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Re - Building Transom

Framing, planking and fairing. Repair, or reconstruction. If it's hull related, you'll find it here.

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allanguhl
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Re - Building Transom

Post by allanguhl » Tue Jan 05, 2016 1:31 pm

I am rebuilding my transom and would like to know is it better to use solid wood and try to bend it to get that 4 inch curve in it or can I Laminate pieces together to make it easier to make the curve ?

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offshorespars
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Re: Re - Building Transom

Post by offshorespars » Tue Jan 05, 2016 4:27 pm

If you are speaking about the transom bow (the aft most piece that the ends of the bottom planks fasten to) I would suggest steaming bending white oak if that is what was used originally. Oak does not laminate well. I am not certain if the 1950 Riviera used oak for the transom bow but assume so. If the transom bow is mahogany then I would say you could laminate.

Mike
1978 30' CC Sportsman
1948 22' CC Sportsman

allanguhl
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Re: Re - Building Transom

Post by allanguhl » Tue Jan 05, 2016 8:13 pm

Thanks Mike,they did use white oak

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Bilge Rat
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Re: Re - Building Transom

Post by Bilge Rat » Wed Jan 06, 2016 8:15 am

This piece is one of the most stressed in the framework of the boat. It has a lot of twisting force applied to it as it moves through the water from the prop and forces applied as the rudder swings the stern from side to side. Go over a big wake and the longitudinal forces from bow to stern are trying to twist this laterally. Couple that with the inevitable condition of water in the bilge washing aft to this piece and probably 100 or so fasteners screwed into it . Solid wood would have to be selected for quality straight grain, no knots and be successfully bent accordingly with no cracks. Laminated oak with alternating grain directions would probably produce the strongest piece and of course would be easier to bend to shape. This piece, like all framework should be sealed well and securely bedded to keep rot away.
1966 Lyman Cruisette 25 foot "Serenity Now!"
1953 Chris Craft Sportsman 22 foot "Summerwind"

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maritimeclassics
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Re: Re - Building Transom

Post by maritimeclassics » Wed Jan 06, 2016 8:39 am

I usually cut it out of one piece of oak or mahogany. It may cost a bit more for materials but it saves us time in cutting, soaking, steaming and then finishing fit to the boat. There is no stress to the wood if you cut it out of one. I have laminated a top piece of mahogany on oak but it depends on the boat and how the crown of the deck is.
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1936 25' Gar Wood Custom
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steve bunda
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Re: Re - Building Transom

Post by steve bunda » Wed Jan 06, 2016 7:09 pm

I cut the bottom transom frame out of a solid piece of mahogany, African is easier to find in 8/4 to 12/4. This method is faster and takes away the worry of future spring back. My second choice would be a laminated frame as Century or Shepard did.

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robertpaul
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Re: Re - Building Transom

Post by robertpaul » Thu Feb 04, 2016 2:48 pm

My transom bow was severely deteriorated as was the bent oak plank behind it. I decided to laminate a new one out of dark red merit because it was available from a trusted supplier, it glues very well and it will hold fasteners. Here are a few pics with the piece dry fitted. You can see the new piece of oak that I steam bent and used to replace the original that was 80% gone. I have since treated and painted both and the fit is quite satisfactory to me.
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1937 35' Double Stateroom Enclosed Cruiser

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robertpaul
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Re: Re - Building Transom

Post by robertpaul » Thu Feb 04, 2016 2:51 pm

First pic didn't make it.... I'll try again
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1937 35' Double Stateroom Enclosed Cruiser

joanroy
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Re: Re - Building Transom

Post by joanroy » Thu Feb 04, 2016 6:14 pm

Very nice work! I did the same repair on my 1948 Double Stateroom a few years back. That's an area thats always a problem on the old cruisers. The cockpit hatches tend to leak when it rains and water sits back there. I made sure my cockpit is water tight so it won't happen again any time soon. It's a lot of work making those bends. Thanks for the photos.

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steve bunda
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Re: Re - Building Transom

Post by steve bunda » Thu Feb 04, 2016 6:26 pm

Very Good and Nice, that will hold well. We have in stock the light red Meranti, it has a little less silica in it, thus not as brittle.

jfrprops
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Re: Re - Building Transom

Post by jfrprops » Thu Feb 04, 2016 10:01 pm

I firmly believe in laminating and with 5200.....just my pref
Way strong and simpler
John in Va
1980 Fairchild Scout 30
19?? custom Argentine Runabout 16'
1954 Whirlwind deluxe dual ckpt 16'
1921 Old Town Charles River 17' (founding Captain, James River Batteau Festival)

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robertpaul
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Re: Re - Building Transom

Post by robertpaul » Fri Feb 05, 2016 9:21 am

To this point I have found that laminating or scarfing with epoxy yields a pretty good bond. Even sorting through many boards of dark red meranti at my supplier, I found it challenging to get the consistency I was looking for. Consequently every new frame is laminated from two pieces of stock and planed to the proper thickness. I have redone 2/3 of both chines the same way and I found it quite straightforward. Laminating is strong and yields a nice, exact compound curve. I know that with my limited skills, trying to bend a solid piece would be a test. As for 5200, I used it for the scarf joint between the new chine and the original. It does a great job in that application, and I agree that it would be excellent for laminating as well. One reason I prefer epoxy for laminating is that I have very little product left over to harden in the cup. After doing the chine scarf with 5200, I was left with 1/2 tube that is now cured and stares at me from the corner of the dome shelter. I built the new chines one layer at a time. Working by myself, trying to get everything glued up, mounted and clamped in one shot would have been a fright show. Consequently I wasted very little glue. Here is a pic of the stbd chine dry fitted. That little piece of pine you see screwed to the frame is simply there to provide a square surface for clamping.
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1937 35' Double Stateroom Enclosed Cruiser

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dag55
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Re: Re - Building Transom

Post by dag55 » Fri Feb 05, 2016 12:49 pm

You can not compare a bond with epoxy to one with 5200 or SikaFlex. Epoxy is many, many times stronger and bonds to wood in a molecular manner that other glues simply don't. Epoxy is also ideal to close end wood. One way I learned to make epoxy penetrate better, especially if there is some soft spots, is to warm up the spot carefully with the heat gun, apply laminating epoxy and warm a little more, not to exceed 50C. Repeat until epoxi stops go into the wood... This method should be better than using epoxi with thinners, since when it warms up the viscosity goes down to less than water. Also using epoxi fillers or thickened with micro ballons, it will form a extremely strong bond, even if there is a gap between the pieces. Note that epoxi is about five times stronger than polyester...
Cavalier 36' Seastrake 1967 "CillaGreta III"
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jfrprops
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Re: Re - Building Transom

Post by jfrprops » Fri Feb 05, 2016 5:10 pm

disagree with the previous post.

The epoxy is certainly "stronger" if by that you mean harder and less (totally) flexible....and in many boat applications that is not what you want. Each has its place....one is not the answer. IMHO....backed by lots of experience.....

John in Va.
1980 Fairchild Scout 30
19?? custom Argentine Runabout 16'
1954 Whirlwind deluxe dual ckpt 16'
1921 Old Town Charles River 17' (founding Captain, James River Batteau Festival)

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dag55
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Re: Re - Building Transom

Post by dag55 » Sat Feb 06, 2016 3:07 am

John in VA; With all respect, but you are not up to date with epoxi products. The idea that epoxi is completely stiff material is a misunderstanding, some laminating epoxies where, but now a days there is products with flexibility but with the strength. I absolutely prefer epoxi before polyurethane glues, to epoxi's better flex, specially when laminating wood that is to be used in a damp environment. One problem with one part products like 5200 or Sikaflex, is that they age much faster than a correct blended epoxi and tend to over age dry out the wood they are attached to. Not to say they are bad products, but for permanent fastening, I go epoxi seven days a week!
Cavalier 36' Seastrake 1967 "CillaGreta III"
http://chris-craft.org/registry/viewboa ... at_id=2318

jfrprops
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Re: Re - Building Transom

Post by jfrprops » Sat Feb 06, 2016 8:12 am

It is absolutely true that I am not up to date with the newest products.

Old school to the core.

you mention the brand names, 5200 and sika.......so what epoxy?

thanks,

John in Va
1980 Fairchild Scout 30
19?? custom Argentine Runabout 16'
1954 Whirlwind deluxe dual ckpt 16'
1921 Old Town Charles River 17' (founding Captain, James River Batteau Festival)

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dag55
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Re: Re - Building Transom

Post by dag55 » Sat Feb 06, 2016 2:50 pm

As I'm in Sweden, I use a Swedish brand Epotex/ Nils Malmgren. They have been working with epoxi for both marine as well as construction applications since late 60''s. They have a range of products, of one I will use for sealing the deck is called 705 elastic, which is specially formulated for joints with much movement and vibrations along with high loads, as keels on sailing boats or even concrete constructions.
Cavalier 36' Seastrake 1967 "CillaGreta III"
http://chris-craft.org/registry/viewboa ... at_id=2318

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mfine
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Re: Re - Building Transom

Post by mfine » Sat Feb 06, 2016 5:14 pm

John,

I need to also disagree with you. 5200 remains flexible which is why it is good for certain tasks like bottom planks. It is a very poor choice for laminating multiple thin(er) pieces of wood into a single structural member. A properly laminated piece will be much stronger than one that is steam bent or cut from a single block of wood. It will be a lot more work though.

jfrprops
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Re: Re - Building Transom

Post by jfrprops » Sun Feb 07, 2016 11:28 am

Mr. Bacon,

While I hope to be with you in Tavares to thrash this out further:

Lamination is a multiple choice deal.

I you can laminate a component in a fixed position...outside of the hull...like on the bench...and you want it to be properly penetrated etc....then the goop may be the best way to go.

BUT: some of the big cruiser jobs, with which I am most familiar, require lamination in place. Like making large sistering ribs for instance.
If you try to add one say 1/8" to 3/16" strips of say 2 " width...in a build up and screw and glue fashion.(stacking)..which is the best way to do it.
Then the epoxy goop is much more difficult to work with and IMHO still not a bit better and perhaps a bit worse than the 5200 method. Different strokes for different blokes.....

See you in Florida? Hope to.

John in Va.
1980 Fairchild Scout 30
19?? custom Argentine Runabout 16'
1954 Whirlwind deluxe dual ckpt 16'
1921 Old Town Charles River 17' (founding Captain, James River Batteau Festival)

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