Rub Rail caulking

M

mawyatt

New Member
Dec 13, 2007
1,001
Clearwater, Fl
Boat Info
2008 Sundancer 38DA
Engines
8.1L Mercruisers
Our new 38DA (3/2008) has the rub rail caulking flaking off. Almost all the caulk has flaked off where the rub rail plastic white mold is caulked to the top side fiberglass/gel coat, the other caulking in other places on the boat are fine. MM said this is not covered under SR warranty. Is this a problem with water intrusion? What caulking was/should be used on the rub rail?

Thanks,

Mike
 
Got a quick response from Jason at SeaRay. The caulking/sealant around the rub rail is cosmetic and the topside and bottom hull fiberglass is completely sealed under the rub rail cover as are all the screws. So no water intrusion issues. The exposed seam is very well defined and actually looks better and cleaner than the caulking/sealant. Everwhere the caulking/sealant had flaked off the seam underneath looked really good. I will examine in more detail when I get out to the boat. I guess the purpose of the caulking/sealant is to "hide" any gaps in the seams.
 
Does this also apply to a 2005 280 DA? I was actually going to caulk within the next couple of weeks, but I know that my caulking job will look like poo! If the caulk is purely cosmetic, then I'm better off leaving it alone.
 
Yup, skip it.

Now, I will say that there are times when we have found a leak through the rubrail. But based on the volume of boats we deal with, I can honestly say that it's the exception, not the rule, when that problem presents itself.
 
Not so fast.................

The caulking is there for a cosmetic reason, but its not to just hide the seam. When the top of the rub rail is left open, water will enter the crack between the deck cap and the rub rail. Over time, all manner of dust, dirt, grime, diesel soot off forklifts, road film on trailered boats, etc. gets behind the rub rail. Eventually, the water behind the rub rail runs out of the bottom crack, between the hull and the rubber rub rail, taking with it some of the collected dirt and grime. This leaves horrible black streaks down the hull. So while the top sealer is cosmetic in nature and no water will enter the hull to deck joint, leaving it off or not replacing it when it comes loose means you will be scrubbing your hull quite regularly to keep it clean. The more you scrub the dirt, the more you will be waxing.

This one is really up to the individual owner and how he wants his boat to look. I can't stand the black streaks, so I replace the silicone sealer on the rub rail about every 3 years.
 
Jasons a great guy !!! An asset for sure to Searay !

I still Miss JERRY..... He is truly missed !

Rob
 
Last edited:
fwebster said:
Not so fast.................

The caulking is there for a cosmetic reason, but its not to just hide the seam. When the top of the rub rail is left open, water will enter the crack between the deck cap and the rub rail. Over time, all manner of dust, dirt, grime, diesel soot off forklifts, road film on trailered boats, etc. gets behind the rub rail. Eventually, the water behind the rub rail runs out of the bottom crack, between the hull and the rubber rub rail, taking with it some of the collected dirt and grime. This leaves horrible black streaks down the hull. So while the top sealer is cosmetic in nature and no water will enter the hull to deck joint, leaving it off or not replacing it when it comes loose means you will be scrubbing your hull quite regularly to keep it clean. The more you scrub the dirt, the more you will be waxing.

This one is really up to the individual owner and how he wants his boat to look. I can't stand the black streaks, so I replace the silicone sealer on the rub rail about every 3 years.
Click to expand...

I agree about the black stains, I have a blue hull which doesn't show the black stains but shows the white salt stains. I have the black stains on the deck and arch which are white. So I get both!!!

Makes sense regarding the sealant, capillary action will cause the water to get "sucked" in carrying dirt and grime with it. I was really worried about water intrusion, which isn't an issue.

Jason at SR suggested taping off the area and roughing up the area along the seam to allow the sealant to stick better and reduce the flaking. I will probably do this but at least I don't have to panic and get it done ASAP!!


Thanks
 
I keep mine caulked with a micro bead of while silicone.

I add a little more along the aft quarter as the diesel fills are outboard and above a long sloping rub rail. Every now and again adribble with make it to the rub rail and diesel will cause most caulks to yellow miserably and you have to be very aggressive keep it bristol. Extra caulk there helps.

Caulk the top of the rail and let the bottom go.
 
Is 4200 sealant the right product for the application? Do you guys have any tips on how properly apply it or is it like regular caulking (apply thin line and follow with a finger trying to maintain even line)?
 
This is a rubber to fiberglass joint that gets some flex every time you bump the dock or a piling. That means you will be redoing the calk joint more other than other bedding chores on a boat. I would use silicone since it can be easily removed and replaced. I also mask off both the deck and the rubrail w/ 3/4" painters tape when I calk a joint like this. That way you control the mess and the width of the calked seam.
 
fwebster said:
This is a rubber to fiberglass joint that gets some flex every time you bump the dock or a piling. That means you will be redoing the calk joint more other than other bedding chores on a boat. I would use silicone since it can be easily removed and replaced. I also mask off both the deck and the rubrail w/ 3/4" painters tape when I calk a joint like this. That way you control the mess and the width of the calked seam.
Click to expand...

Yes, don't use 4200. Also, just cut the tip off really close (small hole). Take your time.
 
Lazy Daze said:
Yes, don't use 4200.
Click to expand...

Lazy Daze, you got me a little confused. Is it YES use 4200 or NO do not use?:huh:

I'm thinking YES use it, b/c it's flexible/removeble. Am I right?
 
Sorry, I was agreeing with what Frank said.

Do not use 4200. I guess you could, but it's overkill. 4200 is an Adhesive/Sealant. All you need is a Sealant - such as 3M Marine Sealant or BoatLIFE Life Seal.
 
fwebster said:
I also mask off both the deck and the rubrail w/ 3/4" painters tape when I calk a joint like this. That way you control the mess and the width of the calked seam.
Click to expand...

Thanks for the tip Frank.
 
fwebster said:
......... I also mask off both the deck and the rubrail w/ 3/4" painters tape when I calk a joint like this. That way you control the mess and the width of the calked seam.
Click to expand...


Pros don't use masking tape :)
 
Right..........that is why a calked seam from most dealers looks like it was applied with someone's thumb!

Besides, I'm not blessed with a lot of patience and masking tape keeps me honest and is quicker than cleaning up the mess when I don't use it.!
 
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