# Modern Transoms in Welded Boats?



## wmk0002 (Dec 10, 2015)

Can someone tell me how the transoms are designed in the modern all welded boats like Weldbilt, Alweld, Xpress, etc? Are they solid plate aluminum or what?

I'm just trying to learn more about tin boats in general. I'm hoping to buy a new one in the next year so I figured transom design may be something that sets one manufacturer apart from another.


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## bassboy1 (Dec 10, 2015)

wmk0002 said:


> Can someone tell me how the transoms are designed in the modern all welded boats like Weldbilt, Alweld, Xpress, etc? Are they solid plate aluminum or what?
> 
> I'm just trying to learn more about tin boats in general. I'm hoping to buy a new one in the next year so I figured transom design may be something that sets one manufacturer apart from another.



Weldbilt - plywood, very poorly fastened to the rest of the transom.

G3 - plywood, well fastened to the rest of the transom.

Xpress - varies, but I've seen a handful with aluminum rect. tube or channel welded to the transom skin. 

SeaArk - formed sheet shapes, welded to the transom skin.


Nothing in that class (production all welded boats similar to the ones you've mentioned), will have thick plate transoms - the same stiffness can be created with less expensive and lighter material by using aluminum structural shapes (channel, tube, formed sheet, etc). 

All of the boats with aluminum transoms will be welded to the transom skin. In something like a G3, there is a combination of bolts and pockets to hold the wood. For example, at the bottom of the wood core, G3 usually welds a Z shaped piece to the transom, which the wood slips down into. Then, they bolt through the knee braces, and through the side boxes, to really pull everything together. 

Weldbilt just slips the piece of wood into place, and then doesn't finish the job. Without fail, it gradually starts to pull away from the transom skin, and eventually breaks the knee brace - I've repaired bunches of those by simply adding a row of bolts across the bottom of the wood. 


The principle behind transom design on mod vee jons is the engine is leveraging back on the top of the transom, and pushing in on the bottom. As such the top of transom needs to be stiff all the way across, as it carries the load from the center of the transom to the corner braces and sides of the boat. 

Ideally, the bottom would be stiffened all the way across as well, though some companies (not many) rely solely on the knee braces to counter this force. The stiff bottom of the transom carries the forward pushing load to the entire bottom skin of the boat, and to a lesser degree, the sides of the boat. 

As the top of the transom is being pulled away from the boat, the structural material really only needs to be well attached to the corners of the boat - the force is pulling it into the back of the corner braces.

The bottom, however, is being pushed in the middle, so it needs to be well attached across the bottom of the boat, as the force is pushing the structure away from where it belongs, not into place. This is where the Weldbilts fail - the wood pushes away from the skin. The G3s have the Z shape piece, and a few boats holding it in place. The metal transom guys will have the lower support stitch welded all the way across the width of the boat.



Many companies put an inner skin on the transom, for aesthetics. SeaArk and Xtreme are two that I remember off the top of my head as leaving the transom structure exposed. They are also good examples of generally good transom design, so they might be good to look at for educational purposes.

Hope this rambling helps a little.


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## ibSteve (Dec 11, 2015)

Wow! I have a L1440M that has a transom with some bend in it.

(Bought it used - looks like the head of the bolt running from the plywood on the outside of the transom thru to the knee brace compressed the plywood to where the head is embedded in the plywood, allowing the transom to flex away from the knee brace leaving a ~1/2 gap between the top of the knee brace and the inside of the transom - pretty hard to explain w/o a picture!). 

Anyway, I've been thinking about how to keep it from getting worse and your (Bassboy1) post is real helpful! Thanks!


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## richg99 (Dec 12, 2015)

Thanks, Bassboy.... very informative post. Excerpts should probably be made a sticky. 

regards, richg99


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## turbotodd (Dec 13, 2015)

Plywood is STILL used, to this day, because it works very well.

At one point in my career, I were selling a brand of boat (no longer in business), that touted the whole "all metal transom" thing. No wood. It was a series of channel aluminum pieces welded to the transom, then the skin put on over it. Mounting the motor-drilling the holes-was a royal pain in the butt. It never failed that on a standard BIA mounting pattern (which, at the time we sold Mercury and Mariner's, 99% of them were BIA) that at least one bolt hole would go into the END of the channel. And of course the drill bit would want to walk to one side or the other, and if you weren't really patient, it'd end up with an egg-shaped bolt hole that wouldn't seal very good. Then, because of the welding, the transom was warped, from the heat, on gloss painted boats, looked like absolute poo. And then on top of that, when you tightened the 1/2" bolts down, the transom would crush. Never could go much more than 15-20 lb-ft of torque without crushing the channels inside the transom.

Every plywood transom boat I've dealt with has had better finish, lasted a long time, sealed properly, was easier to work on if the time came, and was more rigid. That is speaking of tin boats specifically. Fiberglass boats I haven't dealt with all that much, but a bunch of those use wood too.


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## Bob Landry (Dec 13, 2015)

The transon on Seaarks is fabricated using large size, heavy gauge aluminum and the skin welded to the outside of it. No plywood is used in those boats. I have an etec 90 and a 6" jackplate and there is no warping on mu transom.


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## wmk0002 (Dec 14, 2015)

Thanks for the awesome replies. The transom construction on these all welded boats have been something I have been wondering about for quite some time so I am glad that I asked.

Bassboy1 can you elaborate some more on the Weldbilt transom construction? I have them at the top of my list for my next tin purchase due to price and being local to their popular dealer Backwoods Landing.


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## bassboy1 (Dec 14, 2015)

wmk0002 said:


> Thanks for the awesome replies. The transom construction on these all welded boats have been something I have been wondering about for quite some time so I am glad that I asked.
> 
> Bassboy1 can you elaborate some more on the Weldbilt transom construction? I have them at the top of my list for my next tin purchase due to price and being local to their popular dealer Backwoods Landing.




My recommendation would be to pull them off the list completely. All of the problems the guy in this link has, I've seen on multiple boats of theirs. 

https://forum.tinboats.net/viewtopic.php?f=3&t=39292

I'm going to PM you info about one I had last month.

As for the transom design: As mentioned in my first post, the forces at play are pulling out at the top, and pushing in at the bottom. The out at the top is no problem, the transom carries the load to the corner braces. The problem is the in at the bottom. It is simply pushing forward in the center of the transom, but the load needs to be carried to the boat bottom/boat sides. If the transom core is bolted/welded to the skin, all the way across, no problem, the load is transferred all the way across the boat. 

The problem on the weldbilt is that there is nothing holding the bottom of the transom - nothing. As the center of the transom gets pushed forward, it starts to push the wood forward. Since there is nothing holding it, the wood starts to separate from the transom, leaving a gap between the wood and the transom skin big enough to stick a finger into. Every time I've fixed one of those, I've put a row of bolts across the bottom, and that has helped tremendously.


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## onthewater102 (Dec 15, 2015)

All this negative experience with Weldbilt around here makes me sad - I had them on my radar if I were ever to splurge & buy a new tournament sized boat to build out. Sometimes it's true that you get what you pay for.


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## duckfish (Dec 15, 2015)

Just a point to clarify.... G3 no longer uses any wood in their transoms. I believe they made that change in 2013.

My dealer's experience is similar to posted above, it has led to some engine mounting issues and some oil-canning at the transom due to the forces of the motor. They replaced my hull due to a cracked weld 2 years ago and I now have a "no-wood" transom. I have had no issues with mine.


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## Downunder (Dec 16, 2015)

G3 boats arrived in Australia recently and are very impressive and well finished but the 16 footers that I looked at last week had wood reinforced transoms. It appeared to be 1.5" marine ply that was covered with an aluminium skin. The only place the wood could be seen was where the mounting bolt holes were drilled to mount the motor. 
Most of our aluminium boats here are welded hulls with welded reinforced transoms. My own boat is a Quintrex 455 Escape (1566 I think in USA spec) which has a transom made of 6 and 8mm aluminium plate. The motor is a Yamaha 60HP F/S mounted on a pod made of 8mm plate and then welded to the transom. Which makes the back end of the boat very strong and rigid. I know it's very strong after having beached the boat in very shallow water at full cry after missing the channel where I was fishing.
I think there is only one manufacturer of riveted boat in Australia but they are only small fishing and duck shooting boats that can be carried on roof racks on your car. 
All other boats are of welded construction and have been since the 1960s.


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## bassboy1 (Dec 16, 2015)

duckfish said:


> Just a point to clarify.... G3 no longer uses any wood in their transoms. I believe they made that change in 2013.



That is good to know. That was really my biggest complaint with those boats - they have/had their act together with most other portions of the boat moreso than a lot of companies.


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## wmk0002 (Dec 16, 2015)

onthewater102 said:


> All this negative experience with Weldbilt around here makes me sad - I had them on my radar if I were ever to splurge & buy a new tournament sized boat to build out. Sometimes it's true that you get what you pay for.



Yep, me too. I wasn't going to buy a new boat anytime real soon but had all but decided on going with Weldbilt based on price, weight, and dealer proximity. Now, I have to keep looking. Really want an Xpress 1546 or 1650 jon but I have no idea how they are priced...just know their duck and bass boats are up there. 

There is an Alumacraft dealer very close to me and they make a 1546 all welded hull similar to the Xpress but likely much cheaper. Anyone know how these boats' transoms are engineered?


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## Rick_W (Dec 16, 2015)

For what it's worth - Xpress Boats are made by Aluma-Weld.

The warranty registration card for my new Xpress XP18CC shows the boat manufactured by Aluma-Weld, Inc/DBA Xpress Boats.


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## PsychoXP18CC (Dec 18, 2015)

Rick_W said:


> For what it's worth - Xpress Boats are made by Aluma-Weld.
> 
> The warranty registration card for my new Xpress XP18CC shows the boat manufactured by Aluma-Weld, Inc/DBA Xpress Boats.



All of which is owned by Yamaha.


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## xXOnyxXx (Dec 19, 2015)

i have a lowe l1648mt its a riveted boat but they claim a wood free transom ... its solid for sure but then again its new .. i am curious about the composition of my transom too.


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## Bob Landry (Dec 20, 2015)

PsychoXP18CC said:


> Rick_W said:
> 
> 
> > For what it's worth - Xpress Boats are made by Aluma-Weld.
> ...



I just looked at Alumaweld website and there is a lot of advertising/data/information on Mercury outboards, so that doesn't look like a Yamaha owned company. I do know for a fact that Yamaha does own G3 because I owned one.


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