plywood deck installation

[CaptinJD]

Hi,

I Just got a 30ft. 68 Fairliner Express Top in good overall condition but needing some care. I have ripped the rotten plywood out and am looking to replace the decking.

I have BS 6566 12 mm - 1/2"Phillipine Mahogany ( is this over kill ?) It is a 8 x 4 foot area so I am hoping that it won't be a big job to start with.

Other then epoxy on the edges of the Plywood and on the frame where I am using the fasteners what else should I use ?

Am I overlooking anything. Are there specific fasteners I should use for plywood or is there a deck sealer/epoxy I should be using.

If there is anything I am obviously over looking please post it so I can learn what it is I must do to get this Job done right. Your help and experience is appreciated.

JD

[Dutch Peter]

Originally Posted by CaptinJD

Hi,
I have BS 6566 12 mm - 1/2"Phillipine Mahogany ( is this over kill ?) It is a 8 x 4 foot area so I am hoping that it won't be a big job to start with.

What's the original thickness? No need to go over that.

Originally Posted by CaptinJD

Other then epoxy on the edges of the Plywood and on the frame where I am using the fasteners what else should I use ?

Did you scarf the joints?

Originally Posted by CaptinJD

Am I overlooking anything. Are there specific fasteners I should use for plywood or is there a deck sealer/epoxy I should be using.

I'd use stainless or bronze fasteners. How you're gone seal the deck? Layer of glass or with a coat of epoxy. How was it originally done?

Good luck

[CaptinJD]

First off thanks for the reply.

Q: What's the original thickness? No need to go over that.

A: Will do thanks


Q: Did you scarf the joints?


A: No I did not scarf the joints and sorry to say I do not know what scarfing is. However I will for sure find out.



Q: I'd use stainless or bronze fasteners. How you're gone seal the deck? Layer of glass or with a coat of epoxy. How was it originally done?


A: Brass is what I was thinking for a fastener. Originally they had put down a god awful vinyl I am sure it was very hip in the 60s but I would like to keep a wood finish so I was thinking of some kind of epoxy biased sealer any recommendations?

Thanks Again
JD

[CaptinJD]

Q: Did you scarf the joints?

A: No scarfing this is a one piece plywood job nothing more then laying a 8 x 4 piece of plywood over a frame built in the hull.

JD

[PAR]

Do NOT use brass on a boat, unless it's a cheap, easily replaced hanging lamp or something. Brass will not survive long in the marine environment and being under bedding compound or sheathing of some sort will prevent you from inspecting them when necessary. Bronze (and the many grades of it) is a far better material for fasteners. Stainless is my second choice, but it has limitations in it's application and use.

Build the deck as it was previously built (originally?) unless you have a great deal of experience building decks, let alone the rest of the boat, this is always the best/safest way to go.

Now you may make some changes, like dynel or cloth sheathing rather then canvas. Bedding compounds and adhesives have come a long way since the construction of this little yacht and could present some options for you.

You could have a natural finished (varnish) deck, but it would be slick underfoot if wet and large expanses of plywood grain, even the good stuff looks wrong to my eye (you see it's cut the a different way to make plywood and looks weird to woodworkers and boatbuilders) Most folks will not notice this, but the a few will.

More details and a few photos about your project would help greatly in addressing the issues you may have.

[Dutch Peter]

Originally Posted by CaptinJD

Q: Did you scarf the joints?

A: No scarfing this is a one piece plywood job nothing more then laying a 8 x 4 piece of plywood over a frame built in the hull.

JD

JD,

For a proper connection with the rest of the deck, you should scarf!!

[CE_Cox]

It is good practice to coat the top surface of the ply with epoxy as well as the edges and then lay a suitable deck material on top of the ply.
That way the top surface takes the wear and tear and the ply keeps you dry.
BFN
Chris

[CaptinJD]

Thank you for all the help.

One question .. What is scarfing ?

Thanks,
JD

[CE_Cox]

Hi JD
It is a way of jointing planks, keels and spars.
It is a sloping joint with a length 4, 6, 12 times the thickness respectively.
There are various forms see http://www.uscg.mil/hq/g-m/nvic/7_95/n7-95.htm
sec 5.3
Lloyds rules apply to these lengths and the placing of the joints
Regards
Chris

[CaptinJD]

Thanks Chris,

That is a great link thank you all very much I will post some pictures as soon as I can to share my progress.

Thanks again,
JD

[PAR]

Look folks, the construction of this deck doesn't use or need scarf's, the seams fall on deck beams or stringers. The boat had none originally (at least my old buddy who remembers the design said so) and would be typical of this type of construction.

Scarfing is really only necessary when you want to hide a joint under paint, as in a repair that can be made seamless or in pieces needing to made longer/wider than available stock, but maintaining the same properties as the rest of the stock (bending without hard spots, etc.) Scarfing in a repair isn't necessary if it falls on a beams and stringers, to be covered in goo and paint, cloth or whatever.

Typical scarf joints are 8 to 1 ratio or better, less then this results in a hard joint, though it would be seamless under putty and paint, would not have the same bending, twisting, flexing or other qualities as the rest of the piece. I use the biggest ratio I can fit into the piece or my scarfing jig which ever hits first. I'm doing some more ribs for a steam bent, lap strake boat and 10:1 is the average, though a few places I've had to back off to 8:1, but only because I can't reach behind things to get fasteners installed, so they're short scarf's.

Your deck was originally canvas covered and you can do that again, though a better idea may be to set Dynel or cloth in epoxy. Embalm your plywood with epoxy (several coats, the first few thinned or CEPS'd) fill the seams of the installed ply with thickened epoxy and sheath the whole deck with new canvas, cloth or Dynel, then paint.

I'll bet there is rot in the fastener holes and maybe more in the beam ends or lands. Insure you've removed all traces of this before you close everything in. You can use stainless fasteners (except in oak beams or stringers) if they are well coated with epoxy and are not exposed . I'd use bronze to avoid any risk of fastener sickness in the beams/stringers. DO NOT MIX FASTENER TYPES IN THE BOAT. If she is bronze fastened, then you have to use bronze, if steel then steel.