Trailer Bunks PT or Non Treated

WaterOps

Almost A Member
Feb 25, 2011
217
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Wa
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Ken
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22ft
Converting trailer over to bunks, for those that have done this did you go with PT or non treated wood. Plan on just carpeting them for this year to see how it loads.

Thanks
Ken
 

SeaHawk IV

I Post A Lot But I Can't Edit This
Jan 15, 2008
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United States of America
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.....
I was wondering if PT was a better option. So when one of the PT bunks had failed due to a crack, I replaced it with Douglas Fir.

I currently have PT on the two inner bunks (14') and two DF on the outer bunks (10'). All four bunks covered with carpet with about one inch of the wood exposed on the bottom side. It's been six years and all four bunks are in great condition. I launch in saltwater about ten to 18 times per season.

When it's time to replace the bunks again, I'll probably use the wood that is cheaper in cost as I don't see any difference in reliability.
 
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KimH

Someday I'll live the dream.
Mar 4, 2009
2,720
2,611
Tacoma/Westport WA/USA
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Kim
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28' Farallon Walkaround "Paragon"
Not recommended for aluminum boats. The PT lumber has metals in it that are dissimilar to aluminum and can cause corrosion. PT is fine for FG boats.
Good point. I had to modify a bunk to give some space for my transducer and saw on my Pacific trailer the wood was untreated. Glass boat so it doesn't matter for me but I wonder if the manufacture does this on all of the trailers for this reason.
 
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Captain Decent

The Bert makes ‘em Squirt
Nov 2, 2017
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I wouldn’t worry about it too much. Would take a very long time for saltwater soaked wood to rot.

that being said I’d grab the PT unless you have aluminum.
 

Team Sency

Fish!! Or be Fished!!!
Jan 6, 2012
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Chris
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JuiceBox2
I redid my bunks on my old trailer. I was told by a few pros to go Doug Fir non treated.

I did 4x8's and then put bunk slick cover over them that Happy Days sells. Tried to load picture but BD saying to big??

Anyways, worked great and looks clean.
 

calbrewguy

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Jul 12, 2006
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Pressure treated lumber inhibits infestation by boring (as in drilling) organisms, not rot from immersion. So unless the lumber is subjected to long periods of direct contact with water where organisms can establish themselves, why use treated lumber?
 

Happy Daze

Grady Prick
May 17, 2011
339
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Port Orchard Wa.
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Dave Johnson
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24ft Grady White/16ft Moocher
Do not use preasure treated lumber it is made from Hemlock Fir and is not as strong as reg Doug Fir and it also has been compromised by the chemical and the holes put into it during the process and it flexes to much and can break. Carpet holds water and takes for ever to dry under a boat and has a lot of friction for launching and hauling. Cheers HD
 

Fireball

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Jun 23, 2010
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Lynnwood, WA. USA
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Bud
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I really like the way @Chtucker did his when he built his own trailer. If I remember correctly he used something like 1.5" x 6" aluminum stock and then bolts a slick plastic materials with counter sunk heads on the top. I will never rot and he had one hell of a trailer. Only saw the trail one day when I went up to help drill so holes in it but man it was a brick shit house all they way.

Edit: here is the link to his build. look at pages 2 and 4 to see his bunks. Not sure you want to go through all that but you will never replace a piece of wood again.


Good luck with your project.
 
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calbrewguy

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Jul 12, 2006
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Do not use preasure treated lumber it is made from Hemlock Fir and is not as strong as reg Doug Fir and it also has been compromised by the chemical and the holes put into it during the process and it flexes to much and can break. Carpet holds water and takes for ever to dry under a boat and has a lot of friction for launching and hauling. Cheers HD

Unless you're getting your PT from the east coast it's not Hemlock, it's Douglas Fir. I built docks and piers for years here in SoCal and it was always specified PTDF (Pressure Treated Douglas Fir) on the plans. You can either get it SFS (surfaced four sides) or incised. We used incised for under cribbing for better treatment penetration and SFS for decking, facia and hand rail material because of esthetics.
 

G-Spot

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Mar 14, 2008
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Unless you're getting your PT from the east coast it's not Hemlock, it's Douglas Fir. I built docks and piers for years here in SoCal and it was always specified PTDF (Pressure Treated Douglas Fir) on the plans. You can either get it SFS (surfaced four sides) or incised. We used incised for under cribbing for better treatment penetration and SFS for decking, facia and hand rail material because of esthetics.

100% wrong! Many many trees logged in the PNW and Canada are Hemlock... Fact is most lumber sold now is hem/fir... sold as fir.... As a builder I dealt with this regularly... I had a anal retentive client who specifically wanted to ensure his house had no hemlock, so we had to pay a premium to ensure all lumber was Douglas Fir.... Not sure what the East Coast grows, but Hemlock is all over the Northwest and this information is 100% incorrect...

As a dock builder you may want to educate yourself before you try to spout info to others... the reason your plans specify Douglas Fir is because it is a superior lumber, but ordering from a lumber yard if you do not specify Douglas Fir only.... you will get Hem/Fir which is a mixture of whatever the mill has...
 
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