Exterior ply to my new room addition

[CaptainChuck II]

I have a 60' (70' overall) wood head boat I am converting to a live aboard. I just added a 14' x 14' x 8' to the upper deck attached to the wheelhouse. I will use this while I remodel the main deck house. Anyway I sealed, bast coat painted and will apply an exterior quality coat of paint next to the outside walls. Exterior ply, will they last? or do I need to glass and resin them? Thanks.

Chuck

[skipper68]

Throw some shrink wrap or a tarp over it,and get your answer later.It's sealed,time for the real work....If it's not marine grade,you will find out. Pix!

[tomlarkin]

Exterior ply will almost certainly check very quickly, wrecking your paint job, even if it's not a structural issue. Glass and epoxy sheathing will keep that to a minimum.

What's a 'wood head boat'?

You need to post pictures or everyone here will yell at you :-) If you have trouble posting, ask, and Thorne will help you out.

[Soundman67]

The best answer I have found for the whole exterior vs marine grade plywood is to use neither. I have gone and bought a product called MDO. Or in some places its called Crezone. It is a Medium Density Overlay plywood. Basically its a very good exterior grade plywood with waterproof glues and a resin impregnated layer of paper on its outside layer. This is the stuff that sign painters use. Prime it and paint it and it should last for 20 years. And it is a beautiful product to paint. I am only going to add epoxy and tape to the seams between sheets. Only time will tell if it works out for me. But for 17$ a sheet for 1/2 inch you really cant go too far wrong. Especially since the majority of the work sanding and filling is already done for you.

[Ron Williamson]

I'd also recommend the MDO over exterior ply.

$17/sheet for 1/2"?
Nice.
The last time I bought some from my wholesaler,in 2007 maybe,it was in the neighbourhood of $45.
R

[Thorne]

From what I'm getting from the original post, he's already built and painted the structure built from exterior ply. At this stage I guess that's about all he can do, as I don't think you can successfully put fiberglass over painted ply. It can be done, of course, but I suspect will be a waste of money and epoxy.

Since this is a temporary structure, just keep it painted and consider it a lesson learned about 'inexpensive' non-marine materials -- they often end up costing more and looking worse than using proper marine materials. Fasteners are another thing you can't cut corners on, as cheap coated-steel fasteners (non SS or SB) cause staining, rot and failure if used on any sort of materials.

[Soundman67]

yeah I understood that he had already built. just thought other readers of the forum may not have heard of the product and may be looking for something like it if they are reading this thread

[JimD]

Yeah, if its already built and painted then its done and throw a tarp over it for good measure. No point wasting epoxy and glass on it now.

[CaptainChuck II]

Yep, I added canvas and resin, seems hard as a rock, I guess only time will tell. It may be more permanent as it is looking good, and might be a nice guest room or my main sleeping quarters. Building the interior to be nice. Thanks, at least i know this posting works and I do appreciate the advice. I guess if or when it goes south one day i will replace with something better. Ok, major questions. I can purchase a 15kw 2007 Generac propane genset with low hours. The company that is selling it used it once in a while went out of business, so all is being sold. Anyway, what size tank do I need 200, 300gal ? I will need to keep 1- 4'x4'x3'high freezer and a regular size fridge/freezer. The rest I think the 4 big house batteries and 3000/6000 inverter will keep up with running the genset how many hours a day? So two questions, (1)how big tank? and how long a day minimum run time (2), thanks. photo's soon. Head boat? Once it was rated for 49 passengers + crew for fishing or mother ship to bring fishermen out to it.

One more thing, I will place the propane genset in the engine where the old diesel genset is. How about the LP holding tank should I put it in the the engine room or on deck. Thanks again on this fine cold Christmas night, have a good one.

P.S. Not sure how to make a new post in a category or how to add photo(s). Thanks..

[Soundman67]

Hey Chuck. glad things are coming along for you.
Besides the price is there a reason you want to add propane to your boat? You will have to add in bilge blowers and a propane sniffer. Also you will need to make sure that everything in the engine room is spark proof. If you have only had diesel on the boat til now these things may not have been built in.
Propane is heavier than air so it will sink to the bottom of the bilges and just wait there.
I am not sure about tank placement but I would guess it has to be outside the boat because those tanks have to vent if they get too hot or of course if there are any leaks. Also from what I understand you need to make sure that you have a single gas line from the tank to the appliance. no joins in the line at all. I use propane for the BBQ and for a dual burner in the galley. And I just use the 20lb tanks. that way I can easily carry them away to get them refilled. If you have a 200lb tank on board you will have to find a filling station where you can pull your boat up to. I dont know how many marine stations have propane on them.
Personally I would look at repairing,rebuilding or replacing the original diesel. Its safer and easier. One fuel for the boat.

Posting pictures instructions are in the FAQ. Looking forward to seeing your boat and the work you are doing.