Another trailer bunk question - attachment

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yardbird
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Another trailer bunk question - attachment

#1 Post by yardbird » Thu Aug 10, 2017 7:13 am

I need to recover my bunks. I'm just going to use marine grade carpet from pontoonstuff.com. No fancy plastic stuff at this time.

The wood looks to be in decent shape. As in... good shape. No evidence of rot, soft spots, punkiness.

My question is not really about the covering. I'm pretty sure I can mange that part, but rather the attachment of the bunk boards to their respective brackets. Currently, it's using carriage bolts, recessed, with torque washers. Nylon lock nuts with washers on the bottom side. I know for sure they haven't been touched for at LEAST the last 3 years under the previous owner. Appears to be galvanized carriage bolts. I'd probably replace them ... will replace the lock nuts for sure. Is it worth looking for (and paying for) stainless carriage bolts? Or ...if I'm going to do this every few years just replace the bolts with galvanized?

Right now.... the boat is in a slip. At the price we can get the slip for I am reasonably certain we'll put it there again next next year. ($450 for the year includes power and water) so the boat may occasionally be trailered to a lake somewhere, and will be stored for the winter on the trailer, but that's about it. So the trailer will likely get very limited use.

Oh, and after I recover the bunks I'm going to pull the wheels, inspect the hubs, etc. It was great on the 2 and a half hour haul to my house, but as long as the boat's not on it, just seems to make sense to do it.

ralph
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Re: Another trailer bunk question - attachment

#2 Post by ralph » Thu Aug 10, 2017 10:37 am

Good question on the stainless. I looked it up and, assuming your bunks are treated lumber, stainless would hold up best comparing it to hot dipped galvanized fasteners.

HOWEVER, the article goes onto state that consideration should be given on what material the brackets are that the bunks are attached to (example they give is joist connectors). I think they would just be sheet metal if I am not mistaken.

They say that stainless fasteners would hasten the corrosion of the sheet metal. You might want to stay with the hot dipped galvanized fasteners.

Check this article out

http://www.finehomebuilding.com/2012/09 ... ted-lumber
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yardbird
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Re: Another trailer bunk question - attachment

#3 Post by yardbird » Thu Aug 10, 2017 11:39 am

[quote="ralph"]Good question on the stainless. I looked it up and, assuming your bunks are treated lumber, stainless would hold up best comparing it to hot dipped galvanized fasteners.

HOWEVER, the article goes onto state that consideration should be given on what material the brackets are that the bunks are attached to (example they give is joist connectors). I think they would just be sheet metal if I am not mistaken.

They say that stainless fasteners would hasten the corrosion of the sheet metal. You might want to stay with the hot dipped galvanized fasteners.

Check this article out

http://www.finehomebuilding.com/2012/09 ... ted-lumber[/quote]

Thank you! That was an interesting read. My trailer is galvanized steel. So stainless would actually hasten the oxidization. I had no idea. I think of stainless as like.... inert and it is apparently not. I'll just get new bolts and nuts and call it good. The bunk boards are treated. And, yes, I've read about not having treated on aluminum, but at this point I'm guessing those boards are better than 5 years old and probably not leaching much of anything. I do have one that I see is warped pretty good and I'll probably replace that one with untreated wood. I don't recall ever seeing yellow pine 2x4s around here. I'll have to pay attention. Most are SPF.

ralph
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Re: Another trailer bunk question - attachment

#4 Post by ralph » Thu Aug 10, 2017 12:47 pm

You might want to put some kind of a sealer on the untreated wood. I don't know if it would help but it sure couldn't hurt.

Yeah, I've seen a few questions lately on fastener material and corrosion. If I wouldn't have read about it I wouldn't have given it another thought.

Perhaps there are other Members who can chime in on this.
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Re: Another trailer bunk question - attachment

#5 Post by yardbird » Thu Aug 10, 2017 12:58 pm

[quote="ralph"]You might want to put some kind of a sealer on the untreated wood. I don't know if it would help but it sure couldn't hurt.

Yeah, I've seen a few questions lately on fastener material and corrosion. If I wouldn't have read about it I wouldn't have given it another thought.

Perhaps there are other Members who can chime in on this.[/quote]

I'm a woodworker. :)
Any kind of film coating will be destroyed if any water gets under it anywhere. If a natural check opens, the wood will kinda blow apart from the inside as a film finish tries to keep the water from moving through it... problem if the water is inside the wood. End grain will be nearly impossible to seal reliably.
So the next thing you do is use an oil that will penetrate. Linseed oil is the old standby. But now if you oil it... good luck getting any carpet adhesive to stick to it. If we keep doing what we're doing, the trailer will get dunked in the spring and then again in the fall. Between those times it'd see rain. I think I'm going to keep the 7 treated boards that are in good shape (and straight) and replace the one 6ft bunk board that's bowed with untreated. It's one board and I'll get to see how this works.

If I'm gonna tear the carpet up every 3 years or so, maybe it'll be fine. I have no idea.

But.... it's one board.

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Re: Another trailer bunk question - attachment

#6 Post by taylorjm » Thu Aug 10, 2017 2:20 pm

What a lot of people don't understand is that stainless steel will rust, if it comes in contact with a tool that is/or has touched iron. For instance, if you drill a hole in stainless steel, and you have used the drill bit to go through carbon steel, the stainless will rust in the hole. If you use a new drill bit, and it's a non-carbon steel bit, and go through stainless, it will not rust. If you use stainless bolts on your bunks, and you are tightening the stainless nuts on the back side of the metal trailer, which will scuff the metal against the stainless, the stainless will rust wherever it's touching the carbon steel trailer. Or, the stainless nuts will rust where your socket touched them on the edges because you used your socket on zinc bolts.

Or, if you are using stainless screws with a power drill, and you have used the Phillips head bit on other non stainless screws, all of your stainless screws will start to rust in the holes where the bit touched it.

Using a hacksaw, or grinder to cut stainless? If you used the saw blade to cut iron before, then your stainless will rust along the cut. The big thing in auto manufacturing was they were starting to use stainless steel on the exhausts, but if you look, everywhere they welded the stainless is rusting out. That's because they didn't use a stainless filler material in the welds, and it made the stainless rust with it. A big thing is wire brushes. If you used a wire brush on steel, then use it on stainless, everywhere you brushed that stainless will rust.

Think of it as contaminating the stainless. If you contaminate it with a metal that will rust, the stainless will rust.

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Re: Another trailer bunk question - attachment

#7 Post by killerkernrich » Thu Aug 10, 2017 5:09 pm

Well, I just had the boat dealer inststall new bunk boards on my toon trailer with carpet he told me they have had a lot better luck with un-treated 2x4. so thats what I got.
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Re: Another trailer bunk question - attachment

#8 Post by taylorjm » Thu Aug 10, 2017 6:30 pm

[quote="killerkernrich"]Well, I just had the boat dealer inststall new bunk boards on my toon trailer with carpet he told me they have had a lot better luck with un-treated 2x4. so thats what I got.[/quote]

The weathershield brand of wood at home depot is treated for underground usage and contains MCA as the treatment chemicals. Supposedly, it can be used in contact with aluminum without the galvanic corrosion.

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Re: Another trailer bunk question - attachment

#9 Post by ROLAND » Fri Aug 11, 2017 3:08 am

[quote="taylorjm"][quote="killerkernrich"]Well, I just had the boat dealer inststall new bunk boards on my toon trailer with carpet he told me they have had a lot better luck with un-treated 2x4. so thats what I got.[/quote]

The weathershield brand of wood at home depot is treated for underground usage and contains MCA as the treatment chemicals. Supposedly, it can be used in contact with aluminum without the galvanic corrosion.[/quote]

Taylorjim... thanks for posting this.. I just re did my bunks in June and I used PT wood. actually bought it at home depot so I hope it was the MCA wood... I do remember reading it was good for ground contact.. its strange, you can read other boards and they say you should always use pt wood, go to a different board and they'll say never use pt wood... regardless I think I'm okay either way as I covered my bunks with those polymere plastic bunk glides..
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Re: Another trailer bunk question - attachment

#10 Post by ralph » Fri Aug 11, 2017 4:56 am

Lots of great info on here guys
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yardbird
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Re: Another trailer bunk question - attachment

#11 Post by yardbird » Fri Aug 11, 2017 6:12 am

CCA was the "treated wood" preservative for a long time. It was phased out of the residential market in 2004, mostly because of the arsenic and chromium contamination issues. So MOST treated wood you've been using has probably been some form of MCA or MCQ after 2004.

That being said, the new treatments still use copper. And copper eats steel and aluminum. However, by removing the arsenic and changing the way the copper is dispersed this somehow made the copper less corrosive and now MCA treated wood is basically approved to have aluminum in direct contact. Most of the information available is for the building trades. And that "approval" for having aluminum in direct contact is for interior and above ground applications.

In other words.... not wet.

All that being said, and because the new stuff is so much less corrosive than the CCA was, AND because my trailer bunks might GET wet, but they don't STAY wet, AND if I use marine grade carpet on the bunks, it has a latex backing AND a polyester backing.... I think I'd feel pretty safe using MCA treated 2x4s as bunk boards.

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Re: Another trailer bunk question - attachment

#12 Post by JLester273 » Fri Aug 11, 2017 6:39 am

So Yardbird,

Is all CCA treatment the same. As the going thing for re-decking pontoons is Marine grade CCA plywood.

Is that somehow different then the other CCA wood?

I assumed regular pressure treated wood like at the big box stores was somehow a different treatment.
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http://www.pontoonforums.com/viewtopic.php?f=16&t=24807

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Re: Another trailer bunk question - attachment

#13 Post by yardbird » Fri Aug 11, 2017 7:36 am

[quote="JLester273"]So Yardbird,

Is all CCA treatment the same. As the going thing for re-decking pontoons is Marine grade CCA plywood.
To the best of MY knowledge, there is no such animal as CCA treated marine plywood.

Is that somehow different then the other CCA wood?

I assumed regular pressure treated wood like at the big box stores was somehow a different treatment.[/quote]

To the best of my knowledge, marine plywood is not CCA treated. CCA is a treatment against rot and somewhat against bugs just by nature of the chemicals used. Marine plywood is made using heat and pressure (heat kills bugs) and it uses a special waterproof glue. Whatever treatment a marine plywood gets is guarding against moisture. I *think* there is an oil involved somewhere in the process, but I may be wrong on that...been a while....

Pressure treated plywood often uses softer wood species to better enable the chemicals to penetrate.
Marine plywood uses harder woods like douglas fir and larch.

Even exterior grade plywood does not have the moisture resistance of marine plywood.

Keep in mind that in a marine environment, if using wood, it is GOING to get wet! It will swell when wet and shrink when it dries out. Ask anyone that's ever owned a wood lapstreak boat. Put one of those in the water in the spring and be there every morning to bail it out for about a week until the wood swells and it stops leaking.... as much...

CCA treated plywood does not belong on a pontoon boat. Marine plywood does. And marine plywood will outlast CCA treated plywood in a marine environment. So be careful of the terms used. If it's marine plywood, it will be stamped as such. It's a COMPLETELY different animal from any pressure treated plywood.

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Re: Another trailer bunk question - attachment

#14 Post by yardbird » Fri Aug 11, 2017 8:10 am

Was just on pontoonstuff's web site and saw their decking kits and saw "CCA treated marine grade plywood".
I've sent them a request for information on the product. I have a sneaking suspicion that old terminology made its way into their description or something because CCA treated wood can NOT be in direct contact with aluminum. You can't even BELIEVE the headaches it caused when all of the aluminum flashings on a building would "dissolve" over relatively short spans of time anywhere it came in contact with CCA treated wood.

So... request for information sent. Technologies change. I'm not going to keep beating this up as something might be different now than it was before I retired. I'll wait and see what they say.

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Re: Another trailer bunk question - attachment

#15 Post by JLester273 » Fri Aug 11, 2017 9:02 am

I know I got us off topic here. But along with PontoonStuff I found this

http://www.restorepontoon.com/articles/ ... lywood.asp

I'll give them a call or email them too and see. It has me curious now. By the sound of it, there isn't an insulator other than at the cross members where there are edges coming together.
My rebuild thread.
http://www.pontoonforums.com/viewtopic.php?f=16&t=24807

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