Donzi Construction Question

[Francin728]

I recently purchased a 98 Donzi 19LXR. Any idea as to whether the stringers are wood? I read that the transom is closed cell foam and I know the floor is plywood but I can not find any answers on whether the stringers contain wood.

 

[Philster]

Re: Donzi Construction Question

It would be plexus bonded hull and deck joints, vacuum-bagged balsa core in the hullsides, a cockpit liner and Divinycell closed-cell foam coring of bulkheads, stringers and the transom.

 

[Francin728]

Re: Donzi Construction Question

so aside from the floor which is encapsulated plywood there should be no worries of wood rotting?

 

[Francin728]

Re: Donzi Construction Question

Any idea as to whether the foam under the deck is closed cell or subject to becoming saturated?

 

[Bondo]

Re: Donzi Construction Question

Any idea as to whether the foam under the deck is closed cell or subject to becoming saturated?

Ayuh,... It was "Closed cell" when put there,...
But,...
I'll Guarantee it'll suck up tons of water, in Time...

 

[Francin728]

Re: Donzi Construction Question

The floor is SOLID throughout but my concern is one small section less than 1 sq ft under the rear seat is SLIGHTLY soft. I need to pull up the carpet and see what is there. I can fix that small part of the floor if necessary but I am hoping there is no soaked foam.

I am surprised that this section is a little soft as it is under the seat and out of the elements. The upholstery is in excellent condition as is the rest of the boat so I know it was not stored in the elements.

 

[Philster]

Re: Donzi Construction Question

Yep... For all boats, it's accidental damage or outright drilling into cores that exposes parts of boats that shouldn't be exposed to water. You can get rot in some models (wood cores where the covering has been breached) or have a composite boat that supplements strength with foam and is completely waterlogged.

 

[Philster]

Re: Donzi Construction Question

The floor is SOLID throughout but my concern is one small section less than 1 sq ft under the rear seat is SLIGHTLY soft. I need to pull up the carpet and see what is there. I can fix that small part of the floor if necessary but I am hoping there is no soaked foam.

I am surprised that this section is a little soft as it is under the seat and out of the elements. The upholstery is in excellent condition as is the rest of the boat so I know it was not stored in the elements.

Water tends to collect at the stern, and if any water that has collected back there is exposed to freezing temps, it'll outright bust things up, creating the breach... damaging wood or foam.

 

[Francin728]

Re: Donzi Construction Question

The boat has always been here in S. FL so freezing wasn't as issue. The really strange part is the soft spot is roughly 3-4 ft up from the stern not in the back where water should be sitting.

I will pull up the carpet but I'm just affraid of any damage that may exist under the floor. I was hoping for composite stringers or other materials which might not be as prone to rotting.

I was under the impression that closed cell foam was watertight. Does this quality change over time and allow the foam to absorb water?

 

[Philster]

Re: Donzi Construction Question

A closed cell structure can be breached, too. Or... it's billed as closed cell but -- presto -- it absorbs water. Oh, maybe it's worth mentioning that other materials besides wood degrade over time. For foam, it ages/degrades and can absorb water.

There are various 'composites' that deteriorate over time. I've heard some cases for this being worse that wood deteriorating, as wood repair is sound and time tested, wherein one might have to visit NASA to secure the right types of materials, bonding agents, etc to repair various composites, bonds, foams, etc.

 

[sasto]

Re: Donzi Construction Question

Sounds like to me it is more of a delamination problem than soft core. We used closed cell foam for several years. I placed 2 untreated pieces in a jar of water for over a year, and neither retained any water. One was divinycell and the other a less expensive honeycomb closed cell foam board (don't recall name). Mind you, was for a shorter time than your boat's exposure.

I would tap it with a plastic hammer and you may feel it to be hollow, which would likely be delamination.

This coming from a builder.....not a repairman.

 

[Francin728]

Re: Donzi Construction Question

When I pull back the carpet if it is delamination on the plywood should I just cut back to solid fiberglass and reglass the exposed section?

 

[oops!]

Re: Donzi Construction Question

if it is de lam yes.....there might be surface moisture on the wood.....just put a fan on it for a day or so after you get the glass off ....then re glass the area .

if the wood is soft take a skill saw and replace it....


btw......just about all older boats will have water intrusion issues.....even if the hull was made with composite stringers and transom /deck....you would still get some type of moisture under the deck in the foam..... its a natural process.....it will occur. the issue is....how much? is it a cup ....or a few gallons?

 

[Texasmark]

Re: Donzi Construction Question

Ayuh,... It was "Closed cell" when put there,...
But,...
I'll Guarantee it'll suck up tons of water, in Time...

To me closed cell is Styrofoam, like in coffee cups. I bought a '65 Starcraft Holiday 18' I/O that sat semi submerged in Lake Dallas, TX. for a couple of years and fully restored it down to the empty hull....nothing but alum left including the transom redone. The flotation was closed cell styrofoam sheets about 1" thick, 18" wide and 6' long best I can remember.

I originally assumed that I would be replacing the flotation with something else but when I got around to that part of the restoration, it was completely dry and showed no signs of water intrusion other than some mildew some of the surfaces.

Sprayed in foam, will agree, but that's open cell.

Mark

 

[Texasmark]

Re: Donzi Construction Question

The floor is SOLID throughout but my concern is one small section less than 1 sq ft under the rear seat is SLIGHTLY soft. I need to pull up the carpet and see what is there. I can fix that small part of the floor if necessary but I am hoping there is no soaked foam.

I am surprised that this section is a little soft as it is under the seat and out of the elements. The upholstery is in excellent condition as is the rest of the boat so I know it was not stored in the elements.

Well what about the "soft" spots you don't discover. Fiberglassing wood stringers has been done for years on thousands of boats.....but what is the sealing qualities after years of use in rough water. I have been in two boats, one a guide fishing trip and the other a potential purchase of an MFG fiberglass that showed obvious signs of water intrusion....in addition to a '71 Chrysler bass boat that I was about to purchase and a '60 Taylor craft that I bought.

Today I drive an aluminum boat...........

Mark

 

[ezmobee]

Re: Donzi Construction Question

To me closed cell is Styrofoam, like in coffee cups.

I don't think white Styro is considered "closed cell". I could be wrong.

 

[Philster]

Re: Donzi Construction Question

Styrofoam is often incorrectly used as a generic term for expanded (not extruded) polystyrene foam (coffee cups, coolers, or cushioning material in packaging)... which we see as white and made of expanded polystyrene beads.

This is a different material from the extruded polystyrene used for Styrofoam insulation.

The polystyrene foam used for the applications I listed, which can be identified by its roughness and by the fact that it "crunches" when cut, is moderately soluble in many organic solvents, cyanoacrylate, and the propellants and solvents of spray paint, and is not specifically identified as expanded or extruded.



But, nonetheless, expanded polystyrene foam never got soggy holding my coffee, so whatever it is (closed vs. open) doesn't seem to absorb liquids/water!

EDIT: Anyway, upon further investigation, our beloved coffee cup foam is closed cell:

http://www.foambymail.com/EPS/polystyrene-foam-4-pack.html

As a lightweight closed-cell foam, expanded polystyrene, or EPS, is popular in a multitude of applications, including crafts, insulation and construction projects that call for firm closed-cell foam. The unique structure of polystyrene provides almost total resistance to moisture and water vapor. Polystyrene foam has a superior R-value, so polystyrene sheets will insulate to keep heating or cooling inside of any room or commercial space and will not rot, mold or attract fungi or mildew.

 

[Francin728]

Re: Donzi Construction Question

The question then becomes which type of foam Donzi used in their boats in 98. Any ideas as to how I can figure out if I need to worry about foam being saturated without taking up the floor?

 

[sasto]

Re: Donzi Construction Question

The question then becomes which type of foam Donzi used in their boats in 98. Any ideas as to how I can figure out if I need to worry about foam being saturated without taking up the floor?

A surveyer with a good moisture meter may help.

Cut off the top laminate in the suspected area and check your core. You should be able to repair your test area if all is well.

 

[oops!]

Re: Donzi Construction Question

the foam in most newer hulls is closed foam....expandable......but it deteriorates over time and waterloggs.

another neat trick....is to empty the gas tank.....take everything out of the boat and weigh it against manufacturers specs.