Delamination port side - down to bottom paint

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IFish4Tuna

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1999 30' Grady - Bimini 306 - Center Console

I recently had my boat transported to the boat yard where some work is going to be done on engines (2023 Suzuki 250s)

I noticed there was a scuff mark 4 feet back from the rear of the boat.
The transport strapping scuffed the bottom paint onto the gelcoat from the tiedown being removed. There was also a small chip in the gelcoat which was not previously there. <sigh>

While I was getting ready to buff out the scuff mark I noticed the gelcoat has become delaminated in a pretty large area perhaps 18" above the water line (and a few inches below also).
It spans the length of the boat about 3-4 feet. More pronounce above the water line.

What should I expect for repair on this? Does the gelcoat need to be cut off to inspect the balsa? Or does the area need to be injected with resin?
Has anyone had this problem? Cost of repair?

There is no access from the console area without cutting into the sides of the boat where the rod holders are located. So I just don't know what kind of a job this is.

Coincidentally, I am having the boat appraised on monday because I'm moving to a different insurance company. I wonder what else he will find.

Any help/advice/previous experience on the delamination would be appreciated.

Ed
 
I had a similar issue on my 92 Explorer. both sides from the cockpit back to the transom. When thumping it like that, it was hollow, not the normal solid thump.. I had it repaired by filling both sides with pourable marine foam. It was horrible how they did it. My boat is scarred for life, but she is more solid than ever .
 
I think this is a common issue. The question is HOW does one inject foam or go about strengthening these areas?
Maybe drill holes from the INSIDE and inject? Curious...
 
I’m not sure if GW cores the sides but that’s what it looks like to me. Could be wet core delamination. Call customer service and ask. Need feedback from similar boat model and age and how they fixes it.
 
Hookup1 said:
I’m not sure if GW cores the sides but that’s what it looks like to me. Could be wet core delamination. Call customer service and ask. Need feedback from similar boat model and age and how they fixes it.
Click to expand...
GW won't address this problem.
 
Hookup1 said:
They won't tell how the boat was built?
Click to expand...

When I had my transom rebuilt, they sent the spec sheet on how it was constructed. I have a call in to GW requesting the same for gunwale/hull. Left message for Carolyn Ray and waiting to hear back. I am prepared for the worst news, but hoping for something better.
 
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To clear up a possible point of confusion. The gel coat did not delaminate. The outer fiberglass layer (that happens to be gel coated after layup) is no longer adhered to the coring. Actually, there may not be coring left other than mush.
The coring has to be removed to do a proper repair. Cutting an access opening on the outside will expose the core but cleaning out the coring, especially at the extremes can be a challenge.
I am not familiar with any foam applications for the sides of the hull. The foam in the transom has been tackled by a few folks on the internet but depending on how extensive the problem goes, getting the foam to fill all voids is hit and miss.
I don't know I f I would tackle a job of this size.
You also need to figure out how the coring got wet and fix that source. Leaks at the joint between the hull and the deck cap (under the rub rail) are somewhat common. In the case of the Express model instances of core rotting, there was often decay found in the stringers.

One approach to identifying the extent of core damage is to identify a general area that seems to be a transition from hollow sounding to a more solid dull thump. Drill some small (1/4 inch) holes and probe with a screwdriver to see if you hit solid wood, mushy wood, or no core at all.
Note the the bottom of the hull up to and a few inches past the water line is solid fiberglass, not wood coring.
If you are going to commit to opening up the hull and repairing the coring, forget about reusing the outer layer you cut out. It isn't that simple.
 
IFish4Tuna said:
When I had my transom rebuilt, they sent the spec sheet on how it was constructed. I have a call in to GW requesting the same for gunwale/hull. Left message for Carolyn Ray and waiting to hear back. I am prepared for the worst news, but hoping for something better.
Click to expand...
They literally peeled the back half of the boat up from the hull and poured the foam.
 
I would think the right way to tackle this is to have the boat taken to a yard that has a good Fiberglass Guy willing to tackle such a project. As stated, this is not a "DIY" style project. And drilling a bunch of holes and inserting foam or epoxy will accomplish nothing since the bad, wet, coring MUST be removed.

So, I guess it goes something like this:
1. Boat goes on a trailer and taken to a proper boat yard
2. The outer skin gets removed where needed
3. The wet core gets removed and everything dried out
4. A new core gets added. Probably laid up fiberglass mat or sections of marine plywood + epoxy (not sure).
5. The outer skin gets replaced, patched and sanded.
6. Then, the whole side would get properly prepped and painted so as to hide the patchwork in the glass

The above, of course, is quite the major project but is the only way to be really sure the core is strengthened.

Your thoughts?
 
HMBJack's repair is the right way to do it. It won't be cheap though. A good shop is important but I would want a shop that has done this type of repair before.

Some may tell you to use GitRot or foam. It may work but you won't get a full strength repair without getting all the wet coring out. Certainly cheaper but it's not for me.
 
The core was end-grain balsa. Probably use a Divinycell foam board to replace.

Pretty much the same job as a transom. Cut off skin, dig out wood, replace coring. glass back together, fair & paint.

Sounds so easy....

I think a problem would be that the hull is not flat like a Grady transom. You have to match any curves. The inner skin is very thin and probably won't retain the shape.
Boat was shaped with the outer hull against a mold, then core applied, then inner skin.
You would be trying to fix it backwards.

If the problem is only next to the gunnel, you could remove gunnel, cut the liner from deck up to access the inside skin of hull. Work from there.
Then your outer hull is untouched. Easier to fix and fair the liner. Top is hidden under gunnel, bottom hidden by footrail.
..just thinking out loud..
 
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HMBJack said:
I would think the right way to tackle this is to have the boat taken to a yard that has a good Fiberglass Guy willing to tackle such a project. As stated, this is not a "DIY" style project. And drilling a bunch of holes and inserting foam or epoxy will accomplish nothing since the bad, wet, coring MUST be removed.

So, I guess it goes something like this:
1. Boat goes on a trailer and taken to a proper boat yard
2. The outer skin gets removed where needed
3. The wet core gets removed and everything dried out
4. A new core gets added. Probably laid up fiberglass mat or sections of marine plywood + epoxy (not sure).
5. The outer skin gets replaced, patched and sanded.
6. Then, the whole side would get properly prepped and painted so as to hide the patchwork in the glass

The above, of course, is quite the major project but is the only way to be really sure the core is strengthened.

Your thoughts?
Click to expand...
If in step 5 you mean that the original cut out is reused, that doesn't work. It is difficult to get the outer skin fully adhered to the new coring and flat as well without voids. The outer layer should be remade with laid up fiberglass. sanded, faired, and gel coated. In addition, the seam between the old section and the new can't be butted, the old skin has to be tapper ground to allow for a wide over lap of fiberglass layers.
 
Thanks I have the boat at safe harbors boat yard in my geo. They will evaluate in the coming days. I already had the transom done 2 years ago when I repowered. I waited until they determined the rear end was worthy of repair before ordering the engines. My error was I should have done as survey of the boat before the transom in 2023. Had I done that I probably would not have moved forward w/ transom and 60K in engines. 75K later here I am w/ new engines and a more $$ flowing.
 
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If in step 5 you mean that the original cut out is reused, that doesn't work. It is difficult to get the outer skin fully adhered to the new coring and flat as well without voids. The outer layer should be remade with laid up fiberglass. sanded, faired, and gel coated. In addition, the seam between the old section and the new can't be butted, the old skin has to be tapper ground to allow for a wide over lap of fiberglass layers.

>>>> Agreed. And by the way, I would only do such a project if it is truly necessary. I have dead spots like IFish4Tuna on my starboard side. Until I crack open the hull, I will wait on this... There is a thick bulkhead below the lifting point that adds great strength. The transom is not too far aft of that so structurally it's not terrible in that area but each case is different.
 
HMBJack said:
If in step 5 you mean that the original cut out is reused, that doesn't work. It is difficult to get the outer skin fully adhered to the new coring and flat as well without voids. The outer layer should be remade with laid up fiberglass. sanded, faired, and gel coated. In addition, the seam between the old section and the new can't be butted, the old skin has to be tapper ground to allow for a wide over lap of fiberglass layers.

>>>> Agreed. And by the way, I would only do such a project if it is truly necessary. I have dead spots like IFish4Tuna on my starboard side. Until I crack open the hull, I will wait on this... There is a thick bulkhead below the lifting point that adds great strength. The transom is not too far aft of that so structurally it's not terrible in that area but each case is different.
Click to expand...


Mine is soft down to and below the water line along the side, but not below the edge where it wraps under. If it weren't for that I'd be with you on less urgency, but the where it is loose along the paint line has me more worried. I am suspicious the trailering straps and respective pressure is what popped it in this area. I had scuffing in that area, and a new chip in the gelcoat presumably from them removing or throwing the straps.

Also unrelated but of note. I literally just paid this boat yard to redo all of my hatches on the boat for serveral thousand dollars. Have not even yet installed them. I'm really bummed out about this new discovery.
 
IFish4Tuna said:
Mine is soft down to and below the water line along the side, but not below the edge where it wraps under.
Click to expand...
Only the sides have balsa core. The running surface is thick solid glass.
The most likely cause is water getting into balsa core.

You can probably get a peak at it by removing something...like a 4" piehole or rod grommet or drawer unit or behind backrest seat coaming or similar.
On my 265 I can see the back side of the hull thru various places. Doesn't cost anything to look but a screw gun and some silicone.
Here is the port side of a 265 looking behind a 2 drawer unit. You can see under gunnel rod grommets at far end

IMG_3174.jpeg
 
Thanks I appreciate you taking the time to reply w/ suggestions, and the photo. Here is what I got from Grady White : They only had the fore section image. Nothing for rear.

This is what I got for an explanation: "Here’s a photo that shows the inside of the hull on the 306 Bimini that shows the balsa core that is encapsulated in fiberglass. The is present in the full hullsides, bow to the stern of this boat. The aft side of the hull from the styline tape area down to the bottom of the hullside. We do not have the specific layout drawing that I can send."

The first image look like pre-fiberglass, and 2nd with glass laidimage001.pngimage002.png
 
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