2005 43’ Trawler w/ Marine Plywood Core in Deck and Pilot House – Major Concern?

[TJB_Patriot]

Originally Posted by u4ea32

I agree, Tad, that delamination does occur, regardless of core material. However, you certainly know that there are two key reasons for delamination: 1) lousy initial bond during construction, 2) exceeding the strength of the core-skin bond during operations. BOTH are strongly affected by the stiffness of the core: the stiffer the core, the more likely delamination occurs. As I mentioned before, a stiff core is prone to areas of poor initial core-skin bond due to the inability to get consistent core-skin pressure during construction. During operations, a stiff core causes stress concentrations, increasing the likelihood of locally breaking the skin-core bond.

U4ea32,
I understand your comments on reasons for delamination. Do you feel these issues would appear at anytime over the life of the boat or are they more related poor construction and would appear early in life?

While only 6 years old this boat has approx. 1200hrs of ocean use from FL to Nova Scotia. Would the types of delamination issues you refer to above already have materialized? If the boat has no such issues today would you be concerned that they may appear in 5 to 10 years? I can't image that coastal cruising in the northeast would subject the boat to conditions it has not already experience as the owner has stated that the boat has handled significant ocean conditions extremely well over the life to date.

Of course I realize that water intrusion into the core could happen at any time due to poorly installed hardware or damage.

Thanks

[viking north]

Mark why would you think Gonzo was an anomoly, re read the thread. Patriout Thankyou for the thankyou while acknowledgement is not always given it is good for the soul. David, good detailed engineering info but the guy has to work with what was presented to him and in the perfect world we could build a perfect boat but alas we can only strive to get it as close as we can with economics controlling the materials presented. I didn't reply to your first post, I knew as a builder reaction was coming down the pike. Keep the sun shining in L.A. will be there in a couple of weeks to look at a build project. Just love the place.---Geo.

A yacht is not defined by the vessel but by the care and love of her owner.

[Steve W]

When you refer to plywood CORING material you are implying that the deck was laid up in a female mold with plywood being used in lieu of, say, balsa or foam which is a different situation to what a lot of folks who have responded are talking about. In my experience, plywood used this way, while less than ideal, holds up better than balsa to water intrusion. Foam would be a better choice although Airex is not usually used for the horizontal deck sections.
What a lot of the responses seem to refer to is where the plywood is used to stick build the deck and cabin, the plywood is not a CORE in this case and if glued with epoxy (or other suitable adhesive) and glass (or dynel,polypropylene,etc) sheathed with epoxy resin, is an excellent very long lasting, reasonably lightweight method. Unfortunatly a lot of older Asian trawlers used this method from the bare fiberglass hull up but did it with poor materials, and poor building practices and gave the method a bad name.I blame this on poor western supervision,not the asian skill level.
Steve.

[TJB_Patriot]

Originally Posted by Steve W

When you refer to plywood CORING material you are implying that the deck was laid up in a female mold with plywood being used in lieu of, say, balsa or foam which is a different situation to what a lot of folks who have responded are talking about. In my experience, plywood used this way, while less than ideal, holds up better than balsa to water intrusion. Foam would be a better choice although Airex is not usually used for the horizontal deck sections.

Yes my understanding is the deck and pilot house are CORED with 3/4" marine plywood.

Resin: Isophthalic resin used throughout the entire lay-up of hull, deck and components. Resin is hand-batched and catalyzed using dyed catalyzer for control.

The deck and pilot house are painted with awlgrip, hull is gelcoated.

Its interesing that Airex is not typically used on horizontal deck sections. Maybe I misunderstood the other owner of a similar boat made by the same builder. Perhaps only his pilot hose was Airex. I'll have to call and check again.

Thanks

[FAST FRED]

"Its interesing that Airex is not typically used on horizontal deck sections."

Airex is both excellent and expensive,many builders will cheap out when they can get away with it.

"and it (wood ) doesn't collapse like foam when you tighten bolts.

The technique for properly reinforcing a spot load has been used by most pro builders for at least 3 decades.

It does taker time , but only marginal skills and almost no cost.

FF
__________________

[Steve W]

Patriot, if the deck was built as you say in, female molds i cant see why it would have been awlgripped instead of gelcoated at the time of the original build but who knows. As Fast Fred said, Airex is an excellent foam,great for hulls but less so for decks,only because it will soften easier than most other foams when exposed to the heat of intense sunlight such as, say, with a deck painted anything other than white in south Florida. Probably not a problem up north. AlLL i repeat,ALL cored decks require proper tecniques to deal with compressionand water ingress at the location of hardware, it makes no difference if its plywood,foam or balsa,all will last indeffinatly with no issues if built well.
Steve.

[viking north]

Agree with the other posts, I doubt if they ever used airex in the deck mainly in that it would not have been recommended in addition to the cost and extra work to install ply where hardware had to be mounted.It sounds logical they would have used airex in the superstructure for less weight. Also it wouldn't surprise me if the entire superstructure was built in a seperate mold and fastened as a seperate piece. That was the standard method in a planned high production shop.Are you sure the superstructure is ply cored, maybe in the transfer of info you were informed that ply core was used and assumed it was the superstructure as well as the deck. Geo.

[michael pierzga]

Originally Posted by Steve W

Patriot, if the deck was built as you say in, female molds i cant see why it would have been awlgripped instead of gelcoated at the time of the original build but who knows. As Fast Fred said, Airex is an excellent foam,great for hulls but less so for decks,only because it will soften easier than most other foams when exposed to the heat of intense sunlight such as, say, with a deck painted anything other than white in south Florida. Probably not a problem up north. AlLL i repeat,ALL cored decks require proper tecniques to deal with compressionand water ingress at the location of hardware, it makes no difference if its plywood,foam or balsa,all will last indeffinatly with no issues if built well.
Steve.

Ply , foam or Granite blocks will all deteriorate with water ingress. If you Dont allow water ingress, you will not have a problem. Attention to detail when installing deck fittings , waterproofing and distributing load, are the trademarks of a superior boat builder.

When you survey the boat, get on your hands and knees and look carefully at all mechanically fastened, superstructure and deck , hardware joints. If you spot any rust bleeds, ..... it almost always means water, make a note.

Look carefully for any aftermarket hardware installations. Aftermarket fitters, for instance canvas makers and electronic installers, drill plenty of holes in boats, but they are not boatbuilders, often lack boatbuilding craftsmanship and frequently do a poor job when fitting and bedding gear. If you spot aftermarket gear...make a note.

If possible , in the area of any suspect deck hardware, remove the interior headliner and examine the underside of the hardware installation. Again.....any rust bleed staining means water. Make a note

An experienced marine surveyor will know all this, may know the original build shipyard and may be able to spot any aftermarket installations. . A good surveyor is Money well spent.

I was just saying that Gonzo was not alone in his opinion. Plywood is perfect for this application. A sentient being, engineer or not, keeps it dry and it will last longer than any of us.

[u4ea32]

I'll reply this evening, I'm really busy today.

[gonzo]

Michael I agree on that. Keep the water out. There is no reason it can't be done. Leaks on decks are no more acceptable than below the waterline.

[Joe Petrich]

When properly engineered and built for it's intended use, plywood will work just fine as a core material. As stated by others earlier, improper installation of add-ons after the boat is built is what usually leads to rotten core and/or delamination.

I have to concur with others that a proper survey is most important when buying a boat. It's money well spent. I'm not sure where you are but find a good NAMS or SAMS certified surveyor to do a buyers survey for you. Don't trust a seller's survey which sometimes glosses over the bad points.

[gonzo]

You can find reputable surveyors in this website.
http://www.navsurvey.com/

"Leaks on decks are no more acceptable than below the waterline."

[viking north]

Mark, and i thought you were calling Gonzo an anomoly, I should have known better . Is spring peeking thru the perma frost yet in Homer?
Patriot, Do you have any extra info on where the boat was built. It seems to me I heard of Atkinson, I have a feeling your boat might have been built here in Nova Scotia. I am and have always been a sort of a lone wolf in the boat buisness small and specialized, but know or have met most of the builders here in mainland Nova Scotia. I am located sort of on the northern section of the hot spot for boatbuilding most of the big building shops an hour or so drive south of me in Chester,Lunenburg,and further south.If you can give me some further info on Atkinson I could make a few calls and get a feel for his past builds, Information being power.--Geo.