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» Forum Name: PT Boats - General
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» Topic:
ELCO 80' Decking Types
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While going over Dick's ELCO drawings I came across decking types used on the 80' boats:
Boat Number / Construction / Dimensions
103-108
Mahogany planking, 2 layers laid fore and aft
Inner layer 5/16", outer layer 3/8"
109-196, 314-367, 372-383, 487-497, 546-563, 731-760
Mahogany planking, 2 layers laid fore and aft
Inner layer 3/8", outer layer 5/16"
486, 498-545, 565-624
Plywood
9/16"
Notes:
Coaming sits on lower layer of planking on plank decked boats.
Coaming sits on top of plywood on plywood decked boats.
Planked boats have a layer of marine glued airplane fabric between layers.
Information is based on ELCO type section drawings.
Posted By: Jeff D | Posted on: Apr 10, 2010 - 5:16am
Total Posts: 2200 | Joined: Dec 21, 2006 - 1:30am
Interesting that they reversed the size of the planking after the 108 boat. I wonder what drove that change. Cost or quality? Jeff, does it specifiy the width of the planking?
Dave
David Waples
Posted By: David Waples | Posted on: Apr 10, 2010 - 5:36am
Total Posts: 1679 | Joined: Jan 2, 2007 - 9:55pm
Good question about the width, one my rather scatter-brained self didn't think of. I checked assorted drawings and didn't find an answer. I'll post if I run across them. The closest I found was an upper layer deck planking drawing for the 731-760 boats that shows joint locations. It didn't give widths but scaling the drawing comes up with a width of about 5.5".
My guess is that the thicker layer should go down first for strength. Maybe a carpenter put a foot through the thinner layer while laying it down...
Posted By: Jeff D | Posted on: Apr 10, 2010 - 10:13am
Total Posts: 2200 | Joined: Dec 21, 2006 - 1:30am
According to my ORIGINAL ELCO HULL CONSTRUCTION Manual, here is what is says:
Bottom Innr Skin 7/16" x 6" Outer Skin 1/2" x 6"
Sides inner Skin 5/16" by 6" Outer Skin 7/16" x 6:
Transom Inner Skin 1/2" x 6" Outer Skin 9/16" x 6'
Deck Inner Skin 5/16' x 6" Outer Skin 3/8" x 6"
Deck 5/8" Mahogany Plywood
--------------------------------------------------------------------------------------------------------------
There are of course many other measurements within this RTU Manual but too numerous for me to copy unles you guys want something specific............
Posted By: Frank J Andruss Sr | Posted on: Apr 10, 2010 - 10:55am
Total Posts: 3497 | Joined: Oct 9, 2006 - 6:09am
Cool, thanks Frank. That book scanned would be great at the hnsa web site... hint hint. [:-veryhappy-:]
Posted By: Jeff D | Posted on: Apr 10, 2010 - 3:19pm
Total Posts: 2200 | Joined: Dec 21, 2006 - 1:30am
I may give away my age here but thats ok.
Does anyone know if the plywood was made of 4 foot by 8 foot panels overlapped?
Or were there perhaps longer pre-made pieces that might have been wider?
The only reason I ask is that a 2 by 4 in the 40's was exactly that 2" by 4" , not the 1 3/4" by 3 1/2" we have now days.
Denny
Posted By: djwhite | Posted on: Apr 16, 2010 - 7:39pm
Total Posts: | Joined: Unregistered
I would think the finished ply construction would be the same strength whichever thickness was outside. Jeff may be right, it was chosen to facilitate construction, to get the stronger panels on first to provide a better work surface. I might add that since most damage (in our case) was to the skin layer and it was easier to form and work with a thinner ply, it might have influenced the decision.
I didn't understand djwhites question. A lot of people interpret Plywood to mean the 4X8 panels available to the construction industry. Some PTers protest that the boats were NOT plywood. But if you use the dictionary definition of plywood (layers of wood with cross-grain plies) then we can accept that they were indeed plywood, but djwhite's question I think assumes plywood refers to convetional 4X8 sheets. I never saw such plywood used anywhere in the war. Our plywood was built up of mahogany planking laid in a ply configuration. Hence his question is moot.
Posted By: BobPic | Posted on: Apr 17, 2010 - 12:49pm
Total Posts: | Joined: Unregistered
I certainly was not around during the war years, so please excuse my ignorance. The only plywood which I am familiar with is the 4 by 8 foot sheets sold today.
That is why I was asking the questions I asked. Is the 6 inch wide double planking with marine glues fabric between the layers considered "plywood" for the decking? As the later PT boats are listed in Jeffs' listing
If so, how is it visably different than the earlier PT boats which are shown as having the two plank with different thicknesess?
Part of my question was wanting to know if there were longer sections maybe such as two feet wide by ten feet long or was there some other configuration.
I finally received my tax refund so I am ordering our moderators set of Elco plans, so maybe I won't have quite so many stupid questions.
Please explain this to me as I have become very confused and I am not a long time boat person.
Posted By: djwhite | Posted on: Apr 17, 2010 - 5:04pm
Total Posts: | Joined: Unregistered
That's something I didn't know, that lumber dimensions used to be accurate. Now I suppose it's the dimension before final finishing, snd bordering on false advertising in my book because the only logical reason would be to have the consumer suck up the trimmings from the rough cut. It sure makes things more difficult.
Bob, there sure was a LOT of plywood used on PT boats. It looks like ELCO made a lot of it up themselves. And I'm sure a lot of time was saved using a single layer (another thinner doubler layer was added around areas needing extra strength) of ply over a double planking.
Denny, the drawings show different sizes were used, up to 144" length. Max of 68 x 96" for the 577-624. The main layout was two center sections with two wing sections with butt joints along the center line and along each wing piece. Scarphs were made on the fore to aft section joints. One of the YouTube videos shows a bunch of workers at the factory carrying a really long section, maybe they made up the scarphed sections before laying them on the boat? The planked decks are not considered plywood.
Posted By: Jeff D | Posted on: Apr 17, 2010 - 11:30pm
Total Posts: 2200 | Joined: Dec 21, 2006 - 1:30am
Hi, just a note that Frank J. Andruss, Sr. new book Building the PT Boats on page 91 has a very good photo showing the workers at Elco with an outside section of Plywood Decking ( not plyed wood ) about to lay it down on the decking frames, this section runs just about the full length of the Boat (allowing for the centre sections ). This section of Decking would have been made inhouse just as Elco made many of the special timber parts for the Boats.
Hope this helps a little .
D.buck
Posted By: David Buck | Posted on: Apr 18, 2010 - 3:46am
Total Posts: 332 | Joined: May 4, 2008 - 2:59am
Sorry folks, I surely mispoke. But I really do not remember ever seeing construction sheets of plywood being used on the boats. I apologize to djwhite and thanks to JeffD. I suppose my memory lapse is partly due to the fact this subject didn't seem important at that time. Otherwise my memory is perfesc...now what the heck were the wings made of?
Posted By: BobPic | Posted on: Apr 18, 2010 - 7:12am
Total Posts: | Joined: Unregistered
Your memory is great Bob, I try to think back no where near that many years and draw mostly a blank... and you're right in that most decks were planked except the ones listed.
The wings were plywood, the 103-367 was 27/64" and curved wings on later boats were 5 layers of 5/64" birch plywood glued over a mold. I'm not sure if the earlier boats were layered over a mold also.
Another area of the boats that made extensive use of plywood was the chart house and day room top, sides, and fore and aft walls.
Posted By: Jeff D | Posted on: Apr 18, 2010 - 11:50am
Total Posts: 2200 | Joined: Dec 21, 2006 - 1:30am
Hey guys,
I think I saw in Frank Andruss' awesome book "Building the PT Boats" a photo taken at Elco that shows the entire deck as one giant piece made of plywood that was installed as a single piece onto the boat all at once. All of the holes were precut etc, so it fit like a glove in place onto the boat. Frank could probably provide more info on this, but I think this was on the late war 80 foot Elco boats. I am unsure what series. There did not appear to be any 4 foot by 8 foot pieces ever being used in the picture. Just as a related side note, we are redecking the PT658 Higgins in Portland right now. We considered replanking it as a 2 layer planked mahogany deck, but the cost of materials and labor was too prohibitive to do so. We decided to do the next best thing by decking it with custom ordered Marine Grade 12 layer 3/4 inch thick mahogany plywood in 5 foot by 10 foot sheets, which will have the seam down the centerline of the boat. Then we soaked it liberally with clear penetrating epoxy sealer several coats inside and out and on the edges too. Here is a picture of her in the process of being redecked. Jerry
[image]http://i130.photobucket.com/albums/p249/ptboats/Deck19.jpg[/image]
Jerry Gilmartin
Posted By: Jerry Gilmartin | Posted on: Apr 18, 2010 - 2:57pm
Total Posts: 1473 | Joined: Oct 8, 2006 - 11:16pm
Denny . . .
As stated very well by Jerry above, there is also the "Giant Killer" video I uploaded to YouTube a couple a years ago. On video 2 of 3 at about the 7 minute mark they talk about and show the continuous length of plywood being laminated and applied to the boat (ELCO).
Catch it here:
[url]http://www.youtube.com/watch?v=8e6Ei5UvLqI[/url]
Other parts of the video and other PT Related video:
[url]http://www.youtube.com/rjwgdi#p/u[/url]
DIck . . . .
Posted By: Dick | Posted on: Apr 18, 2010 - 4:22pm
Total Posts: 1417 | Joined: Aug 27, 2006 - 6:36pm
Thank You all for your input.
Bob, Sir I was by no means insulted in any way, only confused. I relish hearing and learning from anyone who was there.
I have been gathering information to help me build the interior of the 80" Elco by Italiari.
I intend to display it very much like Dicks poster from PT Boats Inc. David W. and Jerry B. have been helping me a great deal. They are the ones who introduced me to this forum and I have gathered enormous amounts of information from everyone here.
I am thinking of seeing if I can purchase four actual cartridges to hold the deck up and behind the open hull. With a mirror under the deck showing the bottom of the deck which I hope to light with a fiber optic light set up from another model set. I hope it will show the space that these men had to work in.
I have almost printed every page of Jeff D.'s pt103 web site for reference material. I hope that is all right with you Jeff?
Posted By: djwhite | Posted on: Apr 18, 2010 - 5:31pm
Total Posts: | Joined: Unregistered
Sure thing Denny, glad you find my site helpful.
Dayum Jerry, you got your work cut out for you! Thank you for posting that image, very interesting seeing under the deck.
Posted By: Jeff D | Posted on: Apr 19, 2010 - 1:10am
Total Posts: 2200 | Joined: Dec 21, 2006 - 1:30am
Found this article Dec 1944 Popular Science Magazine on the use of plywood during WW2 by Higgins. Thought you might be interested. [url]http://books.google.com/books?id=4CEDAAAAMBAJ&pg=PA176&dq=pt+boat+plywood&as_brr=1&as_pt=MAGAZINES&cd=1#v=onepage&q=pt%20boat%20plywood&f=true[/url]
Gary
Posted By: Gary Paulsen | Posted on: Apr 19, 2010 - 5:33am
Total Posts: 249 | Joined: Feb 14, 2009 - 6:31am
Jerry
When that deck is completed how hard will the outer layer be, and how often will you need to do maintainence on it. If I remember, didn't PT 486 do the same thing to their hull.........
Posted By: Frank J Andruss Sr | Posted on: Apr 19, 2010 - 10:12am
Total Posts: 3497 | Joined: Oct 9, 2006 - 6:09am
Hi Frank,
I did not really mean to hijack this thread. But I will answer you questions about PT658 decking. The deck will add to the stiffness of the boat quite a bit. The hardness of the mahogany plywood should be the same as the two layers of mahogany that was on there originally. (I think originally it was 3/16 thick spruce under 1/2 inch mahogany planks) We are also considering adding a top layer of heavy fiberglass to help waterproof the entire deck. It will be painted over and we are getting a pro to do the installation. We are making sure to liberally soak the entire structure, inside and out with the epoxy (Smiths) before we apply any other covering. So several professional boat builders have been consulted in this and this seems like the way to go. I am really happy with the design which will keep water from being trapped between the edges of the deck and the covering board and rub rail. On our last installation, water was trapped there and contributed to the rotting of the structural members of the boat. Here is a photo showing the new deck being coated with Smiths epoxy. That is me with the roller! Jerry
[image]http://i130.photobucket.com/albums/p249/ptboats/Deck020.jpg[/image]
Jerry Gilmartin
Posted By: Jerry Gilmartin | Posted on: Apr 19, 2010 - 11:31am
Total Posts: 1473 | Joined: Oct 8, 2006 - 11:16pm
Jerry
With the epoxy being put on, and then the advent of Fiberglass, that should really solve any problems you may have with water down the road. I seem to remember PT-486 when it was the SIGHTSEER that the previous owner used epoxy and fiberglass on the hull to seal it. With that type of process your chances of springing a leak or water damge from rot are not to nothing. I am sure we all appreciate seeing the photo's you have put up, so by all means keep them coming. Thanks for the information...........
Posted By: Frank J Andruss Sr | Posted on: Apr 19, 2010 - 2:30pm
Total Posts: 3497 | Joined: Oct 9, 2006 - 6:09am
Hi Jerry,
Did you scarf the fore and aft joins or butt join them ?
I noticed that in your second photo the second centre join is sitting a little high and could be a trip hazard or are you planing to smooth this over?
The photos that you put on the board really shows what it takes to maintain one of these Boats and what a labour of love it must be.
D.buck
Posted By: David Buck | Posted on: Apr 20, 2010 - 3:04am
Total Posts: 332 | Joined: May 4, 2008 - 2:59am
Hi David,
No we did not scarf the plywood. The joints were sanded off to be perfectly smooth so there is no trip hazard from anything sticking up. We are also rebuilding the "rub rail" (or gunwale) out of laminated mahogany planks. It needs to be 4 inches thick and follow the curve of the deck edge so using lamination seems like the way to go. I will send you guys a photo when we get the new deck painted. This week I am working inside the charthouse reinstalling the radar and the radio as well as some structural arches at the corners. It is truly amazing what those PT Boat builders back in the 1940s were able to do at such a fast pace! Stay tuned... Jerry PT658 Portland
Jerry Gilmartin
Posted By: Jerry Gilmartin | Posted on: Apr 20, 2010 - 8:24pm
Total Posts: 1473 | Joined: Oct 8, 2006 - 11:16pm
Hi Jerry how does the new deck look and are you happy with the built up "rub rail" once completed and painted?
How did the fiberglass application go and will it meet your expectations for a longer deck life?
Excuse the time its been for me to follow up this thread but I have been in the outback working with the drop bears and hoop snakes for the last few months.
Cheers,
D.buck
Posted By: David Buck | Posted on: Aug 1, 2010 - 1:32am
Total Posts: 332 | Joined: May 4, 2008 - 2:59am
Hi David,
i will post photos soon of the current status of the boat. It looks really good! In the meantime you can look at our website and see some recent pics when we got underway in June and again in July. [url]http://www.savetheptboatinc.com/[/url] then go to the Photos link. Jerry
Jerry Gilmartin
Posted By: Jerry Gilmartin | Posted on: Aug 1, 2010 - 12:14pm
Total Posts: 1473 | Joined: Oct 8, 2006 - 11:16pm