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View Full Version : Question of the day..."Hatch Foam"



Scott Pearson
10-22-2000, 02:47 PM
Ok here it is. I need some help on this one. The motor hatch on my 68' needs some work on the underside. This is what I found, The underside was soft and weak. You push on it and it moved. Ok...So what I did was cut a large section out of the back. About 3 inches from around the edge and lifted it off. This is what I found, The foam was broken in large sections and was coming away from the hatch glass. This is the same foam that is used in the back areas of the deck itself. You can see this if any of you have ever taken a Vent off of the deck. I have to replace this foam inbetween the hatch. Ok the question...Do they make foam like this to replace it? It looks like it was done with a liquid foam. Because the way its contoured to the form of the hatch.

Let me know your thoughts on this one guys. I would like to get this done ASAP. The deck is primed and should be ready for paint next weekend. I have to paint the hatch with the deck. You know...that whole Pearl and Luminescence thing...Its gotta match.

Thanks (NJ)Scott

GEOO
10-22-2000, 02:59 PM
Scot, My 1975 X-18 has a wood core in the deck & engine hatch. I believe it is End Grain Balsa. I did a seach for Marine Foam and found this site. They sell Balsa. http://www.mertons.com/misc1_04.htm
You might want to use End Grain Balsa or some type of sheet foam. Turn your hatch upside down. Make a template of the core needed. Tranfer the template to the core, cut the core to size, make a resin paste to glue the wood to the hatch. Put weigh on the core to push it tightly against the glass on the hatch. (Test this method first. If the weights don't hold the core down; then I would get four ratchet straps put them around the hatch and core and slide scrap wood under the strap to apply presure on the core) Once it has dried, remove the weights and glass over the core. I'm sure there are several ways of rebuilding the core this is just an Idea I had, Hope it's helpful. GEOO

[This message has been edited by GEOO (edited 10-22-2000).]

Scott Pearson
10-22-2000, 04:17 PM
Geoo,
Thanks for the info. If i cant get any type of foam that will work I will use Balsa. I have some 1/2 laying around. I dont know if that will be better then foam or not. I'm sure balsa will be stronger.

I will keep you informed

(NJ)Scott

Len
10-22-2000, 10:18 PM
Scott, you might want to run the urethane foam over a table saw and "cross-hatch" (score) the under side to help with conformity. About 1/3 to 1/2 way through like a checkerboard. My 2 cents...

Owen
10-23-2000, 02:01 AM
Foam? In '68? This does not compute.
Was this re-done sometime in the past?
I thought all donzis had balsa core.

You might find this thread interesting. http://www.boatered.com/topic.asp?topic_id=4459&forum_id=2&Topic_Title=Powerboat+reports+on+balsa+core&forum_title=The+Marine+Surveyor&M=False&S=True

[This message has been edited by Owen (edited 10-23-2000).]

Len
10-23-2000, 02:14 AM
I thought I was the only Donzi fanatic that didn't sleep...movies over, kids are away. Home Alone, part 10...

Scott Pearson
10-23-2000, 05:50 AM
Owen,
This boat was NEVER touched. Yes it has balsa from the factory from the Dash foward. It also has balsa under the rear seat areas. They are the only places with balsa. From the dash back to the transom its foam. Its about two inches thick. You could never get balsa that thick or even to conform to those areas. Check it out...Take one of your vents off and see whats under there. The floors of the older Donzi's are also wood not balsa. Balsa would never hold up under the seats. Dash is also wood.

Im going to take Geoo's advise and get some 3/4 balsa and replace the hatch foam. This way when I stick the injectors out of the hatch its nice and strong...

(NJ)Scott

Scott Pearson
10-23-2000, 06:12 AM
Owen,
Great site! Lots of good info! As far as Balsa goes...It rots like a bitch! I posted a thread about a week ago on the Balsa in the rear seat area. I had to replace this area because Donzi drilled the drain hole through the glass and the Balsa. This acted like a sponge. My boat has been in storage for 21 years and has never been touched. So of the 10 years it was used the Balsa under the rear seat area was shot. It looked like chopped meat the way it came out.this is the only roted area that I had to replace. As long as balsa isn't exposed to water its a great product. The underside of the deck area, Floors and stringers where perfect! I replaced the transom because I'm running a Merc set-up. And even that wood was perfect. It was a shame I had to remove it. Thanks again!

(NJ)Scott

GeneD
10-23-2000, 07:46 AM
I don't think that it is particularly important what material you use, as long as you use some type of composite.
A hard type foam is okay, but I would rather use the balsa. I have seen the foam used on a lot of race boats of special manufacuture. This was sandwiched between carbon fiber though.
Before I even knew that you could buy end grain balsa, I used little squares of plywood. 3 x 3 inches. A bunch of them. Then bonded that to the underneath of the front deck, then laminated over that. Of course the secret to all this is to make sure it's watertight! When the structure is all bonded, laminated, ect. It becomes VERY strong.
The original material sandwiched between the laminates under my vents are balsa, as is the rest of the stuff. The hatches too. I didn't check the cockpit floor as that was solid as a rock.
Whatever it is that you end up doing, I'm sure it's going to be okay.
Good luck.

------------------
GeneD
007
Melbourne, Florida