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donzi4life
07-21-2010, 09:59 AM
Hello everyone my name is Adam and I am new to the world of Donzi. About a month ago I bought a project 1970 Donzi 18 classic triple hatch barrel back. Which a super stoked on working on! You are probably going to here from me a lot, this is a different project for me which I am new too. The boat has been totally stripped and ready for the next step. As I was looking at the transom the other day, I saw a little rot on the lower part of it. Also I am thinking of putting a mercruiser outdrive rather than the old tired Volvo, Which leads me to a different size hole. Where do I start with the transom? The boat has a 351w that will be bolted in for the powerplant. What are the steps in rebuilding that transom? How thick does it need to be? What materials are needed? And special angles I need to look for? And how difficult is it to do? Ands so on… thanks guys hope this will work!

BlownCrewCab
07-21-2010, 10:26 AM
If you like speed the Merc drive is a good choice (volvos usually top out around the mid 60's mph). the transom should be 2 pieces of 3/4" plywood thick with a layer of glass between the layers of ply. if you do replace the wood cut the bottom of it short so it doesn't cover the drain plug hole. thats the #1 spot for water intrusion.

are you sure yours is a tripple hatch? I didn't think they made them in the 70's. Got any pictures?

Edit... Well, if it's a Barrel back I think it's a mid 60's boat.

donzi4life
07-21-2010, 03:06 PM
is this a hard project to accomplish? meaning the ripping out stage and making sure it is right!

CAPTBEACH
07-21-2010, 03:09 PM
Donzi4life,

Here are a link to the boat I'm finishing now...

Spring paint...

http://www.classicseacraft.com/forum/showflat.php?Cat=&Number=81550&page=0&view=collapsed&sb=5&o=&fpart=1&vc=1


I have previously replaced 3 transoms in boats I've owned...I would not use plywood...too many good options out there...although I did use marine ply on the decks and hatch coring I would strongly advise using 26lb Blue Water Coose board as it is lighter and stronger than ply when finished properly and impervious to water intrusion.

Cut the inner portion of the transom out leaving the skin outside intact...lots of nasty messy work but I've found its the best means to an end and have a superior end product.

Bluewater Coosa 26Lb comes in 3/4" 4'x8' sheets. I would strongly advise buying a sheet and using it vs marine plywood. Two 3/4" layers should be cut large enough to trim to final fit/cut the transom.

Epoxy resin(some use polyester) should be painted on liberally on both insides then 2 layers of 1708 cloth should be wetted out and laid onto the sheets. These should then be joined together on an extremely flat surface covered with visqueen (flat garage floor?) and weighted down with lots of weigh placed on 2x4s to distribute the weight until cured.

You should then template the transom accurately with cardboard until you get a perfect fit then transfer the template to your cured material (after its cured and pulled free of the visqueen you used to keep the mess manageable paint the entire piece with epoxy to seal the entire piece of coosa board.)

Once you cut your new transom out, do lots of trial fitting to ensure a good fit...

Your going to need to complete a lamination schedule to layer 4 min 5-6 preferably layers of 1708 cloth over the entire inside of the new transom to tie in the transom to the floors and hullsides to create a new "integrity" between the hull and the new transom, especially running the kid of ponies we are talking about here...

I will try and dig out pics of when I replaced the last one on the SeaCraft and post them soon.

I've just given you the gist...there is lots of detail...

Go to ClassicMako.com and ClassicSeaCraft.com and do a transom replacement search...you will find a group of guys in love with their boats just like here with Donzi's...don't hesitate to ask me anything...like I said, I've been there, done that and got the epoxy stained t-shirts to go with it...

CAPTBEACH
07-21-2010, 03:17 PM
is this a hard project to accomplish? meaning the ripping out stage and making sure it is right!

Its a dirty messy job but when your finished you'll have loved every minute of it...

Follow the above link from page one...thats the work I've done since 22 Feb until now...got about a weeks worth of work to finish her off...

donzi4life
07-21-2010, 10:04 PM
Awesome thanks for the info! I was looking into a different material to use rather than plywood. but your seacraft is way more intense than the little donzi the transom is sectional, there is the skin of the hull with inside the middle about 2 feet in on both sides is the plywood only about 2 feet wide and two feet high. but thank you for a the great info and materials, it is super helpful, good luck on finishing the seacraft it looks like it is coming along good!

donzi4life
07-21-2010, 10:08 PM
If anyone has pic"s of re-build a transom on a donzi 16 or 18 that would be great!

onesubdrvr
07-21-2010, 10:10 PM
If anyone has pic"s of re-build a transom on a donzi 16 or 18 that would be great!
lol

I'm working on one, but at my pace lately, you'll be done before I get started lol

Wayne

donzi4life
07-21-2010, 10:18 PM
That's what I keep thinking about this project, but this thing called a job keeps getting in the way which is slowing me down from getting it done. need more time in the day!

gcarter
07-21-2010, 10:39 PM
I'm a fan of Coosa, I've studied it extensively, looked at samples and have an opinion about using it for transoms and stringers.
I think using 3/4" w/the amount of foam between the two 'glass skins could be a problem if high clamping forces are used. I'm just concerned about the thickness of the foam.
I think If I were doing a transom or stringers, I'd use more layers of 1/2" instead. It would give more glass w/its extra strength and minimize the thickness of the foam in areas where clamping forces are high.

MOP
07-21-2010, 10:58 PM
Two things!!!! (1) I have been hearing about Coose board not adhering as well as it is touted to be, this was stated by both shops in my area both have been around a very long time. Encapsulated it is very hard to beat as core material, as is wood and foam! (2) The transom of all Donzi's are radius-ed laying panels flat will NOT work, I have done a ton of this kind of work. A radius-ed transom must be built in the hull with careful attention to maintaining the radius, one of the best methods is to pre bend 3/4" ply wood. This is pretty easy to do just by blocking it in a damp area or to use a steam box like we had at out shop, when the wood and laminate is set in place it should be held there under tension. The easy way is to drill a hole in the middle so a threaded rod can be used in conjunction with a leaf spring on the outside, Rootsy used my idea for his 18 it is the simplest and maintains the contour. Do a little reading if this is your first time it in not rocket science, good glass and proper amount of resin will do a great job even for the novice! Spend the extra $$ on treated plywood, also make sure to isolate the stringer wood from the transom wood. Isolation is key, if one or the other does get wet it will not travel through to the other. Another good point is to not carry the plywood down into the drain plug area, it does nothing for strength. 90++% of transom rot starts from hte drain plug up!

donzi4life
07-21-2010, 11:12 PM
So you are saying the transom has a curve in it? is this more work than I want to get in to?

MOP
07-21-2010, 11:20 PM
So you are saying the transom has a curve in it? is this more work than I want to get in to?

Look at the back of the boat from the side the curve is very evident, many many guys have done them over it is not as daunting as it seems!

BlownCrewCab
07-22-2010, 07:26 AM
Look at the back of the boat from the side the curve is very evident, many many guys have done them over it is not as daunting as it seems!


If his is a Barrel Back it has a flat transom. all the BB's I have seen where flat.

Cuda
07-22-2010, 08:45 AM
I haven't done a transom myself, I had one done for me.
I'm wondering if PVC board will work. It's strong, light, and best of all can be glued together. I did two interiors on boats, the first one I used Kingboard, which has to be mechanically put together with screws. The second one I used PVC board. The PVC board was much easier, and not as expensive as king board. I bought it at a plastics company. Here I bought it at Farco Plastics. There is also a Farco Plastics in Clearwater.

CAPTBEACH
07-22-2010, 09:10 AM
Awesome thanks for the info! I was looking into a different material to use rather than plywood. but your seacraft is way more intense than the little donzi the transom is sectional, there is the skin of the hull with inside the middle about 2 feet in on both sides is the plywood only about 2 feet wide and two feet high. but thank you for a the great info and materials, it is super helpful, good luck on finishing the seacraft it looks like it is coming along good!

The principles remain the same...you can buy half sheets of Coosa board...you must maintain some sort of lam schedule or you will do as much harm as good...layers of glass MUST overlap onto the old substrate (hull)...while my transom was different in that it was a whole section versus pieces like I said the principles are the same...

I'll try to dig out some pics to demonstrate...

jdp_509
07-22-2010, 10:58 AM
I don't know if this will help, but I was thinking on using this on a Bass Boat Transom.

http://transomrepair.com/catalog/

donzi4life
07-22-2010, 01:32 PM
what would be a good price if I had someone do it for me. I dont want to screw it up!

CAPTBEACH
07-22-2010, 02:33 PM
what would be a good price if I had someone do it for me. I dont want to screw it up!

I got a quote of $4000 to do the SeaCraft transom...I'd think a good fiberglass guy would charge you between $2000 and $2500 less if you remove the deck cap so he has immediate access and doesn't have to worry with popping the deck off...

CAPTBEACH
07-22-2010, 02:35 PM
I don't know if this will help, but I was thinking on using this on a Bass Boat Transom.

http://transomrepair.com/catalog/

Sea cast has been around for years...I've seen it used on very small boats but I'd never consider using it on anything like a Donzi

gcarter
07-22-2010, 02:53 PM
The central part of the transom is flat. It does start to radius at about the area of the stringers out to the junction w/the sides.
If you think about it, the gimbal asemblies are flat so the transom has to be.

BUIZILLA
07-22-2010, 03:30 PM
About a month ago I bought a project 1974 Donzi 18 classic triple hatch barrel back. '74's were triple hatch barrel back's?

bertsboat
07-22-2010, 05:18 PM
We have had this discussion and every time somebody mentions an alternative to plywood everybody has something to say. some good and some bad. I think the bad comes from the fact that someone spent all that money and time and used PLYWOOD and now that everybody says there’s something better they feel bad and try in every way to defend their decision to use the same old method that rots out sooner or later.
I say there is only one way to go in the year 2010, that's foam period !!

bertsboat
07-22-2010, 05:23 PM
The original method of using wood was a mess.

bertsboat
07-22-2010, 05:27 PM
This is progress !

onesubdrvr
07-22-2010, 08:24 PM
is there an on-line source for coosa board and the foams? I've done some search, and found lots of application information, but no purchase information(?)

Thanks
Wayne

donzi4life
07-22-2010, 10:34 PM
So foam is the way to go? I was told today the the transom is flat, there is no curve. thanks for the pics keep them coming!

CAPTBEACH
07-23-2010, 05:07 PM
http://www.jamestowndistributors.com/userportal/show_product.do?pid=1593&familyName=Baltek+Airex+PXc+Boards

gcarter
07-23-2010, 08:39 PM
is there an on-line source for coosa board and the foams? I've done some search, and found lots of application information, but no purchase information(?)

Thanks
Wayne

Wayne, contact Coosa for the nearest dealer;

http://www.coosacomposites.com/contact.html

Grinder
07-24-2010, 10:29 AM
Penske board is another alternative different densities, thickness and priced better

OFFSHORE GINGER
07-24-2010, 11:10 AM
Wayne, contact Coosa for the nearest dealer;

http://www.coosacomposites.com/contact.html If you are going to go with Coosa i would strongly suggest there Bluewater 26 and to tell you the truth Cossa is some what pricey depending on your budget alot more then wood anyways considering you can get a sheet of 3/4 ply Marine grade anywhere from 75 TO 100 Dollars and when you start priceing out Coosa you will know what i mean . Here is a company that handles Coosa that offers many locations to serve you in the States which is Advanced Plastics & there web site is www.advanced-plastics.com (http://www.advanced-plastics.com) I have to say that i do more wood transoms for people just because of the cost $$ and in the same token i prefere using wood although Coosa is a very good product which i have used mostly for some stringer's systems in the past . I was just curious have you decided on what type of resin you are going to use Epoxy - Vinyl or Poly along with fabric ? Just a quick mention you just might want to stay away from Jamestown Distributors for supplies because there prices are way out of line .

gcarter
07-24-2010, 11:40 AM
Just a quick mention you just might want to stay away from Jamestown Distributors for supplies because there prices are way out of line .

I agree.
I know Artie posted his "favorites" list of suppliers, and I saved them for future reference.
Here's another I use, Merton's, in CT.

http://www.mertons.com/index.html

CAPTBEACH
07-25-2010, 11:19 AM
http://www.uscomposites.com/index.html

Best prices and customer service I have dealt with in the industry...

http://www.uscomposites.com/polyprod.html

Sells in quarts too...pretty sure all his prices include hardeners as well, great turn around time and prompt shipping...

OFFSHORE GINGER
07-25-2010, 12:06 PM
http://www.uscomposites.com/index.html

Best prices and customer service I have dealt with in the industry...

http://www.uscomposites.com/polyprod.html

Sells in quarts too...pretty sure all his prices include hardeners as well, great turn around time and prompt shipping... CAPTBEACH you are right us composites offers great priceing but does not sell Coosa and there epoxy resin may be cheap but does not have a very long pot life or tensile strength just my 2 cents .