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Author Topic:   Trailer bunks rusting

Whalerdog posted 08-05-2013 09:12 PM ET (US)
I have an 07 19 Montauk with the factory Karavan trailer. I use it twice a year to put in and take out the boat. I rinse the trailer immediately after using it through every hole I can.
The trailer is in good shape except the bunks that were gold anodized or plated with some process. They were starting to rust by the carpet covering. So I take them apart and remove the 3/4" head lags holding the wood to the steel bunk plates. The lags were all rotted at the threads so when I took them out they can't go back where they were in the wood bunk. I am not sure if the threads would hold in the wood if same hole was used some wood material came out with them. It is regular wood as far as I can tell in decent shape. No sign of color green suggesting it is treated wood. I guess I could swap it out but then I need to redo the carpeting. If I reuse the wood I can just reverse it front to back to get new location to have lags hold good.
After some good pry bar work I separated the metal bunk plates from the carpet. Rust fused it to the carpet big time. I guess when I put it back I'll get some HD galvanized lags or stainless.
Now what should I do with the 4 metal bunks? Plan one was to get them hot dip galvanized. Plan two was POR15 the 4 bunks.
When something gets HD galv. do I need to remove the rust or do they do it by dipping it before the galvanizing process? Another plan was to get some heavier 5" channel and replace what is there now after hot dipping them.
Also need the 4 bunk brackets HDG and was going to install 4 new stainless bolts with the self locking nuts where the pivoting brackets are mounted to the post on the trailer.
Any dissimilar metal problems doing that?

I have a rust phobia I guess I hate it. Thanks for the help.
Chuck Tribolet posted 08-06-2013 01:55 AM ET (US)
I'd suggest your talk to the galvanizing shop about the rust.
I THINK they pickle it in acid before galvanizing, but they
can tell your for sure.
You shouldn't have a problem with SS hardware in galvanized
steel.
Generally, pressure-treated wood is pretty crummy wood. And
today's pressure treated wood is copper-based and will eat
up any steel except good stainless, and MAYBE hot-dipped
galvanized. When I replaced the bunks on my trailer about
8 years ago, I used clear fir. It's still fine, and in
better shape than the trailer which is, in theory, getting
replaced this week.

Chuck
EJO posted 08-06-2013 12:32 PM ET (US)
Use any wood you like but treat it with CPES. This water-thin penetrating sealant will stop rot from happening or going further. It is a great primer [before] varnishing or painting. I used it in all my Chris-Craft restorations and my new wood boat building projects and I've been using it on my utility and boat trailers and have no problems. Hey--my utility trailer sits out year around in Michigan weather.
CPES from Smith Co.
Whalerdog posted 08-08-2013 01:42 PM ET (US)
Thanks!
Ridge Runner posted 08-08-2013 05:57 PM ET (US)
I had the same problem with my 2005 Karavan trailer for my 170 Montauk. The lag bolts and bunk swivel brackets just rusted away....I suspect as EJO states from the cooper in the pressure treated wood.
I found a SS swivel bracket and SS 1/2"x 1 1/2" lag bolts and replaced my bunks with 2"x6"x8' composite lumber http://www.ultimatebunkboards.com/catalog2.html
You might also be able to use Trex (Home Depot), but I am not sure if it will flex to much.

wezie posted 08-08-2013 09:46 PM ET (US)
Plastic woods generally do not have much strengty.
Trex is too flexible for any support between the uprights.
We have seen hot dip lags come out of treated supports, that were only a shadow of their former self.
Thanks for the reminder to use fir vs treated.
There comes a time when we must re-do these things, even in fresh water.
Take your best shot at it, and go fishing.
andygere posted 08-09-2013 01:02 PM ET (US)
Using lag bolts to fasten the bunk brackets to the bunks is a cheap shortcut. To do it properly, countersink the heads of stainless steel bolts in the bunks, and secure them with nylock nuts. This will last much longer, and isn't that much more work.
I don't use pressure treated wood either. It tends to be low quality timber, full of knots and flaws. Good quality fir has worked quite well for me. Be sure to take the time to select the best planks in the stack.
Whalerdog posted 08-09-2013 11:42 PM ET (US)
Probably can reuse the wood I have and just countersink some stainless steel carriage bolts. Swap out the swivel brackets for SS bolts and nylocks. Heading to steel place tomorrow to see if they can HD galv the brackets and bunk plates. Keep you posted.

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Author	Topic: Trailer bunks rusting
Whalerdog	posted 08-05-2013 09:12 PM ET (US) I have an 07 19 Montauk with the factory Karavan trailer. I use it twice a year to put in and take out the boat. I rinse the trailer immediately after using it through every hole I can. The trailer is in good shape except the bunks that were gold anodized or plated with some process. They were starting to rust by the carpet covering. So I take them apart and remove the 3/4" head lags holding the wood to the steel bunk plates. The lags were all rotted at the threads so when I took them out they can't go back where they were in the wood bunk. I am not sure if the threads would hold in the wood if same hole was used some wood material came out with them. It is regular wood as far as I can tell in decent shape. No sign of color green suggesting it is treated wood. I guess I could swap it out but then I need to redo the carpeting. If I reuse the wood I can just reverse it front to back to get new location to have lags hold good. After some good pry bar work I separated the metal bunk plates from the carpet. Rust fused it to the carpet big time. I guess when I put it back I'll get some HD galvanized lags or stainless. Now what should I do with the 4 metal bunks? Plan one was to get them hot dip galvanized. Plan two was POR15 the 4 bunks. When something gets HD galv. do I need to remove the rust or do they do it by dipping it before the galvanizing process? Another plan was to get some heavier 5" channel and replace what is there now after hot dipping them. Also need the 4 bunk brackets HDG and was going to install 4 new stainless bolts with the self locking nuts where the pivoting brackets are mounted to the post on the trailer. Any dissimilar metal problems doing that? I have a rust phobia I guess I hate it. Thanks for the help.
Chuck Tribolet	posted 08-06-2013 01:55 AM ET (US) I'd suggest your talk to the galvanizing shop about the rust. I THINK they pickle it in acid before galvanizing, but they can tell your for sure. You shouldn't have a problem with SS hardware in galvanized steel. Generally, pressure-treated wood is pretty crummy wood. And today's pressure treated wood is copper-based and will eat up any steel except good stainless, and MAYBE hot-dipped galvanized. When I replaced the bunks on my trailer about 8 years ago, I used clear fir. It's still fine, and in better shape than the trailer which is, in theory, getting replaced this week. Chuck
EJO	posted 08-06-2013 12:32 PM ET (US) Use any wood you like but treat it with CPES. This water-thin penetrating sealant will stop rot from happening or going further. It is a great primer [before] varnishing or painting. I used it in all my Chris-Craft restorations and my new wood boat building projects and I've been using it on my utility and boat trailers and have no problems. Hey--my utility trailer sits out year around in Michigan weather. CPES from Smith Co.
Whalerdog	posted 08-08-2013 01:42 PM ET (US) Thanks!
Ridge Runner	posted 08-08-2013 05:57 PM ET (US) I had the same problem with my 2005 Karavan trailer for my 170 Montauk. The lag bolts and bunk swivel brackets just rusted away....I suspect as EJO states from the cooper in the pressure treated wood. I found a SS swivel bracket and SS 1/2"x 1 1/2" lag bolts and replaced my bunks with 2"x6"x8' composite lumber http://www.ultimatebunkboards.com/catalog2.html You might also be able to use Trex (Home Depot), but I am not sure if it will flex to much.
wezie	posted 08-08-2013 09:46 PM ET (US) Plastic woods generally do not have much strengty. Trex is too flexible for any support between the uprights. We have seen hot dip lags come out of treated supports, that were only a shadow of their former self. Thanks for the reminder to use fir vs treated. There comes a time when we must re-do these things, even in fresh water. Take your best shot at it, and go fishing.
andygere	posted 08-09-2013 01:02 PM ET (US) Using lag bolts to fasten the bunk brackets to the bunks is a cheap shortcut. To do it properly, countersink the heads of stainless steel bolts in the bunks, and secure them with nylock nuts. This will last much longer, and isn't that much more work. I don't use pressure treated wood either. It tends to be low quality timber, full of knots and flaws. Good quality fir has worked quite well for me. Be sure to take the time to select the best planks in the stack.
Whalerdog	posted 08-09-2013 11:42 PM ET (US) Probably can reuse the wood I have and just countersink some stainless steel carriage bolts. Swap out the swivel brackets for SS bolts and nylocks. Heading to steel place tomorrow to see if they can HD galv the brackets and bunk plates. Keep you posted.