2 questions... I have a 29' pontoon with rotted decking; the supports are 24" O.C. I plan to replace the decking with treated plywood. Do I need 3/4" or can I use 1/2" plywood? I just bought 7 sheets of 3/4" but I am thinking that may add too much weight. or would the weight difference be insignificant? Also can I use stainless steel screws to secure the deck to the aluminum supports?
Thanks for you help
you are correct in your thinking, 1/2 inch will free sponge and springy, stainless is the best, but predrill as they are soft and have a tendency to twist off before you get them in. imho, i would use 3/4 inch tougue and groove, so that the joint are totally solid. a little liquid nail in the joint of the tongue and groove is better.
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On a pontoon that long I would not use sheet metal type screws. Pontoons have a great deal or torsional stress (twisting) which could loosen those screws. Special flat head bolts and nuts make a much stronger fastening. One other tip is to make sure the 'toon is perfectly level before you begin attaching the deck. If it's not, you will end up with the superstructure twisted and the rig may not track properly.
On a pontoon that long I would not use sheet metal type screws. Pontoons have a great deal or torsional stress (twisting) which could loosen those screws. Special flat head bolts and nuts make a much stronger fastening. One other tip is to make sure the 'toon is perfectly level before you begin attaching the deck. If it's not, you will end up with the superstructure twisted and the rig may not track properly.
I Agree about Not using Sheetmetal Screws........
I'd use what they use at most of the Manufacturers,...... 3/16" Pop-Rivits..............
Rivits are Much More Secure than Sheetmetal Screws,+ Easier than Nuts,& Bolts.........
The 3/16" Big-Head rivits won't loosen, or pull thru,+ you can get them in Aluminum......
No Dis-similar Metals that way.....
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Tomdc, my only concern is with the new (relatively) chemical process that is used to make PT wood.. I work in construction and have found that stainless is the only thing the chemicals won't eat up.. I built a deck a couple of years ago using galvanized screws and recently had to re-fasten it with stainless as most of the existing screws had corroded down to almost nothing.. maybe aluminum would be ok. I don't know.. something to think about tho..d
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the problem with aluminium and stainless is electrolisis..the two metals dont match well.
replace your wood with what came off the toon, if its 3/4 then same.. 5/8 then same..
I would coat the ply with resin - 50/50 resin/acetone mix at first ( 2 hot coats of that ) then roll pure resin after that.
Im assuming that your gonna recarpet the thing..so mebbe you should put 2 layers of 1.5 oz mat over your whole project. then gel it for a water barrier.
Mainly thats me..what I have done in the past. but..no matter what you decide please please please resin or epoxy coat your edges of your wood that is the main failure of your ply m8.
2 questions... I have a 29' pontoon with rotted decking; the supports are 24" O.C. I plan to replace the decking with treated plywood. Do I need 3/4" or can I use 1/2" plywood? I just bought 7 sheets of 3/4" but I am thinking that may add too much weight. or would the weight difference be insignificant? Also can I use stainless steel screws to secure the deck to the aluminum supports?
Thanks for you help
Wow! You've given me much to consider. The pontoon is a 1972 and SS screws were used to hold the deck down which I believe to be 5/8". I have the 3/4" pt plywood and the SS screws. I couldn't find aluminum pop rivets long enough for this job. Largest I could locate are for 1/2" or smaller..
I hadn't considered what PT wood would do to the aluminum. I know that different chemicals are used for PT than used to be used that are supposed to be less corrosive.. but not sure of plywood??? I plan on using the PT plywood and using marine grade adhesive on edges at the joints.. What specifically should I treat the edges with? I used some PT 1/2" plywood to rebuild the control cabinet about 10 years ago and the wood is as solid now as it was then... I used a deck stain on that.. would deck stain be sufficient????
Thanks for all your replies.... The info has been most helpful and has me reconsidering how I will proceed.
I have removed 3 of the 7 sheets of plywood decking starting at the front of the pontoon. I laid down 2 sheets of the new plywood for fit and I am finding the frame isnt as square as the plywood.:'( I'm not sure if I should make the plywood fit the frame or to try and square the frame of the pontoon; If the plywood is laid perfectly parallel with the supports, the right side of the front support is over approx 1/4" beyond the edge of the plywood over the 8' of the two sheets of plywood. I can tweak the plywood to compensate easily and the edging trim would cover the difference. I'm not sure about tring to pull the front of the frame over, I'm afraid of damaging the pontoons or welds...:%
BTW... this is a 35 year old pontoon which I paid $1500 about 10 years ago for boat, motor and trailer... so I dont want to put alot into it. I just want it to float and be safe... It's definately not a show piece. I have a "don't laugh, it's paid for" sticker on the boat.... hopefully it will float for another 10 years or so..
Thanks in advance for further responses....
tomdc, 1/4 inch in 8 feet isn;t much. I wouldn't worry about it.. you could try to rack the frame it probably wouldn't hurt anything... sounds like you just want to get a few more years out of it. without spending an arm and a leg.. since you already have the ply and the fasteners, I'd just screw the ply down and throw some outdoor carpet on it and call it good.it will last a long time... don't waste money and time trying to glass over the pt.. it won't stick....
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New Deck on Pontoon
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