Mycell 80 and Corelite 450 for TX18 build

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Vundu
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Mycell 80 and Corelite 450 for TX18 build

Post by Vundu »

I have started a new thread with more technical info as advised by Jaques. Thanks very much for the advice in the last thread, I really do appreciate it.

Brief history;
I'm building my second TX18, but increasing the dimensions by 10% all round. Also lifting the gunnels by 10cm. I will not be increasing the depth (height) of the ribs and stringers. She'll be be powered by a motor weighing 180kg +-. I would like to carry approximately 70 litres of fuel and possibly a livewell also 70 Litres.

I would like to keep the hull core BS1088 6mm ply and convert the Transom, stringers, ribs and sole / front deck to Foam core.

I have access to:
Mycell 80 in 10, 15 and 20mm thickness (data sheet below) which I was hoping to use for the stringers, ribs sole and deck.
Corelite 450 in 16mm thickness (data sheet for the transom. I don't have access to Gurit products or Coosa, and my supplier has no data on the Gurit cores or coosa to be able to assist with comparisons.

I do plan to add an additional set of ribs, which should bring the spacing to slightly less than that designed, to aid sole support and the hulls larger dimensions.

Based on the data sheets below I would be extremely grateful for help with what to use and where, and a proposed laminating schedule. Thanks in advance.
MYCELL_M080_Scheda.pdf
(183.53 KiB) Downloaded 9 times
CoreLite Board Data Sheet.pdf
(142.57 KiB) Downloaded 8 times



jacquesmm
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Re: Mycell 80 and Corelite 450 for TX18 build

Post by jacquesmm »

Thanks for starting this new thread.
About materials substitutions, I can not do much until early November.
I never heard of those core materials. Your suppliers should be able to give you specs.
It's impossible to guess shear strength from those specs, I will have to search for boat builders opinions.
Does the seller have some references?
Fortunately, you are doing the right thing and using plywood for the skin.

Some of you know that I am retired and like to travel. Right now, I am camping (in a motorhome) on some beach along the Gulf of Mexico. I travel with all my plans in my laptop and can answer most questions about my designs but not much more. Internet is either spotty or inexistent where I camp but I'll try to do some searches.
Jacques Mertens - Designer
http://boatbuildercentral.com

jonnymac
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Re: Mycell 80 and Corelite 450 for TX18 build

Post by jonnymac »

here is a link to some of the same specs for coosa. some names are different, but the same test is listed

https://www.merrittsupply.com/wp-conten ... t-Data.pdf

fallguy1000
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Re: Mycell 80 and Corelite 450 for TX18 build

Post by fallguy1000 »

Corelite 450 is a substitution for coosa. To me, it is not as good as coosa BW, but I used it on my two small transoms for 90hp engine.

Mycell 80 is 1.06 nominal vs Gurit M80 of 1.09 MPa nominal shear. So, they are nearly comparable. I see the Mycell shows stronger compressive strength, and a cursory review shows no deficiencies.

Anyhow, I see no issue with either choice, but I would still prefer coosa.
My boat build is here -------->

viewtopic.php?f=12&t=62495

jacquesmm
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Re: Mycell 80 and Corelite 450 for TX18 build

Post by jacquesmm »

Thanks Fallguy. Since he does not plan to use any of those for the hull skin, it will probably work.
I will look for more details about the use of those for transom foam but the TX18 is not going to suffer from extreme transom stress.
Thanks again.
Jacques Mertens - Designer
http://boatbuildercentral.com

fallguy1000
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Re: Mycell 80 and Corelite 450 for TX18 build

Post by fallguy1000 »

The only comment I will make is the Mycell 80 used as a stringer offers very little structurally. It will really only be operating as a former for a solid glass stringer. For this reason, the only tangible benefit is that it won't rot. But it doesn't do much structurally. I would prefer to see the stringer structure made with a stronger core and less glass and epoxy. The coosa could or even a coosa 20 or the corelite 450 which is more up front core cost, but less glass, less epoxy, and less time to build. On the other hand, if you are building/specifying solid glass stringers, the core/former could be xps as it is not a concern for shear.

He refers to ribs, which I assume are transverse floors or bulkheads. The Mycell 80 will work nicely for that with proper tabbing to the hull and proper skins. Something on the order of db1700 or 1708 each side.

The sole in my boat is made of two different products. One is Gurit M80 12mm with triaxial glass 850g each side. I can't recall if I doubled it on the bottom; probably not. The other is plascore 25mm with one layer of 850g triaxial each side. The plascore is a far stiffer floor which makes sense based on the cube rule. The sole for the sled should be made fairly durable and db1700 is a bit light, so the obvious choice here is also 1708. For wear, the top layer could be laid with the mat out for a little unnotable tradeoff in flex. The bottom should be mat in, or a better layup could be db1200 times two for both or at least the bottom.
My boat build is here -------->

viewtopic.php?f=12&t=62495

Vundu
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Re: Mycell 80 and Corelite 450 for TX18 build

Post by Vundu »

jacquesmm wrote: Wed Oct 20, 2021 6:59 pm Thanks for starting this new thread.
About materials substitutions, I can not do much until early November.
I never heard of those core materials. Your suppliers should be able to give you specs.
It's impossible to guess shear strength from those specs, I will have to search for boat builders opinions.
Does the seller have some references?
Fortunately, you are doing the right thing and using plywood for the skin.

Some of you know that I am retired and like to travel. Right now, I am camping (in a motorhome) on some beach along the Gulf of Mexico. I travel with all my plans in my laptop and can answer most questions about my designs but not much more. Internet is either spotty or inexistent where I camp but I'll try to do some searches.

Hi Jaques, Firstly thanks very much for taking time away from your break to help out, I am very grateful. I can wait till early November for indepth answers. I took a chance and ordered some cores with my ply already, so will likely just have to add as needed. I attach the core materials Data sheets to my first post, at the bottom. Please let me know if they are accessable.
Corelite450
Compressive Strength ASTM D1621 psi 847
Compressive Modulus ASTM D1621-B psi 423
Tensile Strength ASTM C297 psi 481
Shear Strength ASTM C273 psi 445
Shear Modulus ASTM C273 psi 5519
Shear Elongation at Break ISO 1922 % 1.404
Flexural Strength ASTM D790 psi 1799

Mycell 80:
Compressive strength ASTM D1621-10 MPa average min-ave, min-min 1,43; 1,22; 1,03
Compressive modulus ASTM D1621-10 MPa average min-ave, min-min: 68: 53: 44
Tensile strength ASTM D1623 MPa average min-ave, min-min: 2,60: 1,82: 1,63
Tensile modulus ASTM D1623 MPa average min-ave, min-min: 137: 107: 94
Shear strength ASTM C273 MPa average min-ave, min-min: 1,13: 1,06: 0,92
Shear modulus ASTM C273 MPa average min-ave, min-min: 29: 25: 22
Shear elongation at break ASTM C273 % average 20

To give a general response to the other comments.

I am buying out of South Africa and have been unable to find any coosa products.

I wanted to use the Mycell80 in the stringers and ribs to save weight and rot resistance. I would be happy to use the corelite 450, it would be fractionally heavier if at all as they say 27% ligther than plywood.... so may be the same or lighter, but wider (16mm corelite450 vs 2 x 6mm ply + epoxy), which suits me. I can only buy 16mm corelite450.

The sole, front deck and transom I would like in synthetic core, but only the transom is a real must have. I have access to 20, 15 and 10mm Mycell80 and was hoping to use that on the sole and decks.

Once again, thanks to you all for your comments and advice.

Vundu
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Re: Mycell 80 and Corelite 450 for TX18 build

Post by Vundu »

fallguy1000 wrote: Thu Oct 21, 2021 6:04 am The only comment I will make is the Mycell 80 used as a stringer offers very little structurally. It will really only be operating as a former for a solid glass stringer. For this reason, the only tangible benefit is that it won't rot. But it doesn't do much structurally. I would prefer to see the stringer structure made with a stronger core and less glass and epoxy. The coosa could or even a coosa 20 or the corelite 450 which is more up front core cost, but less glass, less epoxy, and less time to build. On the other hand, if you are building/specifying solid glass stringers, the core/former could be xps as it is not a concern for shear.

He refers to ribs, which I assume are transverse floors or bulkheads. The Mycell 80 will work nicely for that with proper tabbing to the hull and proper skins. Something on the order of db1700 or 1708 each side.

The sole in my boat is made of two different products. One is Gurit M80 12mm with triaxial glass 850g each side. I can't recall if I doubled it on the bottom; probably not. The other is plascore 25mm with one layer of 850g triaxial each side. The plascore is a far stiffer floor which makes sense based on the cube rule. The sole for the sled should be made fairly durable and db1700 is a bit light, so the obvious choice here is also 1708. For wear, the top layer could be laid with the mat out for a little unnotable tradeoff in flex. The bottom should be mat in, or a better layup could be db1200 times two for both or at least the bottom.
Hi Fallguy, Thanks for the thoughts. Less glass and no wood, is ideal, so Corelite450 may be the way to go for the stringers, hopefully Jacques will also have some thoughts when he sees the specs. I mention ribs meaning the crossbracing/bulkheads below the sole. From your other post I recall the advice on keeing the supports close together so will be adding an extra set of ribs, or 2, depending on advice.

fallguy1000
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Re: Mycell 80 and Corelite 450 for TX18 build

Post by fallguy1000 »

There is a fallacy present in boat construction these days. And that is the wood stringers are bad.

The reason for this fallacy or falsehood is for the following reasons:

1. Prior wood stringer boats were made with polyesters and not epoxies.

2. Wood stringers in boats where the stringers are holed, like inboards or i/o are more susceptible to failure.

It is important to understand the likelihood of a stringer covered in two layers of 1200 db glass or more and done properly has almost no chance of leaking or failure from rot.

I am planning to build a PH22, and I will be using specified materials, but will go away from wood on the transom and sole because they get penetrations.
My boat build is here -------->

viewtopic.php?f=12&t=62495

Vundu
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Re: Mycell 80 and Corelite 450 for TX18 build

Post by Vundu »

fallguy1000 wrote: Thu Oct 21, 2021 10:42 am There is a fallacy present in boat construction these days. And that is the wood stringers are bad.

The reason for this fallacy or falsehood is for the following reasons:

1. Prior wood stringer boats were made with polyesters and not epoxies.

2. Wood stringers in boats where the stringers are holed, like inboards or i/o are more susceptible to failure.

It is important to understand the likelihood of a stringer covered in two layers of 1200 db glass or more and done properly has almost no chance of leaking or failure from rot.

I am planning to build a PH22, and I will be using specified materials, but will go away from wood on the transom and sole because they get penetrations.
Hi Fallguy,
We trailer on some extremely bad roads. The last TX18 I built I epoxied the sole to the stringers and ribs then added stainless screws to keep everything tight before the final layer of glass. As you said the issue is penetrations, and that is my major concern. In this build I would like to make some storage under the sole so would have hinges and latches adding to the potential ingress points for water.

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