Substantial Cracks in Gelcoat

[MikeDobbs]

Hey everyone,

I'm trying to determine how to best deal with a series of cracks in my gelcoat. I think these are stress induced; as you will see in the pictures, they appear around the fitting securing the swim ladder to the boat.

The fiberglass seems to be intact underneath the gelcoat- it's as if the gelcoat simply split and left a gap where you can see the glass underneath.

To complicate the situation, I can see a very small amount of water "weeping" through the hull from the inside at the location of the two lower screws securing the ladder.

I'd very much appreciate any help or suggestions as to how to best address these cracks. I'm not concerned with aesthetics so much, I just don't want to have this develop into a serious leak that may threaten the boat at some point.


Thanks!

 

[DeepBlue2010]

Assuming the fiberglass is intact as you mentioned, the leak could be through the screws themselves. Just take the screws out and reseal them with 3M 4200 and most likely the leak will stop.

The cracks in the gel are stress related as you mentioned. Most likely you have a thicker get in this area and it cracked under pressure. There are so many ways to handle this depends on how much time and $$ you want to spend. You can grind the gel in this area down and re-gel or paint the entire area. Alternatively, you can go for a spot treatment; by using a Dremel or similar tool, open this crack into a V shape and fill it with gel then sand and polish. I also know someone who filed this V shape with 4200 just to protect the fiberglass underneath and he did not bother with gelcoat at all. How far you want to take this?

If I were you, I would start by first verifying that the glass is in fact intact and it is just a crack in the gel. A simple way to do this is to seal the screws and see if the leak stops.

 

[MikeDobbs]

OK- sounds like good advice. If I reseal the screws with 4200, will I be able toe easily remove them again to tackle the crack repairs? The cracks go under the ladder, so I'm assuming the ladder will need to be off to fix the cracks.

Or, I suppose I could just hit the part of the crack that's under the ladder with 4200 when I reseal the screws, and then I could still do a better looking repair to the exposed parts of the cracks.

 

[Woodonglass]

If you have water weeping from the screw hole you have some greater issues. That means the wood core is saturated with water. How long has this crack been there and how much time in the water has the boat seen since the crack has been there? Once water has gotten inside to the wood core it's difficult to get it to dry and then rot can/will begin to occur. The weeping water is NOT a good sign. I'd be drilling some core samples on the inside in the general vicinity of the hole to see how far the dampness of the wood has gotten. That's just an Old Dumb Okie's opinion.

 

[MikeDobbs]

If you have water weeping from the screw hole you have some greater issues. That means the wood core is saturated with water. How long has this crack been there and how much time in the water has the boat seen since the crack has been there? Once water has gotten inside to the wood core it's difficult to get it to dry and then rot can/will begin to occur. The weeping water is NOT a good sign. I'd be drilling some core samples on the inside in the general vicinity of the hole to see how far the dampness of the wood has gotten. That's just an Old Dumb Okie's opinion.

Is it s foregone conclusion that there is a wood core? I think it's just solid fiberglass on this part of the boat. I supposed if I remove the ladder I should be able to tell if there is wood in the middle, or just fiberglass, yes?

The boat is new to me, so I can't say about length of exposure. I've had it out half a dozen times (the boat is trailered, not slipped, so it doesn't sit in the water all the time) with these cracks. My attention has been focused on engine and electrical issues since this didn't appear to be a structural issue to me.

It's an 18ft bowrider, if that makes a difference. The more I think about it the more I think there is no wood core- at least not on this part of the boat- maybe deeper in the hull, where it takes a pounding.

 

[jbcurt00]

What 18ft bowrider?

I/O or OB?

Pix showing the entire transom showing it's overall shape will help confirm it does or doesn't have a wood core in that area. Some I/O boats have a stern shape that isn't flat across the back, and on the outer corners of those, there isn't a plywood backer, or possibly a separate piece of plywood that isn't in contact w/ the transom.

If the ladder is mounted to the actual transom, it's more then likely a wood core transom. There may be a few boats that don't have one, but there aren't many and certainly not main older boats. And having water leaking thru a screw hole is never a good sign.

 

[Woodonglass]

Is it s foregone conclusion that there is a wood core? I think it's just solid fiberglass on this part of the boat. I supposed if I remove the ladder I should be able to tell if there is wood in the middle, or just fiberglass, yes?

The boat is new to me, so I can't say about length of exposure. I've had it out half a dozen times (the boat is trailered, not slipped, so it doesn't sit in the water all the time) with these cracks. My attention has been focused on engine and electrical issues since this didn't appear to be a structural issue to me.

It's an 18ft bowrider, if that makes a difference. The more I think about it the more I think there is no wood core- at least not on this part of the boat- maybe deeper in the hull, where it takes a pounding.

Based on the pics you posted, especially the inside pics with the bolts and the woven roving, I'm almost certain you have a thick wood cored transom to which the ladder is thru-bolted. But...I freely admit I AM and Old Dumb Okie and have been proven wrong many times in the past, and will probably be proven wrong many more times in the future.!!! As stated, Pics of the over all boat and ladder will tell the tale!!!

 

[MikeDobbs]

No Title

OK- here's some pics of the entire transom. The ladder is mounted on the Port side of the boat- you can see it in the pictures. The boat is an 18ft C&M Holdings Marada Sport, manufactured in 1998, and fitted with a Mercruiser Alpha 1 gen 2 drive. As stated above, new to me- so I'm slowly working through the various issues.

My wife and I are not all that concerned with aesthetics, we just want the repair to be watertight- and quite frankly, I'd prefer something that takes less time as I'd like to be using the boat right now and not fixing it : )

My current thinking is to pull the ladder off, and remount using either 4200 or 5200 to seal the screws. I have two questions:

1) DeepBlue2010 suggested using 4200 for this repair- my wife is nervous that it isn't considered a "permanent" repair. Can anyone comment on 5200 vs 4200 for this application?

2) Since either one only lasts 24hrs once the seal is broken, I'm leaning towards just widening the cracks a little with a dremel, and filling them all with whatever sealant I end up opening. Once it cures I figure I can sand it down and use some compound and wax over it to make it look decent (obviously the color will not match though). Is this a viable approach to handling these cracks? Again- aesthetics are not a primary concern, we just don't want it to leak.

Thanks

 

[DeepBlue2010]

Based on your signature, I believe this to be the boat we are talking about.. But it seems that your ladder is on the other side of the boat.

Also, it seems like you have a different type ladder that is mounted under the boat. In any event...
AS


When you take the ladder out, you will be able to see if you have a wood core or not and if it is wet or not. 3M 4200 is removable, you will be able to remove the ladder again if you need to. It may take some efforts but you will be able to. If y you want to apply a sealant just to test if the leak will stop or not but not for a day to day use, try the 3M 4000.

The reason I would start with this test is to avoid any unnecessary core sampling. If the leak doesn't stop, there is a structural issue that needs to be addressed.

 

[Woodonglass]

Well, like I said, I've been wrong before, and It appears I am again!!!!:facepalm: I have to agree with you. That's a unique configuration on your boat and based on the pics it might just be all glass. I still would drill into it from the inside and see if you get wood shavings. However, the configuration of the stern means the wood would be for reinforcement for the ladder and glass and not critical to the motor as most Transoms. That's not actually your transom. If it were my boat I'd be putting a 3/4" piece of plywood back there and using longer bolts to reinforce that ladder. Or at the very least some very large washers to distribute the load. The stress cracks are for sure and indication it needs it. Still not sure why Solid fiberglass would be weeping water.

If you're not concerned about the cosmetics, then I'd v-groove out the crack and fill it with PC-11. Get it at ACE Hardware.

 

[MikeDobbs]

DeepBlue2012 - that's my boat exactly (minus the fishing seat). It's the same exact ladder, mine is just unfolded in the picture, and the photo you posted the ladder is fully raised.

A follow up question on the 4000 - the 3M website says:

3M? Marine Adhesive/Sealant 4000 UV is a one-part adhesive sealant that cures to form a firm, rubbery waterproof seal. Its flexibility allows for the dissipation of stress caused by shock, vibration, swelling or shrinking. Designed for marine applications above and below the waterline.


Do you mind if I ask why you said it wouldn't be appropriate for day-to-day use? Seems like it might do the trick. Sorry for all the questions, I'm new to all this stuff, and there's so much to learn.

 

[DeepBlue2010]

Honestly, just out of habit, I always used 4200 & 5200 for sealing; never anything else. I just reviewed the datasheet for both products and they are very similar indeed. 4000 has better adhesion properties to metal which is great for your application. Based on the datasheet,

4200 has % ELONGATION of 900% BEFORE BREAK
4000 has % ELONGATION of 800% BEFORE BREAK .

But honestly, I don't think this makes any difference in your application, so I stand corrected.

 

[MikeDobbs]

Woodonglass - no worries- I think it's a bit of an oddball boat, but I like it : )

OK Thanks DeepBlue2010 - do you think I could use the 4000 to fill in the v-notches after I widen the cracks? Or should I stick with the 4200 or a gel coat repair material instead?

Which reminds me - every time I research gel coat repair, I find videos with scratches and dents, but never large cracks like I have. Will a standard gelcoat repair product work on those cracks? Or am I better off with something like 4200/4000 or the PC-11 stuff?

 

[MikeDobbs]

Woodonglass- I was thinking that reinforcing those ladder attachment points would be a good idea too. Would you just use 3/4" plywood? Or is there some special marine plywood I should use?

 

[Woodonglass]

I'll make one more comment and then I'll butt out. I think I'd be more concerned with ensuring that the stress cracks did not re-occur than just fixing what's there now. Something caused them to happen and that needs to be addressed. Like I stated previously, Most of the members with similar issues have used large backup washers or plates to try to distribute the load over a wider area and alleviate the stress. IMHO you'd be wise to do the same. One last thing, I don't believe the 4200 or 5200 is the correct product for this kind of repair. For sealing hardware, yes, stress cracks in gelcoat, no. But again, I am just an Old Dumb Okie!!! I'm OUT!!!!

 

[MikeDobbs]

I don't believe the 4200 or 5200 is the correct product for this kind of repair. For sealing hardware, yes, stress cracks in gelcoat, no. But again, I am just an Old Dumb Okie!!! I'm OUT!!!!

I appreciate the feedback- and I don't disagree. I don't think anyone is suggesting that 4200/5200 would be the correct way to fix the cracks- just wondering if it would get the job done. Based on your previous post I assume PC-11 would be a "correct" method of fixing the cracks, yes? Would a standard gelcoat repair product work on these cracks as well, or are they too wide?

I absolutely want to brace the ladder so the cracks don't reappear- can I use regular 3/4 ply or do I need something else? I've heard of a product called starboard, but am not sure exactly what it is.

 

[sphelps]

Looks to me someone very large climbed the ladder and it just stress cracked the gell .. Or left down and bumped something . If it was mine I would take the ladder off grind the gell back a bout an 1.5" back on each side . Maybe not even that far and build the thickness back with a couple layers of glass .. Then glass in a piece of wood on the inside for some extra support Redrill and seal with 5200 .. Touch up the gell and let it ride .... If the glass is not cracked then just V-groove the gell crack and fill with thickened resin ..

 

[Woodonglass]

Ok, Here's exactly how I'd fix it if it were mine. I'd remove all the hardware and bolts and inspect the holes to see if there was a wood core or all glass. If wood then I'd treat the holes with some Antifreeze to "Wick Out" the water and let it set for a few days to dry out and help it along with a heat gun and fans. Then I'd go on the inside an sand the area down with 40 grit an prep it for glassing down a piece of 3/4" Ext. Grade plywood as a backer plate. Then I'd coat it with resin and Glass it in with a couple of layers of 1708 biaxial fabric. I'd then v-groove the cracks and mix up my own filler using resin, glass bubbles and a bit of cabosil. Sand and fair then use some Rustoleum Paint to cover my tracks!!!! Drill the holes, Coat the bolts with 3M 4200 install em with BIG washers or make my own from aluminum plate. Re-install the ladder and call it Done!!!

 

[MikeDobbs]

Thanks for the detailed explanation Sphelps and Woodonglass, quick question... If I go with resin, should I be using epoxy or polyester resin? And when you say "glass it in" for the 3/4 plywood, does that just entail brushing on epoxy, then layering with fiberglass cloth, and then more epoxy?

 

[DeepBlue2010]

The reason you don't find any gelcoat repair videos for cracks like yours is that you can't fill these cracks with gel. Gel is too thick to seep into hair cracks. You need to open them up. In other words, deliberately turn them into big scratches with a dremel tool or something similar then follow the repair steps as if it were a big scratch.

In an effort to establish a scale between people who are extremely detail oriented (a.k.a perfection freaks, pain in their own behind such as myself) and people who don't give a rat's behind and just want to go boating, I said I even know of someone who just turned the crack into a scratch as described above and filled with 3M 4200.I wasn't recommending this neither would I do it myself but not because there is something wrong with it. It will protect the fiberglass from being exposed to water. Fiberglass is porous and water (in very minute and microscopic amounts) will seep into fiberglass (over very long time) if I am in a hurry and want to protect my FG from being exposed until I do a "proper" repair, I will use 4200, nothing wrong with that. It would gum up on the surface and collect dirt and look like sh*t but it will create a barrier between the FG and the water. I wish I was the type of person who can be satisfied with these hacks, I would have saved myself a lot of pain, but unfortunately I am not.



If the area is structurally compromised and you will go for a full blown repair, adding an extra backing support - as WoG suggested - is the way to go. I personally use starboard composite material. It is expensive but it saves me the steps of sealing the marine ply. I know the company said that this material is not meant to be structural but based on my own experience, I find the strength of it to be sufficient for providing extra backing support. I have it as a backing plate in my boat for multiple applications and I am happy with the results. If you don't prefer to use it for whatever reason, my second option will be marine ply but of course you will have to seal it. Few cots of thin epoxy (no glass) or a coat of poly resin then glass will do the trick.


You don't need to use epoxy, you can if you want to but you don't need to. Let's take this one step at a time instead of going through every possible route. First, take the ladder off...

Is there wood core?
Is it wet?
Is the boat in saltwater or fresh water?

If saltwater you don't need to worry about rot. The bacteria that causes wood to rot don't exist in saltwater. So the wood can be wet but not rotted or weak. If the wood core - if you have any - is not weak, I wouldn't worry about glassing the backing board at all. I don't really see what is glassing would add to the situation. The backing board is sitting flat on the hull and help distributing the weight across a wider area. Whether it glassed, glued, mechanically fastened to the area, I don't see any difference. Now, if the core wood is weak or rotted, that is a different story all together