New here from St. Louis

[figo]

Hi All,
Just saying Hi and letting everyone know I'll be lurking around. I am about to start a new project, a
15' Bass Boat from Glen-l. My previous experience is
an Uncle Johns Pirougt and a small 1 sheet row boat for my nephew. I have heard a little about using MDO
plywood in leu of marine. Any thoughts? Marine is hard to find in my area.
Frank

[JimD]

Welcome to the forum, Frank. I've never used mdo but I have built two Glen-L boats. Somebody had this to say about mdo:

From: Chuck Merrell

Bernie wrote: " Anyone out there using Medium Density Overlay (MDO)? This stuff was developed for billboards, a very smooth resin impregnated surface."

MDO (medium density overlay) is excellent for boatbuilding. It is usually produced to state highway department specifications and is supposed to last in extreme weather conditions with no checking, with only paint for protection for as I remember fifteen years with no deterioration. It is usually pressed up with douglas fir cores and centers, with a thin face on either side of lauan then over that the MDO, which is a phenolic resin impregnated paper which is stippled to easily take and retain paint. The MDO is impossible to separate from the plywood and is the reason why highway signs last practically forever.

HDO (high density overlay) on the other hand is not good for boat construction. While it is even more indestructible than MDO, paint won't stick to it, and not much else will either. HDO is built using the same process, the paper is a heavy phenolic coated paper, but it is constructed to be used primarily for concrete forms, and formulated to be slippery so that nothing will stick to it.

The reason for the lauan faces is to create a smooth surface which prevents the grain of the fir from telegraphing it's pattern through to the surface. The same system is used for laminating fine-expensive wood veneer faces like teak over fir plywood, but without the MDO.

The cost of MDO varies, but sometimes is pretty expensive. Years ago as a consultant working in the plywood industry, I watched a lot of plywood being laid up in the glue room, and in general MDO gets at least as much care as marine plywood, sometimes more and even better materials on occasion. The plywood, with the thin lauan faces without MDO, HDO, or veneer overlays are called "Decolam Blanks", are occasionally available, and make great boat wood if you can find it. You can tell what it is by measuring it. Usually it is slightly undersize because the MDO or veneer is missing. Most dealers don't know what they've got, and think that the "off dimension" is because it is perhaps imported, but that's not the case. Usually, it is made in 1/2", 5/8", 3/4" and sometimes 1" thicknesses.

[brad9798]

Welcome.

[Paulyboy]

Check online and you may find a decent source of single sided or 2 sided MDO. The 2 faced MDO is finished both sides. I've used both for signs and they all look good, some of them close to 20 years now. The attractive thing about 2 sided is that both sides will present you with a smooth and almost ready surface for that good looking paint job you'll want to put on the boat. BTW, pics please, as you go and when it's done, as well as the one that didn't get away!