Should I use 5200 here?

[RonRock]

Or something else?

I just finished making backing plates for my bow pulpit. I used 1/4" aluminum. I drilled and formed them so that they are a pretty nice fit. But they will be tightened up to the inside fiberglass of my boat. Of course it is not perfectly smooth, and way to much work to make it so. So my thinking is to use 5200 as a bond and filler for the aluminum to the fiberglass. I would bolt it all together until the 5200 has hardened then remove the bolts, clean the holes and finish installing with either buytl tape or Life Caulk.

I also have on hand some fiberglass resin, and feather fill. I considered the feather fill first but not sure how good of a bond to aluminum it would give.

What do you guys think?

 

[philwsailz]

DO NOT USE 5200!!!!

As I read you post, it sounds like you want to use a product that will fill and conform to the irregular gap between the aluminum plate and the fiberglass, in order to privide a line-on-line fit, prior to final assembly.

If you count on 5200 for this it WILL be your final assembly for this backing plate. You will not get it apart without damaging something.

Based on my take on what you are asking for, I would consider thoruoghly cleaning and dewaxing the mating fiberglass surface. Then I would apply a mold release agent to the fiberglass. Use several applications to make sure your filler does not stick...

Then using a fiberglass product, (West Systems is what I am comfy with) use an appropriate filler to thicken the fiberglass resin and hardener to a fairly thick consistensy. Apply it as the filler between the aluminum and the fiberglass.

If you want it to bond to the aluminum at this step, clean the aluminum with acetone and rough it up so it has a good mechanical bond, then wipe it one more time to make sure it is clean. If you want the aluminum to not stick to the fiberglass filler, apply the same mold release product to the aluminum. I would probably just go ahead and leave the aluminum cleaned and ready for bond. Then after kicking I would take the backing plate and the newly attached/bonded filler material out of the boat and run it past an abrasive to clean off any excess filler squeeze out.

Lay up your assembly and wait for it to cure. Then disassemble, clean up, and re-assemble with your preferred bedding material. I like butyl tape...

Now if my assumption is wrong, please correct me so we all have a better understanding of what you are doing!

Hopefully this helps! Some may recommend other methods, but I think we will all agree that 5200 is the wrong product for this job, whether I understand it or not...

 

[Nom De Guerre]

I think you're planning to put the sealant on the wrong side of the hole. You want sealant on the deck side of the hole, underneath the pulpit base plates.

You want no sealant on the cabin side of the hole. Your backing plates, bolts, and nuts do all of the strength work, and you want to see any leaks that are getting past the deck-side seal.

 

[Captn TJ]

DO NOT USE 5200!!!!

As I read you post, it sounds like you want to use a product that will fill and conform to the irregular gap between the aluminum plate and the fiberglass, in order to privide a line-on-line fit, prior to final assembly.

If you count on 5200 for this it WILL be your final assembly for this backing plate. You will not get it apart without damaging something.

Based on my take on what you are asking for, I would consider thoruoghly cleaning and dewaxing the mating fiberglass surface. Then I would apply a mold release agent to the fiberglass. Use several applications to make sure your filler does not stick...

Then using a fiberglass product, (West Systems is what I am comfy with) use an appropriate filler to thicken the fiberglass resin and hardener to a fairly thick consistensy. Apply it as the filler between the aluminum and the fiberglass.

If you want it to bond to the aluminum at this step, clean the aluminum with acetone and rough it up so it has a good mechanical bond, then wipe it one more time to make sure it is clean. If you want the aluminum to not stick to the fiberglass filler, apply the same mold release product to the aluminum. I would probably just go ahead and leave the aluminum cleaned and ready for bond. Then after kicking I would take the backing plate and the newly attached/bonded filler material out of the boat and run it past an abrasive to clean off any excess filler squeeze out.

Lay up your assembly and wait for it to cure. Then disassemble, clean up, and re-assemble with your preferred bedding material. I like butyl tape...

Now if my assumption is wrong, please correct me so we all have a better understanding of what you are doing!

Hopefully this helps! Some may recommend other methods, but I think we will all agree that 5200 is the wrong product for this job, whether I understand it or not...

+1. I only use 5200 for permanent bonding.

 

[RonRock]

Wow that was fast! Thanks for the replies.

I was not very good at explaining my intentions. Now that you mention it maybe my intentions are wrong. My plan was for the 5200 to fill the slight variations in the underside of the fiberglass and create a bond to the aluminum plate. Leaving a solid bond and a firm plate to bolt too. Then buytl tape on topside between the stainless flange and gelcoat.

Philwsails, you had it pegged pretty well.

Maybe I am wrong planning to bond the aluminum plate to the fiberglass?

Maybe some fiberglass filler would be a better choice. That would fill the void, as well as bond the aluminum. But if I ever decide that the aluminum had to be removed I could probably pop them loose with less damage than if they were bonded with 5200.

 

[philwsailz]

Wow that was fast! Thanks for the replies.

I was not very good at explaining my intentions. Now that you mention it maybe my intentions are wrong. My plan was for the 5200 to fill the slight variations in the underside of the fiberglass and create a bond to the aluminum plate. Leaving a solid bond and a firm plate to bolt too. Then buytl tape on topside between the stainless flange and gelcoat.

Philwsails, you had it pegged pretty well.

Maybe I am wrong planning to bond the aluminum plate to the fiberglass?

Maybe some fiberglass filler would be a better choice. That would fill the void, as well as bond the aluminum. But if I ever decide that the aluminum had to be removed I could probably pop them loose with less damage than if they were bonded with 5200.

As I penned it, just use a mold-release compound on the interior fiberglass. That way your filler will release from the fiberglass when you undo it. staying stuck to the now perfectly fitting aluminum plate.

OR.... This might be even better. Rough up your interior fiberglass where the aluminum backing plate goes. Then, use something as simple as a very precisely aplied masking tape on your aluminum plate. Put your filler in place and bolt up the sandwich. When it cures, pull the aluminum plate off and what is left behind will be a perfectly flat surface on your interior fiberglass. Remove the remaining tape from both surfaces, smooth down the edges of the fiberglass filled area and you will be good to go.

Put another way, you are adding fiberglass material to the inside of the boat and using the aluminum plate to "squish" it into a uniformly flat mounting surface for the plate. The tape provides a uniformly thick layer that will allow the aluminum plate to be removed after the 'glass kicks.

Maybe that clears up things even better!

 

[Sumner]

...... This might be even better. Rough up your interior fiberglass where the aluminum backing plate goes. Then, use something as simple as a very precisely aplied masking tape on your aluminum plate. Put your filler in place and bolt up the sandwich. When it cures, pull the aluminum plate off and what is left behind will be a perfectly flat surface on your interior fiberglass. Remove the remaining tape from both surfaces, smooth down the edges of the fiberglass filled area and you will be good to go....

I think this is very good advise.

I'd do as suggested and use one of the kitty hair type products...

http://www.evercoat.com/productDetail.aspx?pID=38

I used that between the hull and all of the fiberglass backing plates for the thru-hulls on the Endeavour. You could also put saran wrap on the backing plate to release it. Why try and bond it, you just want the flat surface. The bolts on the finish install will 'bond' it.

For the thru-hull deal the plates were bonded since you need the watertight seal there between the hull, the kitty hair and the backing plate,

Sum

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[topcat0399]

The last 2 posters are very wise men.

This is the method I will use when I get around to a bow roller set up.

 

[MrBill_FLL]

kitty hair is good stuff.

west system also sells a calk tube of epoxy. the 2 part, mixes in the nozzle. system 6.10 i think.

 

[topcat0399]

kitty hair is good stuff.

west system also sells a calk tube of epoxy. the 2 part, mixes in the nozzle. system 6.10 i think.

I make my own kitty hair; pull apart some csm and mix with some resin. Easy cheesy.

 

[Sumner]

A word of caution. If you use the kitty hair or one of the other similar products make sure everything is ready to go and do a trial run. If it is hot, over 80, I'd also mix it with slightly less hardener. If you mix it a little hot or just right and it starts to kick off before you have things in place you will have a mess and an other un-even surface to deal with,

Sum

[FONT=Arial, sans-serif]============================[/FONT]

Our Endeavour 37

Our MacGregor 26-S Pages

Our Trips to Utah, Idaho, Canada, Florida

Mac-Venture Links

 

[RonRock]

Good help guys. I'll use Kitty Hair, and Saran Wrap. You have convinced me that bonding the aluminum plate to the fiberglass is not necessary.