Lumber Quality in Boats Built with Epoxy Construction Sytems???

[JCP]

I have not really seen this addressed anywhere. I've been wondering when using epoxy to build a boat, either strip or strip with a coldmolded overlay, and going the whole route with complete epoxy encapsulation, is it acceptable to use lumber of a lesser quality than what is usually recommended for traditional carvel construction? What I mean is, can sapwood and lumber from younger trees be used with comparable results since the epoxy should help prevent decay?

[MiddleAgesMan]

Comparing the lumber needed for carvel vs. strip-molded construction you can certainly get away with a few small tight knots in the stripped layer--minor defects that would become serious problems in carvel. You might even get away with very small tight knots in one of the inner veneer layers.

If your question is really asking about various species again the answer is Yes you can use a softer less expensive wood in strip-molded hulls compared to carvel. Judicous use of epoxy and CPES will turn that white pine or cedar into a harder material capable of withstanding stresses that would result in failures in carvel construction.

I would probably choose better quality lumber as boat size increases. For larger designs which will cost many thousands of dollars use the best lumber available to protect your investment. For smaller craft you can probably use lesser grades.

[boatbear]

I'll fess up to using Pinus Radiata (not known for its rot resistance) for the lapstrake planking on my dory, all epoxied to within an inch of its life. Still perfectly sound after 15 years. The bottom and garboards are Hoop Pine ply, also encapsulated (and glassed).
Charlie

[JimConlin]

It depends.

For molds, patterns, jigs and the like, anything goes. I confess that I've occasionally used junk materials such as lauan ply or styrofoam (Gasp!) on projects which I regarded as prototypes that would be thrown away and where the harm of a failure was small. There aren't many such cases in boats.

Whether a material with different mechanical properties than the specified material is adequate is an engineering problem that should be analyzed on a case-by-case basis.

Substituting a material of lower decay resistance might be OK If you do a perfect job of encapsulating it and it's never breached. Only you can assess this likelihood.

Lastly, consider the value of the savings in material vs. the value of the other things you'll put into the boat, like your labor. If I assigned any value to the time I've put into building boats, I've never done a boat where the value of the lumber was over 15% of the total. Why compromise the value of the whole project for such a small saving?

[kc8pql]

...choose better quality lumber as boat size increases. For larger designs which will cost many thousands of dollars use the best lumber available to protect your investment. For smaller craft you can probably use lesser grades.

I think that sums it up in a nutshell. Buy the best you can afford for a 40' cruiser. Cut costs on the 6' dinghy.

[Lew Barrett]

I think that sums it up in a nutshell. Buy the best you can afford for a 40' cruiser. Cut costs on the 6' dinghy.

But it begs the question. Just how much do you save skimping on the dingy? I understand the intent completely, but your labor is all the same on every boat, relatively speaking. Added: I'm not a builder, so maybe I come at this from the wrong point of view.

[kc8pql]

Should have phrased that "If you have to use low quality material, do it on the dinghy."

[Lew Barrett]

I agree, especially because redoing big boats is such a pain. The six footers are less difficult to cut up. But can you make a pleasant little fire from an epoxy soaked one, or is that bad eco juju?:D Get that smilie face in there so you know where I'm coming from!

[Gary Bergman]

hmmm, but if the bigger boat does have a problem, and you need to ditch in the dink, I'd hope for uh, not scrimping too much,eh?

[paladin]

Each boat in turn will take a finite amount of time to properly finish. If you use poor grade materials for the first go around where will you be and will you have time to effect repairs?......