[C320-list] Companion way hatch-is NOT acrylic

[Jeffrey Kapec via C320-list]

Hello to All:

I read this string and thought I would perform a reality check on
the assumption that the sliding hatch is acrylic. I believed otherwise by
the nature of the material and the grey cast tint. I too own a 320 Hull
718. I knew that the companionway was Polycarbonate and not acrylic.
Being a professional Industrial Designer for 40 years I know my polymers.
Nevertheless I did some research with AI. Here is what I found, and I
agree completely with the overview. I have designed products with acrylic
and with polycarbonate. The most important factor is the ductility of
polycarbonate which will accommodate flexural bending and very high impact
loading supporting a great deal under stress. So, for example, if you have
ever closed the hatch and had to stand on it ....the polycarbonate would be
just the material for that. Acrylic on the other hand does not have nearly
as much ability to sustain load before it cracks. Just look up the
mechanical properties ini Modern Plastics engineering. The polycarbonate
in that thickness and color may be purchased online by a number of plastics
suppliers.

For reference....

AI Overview
Learn more <https://support.google.com/websearch?p=ai_overviews&hl=en>
…Opens in new tab
<https://support.google.com/websearch?p=ai_overviews&hl=en>
The Catalina 320 companionway hatch is made of polycarbonate:

- *Polycarbonate*: A strong, impact-resistant material that's ideal for
boat windows and hatches. Polycarbonate is more durable than acrylic and
can withstand impacts 250 times better than glass.
- *Acrylic*: A transparent material that tends to be glossy and stays
clear over time.

Marine plastics and acrylic are the preferred materials for boat hatches
because they are reliable, customizable, and easy to fabricate.

Jeff Kapec
Petite Suite Hull 718

--

Jeffrey Kapec

*Tanaka Kapec Design Group*

11 Brookfield St. Norwalk, CT 06851

203.846.3666


www.tkdg.com

[Jack Brennan via C320-list]

Wow. That puts a whole different spin on things. A 36- x 36-inch sheet of smoked polycarbonate (Lexan?) at McMaster-Carr is $559. A 48- by 48-inch sheet, which is what you would need to match the original exactly, is $970.

That would be really painful if you made a mistake cutting.

I've been having trouble getting quotes on acrylic for this project in part, I suspect, because of the dimensions. To get the correct-sized hatch, you need to buy a 48- by 96-inch sheet at $250 to $300 plus delivery and cutting charge. No one wants to give me a custom cut and get stuck with the partial piece.

For now, I've decided to experiment with the King Starboard route, partly because I was able to get a 24- by 48-inch sheet of half inch for $70 at Home Depot. That gives me the correct width of 36 and 3/8 inches.

With the leftover cut, I can attach a 3 and 5/8 inch attachment to the rear side of the hatch, where it slides under the hood and won't be seen. I think the extra length is there to keep water out of the cabin.

As I said before, I like the Starboard option because reduces the sunlight coming into the cabin. During hot Florida summers, the spot under the sliding hatch never cools, no matter how long the AC is running.

Who knows, I may eat my words and be buying that $970 piece from McMaster-Carr.

Jack Brennan
Sonas, 1998 Catalina 320
Tierra Verde, Fl.





________________________________
From: C320-list <c320-lis...@lists.catalina320.com> on behalf of Jeffrey Kapec via C320-list <c320...@lists.catalina320.com>
Sent: Friday, October 25, 2024 8:47 PM
To: c320...@lists.catalina320.com <c320...@lists.catalina320.com>
Cc: Jeffrey Kapec <jka...@tkdg.com>
Subject: [C320-list] Companion way hatch-is NOT acrylic

www.tkdg.com<http://www.tkdg.com>

[Troy Dunn via C320-list]

Jack et al

The only original polycarbonate material on the 320 is the deadlights on
the cabin top. Polycarbonate is not UV stable. In the short run it is a
superior material to cast acrylic. In the long run, not so much. If you
are building a fighter jet…sure use polycarbonate but be sure to replace at
the reccomended TBFO. For a cruising sailboat… stick with the more
affordable, and in the long run stronger cast acrylic.

-T

[Jack Brennan via C320-list]

So here is what I ended up doing.

Starboard is too flexible and light for my purposes with the sliding hatch. It just didn't feel secure when I stepped on it. I think it would be shot after a couple of seasons. (I have a large bimini, and working the main requires me to step on the hatch.)

I thought once again about plexiglass/acrylic, but came to the same conclusion. I read that half-inch acrylic can handle 40 pounds a square foot, which is way less than me stepping on it. I concluded my weight is what caused the crack.

Lexan is out of the picture due to cost, and also because it's not great with UV tolerance. I didn't want to be buying a new hatch every couple of years.

I ended up going to a great little lumber yard near my house. They sold me a nice-looking, custom-cut piece of half-inch marine plywood. I tested it on the boat today, and it was rock solid.

I sanded it later on, and the third coat of West epoxy is going on in a while. The plywood sucked the resin right up. Tomorrow, I'll wipe it with acetone, sand again and apply a couple of coats of white marine paint, then install it on the boat after it hardens for a day.

This will reduce the temperature in the cabin because I won't have light shining in all day, which is a big problem in Florida.

A smaller problem is that I need a way to keep the hatch from sliding all of the way out. Catalina or someone attached a small piece of wood to the rear of the original hatch, then sealed the hood with 4200 or something similar, making it unremoveable.

I'm thinking of an L-shaped bracket that I can flip downward so it catches the lip of the hood. It would be screwed to the bottom of the sliding hatch. That makes it easily removeable if I need to remove the hatch for some reason.

[Joe Grande via C320-list]

I am confused! I thought this thread was about the sliding hatch through which we enter the boat. If it's all about the opening hatch over the salon, it's a Lewmar 44. Yes, our primary winches are labeled Lewmar 44s. Just order the correct one. Years ago I torqued mine by tacking with the hatch open and the mainstream snagged it. I removed it and bedded its replacement from Catalina.

Joe Grande
Whisper, #772, 2000
Seattle

Sent from my T-Mobile 5G Device
Get Outlook for Android<https://aka.ms/AAb9ysg>
________________________________
From: C320-list <c320-lis...@lists.catalina320.com> on behalf of Jack Brennan via C320-list <c320...@lists.catalina320.com>
Sent: Monday, October 28, 2024 2:28:28 PM
To: C320...@Catalina320.com <C320...@Catalina320.com>
Cc: Jack Brennan <jackbre...@outlook.com>
Subject: Re: [C320-list] Companion way hatch-is NOT acrylic

[Dave Hupe via C320-list]

Jack-
The marine plywood finished white as you describe sounds good (look, functionality and cost). I don't  understand your L- bracket concept to keep the new hatch from sliding out though. 
I suggest keep the sliding surfaces lubricated somehow to prevent deterioration of the finished hatch. 
Please keep us posted about the result.
Dave Hupe 
1994 C320 #32
Holland MI 

Yahoo Mail: Search, Organize, Conquer

On Mon, Oct 28, 2024 at 11:31 PM, Jack Brennan via C320-list<c320...@lists.catalina320.com> wrote: So here is what I ended up doing.

[bruceheyman via C320-list]

Hi Jack,On the sliding surfaces of our companion way I used Nylo-Tape Friction-Free Drawer Slide Tape.  It really made it much easier to slide open and close.  In your case I think it would do good to protect the finish you've applied to the plywood.Very best,
Brucehttps://www.rockler.com/nylo-tape-friction-free-drawer-slide-tape?country=US&promo=shopping&utm_source=google&utm_medium=cpc&utm_term=&utm_content=pla_with_promotion&utm_campaign=PL&utm_campaign=18291976996&utm_source=google&utm_medium=cpc&utm_term=18291976996||&utm_content=&gad_source=1&gclid=Cj0KCQjwj4K5BhDYARIsAD1Ly2o9Igz5543W3nq8AIV1J7_N4G0tTsM1MHuY9ykEz_GUAzYtb1oEyL8aAgE4EALw_wcB

[Richard Walker via C320-list]

Yes, that works very well. When I went to buy it about 10 years ago you had to buy a long piece of it. I’m quite sure that was the original equipment on the earlier boats
Dick Walker

> On Oct 29, 2024, at 10:49, bruceheyman via C320-list <c320...@lists.catalina320.com> wrote:
>
>  Hi Jack,On the sliding surfaces of our companion way I used Nylo-Tape Friction-Free Drawer Slide Tape. It really made it much easier to slide open and close. In your case I think it would do good to protect the finish you've applied to the plywood.Very best,

[Jack Brennan via C320-list]

Hi Bruce:

That's a great idea. I'd never heard of it. I'm ordering some now.

Jack Brennan
Sonas, 1998 Catalina 320
Tierra Verde, Fl.

________________________________
From: C320-list <c320-lis...@lists.catalina320.com> on behalf of bruceheyman via C320-list <c320...@lists.catalina320.com>
Sent: Tuesday, October 29, 2024 1:44 PM
To: c320...@catalina320.com <c320...@catalina320.com>
Cc: bruceheyman <bruce...@cox.net>
Subject: Re: [C320-list] Companion way hatch-is NOT acrylic

[Dennis Cookson via C320-list]

I had a marine engineer booked to replace my cutlass bearing today but things didn’t go exactly to plan. After removing the propeller he fitted a Strut-Pro tool to push out the old bearing but immediately found that the leading surface of the P-bracket/prop strut sleeve around the bearing started to flake away revealing a bright pink rough area. This is apparently bronze that has become dezincified, whereby the zinc content of the bronze has been leached away by either chloride corrosion or galvanic corrosion. Either way, it is irreversible, and the engineer informed me that the P bracket would need to be replaced as it would be weak and prone to further damage.

I’m wondering if any other 320 owner has encountered this, or has knowledge of why it might occur. I replace my sacrificial zinc anode annually, which is bolted to the hull, and grounded. I haven’t yet determined whether the P-bracket is connected in the same way. We’re rarely connected to shore power as the boat is kept on a swinging mooring during summer months and lies on the hard over winter.

Is your P-bracket bonded to your electrical system? Or do you have a zinc anode fitted directly to the bracket, as suggested by Catalina Direct <https://www.catalinadirect.com/shop-by-boat/capri-26/engine/props-etc/prop-strut-zinc/>?

Dennis Cookson
‘Catalina’ #0577

[bruceheyman via C320-list]

HI Dennis,Probably at least 10 years ago we saw signs of galvanic corrosion on the strut.  At the time it did not have a zinc and it was not bonded (that I could find) to the vessel ground.  We did add a smallish disk zinc at that time to the strut.  The monthly diver added it to the inspect/replace as needed list.   
At our last dry dock we found that the strut had cracked along the surface where it comes out of the hull.   We found the original company that cast them for Catalina but they were going to take 8 weeks to get the part to us as they had zero in stock.  I choose to let the yard machine a new one out of G10.   Problem solved as we will never have to worry about galvanic corrosion again....at least for that part.BruceSomerset Los Angeles

[Dennis Cookson via C320-list]

Bruce, thanks for your reply. Never heard of a strut made from fibreglass, very interesting. I don’t know anyone here in the UK that could do that but I have time to find a bronze replacement. CatalinaDirect have it but the price is quite high even before import duty, VAT, shipping etc. Can you remember the name of the original supplier that cast them?

Dennis Cookson
‘Catalina’ #0577

[Jack Brennan via C320-list]

Final report:

The sliding hatch made of marine plywood is great. It's everything I wanted to accomplish with the project.

For anyone who might contemplate this project: Make sure you buy finish-quality plywood to eliminate the need to fill in small nicks and such. It makes the job much easier.

After light sanding, I applied three coats of West System epoxy, waiting until each coat was tacky before applying the next. I let it cure until the next day, then used acetone to remove the blush from the epoxy before sanding lightly again.

For paint, I rolled on Rustoleum marine topcoat white, which in my opinion is the best of the one-part paints. It's important when applying the paint on epoxy to wait 24 hours between each coat to allow it to harden properly. Two coats are enough. If you can, let it harden for another day or so.

For a stopper to keep the hatch from sliding fully out, I bought a four-inch SS mending bracket. I inserted a one-inch bolt into the last hole with a small nylon spacer secured by a nut. (The space under the hood is shallow.) I then slid the hatch in until I could use two screws to attach the bracket to the underside of the hatch.

As I said before, the big benefit for me is that the sliding hatch no longer lets in heat and light in the cabin. It also fits in with the look of the rest of the boat, which is important. Not to mention that I can stand on it without worrying about cracking it.

[Diane Fowler via C320-list]

Hi, Jack, glad you are well. Can you show us a photo of finished product??
Captain Diane Fowler, CRS, GRI, e-PRO
Illinois real estate Broker.

Let me help make your sale a breeze.

239-850-4935
Sent from my iPhone

> On Nov 3, 2024, at 9:30 PM, Jack Brennan via C320-list <c320...@lists.catalina320.com> wrote:
>
> Final report:

[Jack Brennan via C320-list]

Hi Diane:

I'm going to the boat today. I'll take a photo and send it to you.

Jack Brennan




Sent via the Samsung Galaxy A32 5G, an AT&T 5G smartphone

-------- Original message --------
From: Diane Fowler via C320-list <c320...@lists.catalina320.com>
Date: 11/4/24 7:05 AM (GMT-05:00)
To: C320...@catalina320.com
Cc: Diane Fowler <dian...@aol.com>
Subject: Re: [C320-list] Companion way hatch-is NOT acrylic

[Dennis Cookson via C320-list]

Wondering if any 320 owners have replaced their prop strut/P-Bracket with the part advertised on Catalina Direct <https://www.catalinadirect.com/shop-by-boat/catalina-38/engine/props-etc/prop-strut-c-310-c-320c-34-c-36-c-38/>? If so, how accurate was the replacement to the original design and did you have any problem aligning it when bolting it in place? Here in the UK I can find a foundry who could copy the old part, but given that cast bronze will shrink after cooling I’m concerned it might not align with the stern tube etc without some adjustment to the fixings. Grateful for any experience in this area.

Dennis Cookson
‘Catalina’ £0577

[Chris White via C320-list]

Dennis
I would buy the new P bracket from Catalina Direct.I am also in the UK and recently ordered replacement aluminium rub rail from them.It was well packed and arrived in just over a week.Also, you know it will be the right size and be a direct replacement.My P bracket is wired inside to the engine, and I have fitted a round zinc anode each side with a through bolt, bought locally.
Chris WhiteDandy #449PooleUK

[Dave Hupe via C320-list]

Mine doesn't have a strut anode either. Don't see a reason to add based on conditions I see hauling each year.  I just use a magnesium shaft anode for our freshwater location. I replace it each year and see a lot of erosion/activity on each anode without any problems derected elsewhere. So, this seems to work perfectly for us. 

Dave Hupe 
1994 C320 #32
Holland MI 

Yahoo Mail: Search, Organize, Conquer

On Tue, Nov 5, 2024 at 7:53 AM, Steven Morgan via C320-list<c320...@lists.catalina320.com> wrote: Hello ,
My 320 doesn’t have a prop strut zinc. Looks like it never did.  Is this something I should be adding?? And if so, is it just a matter of drilling the hole for the bolt and attaching it ?

Thanks
Steve Morgan
1995 #221
Salt Shaker



> On Nov 5, 2024, at 5:45 AM, Dennis Cookson via C320-list <c320...@lists.catalina320.com> wrote:
>a
> Chris, many thanks for your advice. After talking to a foundry I've pretty much reached the same conclusion. It sounds like your bracket is well protected but ours was never bonded to the other metals in the boat as far as I can see and I wasn't aware of the dezincification risk.
>
> By the way I'm also in Poole and like you have bought replacement rub rail and vinyl from CD in the past! There's always something that needs repair/replacement....
>
> Dennis Cookson
> 'Catalina' #0577
>
>> On 5 Nov 2024, at 07:59, Chris White via C320-list <c320...@lists.catalina320.com> wrote:
>>
>>  Dennis

[Dennis Cookson via C320-list]

Chris, many thanks for your advice. After talking to a foundry I've pretty much reached the same conclusion. It sounds like your bracket is well protected but ours was never bonded to the other metals in the boat as far as I can see and I wasn't aware of the dezincification risk.

By the way I'm also in Poole and like you have bought replacement rub rail and vinyl from CD in the past! There's always something that needs repair/replacement....

Dennis Cookson
'Catalina' #0577

> On 5 Nov 2024, at 07:59, Chris White via C320-list <c320...@lists.catalina320.com> wrote:
>

>  Dennis

[Steven Morgan via C320-list]

Hello ,
My 320 doesn’t have a prop strut zinc. Looks like it never did. Is this something I should be adding?? And if so, is it just a matter of drilling the hole for the bolt and attaching it ?

Thanks
Steve Morgan
1995 #221
Salt Shaker

> On Nov 5, 2024, at 5:45 AM, Dennis Cookson via C320-list <c320...@lists.catalina320.com> wrote:
>
> Chris, many thanks for your advice. After talking to a foundry I've pretty much reached the same conclusion. It sounds like your bracket is well protected but ours was never bonded to the other metals in the boat as far as I can see and I wasn't aware of the dezincification risk.

[Dennis Cookson via C320-list]

I should add that I’m no expert in galvanic corrosion and the right approach to protection likely depends on the material that your P-Bracket is made from. I understand that Manganese Bronze is more prone to corrosion than say Nickel-Aluminium-Bronze, which is highly corrosion resistant and probably needs no protection.

Dennis Cookson
‘Catalina’ #0577


Hi folks,

The only reason this damage came to light is because I recently decided to replace our cutlass bearing, which is exhibiting some play in the rudder shaft, though nothing extreme. Because the strut is painted with antifoul, you wouldn’t normally notice any deterioration and it only became apparent when trying to push out the old bearing using a Strut-Pro tool and a chip of what used to be bronze fell off. So unless you scrape off some of the antifoul to see the colour of the bare metal underneath, you really won’t know whether any dezincification is taking place. If it has turned to a bright pink, it’s gone.

Having now experienced this I would certainly recommend either an anode on the strut itself, or a connection between it and the rest of the ‘ground’ circuit. I’m not sure which is preferable but if an anode is attached directly, it must have a good connection with the brass surface of the strut and the anode must not be painted.

Dennis Cookson
‘Catalina’ #0577

[Dennis Cookson via C320-list]

Hi folks,

The only reason this damage came to light is because I recently decided to replace our cutlass bearing, which is exhibiting some play in the rudder shaft, though nothing extreme. Because the strut is painted with antifoul, you wouldn’t normally notice any deterioration and it only became apparent when trying to push out the old bearing using a Strut-Pro tool and a chip of what used to be bronze fell off. So unless you scrape off some of the antifoul to see the colour of the bare metal underneath, you really won’t know whether any dezincification is taking place. If it has turned to a bright pink, it’s gone.

Having now experienced this I would certainly recommend either an anode on the strut itself, or a connection between it and the rest of the ‘ground’ circuit. I’m not sure which is preferable but if an anode is attached directly, it must have a good connection with the brass surface of the strut and the anode must not be painted.

Dennis Cookson
‘Catalina’ #0577

> On 5 Nov 2024, at 13:03, Dave Hupe via C320-list <c320...@lists.catalina320.com> wrote:
>