Trailer bunk question???
 

Wanted to see everyone's opinion on best practice on attaching bunks on boat trailers.

Is it best to use a nut and bolt, and countersink the wood to conceal the bolt head, then attach the carpet after bolting up?

or

Have carpet already on board and use lag bolts?

or any other ways? What do yall think? This is for an 18ft fiberglass boat, has a rotten 2x4.

I use lag bolts. Tried the other way and still scratched the boat.

Galvanized lag bolts

I used stainless lag bolts

I have 4x4 with carriage bolts sunk 1/4-1/2 inch and they are bolted straight to the trailer without brackets..... I like this setup for the fact that there's no brackets to rust out or break, this is on my marsh boat but it works well.

What ever you decide make sure the bolt you using is okay to use with pressure treated wood. Pressure treated wood eats away at galvanized bolts if they not hot dipped.


What metals and protective coatings does the Treated Wood Industry recommend for use with these products?

Hot-dip galvanized or stainless steel fasteners, anchors and hardware are recommended by the Preservative Treated Wood Industry for use with treated wood. This has been the position of this industry for years and their position has not changed with the transition to the alternative copper-based products. In the past this industry did not address the required levels of galvanizing, however most of those in the industry now provide information regarding the minimum level of galvanizing that should be used.
The thicker the galvanized coating the longer the expected service life of the fastener, connector, anchor, or other hardware will be.
Electroplated / electro galvanized and mechanically galvanized coatings should not be considered to be hot-dip galvanized. (Class 55, or higher, mechanical galvanizing provides galvanizing equivalent to the hot-dip galvanizing used on connectors and fasteners. Ref. ASTM B695 for additional information.)
It is also worth noting that the galvanized coating thickness varies depending on the galvanizing process used. Remember, the thicker the galvanized coating, the longer the expected service life of the steel will be.
Refer to the different chemical manufacturers and/or treaters as well for their recommendations. A list of trade names is included at the bottom of this page.

Are all stainless steels acceptable for use with preservative treated wood?

All stainless steels may not be acceptable for use with preservative treated wood. Testing has shown that Types 304, 305 and 316 stainless steels perform very well with woods that hay have excess surface chemicals. Type 316 stainless steel contains slightly more nickel than other grades, plus 2-3% molybdenum, giving it better corrosion resistance in high chloride environments prone to cause pitting such as environments exposed to sea water.

So I guess 316 stainless lag bolts it is! Thanks for the info guys!

I bolted treated 4x4's straight to the frame so there are no brackets to rust out as well like already stated.

Well right now I just need one done as an emergency, but will be replacing all down the road

Can you post a pic please?

I redid my trailer boards a few years back similar to this after the metal brackest started to fail.

I used 4x4 treated fence post boards, but I did not want to drill holes [weaken the channel iron] in the trailer cross braces so I used Hot dipped galv. U-bolts. I bought the U-bolts so that the bolt and nuts would be counter sunk. After the boards were installed, I filled all the holes with grease to further protect the nuts and threads before installing the carpet.

If it is just an aluminum boat, I have seen a lot of Coonasses down in the parish use 4" PVC with angled cuts at the back of the trailer. Drill and bolt straight to the trailer.
Not good with heavy fiberglass boat.

Check out this thread for pics.

I just don't know if I trust lag bolts. May do carriage bolts

I like carriage bolts for the reason of if the boards wear down or anything allows the boat to contact the bolts then its still a smooth surface plus you have a nut to help hold it together

I disagree with this only because when I had teflon strips on my previous 2x4s, the teflon wore down and the #8 rounded phillips heads stainless screws that were counter sunk rubbed 3 different holes in my boat. So far so good on the lags, it's a light boat. My only concern has been corrosion with dissimilar metals (stainless lags to galvanized trailer).

Agreed


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I've just seen lags fail too many times. Maybe counter sunk carriage and fill the holes with silicon

I understand what you're saying. Do like you said and inspect everytime you launch.


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