View Full Version : "The Ultimate" Updated Pictures

Scott Pearson
11-30-2011, 05:52 PM
Its getting there...

11-30-2011, 06:38 PM
As we all know the balsa core rot issue is a real problem in these early Donzi decks where there is any drilled deck penetration, ( ie: clamshell deck vents, navigation bow & stern lights, gas fill etc. )

Our "Benchseat 18" project actually had living green tree moss growing on the edges of the exposed damp balsa cored clamshell deck vent holes.

Dad & I were going through this deck balsa core replacment headache when Dad suddenly got very sick; and sadly passed away six weeks later.
The project was on hold for over a year since that very time .
I have now re-started this "Benchseat 18" project.

Your Benchseat Hornet "the Ultimate" also has rotted balsa core in it's hull sides & bottom I would assume ?

~~~The Donzi 18 & 16 does not have any balsa core material actually in these lower hull areas.
Only in their decks.

How extensive is your hull's balsa core rot ?

Is this balsa core in the entire hull bottom & sides ?
How thick is your hull's core material ?

Will you use old traditional balsa core material again to replace this old hull core material ?
Or~ the Newer rot resistant core materials ?

How thick is the balsa core on this Hornet's hull's sides & bottom ?

How extensive is the hull's balsa core ?

How extensive are your hull's core rot issues ?

What a real rotten balsa core headache you have there Scott.

The final restored boat will be well worth it in the end however~~~

Good Luck & Keep posting your restoration progress photos.

Scott Pearson
11-30-2011, 06:50 PM
Since this was a Daytona Turbo boat all hull sides and bottom was cored. Also the entire deck.

I'm old school...so everything will be grain end balsa and vacuum bagged. The core is 1/2 think through entire boat (sides and bottom). every single piece of balsa and wood is being replaced...nothing was good.


11-30-2011, 07:50 PM
It's looking good Scott.
I understand the need to be thourough, but I was really surprised it was cored under the tank as the glass/foam/tank make for a really stout assembly.

When you're removing the old core, don't you wish it were all completely rotted?
It's so much easier to remove.

11-30-2011, 08:20 PM
I assum that end grain bulsa does not rott as fast as the bulsa your removing? And what is the bulsa your removing called? The one that took 30 years to turn to dust. Will this new material make it last longer before having to go through this again? Just wondering. Seems I am not the only one wondering this amazing science.

11-30-2011, 09:06 PM
Bert, it's Scott's boat.
I'm sure you read above that he's "Old School", and I think he prefers to use balsa for coring. Some people just like to keep things the way they were and not update to newer materials.
All of us here are aware you are a proponent of newer, non-absorbing materials and that's fine.
It doesn't make other folks wrong that prefer traditional materials.

11-30-2011, 11:13 PM
Great start. I never heard of the bottom being cored (back then), that's interesting. Looking forward to following the progress I'm sure it will turn out great.

- Marshall

12-01-2011, 02:19 AM

Cobalt built a GT-500 which was an exact Donzi Corsican "splash clone" that also had a completely balsa cored bottom in this very same time period . The hull sides were not cored however.

The Cobalt GT-500 is also now noted for extensive bottom balsa core rot.

There is one sitting in South Jersey that has at least 1/3 of the aft rear bottom waterlogged and rotted.
Tap on the outer aft bottom and it sounds dead & hollow.

Rustnrot here got involved with a similar Cobalt GT-500 project with extensive hull bottom core rot issues. ~~~ but the boat's owner eventually gave up on the project after seeing how extensive the bottom's balsa core rot was.

Scott Pearson
12-01-2011, 07:35 AM
The biggest reason these boats rot out so bad is that Donzi never sealed any holes off. They just drilled and assembled. They never enfused the balsa with resin. Once it vaccum bagged and enfused with resin this will stop any core rot. End grain balsa will not wick water throughout the rest of the balsa if one square gets wet. It will stay in that one spot.

But I look at it this way...who cares....in 30 years I will be dead and gone....:wink:

12-01-2011, 09:20 AM
But I look at it this way...who cares....in 30 years I will be dead and gone....

Pearson keep me in mind in 30 yrs would ya...:nilly::smash:


PS Sorry business has been slow:shades::pimp:

Scott Pearson
12-01-2011, 09:33 AM
At the rate I'm going it could be a lot sooner.

12-01-2011, 10:14 AM
I love the fact that you have taken on such a challenging job! And even more so that you share it in pictures here, with all of us. It looks fantastic so far, and I will enjoy watching the progress (and following your decisions) through to completion.

12-01-2011, 10:31 AM
Remember according to the LGDCC by-laws and constitutions Alexander Haig clause. When you go I am in charge. Doing my best dr evil LOL

Long live the king. :)

Rob M
12-01-2011, 08:36 PM
Hi Scott:

Do you happen to know what other models of that era had decks and hulls cored with balsa? Did the 14, 16s and BB 18s do this too? Pretty sure my Corsican (75) is foam cored (of some sort) on the deck.



12-01-2011, 09:01 PM
Rob. My 68 hornet is also foam cored the deck only the hull is straight glass and wood stringers.
My 67 16 had a solid glass deck no coring just PVC pipe supports. The hull coring on the hornets were for the high power engine combos with v drives

They used a few methods over the years I would imagine the arch on the Corsican would be a pita in balsa. Foam would make more sense in that case. the 16 and 18s started with balsa then it seemed in the 67 model they went away from it then went back to it. for the most part on the 16 and 18 just the deck were cored. it is very well possible that an early bb vdrive corsican could have a cored hull and deck. the early hulls were lighter lay ups then the later ones so maybe no hull coring was needed

Scott Pearson
12-02-2011, 07:30 AM
Matty is right on. Also it seemed that Donzi back in that era would use whatever they could get their hands on at the time. The use of Foam, balsa and PVC...yes...PVC was all over the place. You would have two boats built right next to each other that would have two totally different products used.

12-02-2011, 09:06 AM
-----The deck on Marios Corsican was foam core but the ski-locker hatch doors were balsa. I know because they were compromised and we had to do them over......Bill S

Morgan's Cloud
12-02-2011, 07:03 PM
The deck on my St T (reportedly a '66) has both balsa and ply coring ..The benchseat Hornet that my buddy found and bought in without knowing what it even was had a really spongey type of foam core .. I think that boat was a '68.

Rob M
12-04-2011, 06:58 PM
Thanks for the info Scott and Matty. Sounds like they grabbed whatever was handy at the time - and beefed up the rigidity on boats they knew were getting big power.

12-05-2011, 09:07 AM

remember too they were a business and sometimes a change in production was prompted by a shrinking credit line with a supplier. they used a few tank suppliers , motor suppliers, and glass and gel suppliers. the one constant was bilt rite not easy to source out a new interior supplier.

12-05-2011, 10:15 AM
-----Back during those early "Chisholm" days every marine engine supplier was clamoring for business with DONZI. At least in that case I dont think it was a credit line problem as much as cherry picking the best supplier, both monetarily as well as quality wise. The Chisholms had deep pockets,,,very deep, but they always kept an eye on the bottom line.......Bill S

12-05-2011, 12:37 PM
true Bill when it was full Chisolm ownership the product was more consistant . prior to that nothing was sacred