The Glen-L Mist Miss Bill of Materials is pretty clear on what’s necessary to build the craft.

At the minimum, the transom and frame gussets can be 1/4″ AB Exterior plywood, while the stem, breasthook, and floor timbers can be 3/4″ AB Exterior ply. So far so good, except I’d like to go the extra step and get Marine-grade plywood. It’s strictly not necessary, because the exterior glue on the plywood is fine, and the pieces will be encapsulated anyway, so I should be able to go down to Home Depot and take care of business, right?

Here are some notes from Ken Hankinson on Plywood:

Some feel ONLY Marine plywood should be used for hull planking. But I think this is too rigid a rule. The important quality separating Marine grade from Exterior panels is the quality and soundness of the inner plies and their construction (both are made with waterproof glues as noted above). With the Marine panel, there should be no major voids or surface defects, and inner veneer joints (if they occur) should be tightly fitted.

That said, using Marine plywood is most critical in my opinion where panels must conform to rather extreme curvatures (the bow in most boats, especially the bottom), and for boats built with “stitch-and-glue” methods. Another case where Marine plywood would be highly advised is on boats intended for high speeds and/or severe service.

I’m not against using a good grade of Exterior plywood (for example, AB) for planking, and I’ve never heard of a boat falling apart because of it. You may have to make some repairs to the panel (e.g., fill voids) which can get tedious and is not always successful. But in flatter hull areas such panels will suffice for most boats. Exterior panels (with any major defects repaired when possible) can usually also be used for most internal members throughout a boat without problem for such items as transoms, gussets, bulkheads, etc.

Since I hope to have this boat excel in high speeds, and I want the very best in terms of construction, rigidity and strength, I’d opting to go with Marine-grade ply, even for the framing.

Which leads me to the issue. It gets difficult in finding marine-grade plywood here. It’s simply not available locally.

  • Difficult: Finding Marine-grade plywood
  • Extremely Difficult: Finding Marine-grade plywood thinner than 1/2″
  • Impossible: Finding Mahogany marine-grade plywood

Results: Only one vendor in the Valley had any Marine-grade plywood (Doug Fir) thinner than 1/2″. That was Frank Thomas at City Plywood. He had 3 sheets of 1/4″ and 2 sheets of (somewhat damaged) 3/8″, along with plenty of 1/2″ and 3/4″, and some 5/8″. And that’s Douglas Fir!

He said he normally sells to cabinet makers and boat builders. Apparently the cabinet makers trust the thinner no-voids ply when making curves, similar to the need on the bow of the hull as mentioned above.

I took what he had – I rented a U-Haul ($19.95 a day my ass!) and drove up to I-17 and Deer Valley road just to buy six sheets of plywood. Now I could have gotten away with 3 sheets, but I didn’t want to do this again and I wanted a bit of a buffer in case I made major mistakes:

  • 2 1/4″ Doug Fir – for the gussets, possibly for the transom
  • 1 3/8″ Doug Fir – possibly for the transom
  • 1 1/2″ Doug Fir – transom?
  • 2 3/4″ Doug Fir – stem, breasthook, floor timber supports

Interestingly, the plans for the Mist Miss disagree a bit with the Bill of Materials. The plans say the transom is to be “1/4″ or 3/8″. Well I want a robust boat, so I was leaning towards 3/8″, and besides, unlike a car you’re less likely to be rear-ended in a boat. All the same, maybe make it super strong and go with 1/2”. I got all three in order to punt that decision a few months.

If you’re interested, call ahead:

Frank Thomas – City Plywood; 2127 W. Melinda Lane; Phoenix, AZ 85027; 623-587-1500

Incidentally, the “$19.95 per day” U-Haul ended up coming to $122:

  • $19.95 for the day
  • $63.48 mileage – 92 miles round-trip at $0.69/mile
  • $15.54 refilling 6 gallons
  • $12.11 rental tax (rental car rates, not sales tax)
  • $10 CDW “bad day/walk-away” insurance – not sure I needed that
  • $1 environmental fee

Another Result: I was able to find Okume Mahogany plywood in . . . California. Anaheim, specifically, at Anderson International Trading. They would have to ship it to me for $250, which is cheaper than a U-Haul two ways, or a cheap flight and a U-Haul one-way, and safer than renting a regular pickup truck with it’s 6′ bed and trucking expensive Mahogany in the desert sun on I-10 for 350 miles. That $1,200 order will be made in December/January depending on progress

No Luck:

  • Spellman Hardwoods:
    • Interior Okume – 1/4, 3/4
    • Genuine Mahogany – 1/4, 3/4
    • Imported Okume (interior) 1/4, 3/8, 1/2, 5/8, 3/4
    • Doug Fir Marine Ply in 3/4″
  • Peterman Lumber: Doug Fir Marine Ply in 1/2 and 3/4
  • Rugby Applied Building Products: Doug Fir Marine Ply in 3/4
  • Heldt Lumber: Doug Fir Marine Ply in 1/2 and 3/4
  • Timber Woodworking Machinery and Hardwoods: Doug Fir Marine Ply in 1/2 and 3/4
  • Woodworkers Source: Mahogany (interior) only, and veneers
  • 84 Lumber: Doug Fir Marine Ply in 1/2, 5/8, 3/4 (special order)
  • Lowe’s: Doug Fir Marine Ply in 1/2 and 3/4 (special order)
  • Woodcraft of Phoenix: “We only really deal with interior Birch plywood”
  • Rockler: “What do you mean by Marine??

Here are some Glen-L Plywood Links for reference: