-and-a-half of epoxy would be the added outlay), it will make an already strong structure a whole frelling lot stronger and, dare I say it, a whole helluva lot stronger than pretty much anything you’ll find on the new market today.
Of course, while you’re doing the monocoque presto-chango there’s nothing that says you can’t fine tune the interior to better suit your personal needs while you’re at it.
Or, in other words…
Old boats truly rock…

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1 thought on “Why an old plastic boat makes sense…”

  1. On our Pearson Vanguard (32) two semi-structural bulkheads ran about a foot fore and aft of where the deck step was for the mast. Given the Vanguards quite thick hull this is where I cut a hole in the deck and bolted on a mast partners tube for the steel pipe mast for the junk rig. The same for the super thick area around the keel top where the new steel mast step box went into. Never gave it much thought about being precarious and it always seemed rock solid. A few light shrouds completed the rig. I would not do this with, say, a Hunter sailboat.

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