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Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Sun Nov 15, 2020 9:15 pm
by ttownthomas
About a year an a half ago I started refreshing a Bertram 25. I got down to the outdrives after doing a bunch of mechanical work and decided the transom assemblies needed to be replaced. I have removed the transom assemblies and the keyholes are exposed now. The plywood seems ok, but not totally dry. How do I tell if I can proceed without a full transom redo. Here are the pictures:

ImageKeyholes - 1 by ttownthomas, on Flickr

ImageKeyholes - 4 by ttownthomas, on Flickr

ImageKeyholes - 1 (1) by ttownthomas, on Flickr

ImageKeyholes - 2 by ttownthomas, on Flickr

ImageKeyholes - 5 by ttownthomas, on Flickr

ImageKeyholes - 3 by ttownthomas, on Flickr

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Sun Nov 15, 2020 10:29 pm
by Fuzz
A few years ago I pulled an I/O out of a Seasport and installed a bracket on it. I was pretty sure I would need to rebuild the transom but to my surprise it was all good. I really wanted to be sure of the transom so I used a hole saw to cut half a dozen plugs out and look at them. If you cut plugs make sure to set the pilot bit short enough not to drill through the outside skin. I would want to know for sure what I had before moving forward.

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Sun Nov 15, 2020 10:33 pm
by ttownthomas
What am I looking for?

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Sun Nov 15, 2020 10:50 pm
by fallguy1000
ttownthomas wrote: Sun Nov 15, 2020 9:15 pm About a year an a half ago I started refreshing a Bertram 25. I got down to the outdrives after doing a bunch of mechanical work and decided the transom assemblies needed to be replaced. I have removed the transom assemblies and the keyholes are exposed now. The plywood seems ok, but not totally dry. How do I tell if I can proceed without a full transom redo. Here are the pictures:

ImageKeyholes - 1 by ttownthomas, on Flickr

ImageKeyholes - 4 by ttownthomas, on Flickr

ImageKeyholes - 1 (1) by ttownthomas, on Flickr

ImageKeyholes - 2 by ttownthomas, on Flickr

ImageKeyholes - 5 by ttownthomas, on Flickr

ImageKeyholes - 3 by ttownthomas, on Flickr
Awl test. Mushy wood is a redo.

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Mon Nov 16, 2020 8:00 am
by ttownthomas
Ok...here is more information: I had a survey done on the boat prior to purchasing it. for what its worth the transom passed his tests. It sounds decent when you tap on it but I am a little concerned about the wood at the bottom of the keyholes. it may be a little wet. I guess what I'm asking for is suggestions on how to start the evaluation. What progressive steps should I take so I don't peel back the onion too far. I was thinking I'd start with Forstner bits to expose the wood in various places?

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Mon Nov 16, 2020 9:06 am
by fallguy1000
ttownthomas wrote: Mon Nov 16, 2020 8:00 am Ok...here is more information: I had a survey done on the boat prior to purchasing it. for what its worth the transom passed his tests. It sounds decent when you tap on it but I am a little concerned about the wood at the bottom of the keyholes. it may be a little wet. I guess what I'm asking for is suggestions on how to start the evaluation. What progressive steps should I take so I don't peel back the onion too far. I was thinking I'd start with Forstner bits to expose the wood in various places?
Just run a halogen or two about 2 feet away from the hull and feel/watch for steam to rise up out of the keyholes. CAUTION! Do not walk away! Once the system starts to heat up and the water is all gone; it will heat past 212F and catch fire.

Put a couple steam escape holes on the insides of transom on the port n star edges so steam does not migrate to the hull or it can create a blistering environment.

You have to monitor the entire process. Adjust light dostance locations, etc. I did this on a Whaler and got bored and walked away tp do something for like a minute and scorched the boat. Fortunately, I was close enough and smelled it starting to burn. Anyhow, setup a project inside or read or something.

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Mon Nov 16, 2020 10:17 am
by ttownthomas
is this process used to dry the transom or to evaluate for the presence of steam and therefore water?

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Mon Nov 16, 2020 10:42 am
by fallguy1000
ttownthomas wrote: Mon Nov 16, 2020 10:17 am is this process used to dry the transom or to evaluate for the presence of steam and therefore water?
Both. If it stops steaming; you'll know you are dry. You might need to do both sides for a thicker transom. But like I said; you must monitor all the way and too hot to touch means it will catch fire.

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Mon Nov 16, 2020 10:46 am
by fallguy1000
Also, the gelcoat will cook faster than the glass side, You don't need to steam it out. By increasing the temperature to above ambient; the water will want to exit by nature. The process should be slow. It took me about 8 hours to get the Whaler dried enough to stop seeing the steam/water vapor exiting.

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Mon Nov 16, 2020 11:36 am
by ttownthomas
I like the heat idea. Why not sand off the whole inside layer of glass and if it is in moderately good condition use your heat technique to dry it out. Then epoxy over the bare wood and let it soak up the resin? Or does the fact that it is pretty buttoned up allow it to heat up in a way that an opened transom wont allow?

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Mon Nov 16, 2020 2:34 pm
by Fuzz
Never tried to cooking thing so I have no advice there. I do know when I cut plugs out of two different transoms it was clear one was good and one was not. If the plug looks like brand new wood you are good. If the plug is black, wet or soft it needs to come out. Down low or close to openings are the suspect spots.

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Mon Nov 16, 2020 4:55 pm
by fallguy1000
ttownthomas wrote: Mon Nov 16, 2020 11:36 am I like the heat idea. Why not sand off the whole inside layer of glass and if it is in moderately good condition use your heat technique to dry it out. Then epoxy over the bare wood and let it soak up the resin? Or does the fact that it is pretty buttoned up allow it to heat up in a way that an opened transom wont allow?
Works even better the way you suggest and less migration to hull sides.

Make sure to not walk away!

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Mon Nov 16, 2020 7:49 pm
by ttownthomas
I have one of those laser temperature guns. Ill be sure to babysit it and closely monitor the temperature. It's gonna take awhile to sand off all that glass. (wonder if I can chisel it away from the ply without too much damage.) THis way, I assume, If the plywood is in decent shape I can re-soak it in resin to stiffen it up.

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Sun Aug 15, 2021 10:59 pm
by ttownthomas
Ok. after exposing some of the core I decided to replace the core with coosa. Did the engine bed while I was at it. The transom was 1.5" thick and the engine bed was 1"

Imagetransom - 1 by ttownthomas, on Flickr

Imagetransom - 1 (1) by ttownthomas, on Flickr

Imagetransom - 1 (2) by ttownthomas, on Flickr

Imagetransom - 1 (3) by ttownthomas, on Flickr

Imagetransom - 1 (4) by ttownthomas, on Flickr

Imagetransom - 1 (5) by ttownthomas, on Flickr

Imagetransom - 1 (6) by ttownthomas, on Flickr

Imagetransom - 1 (7) by ttownthomas, on Flickr

Imagetransom - 1 (8) by ttownthomas, on Flickr

Imagetransom - 1 (9) by ttownthomas, on Flickr

Imagetransom - 1 (10) by ttownthomas, on Flickr

Imagetransom - 1 (11) by ttownthomas, on Flickr

Imagetransom - 1 (12) by ttownthomas, on Flickr

Imagetransom - 1 (13) by ttownthomas, on Flickr

Imagetransom - 1 (14) by ttownthomas, on Flickr

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Sun Aug 15, 2021 11:20 pm
by fallguy1000
Glass plans? Things look good.

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Mon Aug 16, 2021 12:09 am
by ttownthomas
Yes, glass is next-ish. I got tired of sitting in the bilge and moved onto the topsides. Must have filled 200 holes already on the front deck, the top of the forward area in front of the helm and the top of the gunnels. The patching is nearly complete, and Im re-constructing all the original side panels that were made of malamine

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Mon Aug 16, 2021 4:35 am
by fallguy1000
Now, how do the engines mount? I see no engine mount/stringer.

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Mon Aug 16, 2021 1:03 pm
by ttownthomas
They are inline 6's So fairly long. The aft end of the engine mounts on 2 pegs that are part of the inner transom plate and forward they have adjustable stands that screw down to the engine bed that is the flat part on the forward end of the bilge.

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Mon Aug 16, 2021 1:09 pm
by ttownthomas
does this help?

Imagetransom - 1 (15) by ttownthomas, on Flickr

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Mon Aug 16, 2021 1:45 pm
by fallguy1000
Interesting there is no aft mount. Carry on!

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Fri Sep 17, 2021 11:57 am
by ttownthomas
Structural Glasswork in the bilge is done:

ImageEngine Mount Location - 1 by ttownthomas, on Flickr

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Fri Sep 17, 2021 1:40 pm
by Fuzz
Good looking glass work. I bet you are glad to have that done.

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Fri Sep 17, 2021 1:58 pm
by fallguy1000
Looks pretty clean to me. You might consider a little cpes on the keyhole insides.

Any holes in the repaired transom should be overbored; filled with thickened epoxy and then rebored as needed.

Leaky Holes are what end up killing these.

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Sat Sep 18, 2021 9:47 am
by ttownthomas
Is cpes useful even though I used coosa? How much should I overbore the holes?

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Sat Sep 18, 2021 10:09 am
by fallguy1000
ttownthomas wrote: Sat Sep 18, 2021 9:47 am Is cpes useful even though I used coosa? How much should I overbore the holes?
No need for cpes on coosa.

I thought I saw wood in the keyholes.

Only overbores for wood.

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Sat Sep 18, 2021 10:13 am
by fallguy1000
Ain't this wood?
CEBFCCD5-3EAF-4A1C-B650-FD056CF08646.jpeg

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Sat Sep 18, 2021 10:17 am
by fallguy1000
Oh, shoot. That looks like the garage on closer inspection. Sorry. For some reason, I thought you had jist added some coosa and the wood was still there.

No need for cpes! Hope I didn't screw you up. Very sorry if so.

Cpes won't hurt to have on hand if you ordered some. It is a great product for stopping any rot on questionable wood.

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Sat Sep 18, 2021 11:01 am
by ttownthomas
Lol. That’s the fence at the top of my driveway

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Wed Aug 03, 2022 11:57 pm
by chrisca
Hi,

I came across this discussion as I am currently working on my Bertram 25 flybridge.

I took the motors out and I'm swapping them for another set of 165 Mercruisers that are fresh water cooled.

I cleanup the bilge but the mounting holes for the front engine mounts are rotten out. I drilled a few holes and wood is bad and soft.

I will be cutting out the front engine mount area just as in your pictures and replace it with Coosa just as you did.

My question is, how did you mount the new engine mounts? Did you drill lag screws into the cossa after ? Or did you bolt through with some backing at the bottom.


See image below:
https://photos.app.goo.gl/2JWUtHraoqPWDzUX6

Image

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Thu Aug 04, 2022 7:14 am
by fallguy1000
It would be best to start a new thread. All rot must be removed or the new mounts will rot out as well. Start a new thread in the repair forum and we'll help you there.

Re: Bertram 25. Help me evaluate transom now that keyholes are open

Posted: Wed Aug 10, 2022 5:34 pm
by biasbilt
chrisca wrote: Wed Aug 03, 2022 11:57 pm Hi,

I came across this discussion as I am currently working on my Bertram 25 flybridge.

I took the motors out and I'm swapping them for another set of 165 Mercruisers that are fresh water cooled.

I cleanup the bilge but the mounting holes for the front engine mounts are rotten out. I drilled a few holes and wood is bad and soft.

I will be cutting out the front engine mount area just as in your pictures and replace it with Coosa just as you did.

My question is, how did you mount the new engine mounts? Did you drill lag screws into the cossa after ? Or did you bolt through with some backing at the bottom.


See image below:
https://photos.app.goo.gl/2JWUtHraoqPWDzUX6

Image
Don’t forget the front mount is only supporting 50% of the weight of the engine and any bouncing motion as you go through waves. All the torque that is twisting the engine to one side is taken through the vertical bolts from the bell housing to the inner transom plate, so your lag bolts don’t need to withstand massive pullout forces