Rotted Transom and stringers

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muddkatt

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I had the privilege of helping a friend cut the back out of his 28 ft. boat this morning. Let me say this for the record. When anything is attached to or though the transom, a dab of silicon is not the right way to do it.
Anyway, water had gotten in through "several" openings. After the initial 3x4 foot section was removed, there is still a lot more that has to be done. Water started pouring out of the stringers once the ends were exposed. Also, the board that is in the center of the bilge, where the bilge pumps are mounted was filled with water. I drilled the end out and over a quart of water had ran out before I left. I did find out that the bottom is cored with some kind of foam. Not sure if this is an area of concern or not.

Ken
 
Generally if there is water intrusion/wood core rot in the transom, it is advisable to cut the outer glass of the transom about an inch inside of the outer edges (if done from the outside). If from the inside, then right to the hull sides. The stringers will have to be removed and rebuilt. If the core is balsa, it needs to also be removed and recored. This can be a big job....I personally perfer epoxy for the rebuild because it will seal wood much better and has better secondary adhesion to the old glass.

Agree, that anytime a cored section of a boat has any hole drilled in it or any fitting screwed to it, the hole should be over drilled, the core under cut with a Dremel tool, or short section of a bent coathanger in a drill, and then this entire area filled with epoxy and high density filler. Then the screw or bolt put back in place. (Hause pipes etc, also require the under cutting and smoothing of edges.
 
This is a bigtime job. Other than locating the source of the water and tracing its path once in the structure, there is likely a lot of heavy lifting to be done while replacing the defective structure. I recall seeing a TV Boat Show where a full new grid of fiberglass was used to replace a rotton original. Someone involved needs to be an expert 'glass worker. Depending on the skill level your friend may want to seek some professional help now so he doesn't add to the woes. Good Luck. Please keep us advised. You or yor friend can seek some detailed help here--just try to give full descriptions and info so the gang can think things over before responding.

Likely this has been a hidden problem for a long time.
 
Yea, the problem was there before he bought the boat. He just did not look it over close enough. I am pretty good a glassing, not a pro, but I can do the job, no doubt in my mind.
The only doubt I have is if the old boat is worth all this money and time. If it was mine, I would scrap it. He needs to replace the engine too. All I see is a lot of money going into a boat that is 24 years old. I just don't think its worth it, but he does. He is the one writing the checks.

Ken
 
What kind of boat? Some 24 YO boats are worth the time money and energy.
 
Went thru all that on my 24' searay. Had to end up removing ALL the wood from the transom to the cuddy bulkhead.

The best way to go about it is to remove the engine and start tearing all the wood in the transom and leave the glass alone. As you get to the stringers, you may find you need to replace them, too. There's no reason to touch any part of the fiberglass unless it's damaged. You have to support the boat carefully and evenly if you remove all the inner supporting structure.
 
ITK, I don't remember what kind it is. I will check when I go back up next weekend. It is not a name brand I am familiar with. It came from Indiana is all I know. When he pulled the engine and drive so we could do this repair, I found rust inside the exhaust ports on the heads. A quick tear down fond lots of problems, damaged cylinder walls from intrusion back when it was a fresh water boat. 2 damaged pistons, heads had been replaced, but are damaged again. Gonna need lots of money on the drive too. If he is frugal, and does all labor (me helping) it will cost at least 6 grand. I dont think he gave over 6K for the boat.

Does Meridian sound like a name of a boat manufacture? That just popped in my head.

Ken
 
so I guess the question is....given the propensity for boat builders to continue experimenting with coring in decks, hullsides and bottoms, when will they realize that even the smallest screw hole can turn into a very expensive repair? yes, I understand the argument is that cored hulls are stronger, light-weight, and cheaper, etc. but if one screw can compromise, safety, structural rigidity and sea=worthiness and marina monkeys are unaware, oblivious or just ignorant. Who would buy a cored hull? And why do manufacturer's keep making them. As soon as I see a cored hull I steer clear - isn't this just logical?
 
Muddie, Meridian is the larger Bayliners after Brunswick bought the line. They start at over 30 ft LOA.
 
Thanks Liz, I will drive up today and get the name brand.
I don't think, in fact I know, that the cored hull was not the problem. It might end up having damage, or even be beyond repair, but the problem was the idiots with the drills and screwdrivers. It was taking on water from ALL the accessories that was added. Swim platform, trim tabs, speedometer pilot tube mount an the hole for the tube. Same on the depth/fish finder.
Then to add to the problem, the gel coating in the engine room had lots of cracks and delamination. This could have been caused from water intrusion, or just be from age, I do not know. But it did allow for further damage, or at least is damage that must be repaired. I will try and snap a few pictures and post them. It might be a few days, since I have to work out of town this next week and my laptop just died.

Ken
 
autlaw, hull coring and transom coring are different issues. nearly all small boats have cored transoms, usually plywood, and this is not experimenting... it's been the standard way of building boats for years.

Same with stringers, for years and years, many builders incl. big names, used a plywood box,glassed in. Problem is that some builders used very little glass, relying on the plywood for structural integrity... often they woudl not seal the limber holes resulting in quick rotting and delamination.

As to coring the hull sides and decks, since it's not under water it's not a big deal and the benefits outweight the risks. building a stiff deck out of glass only would weight too much. Nowadays, modern coring material have solved most of these problems with closed cell foams like Divynicel which don't absorb water and wont rot like balsa. Problem is that Dyvinicel cost 2 to 3 times more than balsa...

personally i would stay away from a cored hull (below waterline) especially balsa.

but again, this is different, we're talking transom where plywood is common
 
Well I was half right about the name. It is a Meridien built by Century. At least I don't feel like I have totally lost my mind.

Ken
 
even if he got the boat for free, by the time he's done with the engine, drive and transom, he will have more in the boat than it's worth...

he really needs to bail out now...
 
thanks for the clarification pascal. I know on my regal that the bottom is solid FRG, but deck, hullsides and transom are balsa cored. I've had some issues on my balsa cored deck due to the stanchion mounts not being sealed correctly from the factory I believe. it's a nightmare to get rid of the rotten balsa coring in these area's. I agree that the manufacturer's should be paying closer attention to properly sealing these typical water intrusion points, limber holes, mounting hole's on transom and deck, etc. Do you know what manufacturer's are using Dyvinicel in teh decks and transom? Like you I will always walk from a cored bottom. I've read some of pascoe's postings and agree on the coring issue. thanks
 
Not sure who uses what, it also varies year to year and model to model... I know that these Hatteras uses Dyvinicell above the waterline and solid glass below. On my old 53, the decks are balsa cored and i have a couple of soft areas nears spots where PO have drilled holes and not sealed them.

Cruisers core their hulls (at least some), not sure what they use. SeaRay has had a few disasters with balsa core over the years, again not sure that they use these days.

often the info is hard to get... they use some fancy name for the hull design/shape like liftostratodeltaconicmaximus hull but almost never state in the specs what is cored and what is used... gee... i wonder why!
 
Don't know about other makes but Silvertons from as far back as the early 90's were using divinycel . I removed a plug of this stuff a few years ago when I was cutting something into the deck
. I soaked the foam in water for a few days to see what would happen. It never seemed to soak up any of the water or get wet.
 
Yeah, searay used to call it a duo-conioc hull.

I removed all the foam from my '78 searay and it was ALL wet, but oddly enuff it was not soaked in like I thought. What it did was allow a relatively small amount of water in and have it wet out all the wood that it touched. my 3/4" plywood stringers and bulkheads weighed about 40 lbs for each 1'x8' section so that each 4'x8' panel weighed over 160 lbs(over 3-4 times of dry 3/4" plywood)
 
If the cored bottom is properly made, it is as good, or in some ways better than a solid hull. But very few boats are made properly. As Pascal noted, most stringers and some bulkheads are made of non marine plywood (which is perticularly susceptable to rot because of voids and crossing grains in the layers). When limber holes (to allow water to flow between parts of the bottom of the boat in the bilge) these holes are not sealed, and thus rot in the stringers and bulkheads. This is probably more of a problem that a properly cored hull.

The properly cored hull will have thick layers of glass inside and outside of the core--many did not, and the laminate broke down, or the core apart from the outer glass. There are some boats where the holes in the decks are properly prepared.

The C Dory line has been made for about 30 years with fully cored bottoms of the hull, and there have only been a couple of the boats which had problems--with almost 100% of these boats (close to 10000) still in service. Those which had problems, were related to a factory defect where some resin was not properly catalized. One of the nice features of end grain balsa core, is that it is rare that the rot migrates for any distance, if caught in time.

Various builders have used different techniques and materials through time. You need to check out what was used, and get a good survey on any boat--most problems will be found on a good survey. Certainly, the problems on the boat mentioned in this post would have been obvious on a survey.
 
here we go again, the balsa fans always apologize for balsa saying it needs perfect construction and prefect yard work and perfect owner maintenance so that it wont rot
quote:
if caught in time.

Click to expand...

Foam wont rot, ever. Years ago I submerges a sample of foam in water for a year. It had not absorbed and water that I could tell.
IMO there is no reason other than cost for a builder to use balsa today.
 
Foam is OK as long as it doesn't touch any wood. If there's any place where water can get in, the foam will allow it to migrate thru capillary action throughout the exterior surfaces of the foam. The reason coring is used for fiberglass is because there is less and less compressive support between the walls of FG as the sections get wider. Simply, foam stiffens both walls whether they are panels or larger compartments.
 
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