Water trapped under floor?

[BWalt302]

I recently picked up a 1981 19ft stingray boat. 120HP Mercruiser I/O. Transom is solid, all original interior. No flex when on the water, no damage, just "normal wear and tear".

I have experience repairing boats and have a pretty good understanding of boats in general. I have been unable to find much about this boat, but it fires up, runs great. The deck is solid, other than a soft spot at the rear jump seat beside the motor cover, I lifted the deck and the stringer, from what I can see is solid.

I am not very much concerned with the condition of the boat, for a 38 year old boat, it is solid. I took it out 2 times this week (last on Tuesday) and today when I came home I noticed just a tiny bit of water in the bilge area, I discovered it running from the front area of the bilge, below where the motor mounts. I think it was possible a limber hole that was glassed over years ago during manufacturing, but I am not so sure. After jacking the front of the trailer up, a decent amount of water came out, I jabbed the hole with a screw driver and it is draining as I type this, not a lot, but steady. The good news is that it was already draining without being jacked up, on its own, I just lifted the front to help it along, this in only on one side.

I am concerned that water may be trapped below the deck/floor and a lot of rot may be imminent. Could anyone give me advice on how to drill an access if need be, or should I let it drain and not worry about it? I don't have any symptoms of major rot (stress cracks, flexing when hitting waves at speed, etc).

Attached are a few photos, so you can have an idea of what is going on.

 

[Scott Danforth]

the brown water is evidence of rot and saturated foam

I highly doubt your boat is solid, especially a boat nearly 40 years old with the iffy build quality of nearly every boat in the 80's

looks like a full rebuild is in your future.

 

[kcassells]

That's so crazy you got water in your foam?

 

[BWalt302]

Yeah, so I've read that they rot from the bottom up, so the floor, and stringers that I have seen are all solid, as is the transom (all screws tight, no soft spots) - just a bit of delamination on the side. I took a small core sample from the wood I could access and it isn't rotting.

With that being said, sure, I bet there is some rot happening underneath, where would the best spot be to add one of those inspection cover holes in the floor so that I can get an eye / tools to examine everything.

I know no one can answer this question really, but are there any obvious or "structural importance" areas that I should inspect to determine about how long I have before the floor needs to come up.

One of two things will happen , I ride the boat for a summer or two max and restore it. Or two, I trade/sell it for another project...

My concern at this point is determining the safety and reliability before preparing for summer.

Thanks for any help, it is greatly appreciated!

 

[Scott Danforth]

first and foremost. delamination is an issue

next, when you did the test drills, what color were they? were they dry? any test drill shavings should be light colored and dry as a popcorn fart.

wet foam can not be dried out it has to be physically removed. even if you could get it dry, it is no longer closed-cell foam, it is a sponge.

at that point you will have cut the floor out to get to the foam. which means you will have de-rigged the boat, removed the drive and motor and built a cradle to support the hull. then cut the floor out.

at that point you are into a full re-build

 

[JASinIL2006]

I don't really believe you can tell much about the structural integrity from looks, or knocking on things, or putting weight on the motor. The real test is to drill some 1/4" holes into the stringers about 1" from the hull, and into the transom from the inside, taking care to no penetrate the outer hull skin. If all your holes yield light, dry shavings, you're very lucky and you can fill the holes with 3M 5200 and call it done. Given that you're getting brown water and you already have a soft spot in the deck, I'm guessing you find a lot of dark, wet shavings which means the wood has rotted or is rotting. If you do find rot, you'll have to decide if it's safe to operate the boat. Most folks here would tell you it's not safe.

 

[gm280]

If you are not into rebuilding whatever is presently rotted, I suggest now is the time to sell it off, making sure the new buyer understands the rot possibilities, and buy a newer boat. Because with that old of a hull, you absolutely have rot. No if's what so ever...

 

[BWalt302]

The delamination I speak of was the fiber glass over the engine mounting bracket, not the transom glass covered wood itself. So on the transom wood, there is another block of wood which was used as a supporting brace.

As far as the 1" from the hull stringers, could you elaborate a bit more on where / how I should go about this?

Thanks again everyone!

 

[Scott Danforth]

1" up from the hull, take a 5/16" drill, tape off 1" and drill into the stringers and transom. if the shavings come out light-colored and dry and smell like fresh cut wood - no rot - then plug holes and continue boating. however if the shavings come out wet, dark and smelling like rotten leaves..... full restoration

 

[BWalt302]

Got it, the transom shavings were fine!

For the stringers, you mean 1" up from the bottom, on the left and right side near the bulkhead (part where I/O mounts towards front of boat)... I can only access those for a few feet up from the transom. How should I go about it for the front / middle of the boat? Could I drill a large hole in the middle of the deck between driver/passenger seat for inspection and then place one of those round deck lids in it?

 

[Scott Danforth]

you could, however keep in mind, you may be drilling into the fuel tank. (many boats have tanks under the floor)

however from the trapped water, I can guarantee that there is rot

 

[BWalt302]

Fuel tank is located in the rear of boat, 19 gallon aluminum tank. Closed bow 19ft boat, so do I need to check anything in the front storage area, or would it be fine to check left and right back stringers in bow, left and right in middle of boat via access hole?

Should I worry about the stringers that run across the boat, instead of front to back?

This has been very helpful, thank you.

 

[BWalt302]

I also should mention, mainly because I am very curious, that this boat came from Nags Head, and was used in salt water its entire life. Two owners before me, both in same area.

I have read that salt water rot is less common, although still possible, has anyone "debunked" this myth?

 

[froggy1150]

Here is a good plan for you.....
get you a circular saw and set depth to 1/16 deeper than the thickness of your floor and cut the soft spot in your deck out. That would have to be patched anyway.... dig out foam til you can get to hull. (A pipe with teeth cut into it works)
then from there there keep digging til you find dry stuff. I had a very small soft spot at rear right corner of mine and that's what I did. Unfortunately I stopped at front left corner! But every foot I kept telling myself it was getting dry. Had open hull all summer last year in Vegas DRY 120 DEG HEAT and I still have one spot that still is weeping moisture from between layers of glass that I have to grind out.

 

[Scott Danforth]

I also should mention, mainly because I am very curious, that this boat came from Nags Head, and was used in salt water its entire life. Two owners before me, both in same area.

I have read that salt water rot is less common, although still possible, has anyone "debunked" this myth?

while salt water will deter rot, it doesn't stop rot.

either way, it still doesn't dry out your foam.

 

[kcassells]

I also should mention, mainly because I am very curious, that this boat came from Nags Head, and was used in salt water its entire life. Two owners before me, both in same area.

I have read that salt water rot is less common, although still possible, has anyone "debunked" this myth?

Consider that a BS Nags Head BS myth. Rot is rot...time to demo. No shortcuts. That's why 99% of us got here.

 

[sphelps]

If you have a hole size needed for whatever hatch lid you might install.
You could cut a few of those holes to try and gain access and do some snooping around....