From "Eta Beta" to "Bertraholic"

[franzmerenda]

Someone may remember “Eta Beta”: instead of just fixing one tired set of rotten windows, I went a bit mental and chose the hard way – reverse‑engineering the original geometry, building a mold and turning the whole process into a new glazing system.

After two years of work on the tooling, composite frames and glass, that crazy idea finally turned into a boat. The first Bertram 31 to carry the new window frame set was launched last week and joined the Italian "Bertram Owners Club Rendezvous" this past weekend.

She is not Eta Beta – unfortunately – but standing there and watching her floating with our frames and glass was a pretty emotional moment for me.

It felt like one of my ACME‑style ideas stepping out of the shed and finally finding its place in the water.

This forum has been part of the inspiration from day one, so I thought it was only fair to share these photos with the Sandbox.

Posting a few shots of the boat and some yard pictures of the windshield and side windows during installation. Very grateful to all of you for keeping this place what it is!

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[captbone]

That is stunning and a work of art. You should be very proud!

[Carl]

Amazing what a little fiberglass and a few thousand hours in the right hands can produce.

Nicely done and thank you for sharing!

[Rickysa]

Wow

[Tommy]

Fantastic workmanship, Franz; can hardly wait to see your B-31 work of art when she is finished!

[Carl]

No other boat, aside from a Destroyer or Battleship has that menacing look from the front. Love the pic with her stern in, low wide and ready...

[MarkD]

Looks incredible! Send me a set:)

[neil]

Wow

[Tony Meola]

She looks great. That is a great frame option. Now how to get that in the States.

[franzmerenda]

She looks great. That is a great frame option. Now how to get that in the States.

Thanks Tony, I really appreciate it!
Actually, that’s a puzzle we’ve managed to sort out. Here is a set we recently sent over to the guys at Worton Creek Marina.
So logistics-wise, it's absolutely doable.

[franzmerenda]

No other boat, aside from a Destroyer or Battleship has that menacing look from the front. Love the pic with her stern in, low wide and ready...

Couldn't agree more, Carl.

From the bow the 31 really does look like a battleship - a miniature Bismarck. And from the stern, her classic tumblehome, gives me goosebumps!

What feels a bit off in that particular picture, are some very Italian habits:
- First, the gigantic windlass - as if she were a 20-ton vessel
- Second, since more often than not it's the ladies aboard who end up dropping the anchor, bows get cluttered with guardrails and grab rails - in this case the grab rail on the superstructure looks like a balustrade. But that was already there when we did the install
- Third, that anchor-strike guard panel- I find it abominable.

Everything else aside, with or without the window frames set, she remains the most beautiful boat in the world. I compare the Bertram 31 - and I'm not ashamed to say it - to the Riva Aquarama of fiberglass boats!

[Carl]

lol, yeah I saw that stuff.
But when it n Rome…


Just so impressive and looks like NOTHING else. You managed to keep the look and move forward.



Great job! It takes the Classic Look to another level, not an easy task!
You should be proud.

From a guy who has a 31 and your pictures make me smile.

[Tony Meola]

So that was the first one to the US. Here is the question, from what I understand, the pattern seems to differ slightly from year to year. How did you overcome the differences, so they don't need adjustments when being installed?

[franzmerenda]

So that was the first one to the US. Here is the question, from what I understand, the pattern seems to differ slightly from year to year. How did you overcome the differences, so they don't need adjustments when being installed?

Tony, good question – and you’re absolutely right, the pattern does change over the years.

On my boat - Etabeta, a 1970 SF - we first did a full 3D scan of the boat. That scan made very clear what we all “feel” when we work on these old ladies: nothing is truly square and nothing is truly symmetrical. Not a single bulkhead was perfectly perpendicular to the keel line and port and starboard were definitely not mirror images – and this is on a hull that came out after roughly the first thousand boats, so I’d call it at least a second‑generation mold.

Starting from that point cloud, we ran a series of CAD simulations to understand where the major deviations were and how to “average” them out. The window frames geometry you see is not a blind copy of one random hull: it’s a mathematically engineered profile that compensates those differences as much as possible while keeping the glass geometry consistent and visually balanced.

Once we were happy with that “best fit” solution, we built the plug and the mold.

Since then, we’ve supplied frames to a few different boats, including:
- my own 1970 FBC,
- an early 80s hull,
- and an early boat (’63/’65, going from the records).

In all three cases the installation process has been essentially the same:
- dry‑fit the frame and hold it in place with a good number of clamps,
- make any small fairing adjustments on the cabin face,
- then bond and laminate it in with glass, filler and fairing compound.

No major surgery, but it does require experienced hands – either a competent yard or a serious DIY’er who knows their way around glass work. Like everything on a 31, “plug and play” only exists on paper; in the real world you always fine‑tune to the individual hull.

So the short answer is: we embraced the fact that no two 31s are identical, captured that in a detailed scan, and then let the maths drive us to a frame profile that’s robust enough to work across different years, with the final millimetres taken care of during installation and laminating.

[Charlie J]

wow
looks amazing

[CamB25]

Fantastic! I think you might have solved one of the most challenging parts of a B31 restoration. Congratulations!

How many can you fit in a 20 TEU container? Will Worton be your US-based distributor?

[Amberjack]

the grab rail on the superstructure looks like a balustrade. But that was already there when we did the install

Franzmerda you obviously have never been trapped on the foredeck of a Bertram 31 when the boat is both pitching and rolling in rough seas. I was once and I think my finger impressions are still there on the brow which was the only available grab point and a poor one at that.

I agree the front grab they have mounted interferes with with the clean B31 look. If I were to do it over I would extend the bridge side coating grab rails around the front in one clean run probably with one center point attachment.

[Amberjack]

Should read “side coaming”

[Tony Meola]

Doug

I have to sgree with you on hanging on to the Brow of the bridge.

Hopefully more yards pick up on this windshield design.

[Yannis]

After a necessary pause to absorb the beautiful work of Franz, I can add to the discussion about the rail that I tied a connecting rope on the two bridge side rails, so it runs on top of the forward lip. It works as a forward bridge rail, it is almost invisible and it guides securely from port to starboard as well as halfway to the anchor windlass whereby you can then grab the forward bow rail.

[franzmerenda]

Fantastic! I think you might have solved one of the most challenging parts of a B31 restoration. Congratulations!

How many can you fit in a 20 TEU container? Will Worton be your US-based distributor?

Matt, thank you!

Container math: each crate is a few centimetres shy of three metres long, so in a 40-footer they ride four in single file, double-stacked: eight Window Frame Sets per box.

As for Worton Creek: a treasured client of ours, but the DNA of that distinguished yard has always been bespoke, owner-commissioned refits. When an owner asks for a certain layout, they source accordingly. A wonderful place to bring your B31 for a total refit - deep pockets required - but a distributor's vocation is simply not theirs.

I had thought of High Tide Marine, in the person of Danny Piedra, whom we all know here. But I doubt that at this stage of his life he'd want to take on the marketing effort a distributorship would demand. He already sells: he answers the phone, answers his emails, and boats move - without breaking a sweat.

In an ironic twist, the first to contact me was Cooley Marine. You surely remember Old Fashioned, that magnificent B31 with the continuous-glass windshield: one of a kind which left everyone at Newport Boat Show deeply impressed. Well, when he got in touch with me after some time - the moment I mentioned Worton Creek was already our client, they vanished. No jealousy, no droit du seigneur, I suppose; but it seems some yards would simply not share solutions chosen by others

To make a long story short: we still haven't found our ideal partner. Meanwhile, inquiries keep coming in from owners, private parties, DIYers.

[Carl]

The way I was taught you first skim the cream selling to those that do not want to wait with deep pockets. Then produce n flood the market before others figure ways to make n sell cheaper.


As you have the CAD files and I assume CAM files to produce molds can you setup a shop stateside. Lots of shops with 5 axis CNC’s to replicate molds here. Send a couple talented people to make frames here in quantity to sell as needed.

Another avenue to explore maybe PET-GF 3D printing.or similar. I was going to bore you with my friends answer to eliminating outside fabricating vendors. He now prints all the enclosure panels, hatches, doors, service step and brackets as designs on machine are finalized. Items larger than printer envelope are done in sections with SS Hardware printed into the pieces. When done bolt together….crazy stuff n strong. Just ideas outside the box to possibly eliminate / reduce overseas shipping n related fees.

Then again as you have the technology to reverse engineer, I’m sure you are already familiar.

[franzmerenda]

you obviously have never been trapped on the foredeck of a Bertram 31 when the boat is both pitching and rolling in rough seas. I was once and I think my finger impressions are still there on the brow which was the only available grab point and a poor one at that.

I agree the front grab they have mounted interferes with with the clean B31 look. If I were to do it over I would extend the bridge side coating grab rails around the front in one clean run probably with one center point attachment.

Not on a 31 Doug, but I did have to turn into a gecko on the foredeck of a Riva: nothing whatsoever to grab, and whatever you do grab is a five-figure repair, because everything fitted on an Aquarama is worth its weight in gold, and the deck wears twenty coats of gloss spar varnish.
So I know exactly what pitching-and-rolling with no handhold feels like... we shall have to design something for that too LOL.

Joking aside - for rough anchorages and heavy rolling - I guess FiveFingers by Vibram would come in handy. They basically turn you into Spider-Man.

As for the bow: the beauty of a B31 foredeck is that it's clean. Even a windlass is a bad habit of us Mediterraneans: we drop the hook every time we go out for a swim.

[franzmerenda]

The way I was taught you first skim the cream selling to those that do not want to wait with deep pockets. Then produce n flood the market before others figure ways to make n sell cheaper.


As you have the CAD files and I assume CAM files to produce molds can you setup a shop stateside. Lots of shops with 5 axis CNC’s to replicate molds here. Send a couple talented people to make frames here in quantity to sell as needed.

Another avenue to explore maybe PET-GF 3D printing.or similar. I was going to bore you with my friends answer to eliminating outside fabricating vendors. He now prints all the enclosure panels, hatches, doors, service step and brackets as designs on machine are finalized. Items larger than printer envelope are done in sections with SS Hardware printed into the pieces. When done bolt together….crazy stuff n strong. Just ideas outside the box to possibly eliminate / reduce overseas shipping n related fees.

Then again as you have the technology to reverse engineer, I’m sure you are already familiar.

Wise words as always, Carl - whatever the subject we happen to get fired up about.

And you're touching an open wound here. A very dear friend of mine is the former VP of operations at Pipewelders in Fort Lauderdale: they ran a shop specialized in molds and composite parts for the sportfisherman world. Sadly John - still young and in great shape, but having started working very early in life - decided to retire. Every production sportfish builder out there, Viking excepted (they somehow absorbed Palm Beach Towers), is desperate, because nobody picked up the reins after John. Pipewelders itself has effectively been taken over by Bradford - the Company running the yard next door - if I recall correctly. Otherwise I'd have had a shop stateside ready to go, no effort required: I was practically set to mold in the US.

The other delicate side of the story is the two curved panes. The compound curvature of the windshield glass calls for - much like the composite shell - dedicated tooling and a rather complex lamination-and-tempering process. When I approached ProCurve, the US glass giant that incidentally made the one-off continuous windshield of "Old Fashioned" (the refit handled by Cooley Marine in Connecticut), a very kind and helpful gentleman from their technical department declined any form of cooperation: I would have had to commit to volume production from day one. And it so happens that every prospect and every client picks their own finish - clear, light blue, or smoked gray.

So yes: this could turn into something spectacular, given a fiberglass shop - which, I agree with you, shouldn't be impossible to find - and a glass maker willing to run small batches per production lot.

[Rickysa]

So yes: this could turn into something spectacular

I hope, I hope, I hope, I hope, I hope, I hope, I hope...

[Preston Burrows]

Great stuff......but stating the obvious maybe.....surely this site would be the best 'distributor' point for the frames and shipping can be done on an order by order basis as LCL cargo direct to the customer wherever worldwide?

[Robert lico]

very well done with a huge attention to detail

[franzmerenda]

Great stuff......but stating the obvious maybe.....surely this site would be the best 'distributor' point for the frames and shipping can be done on an order by order basis as LCL cargo direct to the customer wherever worldwide?

Thanks Preston, appreciated - and yes, that's exactly how we're set up. There's no dealer network to build: every set is produced on demand, crated, and shipped LCL on an order-by-order basis, wherever the boat is. More than a few sets are already out there, and shipping has never been the bottleneck.

Yards and pros in general understood the scope of the project immediately. What's harder to convey from pictures is the difference between a frame assembled from fiberglass profiles sealed together and what comes out of proper tooling. Each frame comes out of two molds - one for the outer face, one for the inner face - and the two skins are bonded with Crestomer, a structural urethane acrylate adhesive, into a closed, load-bearing box section. Conceptually it's closer to a motorcycle frame than to traditional glasswork: the frame is structural in its own right, carrying a three-ton load without relying on filler and lamination to become solid once on the boat.

[franzmerenda]

very well done with a huge attention to detail

Thanks Bob - coming from you, that counts double!

[Robert lico]

one of the best feelings in life is to go were no one has gone before ! you start a project and find yourself walking away and then come back with a better idea .Captain Patrick sent me a PM four times on projects I had done on the boat. like attaching your windshield to the boat after is is bolted in place 9 I used SS 1 1/2' lag bolts with washers from the ceiling of the v-berth up into the windshield base. then came up with the idea of using Gaffers tape 9 very strong tape) on the inside (cabin) side and cheap tape on the outside (bow) .I put a nail set hole in the front tape every two inches and used a empty caulking gun tube filled with 50/50 high density filler and colloidal silica ,and epoxy all premixed. starting at one side and squirting into the hole in the tape until it ooze out of the hole next to it , this took the air out and filled every irregular space between the windshield base and the very irregular raise area from the OEM windshield fiberglass surface . the mixture turns to "Granite" and the windshield and the boat become one.after removing the Gaffer tape on the inside you get a perfect contour between the windshield and the fiberglass area above the V-berth entrance and the outside tape removal gives you a blend from windshield and front deck . like I said Captain Patrick gave me a "atta boy" ------RIP

[beachbum]

Wow.....is it around Genova? I see the GE---- registration and recognise that landscape....

EDIT I've just realised it's sat with the other Bertrams at the yacht club.

I'll show these to my mother in law. The boat used to belong to my father in law (who passed away 20+ years ago, I never met him) was the owner for a long long time.