Older vs. newer Donzis.......

[gcarter]

I want to make it real clear.....there is no winner in the older vs. newer Donzi 22C discussion.
Different dicisions were made by the management of the various owners over the years.
For instance, during the Chisolm and Staples eras, there were problems w/underbuilt and undersupported decks, tubs, stringers, and strake pockets.

With OMC and later AMH, other decisions were made regarding some of these issues.
In some cases, like the tub and deck support, improvements were deffinately made, but not in the manner I would have made them. I would have made it so the deck and tub were supported, but it would be easier to disassemble it.

Stringer design in the newer boats (post '92), the stringers definately appear to be beefier but apparently there issues w/how the stringer stock was assembled and that it's plywood (not good for rot prevention).
Also the hull layup between the stringers has been an issue.

These are just a few notes from my observations.

We can really put some meat on this issue if there's any interest.

Like how to map out a stringer design, hull layup scheme for any age boat that a member here could follow along, or a glass shop could follow.

[HOWARD O]

We can really put some meat on this issue if there's any interest.

Like how to map out a stringer design, hull layup scheme for any age boat that a member here could follow along, or a glass shop could follow.

I have an interest! I'd like to do some "beefing up" when restoring the 22 this winter. I have done a fair amount of glasswork myself but it's always been under someone else's direction. I could "guess" where things should be beefed up but it's just that, a guess.

This would be great, George. I'd like to help out if you want to make up a separate area or even a separate website for it, I can do that. :yes:

[MOP]

Not sure who was running Donzi during 85-87, below is a shot of the battery box that "Supported the back end of the tub. The deck had little to no support aft one the battery box broke loose!!

Here is the meat I added!
I added vertical supports glassed to the stringer/hull. The battery box was cut down and sits on 3/4 plywood bridging and lagged to the stringers, the bottom is glassed to the plywood making the back end of the boat very strong. Almost everyone with a 22 has had the transverses tear loose from the hull, that was caused by the bottom flexing upward on impact peeling them away from the hull. Having one of those years I made sure I added more then enough beef, most of the planning and glass work was performed by the head glass guy from Hustler Boats. He says it will hold way more HP then I am making. The second shot besides showing the doubled stringers shows the vertical supports, added bulkhead and transverses. Yes a couple aft also!

P.S. The battery box came out as you see it, completely torn loose from the hull. It made a weird crackling sound with passengers in the back!

[gcarter]

So, what's the difference between an "older" and a "newer" Donzi Classic?
Las year Rick SE and I sort of defined thim with these sketches;
The newer hulls are sort of like this...

http://www.donzi.net/forums/attachment.php?attachmentid=32589&d=1194379181

The stringers are about 2 1/2" thick with "shelves" that actually land on top of the stringers, although Rick's boat may be just like the sketch since it came w/as larger engine. The engine mounts are located between the stringers. The stringers are made up from layers of plywood and some are all chopped up in a number of longitudinal pieces. Also, there're about four gussets on the outboard side of each stringer between the transverse frame and the transom under the shelves. Some of these boats have been found to have a lot of rot in the plywood coring of the stringers and cracks in the hull between the stringers. This style of hull first appeared in '93 or '94.

The older boats, starting from sometime in the '70's to '93 or '94, look like this;

http://www.donzi.net/forums/attachment.php?attachmentid=32671&d=1194546320

Notice the stringers are closer together and are made from clear 1" X 12" pine. The stringers aren't very well supported, have gaps under them, and have very little glass on them. In spite of that, there're plenty of them with pretty potent engines and perform pretty well.

[mattyboy]

not sure where the newer and older classic demarcation point is for the purposes of this discussion is??? but I would not classify a mid 1980's classic as older but more middle age, seeing as there were 20 years of production prior to that. it's a piece of fiberglass that takes a beating nothing lasts for ever, how many people have cars that last for 10 years under that abuse???
or using a hull that was strecthed from another design as a benchmark??? has the the different factory or molds used during those time been taken into account ??? not to say the factory has not done some bone head things like notching the stringers to the raw wood and not sealing them, or drilling holes in the deck and leaving them unsealed. for every rule there is an exception not to mention the drive trains have grown to put more stress on the structure to

are they boats or an everlasting gobstopper?? :tongue:

[Air 22]

from what I have read,, seen and heard...there are no two Donzi's that are exactly the same from bow to stern...each one is has something different regardless of the year made etc...

I'm just say'n...:nilly:

[gcarter]

not sure where the newer and older classic demarcation point is for the purposes of this discussion is??? but I would not classify a mid 1980's classic as older but more middle age, seeing as there were 20 years of production prior to that. it's a piece of fiberglass that takes a beating nothing lasts for ever, how many people have cars that last for 10 years under that abuse???
or using a hull that was strecthed from another design as a benchmark??? has the the different factory or molds used during those time been taken into account ??? not to say the factory has not done some bone head things like notching the stringers to the raw wood and not sealing them, or drilling holes in the deck and leaving them unsealed. for every rule there is an exception not to mention the drive trains have grown to put more stress on the structure to

are they boats or an everlasting gobstopper?? :tongue:

Matty, I think it's important to keep the discussion to the minimum number of differences. You're right in that there're infinite numbers of variations, and we'd go crazy trying to chronicle all of them.
But just like the sharp V keel 18 versus the slightly later round keel 18 w/cutaway strakes makes the two boats really different in nature and performance, there really has been only two basic hull forms since the '70's that made for really structural differences;
1) Early boats with 23.5" stringer spacing, inner strake spacing to match, closed and filled strake pockets, and skinny 1" X 12" unsupported stringers. With production ending in '93 or '94.
2) Later boats with 28.5" stringer spacing and inner strake spacing to match. Inner strakes have open pockets. Stringers are composite 2.5" thick plywood w/glass layup. Four outboard gussets between forward transverse frame and the transom. "Shelves" are integrated from the stringer tops to the inner chine area. Production from '93 or '94 to current.
I'm only talking about hulls here and not decks or deck configurations (of which there are many).
If anyone knows about other major differences in hull configurations like the ones I mentioned above, pipe up!

[mattyboy]

yeah i would think if you had a flat chiner, a reverse chiner from fla , and a boat from goshen that would give a good cross section to make a comparison

[gcarter]

OK.....how about this?
Flat chine boats correspond to the earlier boats and reverse chine boats are relagated to the newer.
Actually, I think that's true within a short period of time.
It may have happened at the exact same time.

[MOP]

George question you have mentioned before the use of plain pine for the stringers, I have yet to see one that people were restoring that had plain wood, All I have seen were plywood, has anyone one else found regular and not plywood used in the Donzi's?

[gcarter]

George question you have mentioned before the use of plain pine for the stringers, I have yet to see one that people were restoring that had plain wood, All I have seen were plywood, has anyone one else found regular and not plywood used in the Donzi's?

All of the older boats I've had any experience with have had 1 X 12's. I've not seen any w/plywood stringers.

It seems newer boats definately have plywood stringers.

Can we get any anecdotal evidence here? Model year and photos would be helpful.

[JaxOutlaw]

Any boady used "preforms"? Its a composite preform stringer. It seems to make the job easier... Any input?

[robertbj]

George question you have mentioned before the use of plain pine for the stringers, I have yet to see one that people were restoring that had plain wood, All I have seen were plywood, has anyone one else found regular and not plywood used in the Donzi's?


I have a 16 ski-sporter with 3/4in stringers. I think it is a 1966 but would like help with the year, and the stringer make-up. It has the through-the-deck manual fuel gauge and metallic donzi emblems above the stickers.

[VetteLT193]

George, I think there is a middle ground too. Maybe when OMC took over, that had thicker stringers with side supports.

I have seen more than one set up identically. My Minx, a few other Minxes, and a bunch of 22's. Not sure on dates, etc.

[mattyboy]

from what I have seen the weight of a 22 has changed over it's life also , not sure why but it was as light as 2900 lbs in the mid 80's and is currently tipping the scales at 3400lbs never mind those "portly" criterions have a salad already would ya ;)

[yeller]

Copied from another thread, here's my stringer measurements from a 04 22':


I took some measurements to compare against the pics that were posted. Inner strakes are 30", outer strakes 48".
Bilge stringers are 29" apart and are about 1.5~1.75" thick.
Forward of the bilge, the stringers are 25" apart and are about 1.25" thick. The forward stringers are also 1.25" higher than the bilge stringers.
My bilge stringers being 1/2" further apart than Rick's is probably because his are thicker.

[gcarter]

Thanks Yeller!
I'd forgotten you had posted those.
It could be the 496 boats are 1/2" further apart, or it may be that there's that much tolerance in the build.

[roadtrip se]

is 28 inches.

Just measured for a cradle less than a week ago.

[gcarter]

As already mentioned, the stringers on these boats were made from 1' X 12" clear pine, which is actually 3/4" X 11 1/2". Maybe a few were plywood like MOP mentioned.
One of the characteristics of the stringers was they were cut square on the bottom so that the only point of contact was the outside corner, then the glass was wrapped around the stringer and the inside hull surface.
This is a picture of the Minx, as I got it, after removing the transverse frame;

http://www.donzi.net/forums/attachment.php?attachmentid=48624&stc=1&d=1248828221

It's easy to see the glass wrapped around the bottom of the stringer.

[gcarter]

On the outboard side of the port stringer you can see the cracking that took place;

http://www.donzi.net/forums/attachment.php?attachmentid=48625&stc=1&d=1248828561

[gcarter]

On the ouboard side of the stbd stringer, there was some delamination that originated at the time of hull layup, notice it's only two layers of cloth;

http://www.donzi.net/forums/attachment.php?attachmentid=48626&stc=1&d=1248828829

[gcarter]

It's really not as bad as it all may seem. All of it was repaired w/o replacing the stringers and w/o removing the deck.
Actually the small block engined boats do better than the 22's w/BBC's.

[MDonziM]

What I found suprizing when gutting my eng compartment was that the stringer leanths were pieced together between the gussetts. Not a continous piece from transom to transverse. 94' 22c. They were 2+ inches thick and bevel cut on the bottom so no hard spot and 28 1/2" spread.

[yeller]

A tidbit to add on the construction: My deck is cored with balsa, but the foot rests are cored with foam. I'm 90% sure the engine hatch is cored with foam as well. Not 100% sure on the hatch because I didn't make an effort to look when I installed the latch mechanism, but what came out with the drill bit seemed like foam.

[Pismo]

Great thread. My 1996 22 has a thicker transom between the exhaust holes. Looks like the plywood used in the transom ends at the exhaust holes. When drilling further outboard to install new tabs, I noticed it was all glass. Seems the stringers run forward from the edge of the transom wood.

When did they use this design? Still using it? Any problems with it?

[gcarter]

Great thread. My 1996 22 has a thicker transom between the exhaust holes. Looks like the plywood used in the transom ends at the exhaust holes. When drilling further outboard to install new tabs, I noticed it was all glass. Seems the stringers run forward from the edge of the transom wood.

When did they use this design? Still using it? Any problems with it?

I think this has been the standard from the beginning.
There's a lot of curvature in the transom, so it wouild be difficult to make a overall thick transom w/o cutting the plywood up into pieces.
The transom is pretty flat in the center and starts curving towards the hull side from about the area of the stringers.
Of course the center must be flat to accept the outdrive.

[Carl C]

The entire transom on my 2005 22 is cored with a foam or composite material.

[Pismo]

When I drilled to install the new lifting bracket in the center, there was lots of glass, wood, etc. When I drilled to install tabs more outboard all I drilled through was about 3/4" of glass. All I got out was that fine white powder of drilled glass. Are the sides of the transom just glass and no wood? Wood only in the center?

[Pismo]

The entire transom on my 2005 22 is cored with a foam or composite material.

Do you have wood anywhere in your transom? or is it all composite of some type? How about the stringers?

[gcarter]

FWIW, the '88 TR's transom sides were about 5/16" thick.
I added about three courses of 24 oz Knytex to the sides and ended up w/about 1/2"-5/8" of glass. W/the tabs I'm adding, I'm glad I did it.

[Pismo]

FWIW, the '88 TR's transom sides were about 5/16" thick.
I added about three courses of 24 oz Knytex to the sides and ended up w/about 1/2"-5/8" of glass. W/the tabs I'm adding, I'm glad I did it.

I did not measure mine but I was surprised how thin it was. I guessed 3/4" but it was probably less.