Finally broke down and bought some float pods for my 1448, I want that extra inch of floatation so I can get skinny. They wont be here for a couple weeks but I was wondering what kind of caulk to use for glue. I have seen posts on here about 5200 and it being corrosive to aluminum. So what to use? I plan on bolting them on. What about Marine Goop? Any suggestions?
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IMHO - the problem with any product corroding aluminum is the silicone content.
then - bare aluminum is the common contributing factor in caulk/adhesive failures.
In my past experiences, applying 3M-5200 or Loc-Tite caulk or any silicone free
product to a properly primed and painted finish holds up very well.
so, if you can avoid the silicone products - you "shouldn't" have any problems.
please come back with some photos after you get your pods for more assistance.
Maybe it is time to share this photo again..... from my last bass boat.
jus my Dos Centavos
.
then - bare aluminum is the common contributing factor in caulk/adhesive failures.
In my past experiences, applying 3M-5200 or Loc-Tite caulk or any silicone free
product to a properly primed and painted finish holds up very well.
so, if you can avoid the silicone products - you "shouldn't" have any problems.
please come back with some photos after you get your pods for more assistance.
Maybe it is time to share this photo again..... from my last bass boat.
jus my Dos Centavos
.
surfman said:
I have used 5200 for numerous different applications on my boat. Many of those are on bare aluminum. Zero corrosion caused by the 5200.
Terp - what is the length of time you have had the 5200 on bare aluminum?
have you removed the items for inspection?
The photo that I posted, the caulks were probably 10-15 years old and used only in fresh water.
The items that were caulked to the transom were plastic based transducers and a speedometer.
There was no "metal to metal" contact that could have contributed to the corrosion.
so, in my very honest opinion, and from my research, the adhesive alone was the culprit in the corrosion.
you will not know if there is any corrosion on anything until you separate the two surfaces.
once an item is sealed to an aluminum surface, there is no way to tell if the underneath metals
are corroding or not - only when the item is removed can you tell.
Bottom line is - "your boat = your call".
Edit: everyone considering using 3M-5200 is encouraged to view the technical data sheet on their website.
And adhere to their conditions of use. https://multimedia.3m.com/mws/media/158830O/adh-seal-fast-cure-5200-tech.pdf
It specifically states:
"Primer:
Use of a primer is an extra step and cost and will depend on the final end use.
Using primer can improve the corrosion resistance of certain metals as well as improve
the durability of the bond when exposed to high humidity conditions. Pre-testing for adhesion
is suggested to determine if a primer is needed.
Contact your 3M Technical Service representative for primer recommendation and application advice."
Typical sealing applications include:
- Fiberglass deck to fiberglass hull
- Some plastics (test before assembly)
- Wood to fiberglass
- Glass
- Portholes
- Metals (priming may be required)
BOATING is definately one of the "high humidity conditions" they refer to.
Product research will always be in your best interest prior to using any
kind of chemical or chemical based products.
.
have you removed the items for inspection?
The photo that I posted, the caulks were probably 10-15 years old and used only in fresh water.
The items that were caulked to the transom were plastic based transducers and a speedometer.
There was no "metal to metal" contact that could have contributed to the corrosion.
so, in my very honest opinion, and from my research, the adhesive alone was the culprit in the corrosion.
you will not know if there is any corrosion on anything until you separate the two surfaces.
once an item is sealed to an aluminum surface, there is no way to tell if the underneath metals
are corroding or not - only when the item is removed can you tell.
Bottom line is - "your boat = your call".
Edit: everyone considering using 3M-5200 is encouraged to view the technical data sheet on their website.
And adhere to their conditions of use. https://multimedia.3m.com/mws/media/158830O/adh-seal-fast-cure-5200-tech.pdf
It specifically states:
"Primer:
Use of a primer is an extra step and cost and will depend on the final end use.
Using primer can improve the corrosion resistance of certain metals as well as improve
the durability of the bond when exposed to high humidity conditions. Pre-testing for adhesion
is suggested to determine if a primer is needed.
Contact your 3M Technical Service representative for primer recommendation and application advice."
Typical sealing applications include:
- Fiberglass deck to fiberglass hull
- Some plastics (test before assembly)
- Wood to fiberglass
- Glass
- Portholes
- Metals (priming may be required)
BOATING is definately one of the "high humidity conditions" they refer to.
Product research will always be in your best interest prior to using any
kind of chemical or chemical based products.
.
I assume they are the sealed versions being sold to attach to the back corners of the boat ? Why use any sealant at all ? if you're going to bolt or rivet them on why not just leave it at that ? All sealant is going to do is make the job messy and create pockets where moisture can be trapped. There should be no mechanical reason why you need "glue"...
Thanks, I've seen the pictures that's why I am asking again because now I need to do it.
Sealant is absolutely necessary, you do not want to just attach them together without sealing the bonding surfaces. Metal to metal, even the same metal will hold water and contribute to corrosion. There are many types of corrosions like, crevice corrosion and others I can't think of right off the top of my head, that occur when there is moisture, especially salt water trapped between two surfaces. The attachment needs to be 100% sealed. With no chance for any moisture to get between the surfaces. Since I am going to bolt it instead of weld it, there is an even greater chance for this to occur. I need to make sure it is done right.
Any recommendations on primer then?
Sealant is absolutely necessary, you do not want to just attach them together without sealing the bonding surfaces. Metal to metal, even the same metal will hold water and contribute to corrosion. There are many types of corrosions like, crevice corrosion and others I can't think of right off the top of my head, that occur when there is moisture, especially salt water trapped between two surfaces. The attachment needs to be 100% sealed. With no chance for any moisture to get between the surfaces. Since I am going to bolt it instead of weld it, there is an even greater chance for this to occur. I need to make sure it is done right.
Any recommendations on primer then?
Surfman - is your boat primed and painted now ??
if it is, is it the factory finish or a repaint from a P/O?
each scenario will require different preparation methods.
and speaking of bolt-on floats, there was a mention here while back, maybe on
another forum, about placing large 1/8" nylon washers between the transom and float.
I am only "assuming" to isolate the two mating surfaces and allow
water to flow freely between the two to keep them clean and issue free ........
(this is noted from third hand information only).
use the search feature here to obtain information from the ones that have actually done it.
if it is, is it the factory finish or a repaint from a P/O?
each scenario will require different preparation methods.
and speaking of bolt-on floats, there was a mention here while back, maybe on
another forum, about placing large 1/8" nylon washers between the transom and float.
I am only "assuming" to isolate the two mating surfaces and allow
water to flow freely between the two to keep them clean and issue free ........
(this is noted from third hand information only).
use the search feature here to obtain information from the ones that have actually done it.
The aviation industry has been simply riveting or bolting aluminum sheet together with some success for many decades without shmearing some material in between the sheets. That goop in between is what will eventually trap salts and moisture. As Johnny suggested, spacers in between the material is the way to go to avoid corrosion best if salt water is part of the equation. Painting the 2 surfaces will also eliminate any fears of corrosion.
Why dirty up that connection with another material that is not needed ? Much better to have a part that I could take off and put on easily and if needed maintain and clean out imo.... my 2 "unglued" cents worth......
Why dirty up that connection with another material that is not needed ? Much better to have a part that I could take off and put on easily and if needed maintain and clean out imo.... my 2 "unglued" cents worth......
Fishfreek
Well-known member
I really like the LIFESEAL from Boat life marine products. Works above and below the water line. I wouldn't spread it all over the pods to make a seal. I would apply some around each hole you make for your bolts then after you get the pods installed use it as you would a caulk and seal the seam created between your boat and the edges of the pods. Make sure you let ut cure completely for a few days for best results.
RiverBottomOutdoors
Well-known member
Johnny said:
If my boat lasts 15 years, I'm not running it hard enough. LOL.
It is already painted with the factory paint. I was not planning on stripping to bare metal, I was only going to clean it thoroughly using a scotch pad and mineral spirits and soap and water and then if needed apply a primer. Any recommendations on a primmer?
personally, I would suggest that you go to the website of the sealant/adhesive that
you plan to use and read as much as you can about it - so you don't use the wrong product.
and in my world, I would not prime the factory painted metal......
If the pods are bare aluminum, they must be etched, primed and painted
prior to installation. (using the installation method of your choice).
https://www.tinboats.net/primer-and-paint-basics/
you plan to use and read as much as you can about it - so you don't use the wrong product.
and in my world, I would not prime the factory painted metal......
If the pods are bare aluminum, they must be etched, primed and painted
prior to installation. (using the installation method of your choice).
https://www.tinboats.net/primer-and-paint-basics/
Johnny said:
I've had 5200 on bare aluminum (mostly rivets attached to the hull) for 3-4 years. So not as long as your experience. But the rivets I've had to remove for whatever reason there were no signs of corrosion on the hull nor on the rivet. Not denying what your experience has shown, just sharing my own. But I've yet to find any other examples of 5200 causing corrosion on bare aluminum, actually I've seen the opposite where 5200 is used between differing metals to prevent corrosion. With the wealth of information on the internet, and as much as 5200 is used for marine applications I would think there would be more evidence of it causing what you experienced. But, like you said, if you follow the manufactures instructions all should be good.
It's a good bet that what Johnny's photos show is a type of poultice corrosion. This occurs under bubbling paint for example. It's when a material is introduced (like silicone) that inevitably loses it's adhesion to the surface and creates pockets of air and moisture that eventually turn acidic and decay the metal. It can be a lot like how your teeth decay... trapped moisture breeds bacteria... bacteria defecates and becomes acidic... Or other chemical reactions as described in the link below.
That's why it's much better to leave clean or painted metals in tight contact with each other or separated by spacers to allow airflow. Tightly mated surfaces have less room for pockets to form than surfaces with a viscous material in between.
At least then you can separate the pieces and clean and repaint the area if required. By gluing everything together with a viscous material you give yourself little alternative but to hope your "glue" has not created voids that trap stagnant moisture and acids against the surfaces...
https://marginalmaritimeadvice.blogspot.com/2011/03/poultice-corrosion_5740.html
That's why it's much better to leave clean or painted metals in tight contact with each other or separated by spacers to allow airflow. Tightly mated surfaces have less room for pockets to form than surfaces with a viscous material in between.
At least then you can separate the pieces and clean and repaint the area if required. By gluing everything together with a viscous material you give yourself little alternative but to hope your "glue" has not created voids that trap stagnant moisture and acids against the surfaces...
https://marginalmaritimeadvice.blogspot.com/2011/03/poultice-corrosion_5740.html
Basically, what you are saying is that the real culprit is probably surface prep, which is usually the case in many instances. Jonny removed material from and existing application, who knows what it looked like when the goo was applied, It is possible that the PO applied the goo right over existing corrosion. That kind of stuff happens all the time and I see people posting pictures of patch jobs on this web site that back that up too.
I also agree that trapped moisture is a problem too.
I also agree that trapped moisture is a problem too.
