MDO (medium density overlay)

[Bigshrimpin]

Has anyone considered using MDO for a floor or as a core material?

It's got some properties that seem really attractive.

- Smooth/Flat surface
- Same exterior grade glue used with marine plywood.
- supposedly no voids (same as marine ply)
- price is much less than marine ply


Not sure about the number of plys?

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[pogden]

Isn't that not so much ply but particle board or coarse saw dust put together with better glue?
It's pretty heavy too!

[Bigshrimpin]

Nah . . . your thinking of MDF medium density fiberboard.

MDO is an exterior grade plywood with one or two paper faces . . . it's used for highway signs.

[Bigshrimpin]

http://www.apawood.org/pdfs/managed/B360.pdf

http://www.apawood.org/level_b.cfm?content=prd_faq_main

Found this from american plywood association.

I'm picking up a sheet tomorrow

[FELLOW-SHIP]

Ha Bigshrimpin
I did my entire boat with marine grade plywood. The Deck with ½ “ and the transom with 2 sheets of ¾”. If I had to do it all over with again I would do things differently. On the transom I would use a composite material and with the deck I would use plywood where the sheet metal screws attach the center consol and the leaning post seat but for the rest of the deck I would use composite materials. When I did my boat the composite materials were being used, but there was not enough years of use on the new boats to influence me from using the traditional materials of marine grade plywood. Usually it takes 5-10 years of use to really know or not if it really works. As for this new type of plywood with paper laminations in it. I personally would not use it due to the possibility of delamination. For me when in doubt either go with what is tried and proven or go one step up in quality.
FellowShip [img]/images/graemlins/grin.gif[/img]

[Bigshrimpin]

Fellow-ship . . . that's good advice. I really don't want to rip the floor up in 5 or 10 years. So I order 5 sheets 3/4" Marine Ply BS1088 for the floor, but I'm still curious about MDO. Apparently MDO was used extensively by chris craft in the 50's and 60's in their sea skiff line of boats.

[thedink9]

Big Shrimpin

I rebuilt my floor just as fellowship stated. I used 5/8 plywood where the console and leaning post bolted into and corecell everywhere else. I also redid my hatches with corecell. I figure I have lightened the boat over a hundred pounds and the hatches are as rigid as ever. I didn't do the transom yet but would probably use coosa board, as the samples I received look good are dense and come in 1 1/2" thickness which would eliminate a few steps of glassing. The stuff is very expensive though, probable $45o -500 for the job.
Dink

[Ed]

Hey Big Shrimpin-

You might want to consider using Greenwood XL plywood. Not sure about costs, but is the stuff Grady uses and is pressure treated and guaranteed for life.

Have no idea where to get it though....sorry!

Ed

[pogden]

Greenwood Forest Products 5895 SW Jean Rd Lake Oswego, OR 97035 Phone: 800-333-3898 Fax: 503-635-5399.