Lowes has something they call "Patriot Ply" taht sounds like this stuff- turns out it is eucaliptus. Sample survived a week in the dishwasher but hasthick cores and paperthin outer plys. This Sande stuff sounds like it may not be for boats. "minimum core voids, core overlaps" If it dosen't have 5 (or more) equal thickness plys I would not consider it for a boat.
It pays to use good materials- unless you want to gamble and hope for the best. Okume is more expensive, easier on tools (Merranti eats the hell out of plane blades and jigsaw blades) and said to be less rot resistant but if you store the boat under cover between trips I don't think this is a problem. I have 4 canoes made with Okume and all are still in top shape.
Guys, what a great resource we have here. Look how much information popped out of the "woodwork" in just a little while. I am once again reminded that Randy has started aa great resource for us all to share and contribute to. Good job everyone.
There have been several posts on Woodenboat forum (less the "people") about sande, most of which were skeptical of its use in boats.
It's really not likly that high quality sheet goods will ever be available from Lowes or HD. Their price points just don't mix with the custom high quality trades. They would never be able to move enough of it to make it cost effective. Jeremy and I both rowed boats built from the same frame set with the same okume. I am not sure okume is below the mark for these boats even it is not what we were after, assuming we could get it at a reasonable cost, which we can't. I will say that 3/8 is too light for boat bottoms which will be running above class III water. I have used a bunch of it in the last few months on my current project in bracing and other items. I will say the manufacturing is very high. I have cut many small strips using 1/8 1/4 and 3/8 and have never found any voids. Today I also made some cuts on 1/4 hydrotek which I had around from past projects. No voids in that either.
I share shop space with a dumpster diver. He has barrels of random pieces of wood from all over the world. It is staggering what cabinet shops throw out. 95 percent of what he makes is from salvaged wood of every expansive variety you can imagine. The table in the attached image was built from dumpster wood. While it's not a boat the point is that there are a lot of materials available for clever folks. We have lots and lots of nice wood in the shop which we can't identify. Many of the woods are harder to drill the steel. Mesquite and the iron woods are the hardest woods I have ever picked up. Many of them don't float. We have hundreds of feet of mahogany strips which were ripped from planks then thrown out after the main board was cut to size. They can be glued up for all kind of thing. This was the stock I used to frame my plascore hatch covers. If I had a wood fired boiler it would be easy to get enough wood to heat my home, all free.
The demands are so high that mahogany (of which there are so many) are going off the chart on price. Veneer plywood is so thin it's no longer reasonable for use as cabinetry. It's as thin as paper. In 20 years of day to day use it won't hold up. One mistake in finish sanding and we are down to the ply or MDF below.
The knock on mahogany plywood is that it's weak and the opinion usually comes from a comparison to doug fir. There isn't much which has the strength and flexibility of douglas fir. We just can't seem to get it in a void less marine configuration.
As fast as a substitute is found the price goes up. Makore is now closing in on mahogany price wise. I remember when teak and mahogany were cheap enough that we painted them. Back in the 70s I worked in a factory which got things packed in crates made from teak. Local wood workers hauled it away for us. On another thread someone mentioned ipe. I picked up a piece of ipe at the shop the other day. It was marked ipe as a sample from a vendor. If it is ipe it is so hard and dense I can't see being able to make plywood from it. Then again, like many woods there may be 50 types of ipe.
The problem with the idea of high quality 5 ply 1/4 fir is that it's not all that good looking as compared to mahogany for clear work and many custom boats don't get painted. So the demand for high quality strong fir plywood is likely going down with the ever increasing production of molded cheap resin boats. Too bad for us.
It's difficult to find suitable marine plywood in Salt Lake. Macbeath carries Aquatek meranti which I've read on here isn't a suitable alternative to Hydrotek. They also carry Okoume which I used on my last boat, but it is expensive and like you said, it's brittle. I asked if they could bring some Hydrotek in with one of their regular shipments from CA, but with shipping it will come out probably more expensive than the Okoume. Then the salesman said something which surprised me, that the Hydrotek has the same core as the Okoume, just different veneers. Is that true?
I'm going to use foam or honeycomb for the floor and bulkheads, and wood for the sides and interior. If building frameless with the sides sheathed in fiberglass and epoxy, is exterior grade plywood from the Home Despot a reasonable alternative, if the panels are glassed before bending?