Cap Sealant and screws?

[dccordell]

After searching on here a lot, I haven't been able to figure out what is the best option for a sealant where the cap joins the hull. I've seen some say use PL and some say use silicone. Which should I go with?

Also, what is the consensus on screwing the rub rail track back in place? Stainless steel screws? I could use rivets but I worry about some time in the future having to remove them all (say what?!) But I also read that screws will work loose over time. So I just don't know.. what do you guys think?

Getting close to putting the cap on... woohoo

Thanks for all the help...

 

[Cadwelder]

Re: Cap Sealant and screws?

How was it attached orginally? I'd go back with the same method. As far as sealing, silcone has been used on most of the boats I've restored. (some had nothing at all) I like screws over rivets, just because they are easier to remove is you ever have too, and yes I don't use anything but stainless steel hardware anywhere on the boat.

 

[sasto]

Re: Cap Sealant and screws?

I have worked with 3 different deck to hull joints while boatbuilding. 1 involves an inward flange of the deck attached to an outward flange of the hull. 2 involves outward flange of both attached. 3 is what is the most common shoe box fit. Our preferred method for each is to thru bolt using fender washers for a backing plate every 8 inches. 5200 for me (or plexis). We tab the inside where accessable. If I was to use self tapping screws I would recommend a wooden backing to help prevent breakdown of the fiberglass.

Good Luck on your choice!

 

[dccordell]

Re: Cap Sealant and screws?

Originally, there were screws (rusty) and silicone used to hold it together. It is a "shoebox" fit. There is a plywood backing plate glassed onto the inside of the hull all the way around the edges to attach the screws. I like the through bolt with washers but almost all of the inside of the seam will not be accessible. Looks like I'll be going with the SS screws and either silicone or PL. I guess that's my biggest question still... silicone or PL? I'm leaning towards PL because it's worked so well for the rest of the boat.

And what is the best way to get the stuff inside the seam without making a huge mess? The idea I have in mind is getting the cap in place with maybe a few "alignment" screws just loosely holding it in place, then using something like a prybar or scraper to pull the flange back a little at a time to apply the sealer. How's everybody else do it?

Thanks for the responses guy..

 

[Yacht Dr.]

Re: Cap Sealant and screws?

Ive never used PL ...but if its a substitute for 4200..then I wouldnt do it..

I would not use Plexis or Proset.

Im leaning toward 3m 4000 or silicone.

Yes on the SS screws.

All I can say for clean application is Tape your seams.. Goop your caulk before you cap..and then after deck it..

YD.

 

[Cadwelder]

Re: Cap Sealant and screws?

There really isn't a NEAT way to do it, I use the masking tape method most of the time, and I always use silcone for this seal. As YD said apply a thin layer before you set the cap on (most of it will come out) and then after the cap is on run another bead along the seam and push it up in the joint with your finger, the rub rail will cover it. The wood strip you mentioned earlier is important for a good hold of the screws, I usally add another layer of 1/4" ply just to give something for a better bite of the stainless screws.

 

[dccordell]

Re: Cap Sealant and screws?

Looks like masking tape and probably silicone for the job then... seems pretty straight forward. I will probably add another 1/4" plywood strip to screw too, even though the original strip is still in good shape. More bite the better.

Oh, can't forget the nitrile gloves for the mess!

Thanks for the help guys...

 

[oops!]

Re: Cap Sealant and screws?

silly cone has no place on boats bud.......sikkens sika flex or 4200........5200 is permanant.....so you dont know if it will ever have to come off again. (hope not)

 

[dccordell]

Re: Cap Sealant and screws?

Yeah I hope not too! See that's why I asked... Some people suggest silicone, others don't. Does lowes or home depot sell the 4200/5200 products? Probably will be another week at the least before I can get it done... Trying to get a plan by then.

 

[oops!]

Re: Cap Sealant and screws?

dont know if they are in the states or not.....we dont have lowes yet....but home depot used to carry 5200 but not any more....they got a different supplyer.

i go to lordco for sikkens

 

[Cadwelder]

Re: Cap Sealant and screws?

silly cone has no place on boats bud.......sikkens sika flex or 4200........5200 is permanant.....so you dont know if it will ever have to come off again. (hope not)

Manufactureres use it for the joint of the cap. (I agree with you below the water line, although I've seen it there too)

3M? Marine Grade Silicone Sealant, 08029, 1/10 Gallon, Clear
Color - Clear. High quality silicone designed for the harsh marine environment. It forms a mildew-resistant, non-yellowing seal that remains flexible even after years of exposure.

Stock Number: 60980042828
UPC: 00 051135 08029 0

 

[sasto]

Re: Cap Sealant and screws?

I've decked a few hulls in my time and we have always used 5200. Never silicone. Out thoughts were if you have to seperate the deck and hull in the future....you have more problems than removing the 5200.

Good Luck in your decision.

 

[Cadwelder]

Re: Cap Sealant and screws?

Not trying to start an argument, just that 3M makes a silcone for marine use, if it has no place on a boat what is this product for?? Anyway, I've removed a few caps over the years that had absolutely nothing to seal the joint. Not saying that's a good way, but I know it's been done that way. I'm not a pro, but have done several and normally never disagree with the pro's but had to chime in on this one. That's what the forum's are all about, difference of opinions.

 

[dccordell]

Re: Cap Sealant and screws?

Thanks for all the input guys. I think the deciding factor for me will be what is available locally. Unfortunately, we don't have any of the other hardware supply stores mentioned. It's basically Lowes, Home Depot or Ace around here. I'm going to stop by today and see what I can get my hands on.

Difference of opinion is always good I suppose.. shows more than one side. It's interesting to see the different materials that are used successfully across the board. I respect everybody's opinion on here and it leaves a lot to consider.

Thanks again..

 

[Yacht Dr.]

Re: Cap Sealant and screws?

If you have an Ace hardware store near ya ( you said you did ) .. grab a tube of caulk.. go up to customer service and ask them if you can go through there caulk section of that book ( the first number in there product sku is the number of the book ).

Thumb through the thing untill you find what you want .. they have ALOT more in the book then on the shelves.

I used to manage an Ace hardware..

YD.

 

[dccordell]

Re: Cap Sealant and screws?

Great YD, I'll do that. I actually looked on the Ace website for the 4200/5200 with no luck. Maybe their catalogue has more options. We have them all over down here, some bigger/better than others. Thanks for the tip...

 

[barbosam]

Re: Cap Sealant and screws?

I know lowes sells 5200 and i think also 4200. Every production boat I've been involved with has used 5200 for this joint. There seems to be a perception that 5200 cannot be removed or is unbreakable but that is not exactly the case. Yes it produces an extremely strong bond but there are plenty of sealant removers that make the job of removing 5200 much easier.

However I can see that point of view that 5200 may be overkill because you would not be using it (or depending on it anyway) for any of its structural bonding properties as you will be using plenty of SS screws. In your case 3m 4200 or 3M 4000 would be your best bet. Here is a description of 3M 4000 straight off the 3M website..."Resistant to weathering, saltwater, and stresses caused by joint movement. Seals between mechanically fastened joints on wood, fiberglass, metal and most plastics above and below the waterline." Sounds like a perfect fit to me, may not be available at your local hardware store but maybe here on iboats or your local west marine.

Silicone does seal well however I don't believe that it has enough adhesion to the two surfaces to work well through years of expansion contraction and flex.

 

[Cadwelder]

Re: Cap Sealant and screws?

There seems to be a perception that 5200 cannot be removed or is unbreakable but that is not exactly the case. Yes it produces an extremely strong bond but there are plenty of sealant removers that make the job of removing 5200 much easier.

True, with a big enough hammer and pry bar most anything can be removed, it's the damage to the mating surfaces I've always run into. And I agree with you in saying the 5200 is an overkill for this joint. 3M 4000, is great for this, and I've used it, but have also used 3M Marine Grade Silcone with no problems either. (just poking at you with the hammer and pry bar, but it has some merit, : ) )

 

[barbosam]

Re: Cap Sealant and screws?

ya thats ok I can take it. But seriously if you are able to score/cut/scratch the surface of the 5200 then apply an adhesive remover like Marine Formula by Debond Corp its amazing how it just starts peel up once you get it started. Works wonders on small items but I do admit it would still be quite a monumental task to do on that whole joint.

Anyway, if you think about it, the seal at that joint really won't be detrimental to you boat. Even without a sealer if you are getting significant amounts of water coming in through that joint than you are probably getting even more water over the bow and gunnels any way and the joint will be the least of your worries. The sealing properties of silicone or an adhesive are not the only advantage they provide, they will also help prevent those screws from working loose. Thats why on the boats I work on I use something with more adhesive properties.

So in my opinion, would silicon work? yes. Would I use it on my own boat? no. But I would also build the boat in a way that I could be damn sure that cap would never have to come up in my lifetime.

There's lots of right answers, this is just my opinion.

 

[Yacht Dr.]

Re: Cap Sealant and screws?

Looks like masking tape and probably silicone for the job then... seems pretty straight forward. I will probably add another 1/4" plywood strip to screw too, even though the original strip is still in good shape. More bite the better.

Oh, can't forget the nitrile gloves for the mess!



Thanks for the help guys...

You had this Right spot on DC...

Silicone and SS screws ( you dont need to add more strips of wood if its in good shape )..

Im giving you good info here..and your quote here is probably the best way to go..

There are some things on boats that should NOT be bonded together "too" much..

Say you bond your hull deck joint together with some plexus or 5200 ( really good bond there ) .. now you happend to impact your hull at that same deck joint. If that joint is Bonded..it will transfer the energy to the deck.

Now you have your impacted hull AND Deck cracked because your deck didnt release off of the hull ( fiberglass being stronger to silicone will win and auto-separate from the hull ). Twice the damage from too much bonding.

Unless your going to go underside and GLASS the Whole hull deck joint..your setting yourself up for a bad experiance..

You keep 2 things separate..or make 2 things into one in Fiberglass .

Clean your hull deck joint well..then use 1.5-2" tape .. good 3m 4000 or silicone..screw the hull/deck ( oh yea..dry fit your deck first..pre-drill Hull/Deck .. then oversize drill the DECK flange ONLY. The screws should not to bite into your deck flange only into the Hull ).

Its not as easy as some make it out to be to install hull/deck .. this IS the way..

YD.

PS. Remember..DRY fit and drill first..caulk and seat last..